Search Results (136)

Agave species are plants with great economic value and multiple possibilities of use as ornamentals, medicinal plants, and fibers, as well as being significant sources of bioethanol. However, their long life cycles hinder their conventional breeding. Therefore, biotechnology tools are the most effective means for clonal propagation and genetic improvement. In vitro micropropagation of A. sisalana via axillary shoot proliferation from bulbil explants was attained using Murashige and Skoog medium (MS) supplemented with cytokinins (CKs), such as 6-benzyladenine (BA), kinetin (KIN), or thidiazuron (TDZ). The optimum significant shoot proliferation (14.67 shoots/explant) was achieved on 1.0 mg L⁻¹ TDZ. The carry-over effect of CKs on subsequent rooting could be detected. Control and KIN treatments could enhance the rooting of shoots on shoot proliferation media. The regenerated plantlets were acclimatized directly with 100% survival. To mitigate this carry-over effect, that causes hindering further root growth and development, and promote healthy growth of roots, subculturing shoots onto a CK-free medium is a recommended practice. The shoots induced on all BA treatments, and TDZ at 0.5 and 1.0 mg L⁻¹ could be rooted after two subcultures on CK-free medium, then they were acclimatized with 100% survival. However, the higher concentrations of TDZ inhibited in vitro rooting even after two subcultures on CK-free medium, and the acclimatization percentage was reduced by increasing the TDZ concentration recorded from 10 to 0%. Full article

Background/Objectives: Possessing red and white ecotypes, and utilized in traditional Guyanese medicine, Doliocarpus dentatus’ red ecotype is preferred locally for its purported superior therapeutic efficacy. Although therapeutic metabolites were detected in D. dentatus previously, phytohormones remain largely unexplored, until now. Cytokinins, phytohormones responsible for plant cell division, growth and differentiation, are gaining traction for their therapeutic potential in human health. This study screened and quantified endogenous cytokinins and correlated detected cytokinins with selected secondary metabolites. Methods: Liquid chromatography–mass spectrometry was used to acquire phytohormone and metabolite data. Bioinformatics tools were used to assess untargeted metabolomics datasets via statistical and pathway analyses, and chemical groupings of putative metabolites. Results: In total, 20 of the 35 phytohormones were detected and quantified in both ecotypes, with the red ecotype displaying higher free base and glucoside cytokinin concentrations and exhibited 6.2 times the total CK content when compared to the white ecotype. Pathway analysis revealed flavonoid and monoterpenoid biosynthesis in red and white ecotypes, respectively. Positive correlations between specific cytokinins and alkaloids, and between trans-Zeatin and isopentenyladenosine riboside with phenolic compounds were observed. Conclusions: These results suggest that the red ecotype’s elevated cytokinin levels coupled with flavonoid biosynthesis enrichment support its preference in Guyanese traditional medicine. Full article

Soybean is a dual-purpose crop for food and oil, playing a crucial role in China’s grain production. Seed size and weight are key agronomic traits directly influencing the yield. Cytokinin oxidases/dehydrogenases (CKXs) specifically degrade certain isoforms of endogenous cytokinins (CKs), thereby modulating plant growth and seed development. However, their role in soybeans remains largely uncharacterized. In a previous genome-wide association study of 250 soybean core germplasms, we identified GmCKX3 as a yield-related gene. To elucidate its function, we developed GmCKX3-deficient mutants using CRISPR/Cas9 gene editing in soybean Williams82 and conducted a three-year phenotypic analysis. Loss of GmCKX3 function significantly enhanced the seed size and weight, which was attributed to an increased cell size and fat accumulation in the endosperm. This enhancement was driven by elevated endogenous CK levels resulting from suppressed GmCKX3 expression. Subcellular localization revealed that GmCKX3 resides in the endoplasmic reticulum and predominantly degrades the isopentenyladenine (iP)-type CK. Integrated transcriptomic and metabolomic analyses uncovered key genes and pathways involved in CK regulation, supporting GmCKX3’s central role in seed-trait modulation. These findings advance our understanding of cytokinin-mediated seed development and offer promising targets for molecular breeding aimed at improving the soybean yield. Full article

