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Physiological and Genetic Mechanisms of Abiotic Stress Tolerance in Crops II

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A special issue of Plants (ISSN 2223-7747). This special issue belongs to the section "Crop Physiology and Crop Production".

Deadline for manuscript submissions: 30 June 2024 | Viewed by 12246

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Special Issue Editors

Dr. Peng Zhang

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Guest Editor

China National Rice Research Institute, Hangzhou, Hangzhou 310006, China
Interests: abiotic stress tolerance; GWAS; rice molecular breeding

Dr. Hanhua Tong

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Guest Editor

China National Rice Research Institute, Hangzhou 310006, China
Interests: crop abiotic stress resistance; crop nutrient utilization; rice breeding

Prof. Dr. Dezhi Wu

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Guest Editor

Agricultural College, Hunan Agricultural University, Changsha, China
Interests: crop biotechnology; genomics; molecular mechanism of crop salt tolerance; ion transporters
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Dear Colleagues,

Abiotic stress caused by either natural or human activities has become a great threat to sustainable agricultural production in the world, with examples being drought, salinity, high or low temperature, nutrient deficiency and heavy metal stresses. It is a significant challenge to produce enough crop food to feed the growing global population. Abiotic stresses seriously affect crop growth and development, eventually leading to yield loss. Under abiotic stress conditions, crops may suffer from osmotic and oxidative stress, photosynthetic and metabolic damage, nutrient imbalance and ion toxicity. To deal with these stresses, crops have developed a series of tolerance mechanism, including osmotic adjustment through compatible solutes in the cytoplasm, reactive oxygen species (ROS) scavenging system through antioxidative enzymes and nutrient homeostasis through membrane channels and transporters. However, progress in developing tolerant crops is significantly hampered by the complexity of the physiological and genetic mechanisms of abiotic stress tolerance.

Dr. Peng Zhang
Dr. Hanhua Tong
Prof. Dr. Dezhi Wu
Guest Editors

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Keywords

abiotic stress
crop physiology
gene mining
genetic regulation
metabolomics
molecular response
proteomics transcriptomics

Related Special Issue

Physiological and Genetic Mechanisms of Abiotic Stress Tolerance in Crops in Plants (13 articles)

Published Papers (14 papers)

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Research

19 pages, 7978 KiB

Open AccessArticle

Transcriptome Analysis for Salt-Responsive Genes in Two Different Alfalfa (Medicago sativa L.) Cultivars and Functional Analysis of MsHPCA1

by Qican Gao, Ruonan Yu, Xuesong Ma, Hada Wuriyanghan and Fang Yan

Plants 2024, 13(8), 1073; https://doi.org/10.3390/plants13081073 - 11 Apr 2024

Viewed by 426

Abstract

Alfalfa (Medicago sativa L.) is an important forage legume and soil salinization seriously affects its growth and yield. In a previous study, we identified a salt-tolerant variety ‘Gongnong NO.1’ and a salt-sensitive variety ‘Sibeide’. To unravel the molecular mechanism involved in salt stress, we conducted transcriptomic analysis on these two cultivars grown under 0 and 250 mM NaCl treatments for 0, 12, and 24 h. Totals of 336, and 548 differentially expressed genes (DEGs) in response to NaCl were, respectively, identified in the ‘Gongnong NO.1’ and ‘Sibeide’ varieties. The Kyoto Encyclopedia of Genes and Genomes (KEGG) and Gene Ontology (GO) pathway enrichment analysis showed that the DEGs were classified in carbohydrate metabolism, energy production, transcription factor, and stress-associated pathway. Expression of MsHPCA1, encoding a putative H₂O₂ receptor, was responsive to both NaCl and H₂O₂ treatment. MsHPCA1 was localized in cell membrane and overexpression of MsHPCA1 in alfalfa increased salt tolerance and H₂O₂ content. This study will provide new gene resources for the improvement in salt tolerance in alfalfa and legume crops, which has important theoretical significance and potential application value. Full article

(This article belongs to the Special Issue Physiological and Genetic Mechanisms of Abiotic Stress Tolerance in Crops II)

