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Special Issue "Phytohormones and Their Crosstalk during Plant Growth, Development and Environmental Stress Adaptation: New Prospects and Challenges to Cope with Global Climate Change"

A special issue of International Journal of Molecular Sciences (ISSN 1422-0067). This special issue belongs to the section "Molecular Plant Sciences".

Deadline for manuscript submissions: closed (31 August 2019).

Special Issue Editors

Dr. Lam-Son Phan Tran
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Guest Editor
Prof. Mohammad Golam Mostofa
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Guest Editor
Department of Biochemistry and Molecular Biology, Bangabandhu Sheikh Mujibur Rahman Agricultural University, Gazipur-1706, Bangladesh
Interests: phytohormones; abiotic stress; stress mitigation; gene regulation; physiology; heavy metal toxicity; antioxidant metabolism; oxidative stress; methylglyoxal; sulphur metabolism; redox balance; nutrient homeostasis
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Special Issue Information

Dear Colleagues,

Phytohormones are major growth regulators, contributing to every aspect of a plant’s life. Plants produce a delicate level of hormones to support their growth and metabolism under normal conditions. Plants are also intermittently exposed to environmental stresses, both biotic and abiotic, which are major constraints to sustainable agriculture. To survive in stress situations, plants have to elicit appropriate adaptive responses, most of which are governed and directed by a number of plant hormones, including auxin, abscisic acid, cytokinins, jasmonic acids, salicylic acid, brassinosteroids and strigolactones. Phytohormones are also known to regulate plant adaptation to environmental stresses by controlling the production of various stress proteins, osmoprotectants, antioxidants, and ion transporters. Plants attain most of these strategies by modulating the cellular level of multiple phytohormones, which then relay the signals into morphological and physiological adaptations, including changes in root and shoot biomass, water transport, stomatal movement, leaf senescence and the rate of grain filling. Moreover, phytohormones coordinate with various signaling molecules like hydrogen peroxide, nitric oxide and hydrogen sulphide to maintain sophisticated networks that finally determine the output of hormonal actions. Although a massive effort has been devoted to understanding the regulatory networks of phytohormones, the underlying mechanisms of phytohormone-mediated plant adaptation to various stresses are still waiting to be deciphered. After the success of the previous Special Issue, we are reopening this issue and inviting potential authors to submit their latest interesting findings on the roles of phytohormones and their crosstalk in various aspects of plant growth and development, as well as stress adaptation. The topics of this Special Issue will include, but are not limited to:

  1. The central roles of phytohormones in plant growth and development, especially under environmental stress conditions.
  2. How plant hormones interact with each other and also with other signaling molecules to orchestrate signal transduction.
  3. How environmental stresses modify biosynthesis and the production of plant hormones.
  4. How interactions between phytohormones and environmental stresses regulate the induction or repression of stress-responsive genes.
  5. Screening for new chemical compounds with inhibitory or stimulating actions on phytohormones/phytohormonal networks.

We welcome research and review articles that will augment our understanding of this fascinating field of phytohormonal research, in order to facilitate the development of plants with greater fitness in these ever-changing environmental conditions.

Dr. Lam-Son Phan Tran
Assoc. Prof. Dr. Mohammad Golam Mostofa
Guest Editors

Manuscript Submission Information

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Keywords

  • plant hormones
  • hormonal crosstalk
  • signal transduction
  • stress signaling
  • root system architecture
  • shoot branching
  • leaf development
  • phytohormone-responsive factors
  • transcriptional regulators
  • gene expression
  • plant physiology
  • senescence
  • plant plasticity
  • regulatory mechanisms
  • hormone homeostasis
  • stress adaptation

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Published Papers (23 papers)