Epigeal cotyledons with excised embryonic axes are often used as a model system to study the processes of cell division and expansion. These processes are regulated by diverse phytohormones and signaling molecules. Phytohormones modulate antioxidant defense systems and interact with reactive oxygen species (ROS) to synchronize normal plant cell growth. This study provides new information concerning alterations in enzymatic antioxidants linked to the production and scavenging of ROS in excised epigeal cotyledons of zucchini grown on solutions of methyl jasmonate (MeJA) and cytokinins (CKs)—N⁶-benzyl adenine and N₁-(2-chloropyridin-4-yl)-N₂-phenylurea—in the presence or absence of light under laboratory conditions. The cotyledon material was used to determine the dynamics of selected biochemical parameters starting from the 2nd to the 6th day of incubation. In general, our results revealed that exogenous MeJA caused a reduction in the content of hydrogen peroxide (H₂O₂) and free proline, as well as in the activity of superoxide dismutase (SOD), guaiacol peroxidase (POX) and catalase (CAT) in dark-grown cotyledons. Applied alone, both cytokinins increased most of the parameters studied, except proline and protein levels. However, when MeJA was combined with CKs, it acted in a diverse manner, ranging from antagonistic to synergistic depending on the cytokinin type, parameter measured and light regime. Similar alterations were also found in the levels of leaf pigments in the cotyledons grown under light conditions. In general, the changes in the antioxidant enzyme activities due to light were more intense than those observed in dark-grown cotyledons. The data obtained show, for the first time, the involvement of the hormonal interplay between MeJA and CKs on the biochemical changes in antioxidant defense during cotyledon growth under different light conditions. Full article

Alginate oligosaccharides (AOSs) have been shown to be effective in enhancing crop growth. However, their functions in horticulture crops and growth-promoting mechanisms remain insufficiently characterized. This study employed pot cultivation experiments to investigate the effects of AOS root drenching (0, 15, 30, 45 mg·L⁻¹) on tomato (Solanum lycopersicum L.) seedling growth, photosynthetic performance, and phytohormone accumulation. The results showed that AOS promoted the leaf count per plant, leaf area of the youngest fully expanded leaves, shoot and root dry mass, chloroplast pigment contents and photosynthetic rate of tomato seedlings. And the 30 mg·L⁻¹ treatment consistently showed optimal efficacy, in which tomato seedlings also exhibited a significantly longer total root length, a larger root surface area and a greater number of root tips compared to the control. Phytohormone profiling revealed that AOS differentially regulated shoot/root phytohormones as follows: increasing auxins/cytokinins (CKs)/GA₁₉ content in shoots and Indole-3-acetic acid (IAA)/CKs/1-aminocyclopropane-1-carboxylic acid (ACC) content in roots, while decreasing root Jasmonic acid (JA)/5-deoxystrigol (5DS) contents. Finally, these findings demonstrate that AOS enhances tomato growth by coordinately reprogramming phytohormone homeostasis. Full article