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21 pages, 5594 KiB

Open AccessArticle

Carotenoid Accumulation in the Rhododendron chrysanthum Is Mediated by Abscisic Acid Production Driven by UV-B Stress

by Fushuai Gong, Xiangru Zhou, Wang Yu, Hongwei Xu and Xiaofu Zhou

Plants 2024, 13(8), 1062; https://doi.org/10.3390/plants13081062 - 09 Apr 2024

Viewed by 359

Abstract

Rhododendron chrysanthum (R. chrysanthum) development is hampered by UV-B sunlight because it damages the photosynthetic system and encourages the buildup of carotenoids. Nevertheless, it is still unclear how R. chrysanthum repairs the photosynthetic system to encourage the formation of carotenoid pigments. The carotenoid and abscisic acid (ABA) concentrations of the R. chrysanthum were ascertained in this investigation. Following UV-B stress, the level of carotenoids was markedly increased, and there was a strong correlation between carotenoids and ABA. The modifications of R. chrysanthum’s OJIP transient curves were examined in order to verify the regulatory effect of ABA on carotenoid accumulation. It was discovered that external application of ABA lessened the degree of damage on the donor side and lessened the damage caused by UV-B stress on R. chrysanthum. Additionally, integrated metabolomics and transcriptomics were used to examine the changes in differentially expressed genes (DEGs) and differential metabolites (DMs) in R. chrysanthum in order to have a better understanding of the role that ABA plays in carotenoid accumulation. The findings indicated that the majority of DEGs were connected to carotenoid accumulation and ABA signaling sensing. To sum up, we proposed a method for R. chrysanthum carotenoid accumulation. UV-B stress activates ABA production, which then interacts with transcription factors to limit photosynthesis and accumulate carotenoids, such as MYB-enhanced carotenoid biosynthesis. This study showed that R. chrysanthum’s damage from UV-B exposure was lessened by carotenoid accumulation, and it also offered helpful suggestions for raising the carotenoid content of plants. Full article

(This article belongs to the Special Issue Physiological and Genetic Mechanisms of Abiotic Stress Tolerance in Crops II)

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11 pages, 1448 KiB

Open AccessArticle

Screening of Rice (Oryza sativa L.) Genotypes for Salinity Tolerance and Dissecting Determinants of Tolerance Mechanism

by Tianxiao Chen, Yanan Niu, Changdeng Yang, Yan Liang and Jianlong Xu

Plants 2024, 13(7), 1036; https://doi.org/10.3390/plants13071036 - 06 Apr 2024

Viewed by 477

Abstract

Soil salinity imposes osmotic, ionic, and oxidative stresses on plants, resulting in growth inhibition, developmental changes, metabolic adaptations, and ion sequestration or exclusion. Identifying salinity-tolerant resources and understanding physiological and molecular mechanisms of salinity tolerance could lay a foundation for the improvement of salinity tolerance in rice. In this study, a series of salinity-tolerance-related morphological and physiological traits were investigated in 46 rice genotypes, including Sea Rice 86, to reveal the main strategies of rice in responding to salinity stress at the seedling stage. No genotypes showed the same tolerance level as the two landraces Pokkali and Nona Bokra, which remain the donors for improving the salinity tolerance of rice. However, due to undesirable agronomic traits of these donors, alternative cultivars such as JC118S and R1 are recommended as novel source of salinity tolerance. Correlation and principal component analyses revealed that the salinity tolerance of rice seedlings is not only controlled by growth vigor but also regulated by ion transport pathways such as long-distance Na⁺ transport, root Na⁺ sequestration, and root K⁺ retention. Therefore, such key traits should be targeted in future breeding programs as the strategy of obtaining better Na⁺ exclusion is still the bottleneck for improving salinity tolerance in rice. Full article

(This article belongs to the Special Issue Physiological and Genetic Mechanisms of Abiotic Stress Tolerance in Crops II)