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Open AccessArticle
Interactive Effects of Salicylic Acid and Nitric Oxide in Enhancing Rice Tolerance to Cadmium Stress
Int. J. Mol. Sci. 2019, 20(22), 5798; https://doi.org/10.3390/ijms20225798 - 18 Nov 2019
Abstract
Cadmium (Cd) is one of the prominent environmental hazards, affecting plant productivity and posing human health risks worldwide. Although salicylic acid (SA) and nitric oxide (NO) are known to have stress mitigating roles, little was explored on how they work together against Cd-toxicity [...] Read more.
Cadmium (Cd) is one of the prominent environmental hazards, affecting plant productivity and posing human health risks worldwide. Although salicylic acid (SA) and nitric oxide (NO) are known to have stress mitigating roles, little was explored on how they work together against Cd-toxicity in rice. This study evaluated the individual and combined effects of SA and sodium nitroprusside (SNP), a precursor of NO, on Cd-stress tolerance in rice. Results revealed that Cd at toxic concentrations caused rice biomass reduction, which was linked to enhanced accumulation of Cd in roots and leaves, reduced photosynthetic pigment contents, and decreased leaf water status. Cd also potentiated its phytotoxicity by triggering reactive oxygen species (ROS) generation and depleting several non-enzymatic and enzymatic components in rice leaves. In contrast, SA and/or SNP supplementation with Cd resulted in growth recovery, as evidenced by greater biomass content, improved leaf water content, and protection of photosynthetic pigments. These signaling molecules were particularly effective in restricting Cd uptake and accumulation, with the highest effect being observed in “SA + SNP + Cd” plants. SA and/or SNP alleviated Cd-induced oxidative damage by reducing ROS accumulation and malondialdehyde production through the maintenance of ascorbate and glutathione levels, and redox status, as well as the better activities of antioxidant enzymes superoxide dismutase, catalase, glutathione S-transferase, and monodehydroascorbate reductase. Combined effects of SA and SNP were observed to be more prominent in Cd-stress mitigation than the individual effects of SA followed by that of SNP, suggesting that SA and NO in combination more efficiently boosted physiological and biochemical responses to alleviate Cd-toxicity than either SA or NO alone. This finding signifies a cooperative action of SA and NO in mitigating Cd-induced adverse effects in rice, and perhaps in other crop plants. Full article
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Open AccessArticle
Endophytic Bacteria Potentially Promote Plant Growth by Synthesizing Different Metabolites and their Phenotypic/Physiological Profiles in the Biolog GEN III MicroPlateTM Test
Int. J. Mol. Sci. 2019, 20(21), 5283; https://doi.org/10.3390/ijms20215283 - 24 Oct 2019
Abstract
Endophytic bacteria, as the most promising components of effective, biofertilizers biostimulating and biocontrol preparations, should be very intensively obtained from various plants and studied in terms of the conditions determining the potential ability to promote plant growth. For this reason, endophytic bacteria have [...] Read more.
Endophytic bacteria, as the most promising components of effective, biofertilizers biostimulating and biocontrol preparations, should be very intensively obtained from various plants and studied in terms of the conditions determining the potential ability to promote plant growth. For this reason, endophytic bacteria have been isolated from both stems and roots of up to six systematically distant species of vascular plants: one species belonging to the seedless vascular plants (Monilophyta), and five seed plants (Spermatophyta). The 23 isolated strains represented nine genera: Delftia, Stenotrophomonas, Rhizobium, Brevundimonas, Variovorax, Achromobacter, Novosphingobium, Comamonas and Collimonas, notably which were closely related—belonging to the phylum Proteobacteria. Stenotrophomonas sp. strains showed the greatest ability to synthesize indole-3-acetic acid (IAA)-like compounds, while Achromobacter sp. strains produced the highest levels of siderophores. The presence of the nifH gene and nitrogen binding activity was demonstrated for 95% of the strains tested. Stenotrophomonas maltophila (ES2 strain) showed the highest metabolic activity based on Biolog GEN III test. The ability to solubilize phosphate was determined only for three tested strains from genus: Delftia, Rhizobium and Novosphingobium. The presented work demonstrated that the metabolic and phenotypic properties of plant growth-promoting endophytes are correlated with the genus of bacteria and are not correlated with the host plant species or part of plant (stem, root). Full article
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Open AccessArticle
Phytohormones (Auxin, Gibberellin) and ACC Deaminase In Vitro Synthesized by the Mycoparasitic Trichoderma DEMTkZ3A0 Strain and Changes in the Level of Auxin and Plant Resistance Markers in Wheat Seedlings Inoculated with this Strain Conidia
Int. J. Mol. Sci. 2019, 20(19), 4923; https://doi.org/10.3390/ijms20194923 - 04 Oct 2019
Abstract
Both hormonal balance and plant growth may be shaped by microorganisms synthesizing phytohormones, regulating its synthesis in the plant and inducing plant resistance by releasing elicitors from cell walls (CW) by degrading enzymes (CWDE). It was shown that the Trichoderma DEMTkZ3A0 strain, isolated [...] Read more.
Both hormonal balance and plant growth may be shaped by microorganisms synthesizing phytohormones, regulating its synthesis in the plant and inducing plant resistance by releasing elicitors from cell walls (CW) by degrading enzymes (CWDE). It was shown that the Trichoderma DEMTkZ3A0 strain, isolated from a healthy rye rhizosphere, colonized the rhizoplane of wheat seedlings and root border cells (RBC) and caused approximately 40% increase of stem weight. The strain inhibited (in over 90%) the growth of polyphagous Fusarium spp. (F. culmorum, F. oxysporum, F. graminearum) phytopathogens through a mechanism of mycoparasitism. Chitinolytic and glucanolytic activity, strongly stimulated by CW of F. culmorum in the DEMTkZ3A0 liquid culture, is most likely responsible for the lysis of hyphae and macroconidia of phytopathogenic Fusarium spp. as well as the release of plant resistance elicitors. In DEMTkZ3A0 inoculated plants, an increase in the activity of the six tested plant resistance markers and a decrease in the concentration of indoleacetic acid (IAA) auxin were noted. IAA and gibberellic acid (GA) but also the 1-aminocyclopropane-1-carboxylic acid (ACC) deaminase (ACCD) enzyme regulating ethylene production by plant were synthesized by DEMTkZ3A0 in the liquid culture. IAA synthesis was dependent on tryptophan and negatively correlated with temperature, whereas GA synthesis was positively correlated with the biomass and temperature. Full article