Glycyrrhiza uralensis Fisch. is considered one of the most economically important medicinal plants worldwide. However, the quality of cultivated G. uralensis has not been adequate to meet the market demand. As one of the most important factors for plant growth, light influences the production and accumulation of metabolites in plants. However, the effect of light on the development and accumulation of components of G. uralensis is unclear. In this study, we found that red light and 4R1B (red/blue = 4:1) could promote the growth of licorice, such as the plant height, diameter of the reed head, and biomass accumulation, while blue light inhibited indicators of reed head diameter, biomass accumulation, etc. The impact of the light system is reflected in blue light significantly suppressing the photosynthetic rate and stomatal conductance, while red light and mixed light had the opposite effects. The red group had the lowest superoxide dismutase (SOD) activity and malondialdehyde (MDA) content, which suggested the production and scavenging of O₂ was balanced in red light. Additionally, the red group had the highest content of soluble sugars and soluble proteins. We combined metabolomic and transcriptomic analysis and found that the gene expression in the treatment groups was up-regulated in the liquiritin synthesis pathway, and the liquiritin content of the 4R1B group and R group was significantly increased by 275% and 191% that of the CK group. Moreover, 4R1B significantly promoted the accumulation of glycyrrhizic acid (94% higher than in the CK group) and the expression of genes in the glycyrrhizic acid synthesis pathway. In addition, the light treatments affected seven phytohormone pathways (abscisic acid, brassinosteroid, salicylic acid, auxin, gibberellin, cytokinin, and jasmonic acid) in G. uralensis, which was related to cell elongation, stem elongation, stress resistance, and other aspects. In general, we analyzed the response mechanism of G. uralensis to red and blue light at the physiological, medicinal component, and molecular levels. The results will provide a new perspective for studying the regulatory effect of light quality on the growth and medicinal components of G. uralensis. Full article

In this study, red–blue light (7R3B) was used as the control (CK), while far-red (FR) and ultraviolet-A (UVA) light were supplemented to evaluate their effects on basil growth. The results showed that the FR treatment promoted plant height, stem diameter, and biomass, but reduced chlorophyll and carotenoid content, while the UVA treatment increased stem diameter and chlorophyll b content. Meanwhile, transcriptomic and metabolomic analyses were employed to examine changes in gene expression and metabolite accumulation in basil. The FR treatment reduced the levels of differentially accumulated metabolites (DAMs) in the carotenoid biosynthesis pathway, potentially contributing to the observed decrease in chlorophyll. The FR treatment upregulated the levels of five DAMs (gibberellin, cytokinin, brassinosteroid, jasmonic acid, and salicylic acid) and altered the differentially expressed genes (DEGs) such as gibberellin receptor (GID1) and jasmonate ZIM domain-containing protein (JAZ) in the plant hormone signal transduction pathway, thereby promoting plant growth and shade avoidance responses. The UVA treatment upregulated the 9-cis-epoxycarotenoid dioxygenase (NCED) expression in the carotenoid biosynthesis pathway, possibly indirectly promoting flavonoid synthesis. In the flavonoid biosynthesis pathway, the UVA treatment also promoted flavonoid accumulation by upregulating DEGs including flavonol synthase (FLS), anthocyanidin synthase (ANS), 5-O-(4-coumaroyl)-D-quinate 3′-monooxygenase (CYP98A), and flavanone 7-O-glucoside 2″-O-beta-L-rhamnosyltransferase (C12RT1), as well as increasing the levels of DAMs such as kaempferol, luteolin, apigenin, and leucopelargonidin. The accumulation of flavonoids improved antioxidant capacity and nutritional value in basil. Through a Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analysis, this study provided valuable insights into the molecular and metabolic mechanisms of the FR and UVA regulation of basil growth, providing guidance for optimizing supplementary lighting strategies in plant factories. Full article