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16 pages, 23675 KiB

Open AccessArticle

Comparative Morpho-Physiological, Biochemical, and Gene Expressional Analyses Uncover Mechanisms of Waterlogging Tolerance in Two Soybean Introgression Lines

by Ripa Akter Sharmin, Benjamin Karikari, Mashiur Rahman Bhuiyan, Keke Kong, Zheping Yu, Chunting Zhang and Tuanjie Zhao

Plants 2024, 13(7), 1011; https://doi.org/10.3390/plants13071011 - 02 Apr 2024

Viewed by 983

Abstract

Waterlogging is one of the key abiotic factors that severely impedes the growth and productivity of soybeans on a global scale. To develop soybean cultivars that are tolerant to waterlogging, it is a prerequisite to unravel the mechanisms governing soybean responses to waterlogging. Hence, we explored the morphological, physiological, biochemical, and transcriptional changes in two contrasting soybean introgression lines, A192 (waterlogging tolerant, WT) and A186 (waterlogging sensitive, WS), under waterlogging. In comparison to the WT line, waterlogging drastically decreased the root length (RL), shoot length (ShL), root fresh weight (RFW), shoot fresh weight (ShFW), root dry weight (RDW), and shoot dry weight (ShDW) of the WS line. Similarly, waterlogging inhibited soybean plant growth by suppressing the plant’s photosynthetic capacity, enhancing oxidative damage from reactive oxygen species, and decreasing the chlorophyll content in the WS line but not in the WT line. To counteract the oxidative damage and lipid peroxidation, the WT line exhibited increased activity of antioxidant enzymes such as peroxidase (POD), superoxide dismutase (SOD), and catalase (CAT), as well as higher levels of proline content than the WS line. In addition, the expression of antioxidant enzyme genes (POD1, POD2, FeSOD, Cu/ZnSOD, CAT1, and CAT2) and ethylene-related genes (such as ACO1, ACO2, ACS1, and ACS2) were found to be up-regulated in WT line under waterlogging stress conditions. In contrast, these genes showed a down-regulation in their expression levels in the stressed WS line. The integration of morpho-physiological, biochemical, and gene expression analyses provide a comprehensive understanding of the responses of WT and WS lines to waterlogging conditions. These findings would be beneficial for the future development of soybean cultivars that can withstand waterlogging. Full article

(This article belongs to the Special Issue Physiological and Genetic Mechanisms of Abiotic Stress Tolerance in Crops II)

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28 pages, 6624 KiB

Open AccessArticle

DEAD-Box RNA Helicase Family in Physic Nut (Jatropha curcas L.): Structural Characterization and Response to Salinity

by Rahisa Helena da Silva, Manassés Daniel da Silva, José Ribamar Costa Ferreira-Neto, Bruna de Brito Souza, Francielly Negreiros de Araújo, Elvia Jéssica da Silva Oliveira, Ana Maria Benko-Iseppon, Antonio Félix da Costa and Éderson Akio Kido

Plants 2024, 13(6), 905; https://doi.org/10.3390/plants13060905 - 21 Mar 2024

Viewed by 618

Abstract

Helicases, motor proteins present in both prokaryotes and eukaryotes, play a direct role in various steps of RNA metabolism. Specifically, SF2 RNA helicases, a subset of the DEAD-box family, are essential players in plant developmental processes and responses to biotic and abiotic stresses. Despite this, information on this family in the physic nut (Jatropha curcas L.) remains limited, spanning from structural patterns to stress responses. We identified 79 genes encoding DEAD-box RNA helicases (JcDHX) in the J. curcas genome. These genes were further categorized into three subfamilies: DEAD (42 genes), DEAH (30 genes), and DExH/D (seven genes). Characterization of the encoded proteins revealed a remarkable diversity, with observed patterns in domains, motifs, and exon–intron structures suggesting that the DEAH and DExH/D subfamilies in J. curcas likely contribute to the overall versatility of the family. Three-dimensional modeling of the candidates showed characteristic hallmarks, highlighting the expected functional performance of these enzymes. The promoter regions of the JcDHX genes revealed potential cis-elements such as Dof-type, BBR-BPC, and AP2-ERF, indicating their potential involvement in the response to abiotic stresses. Analysis of RNA-Seq data from the roots of physic nut accessions exposed to 150 mM of NaCl for 3 h showed most of the JcDHX candidates repressed. The protein–protein interaction network indicated that JcDHX proteins occupy central positions, connecting events associated with RNA metabolism. Quantitative PCR analysis validated the expression of nine DEAD-box RNA helicase transcripts, showing significant associations with key components of the stress response, including RNA turnover, ribosome biogenesis, DNA repair, clathrin-mediated vesicular transport, phosphatidyl 3,5-inositol synthesis, and mitochondrial translation. Furthermore, the induced expression of one transcript (JcDHX44) was confirmed, suggesting that it is a potential candidate for future functional analyses to better understand its role in salinity stress tolerance. This study represents the first global report on the DEAD-box family of RNA helicases in physic nuts and displays structural characteristics compatible with their functions, likely serving as a critical component of the plant’s response pathways. Full article