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Open AccessArticle
MYB Gene Family in Potato (Solanum tuberosum L.): Genome-Wide Identification of Hormone-Responsive Reveals Their Potential Functions in Growth and Development
Int. J. Mol. Sci. 2019, 20(19), 4847; https://doi.org/10.3390/ijms20194847 - 29 Sep 2019
Abstract
As an important nongrain crop, the growth and yield of potato (Solanum tuberosum L.) is often affected by an unfavorable external environment in the process of cultivation. The MYB family is one of the largest and most important gene families, participating in [...] Read more.
As an important nongrain crop, the growth and yield of potato (Solanum tuberosum L.) is often affected by an unfavorable external environment in the process of cultivation. The MYB family is one of the largest and most important gene families, participating in the regulation of plant growth and development and response to abiotic stresses. Several MYB genes in potato that regulate anthocyanin synthesis and participate in abiotic stress responses have been identified. To identify all Solanum tuberosum L. MYB (StMYB) genes involved in hormone or stress responses to potentially regulate potato growth and development, we identified the MYB gene family at the genome-wide level. In this work, 158 StMYB genes were found in the potato genome. According to the amino acid sequence of the MYB domain and gene structure, the StMYB genes were divided into R2R3-MYB and R1R2R3-MYB families, and the R2R3-MYB family was divided into 20 subgroups (SGs). The expression of 21 StMYB genes from different SGs in roots, stems, leaves, flowers, shoots, stolons, young tubers, and mature tubers was determined by quantitative real-time polymerase chain reaction (qRT-PCR). The expression patterns of StMYB genes in potatoes treated with abscisic acid (ABA), indole-3-acetic acid (IAA), gibberellin acid 3 (GA3), NaCl, mannitol, and heat were also measured. We have identified several potential candidate genes that regulate the synthesis of potato flavonoids or participate in hormone or stress responses. This work provides a comprehensive understanding of the MYB family in potato and will lay a foundation for the future investigation of the potential functions of StMYB genes in the growth and development of potato. Full article
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Open AccessArticle
Expression and Distribution of the Auxin Response Factors in Sorghum bicolor During Development and Temperature Stress
Int. J. Mol. Sci. 2019, 20(19), 4816; https://doi.org/10.3390/ijms20194816 - 27 Sep 2019
Abstract
Auxin response factor (ARF) is a transcription factor that can specifically bind to the promoter of auxin-responsive genes in plants and plays an important regulatory role in plant growth and development. The previous studies have predicted 25 ARF genes in Sorghum bicolor ( [...] Read more.
Auxin response factor (ARF) is a transcription factor that can specifically bind to the promoter of auxin-responsive genes in plants and plays an important regulatory role in plant growth and development. The previous studies have predicted 25 ARF genes in Sorghum bicolor (SbARFs) and indicated that SbARFs play complex roles in salt and drought stresses. In this study, we reclassified and analyzed the structures of ARFs in three plants, including sorghum, rice, and Arabidopsis. Phylogenetic analyses categorized 73 ARF into five classes. By studying the characterization of the structures, it was found that SbARFs from the same evolutionary branches showed similar motif patterns. Furthermore, the expression patterns of SbARF genes during development and temperature stress were investigated in sorghum. Quantitative transcription-quantitative polymerase chain reaction (qRT-PCR) results suggested that they had different expression patterns in vegetative and reproductive organs at various developmental stages. High and low-temperature treatments and qRT-PCR demonstrated some of them changed dramatically along with the increase of treatment time. Additionally, in situ hybridization results displayed that SbARF genes were accumulated in vascular tissues under temperature stress. These findings provide evidence that SbARFs may play important roles in sorghum vegetative development, reproductive development, and auxin response to temperature stress. Full article
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Open AccessArticle
Genome-Wide Analysis and Identification of the Aux/IAA Gene Family in Peach
Int. J. Mol. Sci. 2019, 20(19), 4703; https://doi.org/10.3390/ijms20194703 - 23 Sep 2019
Abstract
The Auxin/indole-3-acetic acid (Aux/IAA) repressor genes down-regulate the auxin response pathway during many stages of plant and fruit development. In order to determine if and how Aux/IAAs participate in governing texture and hardness in stone fruit maturation, we identified 23 Aux/IAA [...] Read more.
The Auxin/indole-3-acetic acid (Aux/IAA) repressor genes down-regulate the auxin response pathway during many stages of plant and fruit development. In order to determine if and how Aux/IAAs participate in governing texture and hardness in stone fruit maturation, we identified 23 Aux/IAA genes in peach, confirmed by the presence of four conserved domains. In this work, we used fluorescence microscopy with PpIAA-GFP fusion reporters to observe their nuclear localization. We then conducted PCR-based differential expression analysis in “melting” and “stony hard” varieties of peach, and found that in the “melting” variety, nine PpIAAs exhibited peak expression in the S4-3 stage of fruit maturation, with PpIAA33 showing the highest (>120-fold) induction. The expression of six PpIAAs peaked in the S4-2 stage, with PpIAA14 expressed the most highly. Only PpIAA15/16 showed higher expression in the “stony hard” variety than in the “melting” variety, both peaking in the S3 stage. In contrast, PpIAA32 had the highest relative expression in buds, flowers, young and mature leaves, and roots. Our study provides insights into the expression patterns of Aux/IAA developmental regulators in response to auxin during fruit maturation, thus providing insight into their potential development as useful markers for quantitative traits associated with fruit phenotype. Full article
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Open AccessArticle