Malformed coconut fruit occurrence exhibits dual impacts on agricultural productivity and economic returns, primarily through substantial yield reduction and compromised commercial value resulting from morphological defects. To elucidate the molecular determinants underlying this developmental anomaly, we conducted a systematic investigation integrating physiological profiling and transcriptomic sequencing on pulp tissues from malformed (MF) and normal (NF) coconut fruits. Notably, MF specimens displayed marked depletion in carbohydrate reserves, with soluble sugars (SS), reducing sugars (RS), starch (SH), soluble proteins (SP), and fat (FA) declining by 28.57%, 20.43%, 15.51%, 36.78%, and 50.18%, respectively, compared to NF controls. Conversely, a coordinated upregulation of phytohormones was observed, where indole acetic acid (IAA), abscisic acid (ABA), cytokinin (CK), gibberellic acid (GA), brassinosteroid (BR), jasmonic acid (JA), and salicylic acid (SA) levels increased by 31.82–92.97%, while ethylene (ETH) exhibited a paradoxical 30.09% reduction. Transcriptomic dissection revealed 6370 functionally annotated differentially expressed genes (DEGs), comprising 4235 upregulated and 2135 downregulated transcripts. These DEGs were predominantly enriched in critical pathways including plant hormone signal transduction, flavonoid/phenylpropanoid biosynthesis, and carbohydrate metabolic networks. Particularly noteworthy was the enhanced activity of cell wall remodeling enzymes—cellulase (CEL), polygalacturonase (PG), and pectinesterase (PE)—accompanied by differential expression of nine cell wall-associated gene families (CEL, PE, PG, PEL, URG, UTR, VTC2, EXP, XET/XTH) and eight phytohormone-related gene clusters. Functional stratification analysis further identified key transcriptional regulators, with MYB, ERF/AP2, BHLH, WRKY, bZIP, and MADS transcription factors demonstrating significant expression divergence, suggesting their pivotal regulatory roles in MF pathogenesis. This multi-omics integration not only deciphers the molecular choreography of coconut fruit malformation but also establishes a novel conceptual framework for developmental disorder research in perennial crops. Full article

Drought is a serious environmental challenge that reduces the productivity of valuable crops, including wheat. Brassinosteroids (BRs) is a group of phytohormones that have been used to enhance wheat drought tolerance. Wheat cultivars with different adaptation strategies could have their own specific drought tolerance mechanisms, and could react differently to treatment with growth regulators. In this work, the effect of seed pretreatment with 0.4 µM 24-epibrassinolide (EBR) was investigated in two wheat (Triticum aestivum L.) cultivars contrasting in drought behavior, tolerant Ekada 70 (cv. E70) and sensitive Zauralskaya Zhemchuzhina (cv. ZZh), in early ontogenesis under dehydration (PEG-6000) or soil drought conditions. EBR pretreatment mitigated the stress-induced inhibition of seedling emergence and growth, as well as membrane damage in cv.E70 but not in ZZh. An enzyme-linked immunosorbent assay (ELISA) revealed substantial changes in hormonal balance associated with ABA accumulation and a drop in the levels of IAA and cytokinins (CKs) in drought-subjected seedlings of both cultivars, especially ZZh. EBR-pretreatment reduced drought-induced hormone imbalance in cv. E70, while it did not have the same effect on ZZh. EBR-induced changes in the content of wheat germ agglutinin (WGA) belonging to the protective proteins in E70 seedlings suggest its contribution to EBR-dependent adaptive responses. The absence of a detectable protective effect of EBR on the ZZh cultivar may be associated with its insensitivity to pre-sowing EBR treatment. Full article

Field crops are expected to be increasingly threatened by climate change, which will negatively impact plant development, growth and yield. Phytohormones play a crucial role in regulating specific signalling pathways to induce rapid adaptive responses to environmental stresses. Exogenous phytohormone application alters hormonal balance, thereby enhancing plant adaptation to adverse conditions. While several studies have advanced our understanding of the use of phytohormones in field crops, yield responses and species-specific application strategies remain inconsistent and rarely assessed under field conditions. The application of cytokinins (CKs), abscisic acid (ABA), and gibberellic acid (GA) has been shown to maintain prolonged photosynthetic activity, stabilize plasma membrane, and reduce lipid peroxidation and ion accumulation under salinity stress in wheat. Additionally, inhibitors of ethylene synthesis and receptors can mitigate stress symptoms under drought and heat stress, which typically accelerates senescence and shortens the grain-filling period in cereal crops. In this way, exogenous application of CKs, GA, and ethylene inhibitors can delay senescence by sustaining leaf photosynthetic activity and postponing nutrient remobilization. However, these benefits may not consistently translate into improvements in grain yield and quality. This review explores the molecular mechanisms of phytohormones in abiotic stress tolerance, delineates their specific functions and evaluates experimental findings from field applications. It also summarizes the potential of phytohormone applications in field crops, emphasizing the need for species-specific investigations on application timing and dosages under open-field conditions to optimize their agronomic potential. Full article