(This article belongs to the Special Issue Physiological and Genetic Mechanisms of Abiotic Stress Tolerance in Crops II)

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10 pages, 1826 KiB

Open AccessCommunication

ABA Inhibits Rice Seed Aging by Reducing H₂O₂ Accumulation in the Radicle of Seeds

by Qin Zheng, Zhenning Teng, Jianhua Zhang and Nenghui Ye

Plants 2024, 13(6), 809; https://doi.org/10.3390/plants13060809 - 12 Mar 2024

Viewed by 633

Abstract

The seed, a critical organ in higher plants, serves as a primary determinant of agricultural productivity, with its quality directly influencing crop yield. Improper storage conditions can diminish seed vigor, adversely affecting seed germination and seedling establishment. Therefore, understanding the seed-aging process and exploring strategies to enhance seed-aging resistance are paramount. In this study, we observed that seed aging during storage leads to a decline in seed vigor and can coincide with the accumulation of hydrogen peroxide (H₂O₂) in the radicle, resulting in compromised or uneven germination and asynchronous seedling emergence. We identified the abscisic acid (ABA) catabolism gene, abscisic acid 8′-hydroxylase 2 (OsABA8ox2), as significantly induced by aging treatment. Interestingly, transgenic seeds overexpressing OsABA8ox2 exhibited reduced seed vigor, while gene knockout enhanced seed vigor, suggesting its role as a negative regulator. Similarly, seeds pretreated with ABA or diphenyleneiodonium chloride (DPI, an H₂O₂ inhibitor) showed increased resistance to aging, with more robust early seedling establishment. Both OsABA8ox2 mutant seeds and seeds pretreated with ABA or DPI displayed lower H₂O₂ content during aging treatment. Overall, our findings indicate that ABA mitigates rice seed aging by reducing H₂O₂ accumulation in the radicle. This study offers valuable germplasm resources and presents a novel approach to enhancing seed resistance against aging. Full article

(This article belongs to the Special Issue Physiological and Genetic Mechanisms of Abiotic Stress Tolerance in Crops II)

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21 pages, 6788 KiB

Open AccessArticle

Potential Response Patterns of Endogenous Hormones in Cliff Species Opisthopappus taihangensis and Opisthopappus longilobus under Salt Stress

by Yimeng Zhang, Yuexin Shen, Mian Han, Yu Su, Xiaolong Feng, Ting Gao, Xiaojuan Zhou, Qi Wu, Genlou Sun and Yiling Wang