Molecular and Hormonal Aspects of Drought-Triggered Flower Shedding in Yellow Lupine
Int. J. Mol. Sci. 2019, 20(15), 3731; https://doi.org/10.3390/ijms20153731 - 31 Jul 2019
Cited by 1
Abstract
The drought is a crucial environmental factor that determines yielding of many crop species, e.g., Fabaceae, which are a source of valuable proteins for food and feed. Herein, we focused on the events accompanying drought-induced activation of flower abscission zone (AZ)—the structure [...] Read more.
The drought is a crucial environmental factor that determines yielding of many crop species, e.g., Fabaceae, which are a source of valuable proteins for food and feed. Herein, we focused on the events accompanying drought-induced activation of flower abscission zone (AZ)—the structure responsible for flower detachment and, consequently, determining seed production in Lupinus luteus. Therefore, detection of molecular markers regulating this process is an excellent tool in the development of improved drought-resistant cultivars to minimize yield loss. We applied physiological, molecular, biochemical, immunocytochemical, and chromatography methods for a comprehensive examination of changes evoked by drought in the AZ cells. This factor led to significant cellular changes and activated AZ, which consequently increased the flower abortion rate. Simultaneously, drought caused an accumulation of mRNA of genes inflorescence deficient in abscission-like (LlIDL), receptor-like protein kinase HSL (LlHSL), and mitogen-activated protein kinase6 (LlMPK6), encoding succeeding elements of AZ activation pathway. The content of hydrogen peroxide (H2O2), catalase activity, and localization significantly changed which confirmed the appearance of stressful conditions and indicated modifications in the redox balance. Loss of water enhanced transcriptional activity of the abscisic acid (ABA) and ethylene (ET) biosynthesis pathways, which was manifested by elevated expression of zeaxanthin epoxidase (LlZEP), aminocyclopropane-1-carboxylic acid synthase (LlACS), and aminocyclopropane-1-carboxylic acid oxidase (LlACO) genes. Accordingly, both ABA and ET precursors were highly abundant in AZ cells. Our study provides information about several new potential markers of early response on water loss, which can help to elucidate the mechanisms that control plant response to drought, and gives a useful basis for breeders and agronomists to enhance tolerance of crops against the stress. Full article
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Open AccessArticle
Low Overnight Temperature-Induced Gibberellin Accumulation Increases Locule Number in Tomato
Int. J. Mol. Sci. 2019, 20(12), 3042; https://doi.org/10.3390/ijms20123042 - 21 Jun 2019
Abstract
The number of locules in tomato affects fruit size, shape, and the incidence of malformation. Low temperature increases locule number and the incidences of malformation in tomato plants. In this study, three flower bud developmental stages (pre-flower bud differentiation, sepal and petal primordium [...] Read more.
The number of locules in tomato affects fruit size, shape, and the incidence of malformation. Low temperature increases locule number and the incidences of malformation in tomato plants. In this study, three flower bud developmental stages (pre-flower bud differentiation, sepal and petal primordium formation, and carpel primordium formation) under different night temperatures (10, 15, and 20 °C) were used to analyze the reason behind locule number change using an RNA sequencing (RNA-seq) approach, Quantitative real-time PCR (qRT-PCR), and ultra-performance liquid chromatography–tandem mass spectrometry (UPLC-MS). The results showed that the “plant hormone signal transduction”, “starch and sucrose metabolism”, and “diterpenoid biosynthesis” categories were remarkably activated during flower bud differentiation. Transcripts of gibberellin (GA)-related genes and endogenous levels of GAs were analyzed, and it was discovered that SlGA2ox genes were significantly downregulated and bioactive GA1 and GA4 accumulated at lower overnight temperature. Exogenous application of bioactive GA1, GA4, and PAC (paclobutrazol) showed that GA1 and GA4 increased the locule number, while PAC decreased the locule number. Taken together, our results suggest that lower overnight temperature reduced the expression of SlGA2ox genes, leading to GA1 and GA4 accumulation, thereby increasing locule number in tomato. Full article
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Open AccessArticle
Transcriptomic Analysis Reveals a Comprehensive Calcium- and Phytohormone-Dominated Signaling Response in Leymus chinensis Self-Incompatibility
Int. J. Mol. Sci. 2019, 20(9), 2356; https://doi.org/10.3390/ijms20092356 - 13 May 2019
Abstract
Sheepgrass (Leymus chinensis (Trin.) Tzvel.) is an economically and ecologically important forage in the grass family. Self-incompatibility (SI) limits its seed production due to the low seed-setting rate after self-pollination. However, investigations into the molecular mechanisms of sheepgrass SI are lacking. Therefore, [...] Read more.
Sheepgrass (Leymus chinensis (Trin.) Tzvel.) is an economically and ecologically important forage in the grass family. Self-incompatibility (SI) limits its seed production due to the low seed-setting rate after self-pollination. However, investigations into the molecular mechanisms of sheepgrass SI are lacking. Therefore, microscopic observation of pollen germination and pollen tube growth, as well as transcriptomic analyses of pistils after self- and cross-pollination, were performed. The results indicated that pollen tube growth was rapidly inhibited from 10 to 30 min after self-pollination and subsequently stopped but preceded normally after cross-pollination. Time course comparative transcriptomics revealed different transcriptome dynamics between self- and cross-pollination. A pool of SI-related signaling genes and pathways was generated, including genes related to calcium (Ca2+) signaling, protein phosphorylation, plant hormone, reactive oxygen species (ROS), nitric oxide (NO), cytoskeleton, and programmed cell death (PCD). A putative SI response molecular model in sheepgrass was presented. The model shows that SI may trigger a comprehensive calcium- and phytohormone-dominated signaling cascade and activate PCD, which may explain the rapid inhibition of self-pollen tube growth as observed by cytological analyses. These results provided new insight into the molecular mechanisms of sheepgrass (grass family) SI. Full article
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Open AccessArticle