The cytokinin (CK) type B response regulator (RRB) gene is involved in the CK signaling pathway and performs a key function for mediating reactions to amounts of abiotic stresses. Nevertheless, the RRB gene family remains to be characterized in Poaceae (also known as Gramineae or grasses). Here, we performed a comprehensive analysis encompassing phylogenetic relationships, evolutionary pressures, and expression patterns of the RRB gene family in six Poaceae species, including rice, Panicum, Sorghum, Setaria, maize, and wheat. Phylogenetic tree and syntenic analyses revealed that the RRB genes were divided into seven orthologous gene clusters (OGCs), indicating that the common ancestor of these Poaceae species possessed at least seven RRB genes. Further analysis revealed that the evolution of the Poaceae RRB gene family was primarily driven by purifying selection. The expression pattern of rice OsRRB toward phytohormonal and abiotic stresses was also investigated. The findings revealed that several phytohormones, including cytokinin (CK), abscisic acid (ABA), and methyl jasmonate (MeJA), as well as abiotic factors such as drought and cold, significantly increased the expression levels of these genes. Importantly, haplotype analysis identified four crucial variation sites within the OsRRB5 genomic regions that may contribute to drought resistance in rice. Our findings lay the groundwork for further elucidating the biological function of OsRRB genes and provide a promising new target for developing stress-resistant rice varieties. Full article

Crown root (CR) initiation and development are crucial for the establishment of robust root systems in plants, contributing significantly to stress tolerance and overall growth. This manuscript explores the regulatory roles of key hormones and genes involved in CR formation, with a focus on their interactions under conditions of drought and salt stress. Cytokinins (CK) act as a negative regulator of CR development, while auxin (AUX) serves as a positive driver, facilitating cellular growth and division. Wuschel-related homeobox (WOX) genes, particularly OsWOX11, play a central role by integrating CK and AUX signalling to regulate downstream targets such as OsCRL1 and auxin biosynthetic pathways. Other hormones, including jasmonic acid (JA) and gibberellin (GA), display context-dependent effects, modulating CR initiation based on environmental conditions. Critical genes like OsESG1 and OsFBX257 have been associated with improved drought resilience, interacting with proteins and kinases such as OsGF14b/c and OsCDPK1. Despite progress, significant challenges remain in mapping the full extent of hormonal crosstalk and gene regulation under stress conditions. This manuscript emphasises the need for future studies to incorporate comprehensive multi-omics approaches, expand the exploration of stress-related hormones like abscisic acid (ABA), and leverage advanced gene-editing techniques. Addressing these gaps will enhance our understanding of CR development and contribute to the development of crops with greater resistance to environmental stresses. Full article

In order to fully elucidate the roles and systems of phytohormones in UV-B radiation (UV-B) leaves of the Rhododendron chrysanthum Pall. (R. chrysanthum), we conducted a comprehensive analysis of how R. chrysanthum protects itself against UV-B using transcriptomic and metabolomic data. Transcript and metabolite profiles were generated by a combination of deep sequencing and LC-MS/MS (liquid chromatography–tandem mass spectrometry), respectively. Combined with physiological and biochemical assays, we studied compound accumulation, biosynthesis and expression of signaling genes of seven hormones and the effects of hormones on plant photosynthesis. The findings indicate that during leaf defense against UV-B, photosynthesis declined, the photosynthetic system was impaired and the concentration of salicylic acid (SA) hormones increased, whereas the contents of cytokinin (CK), abscisic acid (ABA), ethylene, auxin, jasmonic acid (JA) and gibberellins (GAs) continued to decrease. Finally, correlation tests between hormone content and genes were analyzed, and genes closely related to leaf resistance to UV-B were identified in seven pathways. These results will expand our understanding of the hormonal regulatory mechanisms of plant resistance to UV-B and at the same time lay the foundation for plant resistance to adversity stress. Full article