Plants 2024, 13(4), 557; https://doi.org/10.3390/plants13040557 - 19 Feb 2024

Cited by 1 | Viewed by 587

Abstract

When plants are exposed to salt stress, endogenous hormones are essential for their responses through biosynthesis and signal transduction pathways. However, the roles of endogenous hormones in two cliff species (Opisthopappus taihangensis and Opisthopappus longilobus (Opisthopappus genus)) in the Taihang Mountains under salt stress have not been investigated to date. Following different time treatments under 500 mM salt concentrations, 239 differentially expressed gene (DEG)-related endogenous hormones were identified that exhibited four change trends, which in Profile 47 were upregulated in both species. The C-DEG genes of AUX, GA, JA, BR, ETH, and ABA endogenous hormones were significantly enriched in Opisthopappus taihangensis (O. taihangensis) and Opisthopappus longilobus (O. longilobus). During the responsive process, mainly AUX, GA, and JA biosynthesis and signal transduction were triggered in the two species. Subsequently, crosstalk further influenced BR, EHT, ABA, and MAPK signal transduction pathways to improve the salt resistance of the two species. Within the protein–protein interactions (PPI), seven proteins exhibited the highest interactions, which primarily involved two downregulated genes (SAUR and GA3ox) and eight upregulated genes (ACX, MFP2, JAZ, BRI1, BAK1, ETR, EIN2, and SNRK2) of the above pathways. The more upregulated expression of ZEP (in the ABA biosynthesis pathway), DELLA (in the GA signaling pathway), ABF (in the ABA signaling pathway), and ERF1 (in the ETH signaling pathway) in O. taihangensis revealed that it had a relatively higher salt resistance than O. longilobus. This revealed that the responsive patterns to salt stress between the two species had both similarities and differences. The results of this investigation shed light on the potential adaptive mechanisms of O. taihangensis and O. longilobus under cliff environments, while laying a foundation for the study of other cliff species in the Taihang Mountains. Full article

(This article belongs to the Special Issue Physiological and Genetic Mechanisms of Abiotic Stress Tolerance in Crops II)

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17 pages, 909 KiB

Open AccessArticle

Comparative Analysis of the Effect of Gamma-, Electron, and Proton Irradiation on Transcriptomic Profile of Hordeum vulgare L. Seedlings: In Search for Molecular Contributors to Abiotic Stress Resilience

by Alexander Prazyan, Mikhail Podlutskii, Polina Volkova, Elizaveta Kazakova, Sofia Bitarishvili, Ekaterina Shesterikova, Vyacheslav Saburov, Ekaterina Makarenko, Maria Lychenkova, Marina Korol, Evgeniy Kazakov, Alexander Moiseev, Stanislav Geras’kin and Ekaterina Bondarenko

Plants 2024, 13(3), 342; https://doi.org/10.3390/plants13030342 - 23 Jan 2024

Viewed by 856

Abstract

The development of adaptation strategies for crops under ever-changing climate conditions is a critically important food security issue. Studies of barley responses to ionising radiation showed that this evolutionarily ancient stress factor can be successfully used to identify molecular pathways involved in adaptation to a range of abiotic stressors. In order to identify potential molecular contributors to abiotic stress resilience, we examined the transcriptomic profiles of barley seedlings after exposure to γ-rays, electrons, and protons. A total of 553 unique differentially expressed genes with increased expression and 124 with decreased expression were detected. Among all types of radiation, the highest number of differentially expressed genes was observed in electron-irradiated samples (428 upregulated and 56 downregulated genes). Significant upregulation after exposure to the three types of radiation was shown by a set of ROS-responsive genes, genes involved in DNA repair, cell wall metabolism, auxin biosynthesis and signalling, as well as photosynthesis-related genes. Most of these genes are known to be involved in plant ROS-mediated responses to other abiotic stressors, especially with genotoxic components, such as heavy metals and drought. Ultimately, the modulation of molecular pathways of plant responses to ionising radiation may be a prospective tool for stress tolerance programmes. Full article

(This article belongs to the Special Issue Physiological and Genetic Mechanisms of Abiotic Stress Tolerance in Crops II)

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19 pages, 2470 KiB

Open AccessArticle

Comparison of the Morpho-Physiological and Molecular Responses to Salinity and Alkalinity Stresses in Rice

by Abdelghany S. Shaban, Fatmah Ahmed Safhi, Marwa A. Fakhr, Rajat Pruthi, Mahmoud S. Abozahra, Amira M. El-Tahan and Prasanta K. Subudhi