Involvement of BIG5 and BIG3 in BRI1 Trafficking Reveals Diverse Functions of BIG-subfamily ARF-GEFs in Plant Growth and Gravitropism
Int. J. Mol. Sci. 2019, 20(9), 2339; https://doi.org/10.3390/ijms20092339 - 11 May 2019
Cited by 1
Abstract
ADP-ribosylation factor-guanine nucleotide exchange factors (ARF-GEFs) act as key regulators of vesicle trafficking in all eukaryotes. In Arabidopsis, there are eight ARF-GEFs, including three members of the GBF1 subfamily and five members of the BIG subfamily. These ARF-GEFs have different subcellular localizations and [...] Read more.
ADP-ribosylation factor-guanine nucleotide exchange factors (ARF-GEFs) act as key regulators of vesicle trafficking in all eukaryotes. In Arabidopsis, there are eight ARF-GEFs, including three members of the GBF1 subfamily and five members of the BIG subfamily. These ARF-GEFs have different subcellular localizations and regulate different trafficking pathways. Until now, the roles of these BIG-subfamily ARF-GEFs have not been fully revealed. Here, analysis of the BIGs expression patterns showed that BIG3 and BIG5 have similar expression patterns. big5-1 displayed a dwarf growth and big3-1 big5-1 double mutant showed more severe defects, indicating functional redundancy between BIG3 and BIG5. Moreover, both big5-1 and big3-1 big5-1 exhibited a reduced sensitivity to Brassinosteroid (BR) treatment. Brefeldin A (BFA)-induced BR receptor Brassinosteroid insensitive 1 (BRI1) aggregation was reduced in big5-1 mutant, indicating that the action of BIG5 is required for BRI1 recycling. Furthermore, BR-induced dephosphorylation of transcription factor BZR1 was decreased in big3-1 big5-1 double mutants. The introduction of the gain-of-function of BZR1 mutant BZR1-1D in big3-1 big5-1 mutants can partially rescue the big3-1 big5-1 growth defects. Our findings revealed that BIG5 functions redundantly with BIG3 in plant growth and gravitropism, and BIG5 participates in BR signal transduction pathway through regulating BRI1 trafficking. Full article
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Open AccessCommunication
AHK3-Mediated Cytokinin Signaling Is Required for the Delayed Leaf Senescence Induced by SSPP
Int. J. Mol. Sci. 2019, 20(8), 2043; https://doi.org/10.3390/ijms20082043 - 25 Apr 2019
Abstract
Leaf senescence is a highly-programmed developmental process regulated by an array of multiple signaling pathways. Our group previously reported that overexpression of the protein phosphatase-encoding gene SSPP led to delayed leaf senescence and significantly enhanced cytokinin responses. However, it is still unclear how [...] Read more.
Leaf senescence is a highly-programmed developmental process regulated by an array of multiple signaling pathways. Our group previously reported that overexpression of the protein phosphatase-encoding gene SSPP led to delayed leaf senescence and significantly enhanced cytokinin responses. However, it is still unclear how the delayed leaf senescence phenotype is associated with the enhanced cytokinin responses. In this study, we introduced a cytokinin receptor AHK3 knockout into the 35S:SSPP background. The phenotypic analysis of double mutant revealed that AHK3 loss-of-function reversed the delayed leaf senescence induced by SSPP. Moreover, we found the hypersensitivity of 35S:SSPP to exogenous cytokinin treatment disappeared due to the introduction of AHK3 knockout. Collectively, our results demonstrated that AHK3-mediated cytokinin signaling is required for the delayed leaf senescence caused by SSPP overexpression and the detailed mechanism remains to be further elucidated. Full article
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Open AccessArticle
Strigolactones Promote Leaf Elongation in Tall Fescue through Upregulation of Cell Cycle Genes and Downregulation of Auxin Transport Genes in Tall Fescue under Different Temperature Regimes
Int. J. Mol. Sci. 2019, 20(8), 1836; https://doi.org/10.3390/ijms20081836 - 13 Apr 2019
Abstract
Strigolactones (SLs) have recently been shown to play roles in modulating plant architecture and improving plant tolerance to multiple stresses, but the underlying mechanisms for SLs regulating leaf elongation and the influence by air temperature are still unknown. This study aimed to investigate [...] Read more.
Strigolactones (SLs) have recently been shown to play roles in modulating plant architecture and improving plant tolerance to multiple stresses, but the underlying mechanisms for SLs regulating leaf elongation and the influence by air temperature are still unknown. This study aimed to investigate the effects of SLs on leaf elongation in tall fescue (Festuca arundinacea, cv. ‘Kentucky-31’) under different temperature regimes, and to determine the interactions of SLs and auxin in the regulation of leaf growth. Tall fescue plants were treated with GR24 (synthetic analog of SLs), naphthaleneacetic acid (NAA, synthetic analog), or N-1-naphthylphthalamic acid (NPA, auxin transport inhibitor) (individually and combined) under normal temperature (22/18 °C) and high-temperature conditions (35/30 °C) in controlled-environment growth chambers. Exogenous application of GR24 stimulated leaf elongation and mitigated the heat inhibition of leaf growth in tall fescue. GR24-induced leaf elongation was associated with an increase in cell numbers, upregulated expression of cell-cycle-related genes, and downregulated expression of auxin transport-related genes in elongating leaves. The results suggest that SLs enhance leaf elongation by stimulating cell division and interference with auxin transport in tall fescue. Full article
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Open AccessArticle
Effects of Naphthazarin (DHNQ) Combined with Lawsone (NQ-2-OH) or 1,4-Naphthoquinone (NQ) on the Auxin-Induced Growth of Zea mays L. Coleoptile Segments
Int. J. Mol. Sci. 2019, 20(7), 1788; https://doi.org/10.3390/ijms20071788 - 11 Apr 2019
Abstract
Naphthoquinones, plants secondary metabolites are known for their antibacterial, antifungal, anti-inflammatory, anti-cancer and anti-parasitic properties. The biological activity of naphthoquinones is connected with their ability to generate reactive oxygen species and to modify biological molecules at their nucleophilic sites. In our research, the [...] Read more.