Ficus trees (Moraceae) play a vital role in sustaining the stability of tropical and subtropical rainforests. The obligate mutualism between Ficus species and their pollinating fig wasps renders them an exemplary model for investigating insect–plant coevolution. In this study, we employed Ficus hispida Linn. f., an ecologically significant fig species in tropical rainforests, to conduct a wasp-introduction controlled experiment in the field. This method enabled us to precisely delineate the developmental stages of figs. We collected samples at specific intervals and examined the impact of pollinating fig wasp entry on the hormonal metabolism of male and female figs using liquid chromatography–tandem mass spectrometry analysis. The findings demonstrate that pollinator entry significantly decreases fig abscission. Moreover, it substantially altered the developmental indices of the figs. Unpollinated figs exhibit elevated levels of abscisic acid (ABA), which increases the likelihood of fig abortion and reduces the probability of pollinator entry into senescent figs. Following pollinator entry, indole-3-acetic acid (IAA) levels rise in both male and female figs. Male figs show higher concentrations of 1-aminocyclopropane-1-carboxylic acid (ACC), jasmonic acid (JA), and salicylic acid (SA), whereas these changes are less pronounced in female figs. Additionally, pollinated male figs display increased levels of cytokinins (CKs) and other hormones compared to female figs, suggesting a coordinated hormonal response to the stress induced by pollinator oviposition and gall development. Our findings suggest that the entry of pollinators likely triggers the transition from the female to the interfloral phase, with hormonal regulation playing a crucial role in the reproductive dimorphism of figs. This research can offer novel insights into the mechanisms underlying fig–wasp mutualism. Full article

Paclobutrazol (PAC) is a significant inhibitor of gibberellin biosynthesis that profoundly influences grape seed development (GSD) through the modulation of key molecular pathways. Here, we identified 6659 differentially expressed genes (DEGs) in GSD under PAC treatment, with 3601 up-regulated and 3058 down-regulated. An analysis of hormone-associated DEGs revealed that auxin-related genes (16) were the most up-regulated, followed by genes associated with brassinosteroid and ABA. In contrast, cytokinin- and gibberellin-related genes exhibited a suppressive response. PAC treatment also triggered extensive reprogramming of metabolic pathways, including 44 genes involved in starch and sucrose metabolism (24 up-regulated, 20 down-regulated), 101 cell wall-related genes (53 up-regulated, 48 down-regulated), and 110 transcription factors (77 up-regulated, 33 down-regulated). A cis-element analysis of the promoters of 76 hormone-responsive genes identified 14 types of hormone-responsive cis-elements, with ABRE being the most prevalent. Genes responsible for inactivating active hormones, such as ABA-VvPP2CA, IAA-VvGH3.1, and CK-VvARR9-1, were also identified. Concurrently, PAC negatively regulated hormone-active genes, including BR-VvXTH25, SA-VvTGA21-3, and JA-VvTIFY3B, leading to reduced levels of these hormones. PAC modulates GSD by mediating the dynamic balance of multi-hormone accumulations. Furthermore, development-related cis-elements such as the AACA-motif, AAGAA-motif, AC-I, AC-II, O2-site, as-1, CAT-box, CCAAT-box, circadian, GCN4-motif, RY-element, HD-Zip 1, HD-Zip 3, MSA-like, MYB-like sequence, MYB-binding site, and MYB recognition site, were found in key DEGs involved in starch and sucrose metabolism, cell wall remodeling, and epigenetic regulation. This indicates that these pathways are responsive to PAC modulation during GSD. Finally, we developed a comprehensive regulatory network to illustrate the PAC-mediated pathways involved in GSD. This network integrates multi-hormonal signaling, cell wall remodeling, epigenetic regulation, and transcription factors, highlighting PAC’s pivotal role in GSD. Our findings provide new insights into the complex mechanisms underlying PAC’s effects on grapevine development. Full article