Plants 2024, 13(1), 60; https://doi.org/10.3390/plants13010060 - 23 Dec 2023

Cited by 1 | Viewed by 740

Abstract

Rice is a major food crop that has a critical role in ensuring food security for the global population. However, major abiotic stresses such as salinity and alkalinity pose a major threat to rice farming worldwide. Compared with salinity stress, there is limited progress in elucidating the molecular mechanisms associated with alkalinity tolerance in rice. Since both stresses coexist in coastal and arid regions, unraveling of the underlying molecular mechanisms will help the breeding of high-yielding stress-tolerant rice varieties for these areas. This study examined the morpho-physiological and molecular response of four rice genotypes to both salinity and alkalinity stresses. Geumgangbyeo was highly tolerant and Mermentau was the least tolerant to both stresses, while Pokkali and Bengal were tolerant to only salinity and alkalinity stress, respectively. A set of salinity and alkalinity stress-responsive genes showed differential expression in the above rice genotypes under both stress conditions. The expression patterns were consistent with the observed morphological responses in these rice genotypes, suggesting the potential role of these genes in regulating tolerance to these abiotic stresses. Overall, this study suggested that divergence in response to alkalinity and salinity stresses among rice genotypes could be due to different molecular mechanisms conferring tolerance to each stress. In addition to providing a basis for further investigations into differentiating the molecular bases underlying tolerance, this study also emphasizes the possibilities of developing climate-resilient rice varieties using donors that are tolerant to both abiotic stresses. Full article

(This article belongs to the Special Issue Physiological and Genetic Mechanisms of Abiotic Stress Tolerance in Crops II)

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21 pages, 2263 KiB

Open AccessArticle

Identification of Wheat Ideotype under Multiple Abiotic Stresses and Complex Environmental Interplays by Multivariate Analysis Techniques

by Ibrahim Al-Ashkar, Mohammed Sallam, Abdullah Ibrahim, Abdelhalim Ghazy, Nasser Al-Suhaibani, Walid Ben Romdhane and Abdullah Al-Doss

Plants 2023, 12(20), 3540; https://doi.org/10.3390/plants12203540 - 11 Oct 2023

Viewed by 867

Abstract

Multiple abiotic stresses negatively impact wheat production all over the world. We need to increase productivity by 60% to provide food security to the world population of 9.6 billion by 2050; it is surely time to develop stress-tolerant genotypes with a thorough comprehension of the genetic basis and the plant’s capacity to tolerate these stresses and complex environmental reactions. To approach these goals, we used multivariate analysis techniques, the additive main effects and multiplicative interaction (AMMI) model for prediction, linear discriminant analysis (LDA) to enhance the reliability of the classification, multi-trait genotype-ideotype distance index (MGIDI) to detect the ideotype, and the weighted average of absolute scores (WAASB) index to recognize genotypes with stability that are highly productive. Six tolerance multi-indices were used to test twenty wheat genotypes grown under multiple abiotic stresses. The AMMI model showed varying differences with performance indices, which disagreed with the trait and genotype differences used. The G01, G12, G16, and G02 were selected as the appropriate and stable genotypes using the MGIDI with the six tolerance multi-indices. The biplot features the genotypes (G01, G03, G11, G16, G17, G18, and G20) that were most stable and had high tolerance across the environments. The pooled analyses (LDA, MGIDI, and WAASB) showed genotype G01 as the most stable candidate. The genotype (G01) is considered a novel genetic resource for improving productivity and stabilizing wheat programs under multiple abiotic stresses. Hence, these techniques, if used in an integrated manner, strongly support the plant breeders in multi-environment trials. Full article

(This article belongs to the Special Issue Physiological and Genetic Mechanisms of Abiotic Stress Tolerance in Crops II)

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16 pages, 3811 KiB

Open AccessArticle

Transcriptomic Profiling of Cold Stress-Induced Differentially Expressed Genes in Seedling Stage of Indica Rice

by Tao Yan, Meng Sun, Rui Su, Xiaozhong Wang, Xuedan Lu, Yunhua Xiao, Huabing Deng, Xiong Liu, Wenbang Tang and Guilian Zhang