Naphthoquinones, plants secondary metabolites are known for their antibacterial, antifungal, anti-inflammatory, anti-cancer and anti-parasitic properties. The biological activity of naphthoquinones is connected with their ability to generate reactive oxygen species and to modify biological molecules at their nucleophilic sites. In our research, the effect of naphthazarin (DHNQ) combined with 2-hydroxy-1,4-naphthoquinone (NQ-2-OH) or 1,4-naphthoquinone (1,4-NQ) on the elongation growth, pH changes of the incubation medium, oxidative stress and redox activity of maize coleoptile cells were investigated. This paper describes experiments performed with maize (Zea mays L.) coleoptile segments, which is a classical model system to study plant cell elongation growth. The data presented clearly demonstrate that lawsone and 1,4-naphthoquinone combined with naphthazarin, at low concentrations (1 and 10 nM), reduced the endogenous and IAA-induced (Indole-3-Acetic Acid) elongation growth of maize coleoptile segments. Those changes in growth correlated with the proton concentration in the incubation medium, which suggests that the changes in the growth of maize coleoptile segments observed in the presence of naphthoquinones are mediated through the activity of PM H+-ATPase. The presence of naphthoquinones induced oxidative stress in the maize coleoptile tissue by producing hydrogen peroxide and causing changes in the redox activity. Moreover, the incubation of maize segments with both naphthoquinones combined with naphthazarin resulted in lipid peroxidation and membrane damage. The regulation of PM H+-ATPase activity, especially its inhibition, may result from two major types of reaction: first, a direct interaction between an enzyme and naphthoquinone, which leads to the covalent modification of the protein thiols and the generation of thioethers, which have been found to alter the activity of the PM H+-ATPases; second, naphthoquinones induce reactive oxygen species (ROS) production, which inhibits PM H+-ATPases by increasing cytosolic Ca2+. This harmful effect was stronger when naphthazarin and 1,4-naphthoquinone were added together. Taking these results into account, it can be suggested that by combining naphthoquinones in small quantities, an alternative to synthetic pesticides could be developed. Full article
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Open AccessArticle
Identification and Expression Profiling of the Regulator of Chromosome Condensation 1 (RCC1) Gene Family in Gossypium Hirsutum L. under Abiotic Stress and Hormone Treatments
Int. J. Mol. Sci. 2019, 20(7), 1727; https://doi.org/10.3390/ijms20071727 - 08 Apr 2019
Cited by 1
Abstract
The regulator of chromosome condensation 1 (RCC1) is the nucleotide exchange factor for a GTPase called the Ras-related nuclear protein, and it is important for nucleo-plasmic transport, mitosis, nuclear membrane assembly, and control of chromatin agglutination during the S phase of mitosis in [...] Read more.
The regulator of chromosome condensation 1 (RCC1) is the nucleotide exchange factor for a GTPase called the Ras-related nuclear protein, and it is important for nucleo-plasmic transport, mitosis, nuclear membrane assembly, and control of chromatin agglutination during the S phase of mitosis in animals. In plants, RCC1 molecules act mainly as regulating factors for a series of downstream genes during biological processes such as the ultraviolet-B radiation (UV-B) response and cold tolerance. In this study, 56 genes were identified in upland cotton by searching the associated reference genomes. The genes were found to be unevenly distributed on 26 chromosomes, except A06, A12, D03, and D12. Phylogenetic analysis by maximum-likelihood revealed that the genes were divided into five subgroups. The RCC1 genes within the same group shared similar exon/intron patterns and conserved motifs in their encoded proteins. Most genes of the RCC1 family are expressed differently under various hormone treatments and are negatively controlled by salt stress. Gh_A05G3028 and Gh_D10G2310, which encode two proteins located in the nucleus, were strongly induced under salt treatment, while mutants of their homoeologous gene (UVR8) in Arabidopsis and VIGS (virus induced gene silencing) lines of the two genes above in G. hirsutum exhibited a salt-sensitive phenotype indicating their potential role in salt resistance in cotton. These results provide valuable reference data for further study of RCC1 genes in cotton. Full article
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Open AccessArticle
Effects of High Temperature on Embryological Development and Hormone Profile in Flowers and Leaves of Common Buckwheat (Fagopyrum esculentum Moench)
Int. J. Mol. Sci. 2019, 20(7), 1705; https://doi.org/10.3390/ijms20071705 - 05 Apr 2019
Cited by 1
Abstract
Common buckwheat is a valuable crop, mainly due to the beneficial chemical composition of its seeds. However, buckwheat cultivation is limited because of unstable seed yield. The most important reasons for the low yield include embryo and flower abortion. The aim of this [...] Read more.
Common buckwheat is a valuable crop, mainly due to the beneficial chemical composition of its seeds. However, buckwheat cultivation is limited because of unstable seed yield. The most important reasons for the low yield include embryo and flower abortion. The aim of this work is to verify whether high temperature affects embryological development in this plant species. The experiment was conducted on plants of a Polish cultivar ‘Panda’ and strain PA15, in which the percentage of degenerating embryo sacs was previously determined and amounted to 32% and 10%, respectively. The plants were cultivated in phytotronic conditions at 20 °C (control), and 30 °C (thermal stress). The embryological processes and hormonal profiles in flowers at various developmental stages (buds, open flowers, and wilted flowers) and in donor leaves were analyzed in two-month-old plants. Significant effects of thermal stress on the defective development of female gametophytes and hormone content in flowers and leaves were observed. Ovules were much more sensitive to high temperature than pollen grains in both genotypes. Pollen viability remained unaffected at 30 °C in both genotypes. The effect of temperature on female gametophyte development was visible in cv. Panda but not in PA15 buds. A drastic reduction in the number of properly developed embryo sacs was clear in open flowers at 30 °C in both genotypes. A considerable increase in abscisic acid in open flowers ready for fertilization may serve as a signal inducing flower senescence observed in the next few days. Based on embryological analyses and hormone profiles in flowers, we conclude that cv. ‘Panda’ is more sensitive to thermal stress than strain PA15, mainly due to a much earlier response to thermal stress involving impairment of embryological processes already in the flower buds. Full article