Plants 2023, 12(14), 2675; https://doi.org/10.3390/plants12142675 - 17 Jul 2023

Cited by 1 | Viewed by 1267

Abstract

Cold stress significantly constrains the growth, development, productivity, and distribution of rice, particularly the indica cultivar, known for its susceptibility to cold, limiting its cultivation to specific regions. This study investigated the genes associated with cold responsiveness in the roots of two indica cultivars, SQSL (cold-tolerant) and XZX45 (cold-susceptible), through transcriptome dynamics analysis during the seedling stage. The analysis identified 8144 and 6427 differentially expressed genes (DEGs) in XZX45 and SQSL, respectively. Among these DEGs, 4672 (G2) were shared by both cultivars, while 3472 DEGs (G1) were specific to XZX45, and 1755 DEGs (G3) were specific to SQSL. Additionally, 572 differentially expressed transcription factors (TFs) from 48 TF families, including WRKY, NAC, bHLH, ERF, bZIP, MYB, C2H2, and GRAS, were identified. Gene Ontology (GO) enrichment analysis revealed significant enrichment of DEGs in the G3 group, particularly in the “response to cold” category, highlighting the crucial role of these specific genes in response to cold stress in SQSL. Furthermore, Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis indicated pronounced enrichment of DEGs in the G3 group in metabolic pathways such as “Pyruvate metabolism”, “Glycolysis/Gluconeogenesis”, and “Starch and sucrose metabolism”, contributing to cold tolerance mechanisms in SQSL. Overall, this study provides comprehensive insights into the molecular mechanisms underlying cold responses in the indica cultivar, informing future genetic improvement strategies to enhance cold tolerance in susceptible indica rice cultivars. Full article

(This article belongs to the Special Issue Physiological and Genetic Mechanisms of Abiotic Stress Tolerance in Crops II)

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17 pages, 4631 KiB

Open AccessArticle

Abscisic Acid Enhances Trehalose Content via OsTPP3 to Improve Salt Tolerance in Rice Seedlings

by Nenghui Ye, Yuxing Wang, Huihui Yu, Zhonge Qin, Jianhua Zhang, Meijuan Duan and Ling Liu

Plants 2023, 12(14), 2665; https://doi.org/10.3390/plants12142665 - 17 Jul 2023

Cited by 3 | Viewed by 1176

Abstract

Salt stress is one of the major environmental stresses that imposes constraints to plant growth and production. Abscisic acid (ABA) has been well-proven to function as a central integrator in plant under salt stress, and trehalose (Tre) has emerged as an excellent osmolyte to induce salt tolerance. However, the interacting mechanism between ABA and Tre in rice seedlings under salt stress is still obscure. Here, we found that the application of exogenous Tre significantly promoted the salt tolerance of rice seedlings by enhancing the activities of antioxidant enzymes. In addition, the expression of OsNCED3 was significantly induced by salt stress. The overexpression of the OsNCED3 gene enhanced the salt tolerance, while the knockout of OsNCED3 reduced the salt tolerance of the rice seedlings. Metabolite analysis revealed that the Tre content was increased in the OsNCED3-overexpressing seedlings and reduced in the nced3 mutant. The application of both ABA and Tre improved the salt tolerance of the nced3 mutant when compared with the WT seedling. OsTPP3 was found to be induced by both the ABA and salt treatments. Consistent with the OsNCED3 gene, the overexpression of OsTPP3 enhanced salt tolerance while the knockout of OsTPP3 reduced the salt tolerance of the rice seedlings. In addition, the Tre content was also higher in the OsTPP3-overexpressing seedling and lower in the tpp3 mutant seedling than the WT plant. The application of exogenous Tre also enhanced the salt tolerance of the tpp3 mutant plant. Overall, our results demonstrate that salt-increased ABA activated the expression of OsTPP3, which resulted in elevated Tre content and thus an improvement in the salt tolerance of rice seedlings. Full article

(This article belongs to the Special Issue Physiological and Genetic Mechanisms of Abiotic Stress Tolerance in Crops II)