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Open AccessArticle
Assessment of the Efficacy and Mode of Action of Benzo(1,2,3)-Thiadiazole-7-Carbothioic Acid S-Methyl Ester (BTH) and Its Derivatives in Plant Protection Against Viral Disease
Int. J. Mol. Sci. 2019, 20(7), 1598; https://doi.org/10.3390/ijms20071598 - 30 Mar 2019
Abstract
Systemic acquired resistance (SAR) induction is one of the primary defence mechanisms of plants against a broad range of pathogens. It can be induced by infectious agents or by synthetic molecules, such as benzo(1,2,3)-thiadiazole-7-carbothioic acid S-methyl ester (BTH). SAR induction is associated with [...] Read more.
Systemic acquired resistance (SAR) induction is one of the primary defence mechanisms of plants against a broad range of pathogens. It can be induced by infectious agents or by synthetic molecules, such as benzo(1,2,3)-thiadiazole-7-carbothioic acid S-methyl ester (BTH). SAR induction is associated with increases in salicylic acid (SA) accumulation and expression of defence marker genes (e.g., phenylalanine ammonia-lyase (PAL), the pathogenesis-related (PR) protein family, and non-expressor of PR genes (NPR1)). Various types of pathogens and pests induce plant responses by activating signalling pathways associated with SA, jasmonic acid (JA) and ethylene (ET). This work presents an analysis of the influence of BTH and its derivatives as resistance inducers in healthy and virus-infected plants by determining the expression levels of selected resistance markers associated with the SA, JA, and ET pathways. The phytotoxic effects of these compounds and their influence on the course of viral infection were also studied. Based on the results obtained, the best-performing BTH derivatives and their optimal concentration for plant performance were selected, and their mode of action was suggested. It was shown that application of BTH and its derivatives induces increased expression of marker genes of both the SA- and JA-mediated pathways. Full article
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Open AccessArticle
Physiological Diversity of Spitsbergen Soil Microbial Communities Suggests Their Potential as Plant Growth-Promoting Bacteria
Int. J. Mol. Sci. 2019, 20(5), 1207; https://doi.org/10.3390/ijms20051207 - 09 Mar 2019
Cited by 3
Abstract
The objective of the study was to assess the physiological diversity and metabolic activity of the soil bacterial communities inhabiting Spitsbergen soils in search of bacterial abilities facilitating plant growth promotion. In the soil, the total number of culturable microorganisms, the number of [...] Read more.
The objective of the study was to assess the physiological diversity and metabolic activity of the soil bacterial communities inhabiting Spitsbergen soils in search of bacterial abilities facilitating plant growth promotion. In the soil, the total number of culturable microorganisms, the number of their individual physiological groups (including Siderophore Synthesizing; SSB and Phosphate Solubilizing Bacteria; PSB), the dehydrogenase (DH) activity, and the ability to utilize sources of C, N, P (EcoPlate) were analysed. In bacterial isolates, siderophores production, ACC (1-aminocyclopropane-1-carboxylate) deaminase (ACCD) activity, IAA (indole-3-acetic acid) synthesis were examined. The isolates were applied to the seeds of Phaseolus coccineus regarding their germination and root length. The results showed differences between copio- and oligotrophic bacteria. A usually high number of SSB was accompanied by the raised number of PSB. A bigger number of SSB was connected with low values of Fe in the soil. High DH activity was assisted by greater number of copio- and oligotrophic bacteria, raised average well color development value, and N and C contents in the soil. Germination index was more alike relative seed germination than relative root growth. IAA concentration and ACCD activity were conversely related. Synthesis of siderophores was matched with ACCD activity and its high level was combined with elevated germination index. In spite of different localization of soil samples, some isolates proved similar traits of activity. Distinct affiliation of isolates and their various localizations were displayed. Among all isolates tested, some possessed one main trait of activity, but most of them had two or more significant features for potential plant growth stimulation. These isolates could be an important source of useful bacteria. Full article
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Open AccessArticle
Populus euphratica JRL Mediates ABA Response, Ionic and ROS Homeostasis in Arabidopsis under Salt Stress
Int. J. Mol. Sci. 2019, 20(4), 815; https://doi.org/10.3390/ijms20040815 - 14 Feb 2019
Abstract
Sodium chloride (NaCl) induced expression of a jacalin-related mannose-binding lectin (JRL) gene in leaves, roots, and callus cultures of Populus euphratica (salt-resistant poplar). To explore the mechanism of the PeJRL in salinity tolerance, the full length of PeJRL was cloned from [...] Read more.
Sodium chloride (NaCl) induced expression of a jacalin-related mannose-binding lectin (JRL) gene in leaves, roots, and callus cultures of Populus euphratica (salt-resistant poplar). To explore the mechanism of the PeJRL in salinity tolerance, the full length of PeJRL was cloned from P. euphratica and was transformed into Arabidopsis. PeJRL was localized to the cytoplasm in mesophyll cells. Overexpression of PeJRL in Arabidopsis significantly improved the salt tolerance of transgenic plants, in terms of seed germination, root growth, and electrolyte leakage during seedling establishment. Under NaCl stress, transgenic plants retained K+ and limited the accumulation of Na+. PeJRL-transgenic lines increased Na+ extrusion, which was associated with the upward regulation of SOS1, AHA1, and AHA2 genes encoding plasma membrane Na+/proton (H+) antiporter and H+-pumps. The activated H+-ATPases in PeJRL-overexpressed plants restricted the channel-mediated loss of K+ that was activated by NaCl-induced depolarization. Under salt stress, PeJRL–transgenic Arabidopsis maintained reactive oxygen species (ROS) homeostasis by activating the antioxidant enzymes and reducing the production of O2 through downregulation of NADPH oxidases. Of note, the PeJRL-transgenic Arabidopsis repressed abscisic acid (ABA) biosynthesis, thus reducing the ABA-elicited ROS production and the oxidative damage during the period of salt stress. A schematic model was proposed to show the mediation of PeJRL on ABA response, and ionic and ROS homeostasis under NaCl stress. Full article
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Review

Jump to: Research

Open AccessReview
The Roles of Plant Hormones and Their Interactions with Regulatory Genes in Determining Meristem Activity
Int. J. Mol. Sci. 2019, 20(16), 4065; https://doi.org/10.3390/ijms20164065 - 20 Aug 2019
Abstract
Plants, unlike animals, have developed a unique system in which they continue to form organs throughout their entire life cycle, even after embryonic development. This is possible because plants possess a small group of pluripotent stem cells in their meristems. The shoot apical [...] Read more.
Plants, unlike animals, have developed a unique system in which they continue to form organs throughout their entire life cycle, even after embryonic development. This is possible because plants possess a small group of pluripotent stem cells in their meristems. The shoot apical meristem (SAM) plays a key role in forming all of the aerial structures of plants, including floral meristems (FMs). The FMs subsequently give rise to the floral organs containing reproductive structures. Studies in the past few decades have revealed the importance of transcription factors and secreted peptides in meristem activity using the model plant Arabidopsis thaliana. Recent advances in genomic, transcriptomic, imaging, and modeling technologies have allowed us to explore the interplay between transcription factors, secreted peptides, and plant hormones. Two different classes of plant hormones, cytokinins and auxins, and their interaction are particularly important for controlling SAM and FM development. This review focuses on the current issues surrounding the crosstalk between the hormonal and genetic regulatory network during meristem self-renewal and organogenesis. Full article
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Open AccessReview
Autophagy in Plant: A New Orchestrator in the Regulation of the Phytohormones Homeostasis
Int. J. Mol. Sci. 2019, 20(12), 2900; https://doi.org/10.3390/ijms20122900 - 14 Jun 2019
Cited by 2
Abstract
Autophagy is a highly evolutionarily-conserved catabolic process facilitating the development and survival of organisms which have undergone favorable and/or stressful conditions, in particular the plant. Accumulating evidence has implicated that autophagy is involved in growth and development, as well as responses to various [...] Read more.
Autophagy is a highly evolutionarily-conserved catabolic process facilitating the development and survival of organisms which have undergone favorable and/or stressful conditions, in particular the plant. Accumulating evidence has implicated that autophagy is involved in growth and development, as well as responses to various stresses in plant. Similarly, phytohormones also play a pivotal role in the response to various stresses in addition to the plant growth and development. However, the relationship between autophagy and phytohormones still remains poorly understood. Here, we review advances in the crosstalk between them upon various environmental stimuli. We also discuss how autophagy coordinates the phytohormones to regulate plant growth and development. We propose that unraveling the regulatory role(s) of autophagy in modulating the homeostasis of phytohormones would benefit crop breeding and improvement under variable environments, in particular under suboptimal conditions. Full article
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Open AccessReview
Signaling Crosstalk between Salicylic Acid and Ethylene/Jasmonate in Plant Defense: Do We Understand What They Are Whispering?
Int. J. Mol. Sci. 2019, 20(3), 671; https://doi.org/10.3390/ijms20030671 - 04 Feb 2019
Cited by 12
Abstract
During their lifetime, plants encounter numerous biotic and abiotic stresses with diverse modes of attack. Phytohormones, including salicylic acid (SA), ethylene (ET), jasmonate (JA), abscisic acid (ABA), auxin (AUX), brassinosteroid (BR), gibberellic acid (GA), cytokinin (CK) and the recently identified strigolactones (SLs), orchestrate [...] Read more.
During their lifetime, plants encounter numerous biotic and abiotic stresses with diverse modes of attack. Phytohormones, including salicylic acid (SA), ethylene (ET), jasmonate (JA), abscisic acid (ABA), auxin (AUX), brassinosteroid (BR), gibberellic acid (GA), cytokinin (CK) and the recently identified strigolactones (SLs), orchestrate effective defense responses by activating defense gene expression. Genetic analysis of the model plant Arabidopsis thaliana has advanced our understanding of the function of these hormones. The SA- and ET/JA-mediated signaling pathways were thought to be the backbone of plant immune responses against biotic invaders, whereas ABA, auxin, BR, GA, CK and SL were considered to be involved in the plant immune response through modulating the SA-ET/JA signaling pathways. In general, the SA-mediated defense response plays a central role in local and systemic-acquired resistance (SAR) against biotrophic pathogens, such as Pseudomonas syringae, which colonize between the host cells by producing nutrient-absorbing structures while keeping the host alive. The ET/JA-mediated response contributes to the defense against necrotrophic pathogens, such as Botrytis cinerea, which invade and kill hosts to extract their nutrients. Increasing evidence indicates that the SA- and ET/JA-mediated defense response pathways are mutually antagonistic. Full article
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Open AccessReview
Brassinosteroids, the Sixth Class of Phytohormones: A Molecular View from the Discovery to Hormonal Interactions in Plant Development and Stress Adaptation
Int. J. Mol. Sci. 2019, 20(2), 331; https://doi.org/10.3390/ijms20020331 - 15 Jan 2019
Cited by 3
Abstract
Phytohormones are natural chemical messengers that play critical roles in the regulation of plant growth and development as well as responses to biotic and abiotic stress factors, maintaining plant homeostasis, and allowing adaptation to environmental changes. The discovery of a new class of [...] Read more.
Phytohormones are natural chemical messengers that play critical roles in the regulation of plant growth and development as well as responses to biotic and abiotic stress factors, maintaining plant homeostasis, and allowing adaptation to environmental changes. The discovery of a new class of phytohormones, the brassinosteroids (BRs), almost 40 years ago opened a new era for the studies of plant growth and development and introduced new perspectives in the regulation of agronomic traits through their use in agriculture. BRs are a group of hormones with significant growth regulatory activity that act independently and in conjunction with other phytohormones to control different BR-regulated activities. Genetic and molecular research has increased our understanding of how BRs and their cross-talk with other phytohormones control several physiological and developmental processes. The present article provides an overview of BRs’ discovery as well as recent findings on their interactions with other phytohormones at the transcriptional and post-transcriptional levels, in addition to clarifying how their network works to modulate plant growth, development, and responses to biotic and abiotic stresses. Full article
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Open AccessReview
Abiotic Stresses Intervene with ABA Signaling to Induce Destructive Metabolic Pathways Leading to Death: Premature Leaf Senescence in Plants
Int. J. Mol. Sci. 2019, 20(2), 256; https://doi.org/10.3390/ijms20020256 - 10 Jan 2019
Cited by 3
Abstract
Abiotic stresses trigger premature leaf senescence by affecting some endogenous factors, which is an important limitation for plant growth and grain yield. Among these endogenous factors that regulate leaf senescence, abscisic acid (ABA) works as a link between the oxidase damage of cellular [...] Read more.
Abiotic stresses trigger premature leaf senescence by affecting some endogenous factors, which is an important limitation for plant growth and grain yield. Among these endogenous factors that regulate leaf senescence, abscisic acid (ABA) works as a link between the oxidase damage of cellular structure and signal molecules responding to abiotic stress during leaf senescence. Considering the importance of ABA, we collect the latest findings related to ABA biosynthesis, ABA signaling, and its inhibitory effect on chloroplast structure destruction, chlorophyll (Chl) degradation, and photosynthesis reduction. Post-translational changes in leaf senescence end with the exhaustion of nutrients, yellowing of leaves, and death of senescent tissues. In this article, we review the literature on the ABA-inducing leaf senescence mechanism in rice and Arabidopsis starting from ABA synthesis, transport, signaling receptors, and catabolism. We also predict the future outcomes of investigations related to other plants. Before changes in translation occur, ABA signaling that mediates the expression of NYC, bZIP, and WRKY transcription factors (TFs) has been investigated to explain the inducing effect on senescence-associated genes. Various factors related to calcium signaling, reactive oxygen species (ROS) production, and protein degradation are elaborated, and research gaps and potential prospects are presented. Examples of gene mutation conferring the delay or induction of leaf senescence are also described, and they may be helpful in understanding the inhibitory effect of abiotic stresses and effective measures to tolerate, minimize, or resist their inducing effect on leaf senescence. Full article
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