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17 pages, 4532 KiB

Open AccessArticle

Mechanism of Mepiquat Chloride Regulating Soybean Response to Drought Stress Revealed by Proteomics

by Shoukun Dong, Xin Wang, Xiaomei Li, Yumei Tian, Xinyu Zhou, Zhipeng Qu, Xiyue Wang and Lijun Liu

Plants 2023, 12(10), 2037; https://doi.org/10.3390/plants12102037 - 19 May 2023

Cited by 2 | Viewed by 1103

Abstract

Soybeans are the main sources of oil and protein for most of the global population. As the population grows, so does the demand for soybeans. However, drought is a major factor that limits soybean production. Regulating soybean response to drought stress using mepiquat chloride (MC) is a feasible method; however, its mechanism is still unclear. This study used PEG-6000 to simulate drought stress and quantitative proteomic techniques to reveal changes in Heinong44 (HN44) and Heinong65 (HN65) subjected to drought following the application of 100 mg/L of MC. The results showed that SOD in HN44 did not change significantly but decreased by 22.61% in HN65 after MC pretreatment, and MDA content decreased by 22.75% and 21.54% in HN44 and HN65, respectively. Furthermore, MC improved the GSH–ASA cycle and simultaneously promoted the Calvin cycle process to enable the plant to maintain a certain carbon assimilation rate under osmotic stress. In addition, MC upregulated some proteins during gluconeogenesis and starch metabolism and increased soluble sugar content by 8.41% in HN44. MC also reduced ribosomal protein abundance, affecting translation and amino acid metabolism. In summary, MC improved GSH–ASA cycle and Calvin cycle under stress to alleviate oxidative damage and maintain crop growth. Our study is the first to report the mechanism of MC regulation in soybean under osmotic stress, providing new insights for the rational application of MC in soybean. Full article

(This article belongs to the Special Issue Physiological and Genetic Mechanisms of Abiotic Stress Tolerance in Crops II)

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15 pages, 1952 KiB

Open AccessArticle

The Role of IAA in Regulating Root Architecture of Sweetpotato (Ipomoea batatas [L.] Lam) in Response to Potassium Deficiency Stress

by Ming Liu, Qiangqiang Zhang, Rong Jin, Peng Zhao, Xiaoya Zhu, Jing Wang, Yongchao Yu and Zhonghou Tang

Plants 2023, 12(9), 1779; https://doi.org/10.3390/plants12091779 - 26 Apr 2023

Cited by 4 | Viewed by 1314

Abstract

Plants can adapt to the spatial heterogeneity of soil nutrients by changing the morphology and architecture of the root system. Here, we explored the role of auxin in the response of sweetpotato roots to potassium (K⁺) deficiency stress. Two sweetpotato cultivars, Xushu 32 (low-K-tolerant) and Ningzishu 1 (low-K-sensitive), were cultured in low K⁺ (0.1 mmol L⁻¹, LK) and normal K⁺ (10 mmol L⁻¹, CK) nutrient solutions. Compared with CK, LK reduced the dry mass, K⁺ content, and K⁺ accumulation in the two cultivars, but the losses of Xushu 32 were smaller than those of Ningzishu 1. LK also affected root growth, mainly impairing the length, surface area, forks number, and crossings number. However, Xushu 32 had significantly higher lateral root length, density, and surface area than Ningzishu 1, closely related to the roots’ higher indole-3-acetic acid (IAA) content. According to the qPCR results, Xushu 32 synthesized more IAA (via IbYUC8 and IbTAR2) in leaves but transported and accumulated in roots through polar transport (via IbPIN1, IbPIN3, and IbAUX1). It was also associated with the upregulation of auxin signaling pathway genes (IbIAA4 and IbIAA8) in roots. These results imply that IAA participates in the formation of lateral roots and the change in root architecture during the tolerance to low K⁺ stress of sweetpotato, thus improving the absorption of K⁺ and the formation of biomass. Full article

(This article belongs to the Special Issue Physiological and Genetic Mechanisms of Abiotic Stress Tolerance in Crops II)

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