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Effects of GA3, PAC, and GA3 + PAC on the expression levels of GA biosynthetic pathway related genes. Error bars represent standard deviation (SD) among three independent replicates. Data are the means ± SD of three replicates. The asterisk indicates a significant difference (P < 0.05) compared with control group, according to Duncan’s test
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Gibberellins (GAs) play a key role in plant growth and development including cell elongation, cell expansion, and xylem differentiation. Eucalyptus are the world’s most widely planted hardwood trees providing fiber and energy. However, the roles of GAs in Eucalyptus remain unclear and their effects on xylem development remain to be determined. In t...
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... In the present investigation, the exogenous application of GA 3 had a profound positive impact on root growth, including enhancements in root volume (Fig.3 B), surface area ( Fig.2A), total root length (Fig.1A), root tips (Fig.4A), and root diameter (Fig.2 B). This contrasts a prior study involving Eucalyptus (Liu et al.,2018), which reported a decrease in average root diameter under non-saline conditions (NS). This suggests that GA 3 may alleviate salinity stress's adverse effects on root growth. ...
Linseed (Linum usitatissimum) is a versatile crop cultivated for its seeds, which are valuable source of ω-3 fatty acids. It adversely affected by soil salinity, as high salt levels can hinder their growth and reduce yields. To assess the potential for mitigating the adverse effects of high salinity concentrations, enhancing the resilience of three genotypes (Shekhar, Sheela, and Kartika) of linseed plants, this research aimed to find out the impact of Gibberellic acid (GA3) and Calcium (Ca) on various aspects of root morphology, osmotic potential of linseed, under varying levels of Cl- dominated salinity. The study employed three salinity levels (0, 5, and 10 dSm-1) and exogenous application of 10−6 M GA3 and/or 10 mg CaCl2 kg-1 in potted plants.The findings indicated that increasing salinity stress significantly (p≤0.05) affected root parameters, including total surface area(43.45%), average diameter(42.06%), total projected area(44.45%), length per volume (66.23%), root length, total root volume (73.23%), tips, forks,fine roots, and osmotic potential(66.67%). Correlations among linseed genotypes were observed between various root morphology and osmotic potential parameters. The application of GA3 and Ca effectively ameliorated the impact of salinity stress at its highest level (10 dSm-1), resulting in increased root parameters while decreasing the osmotic potential (Ψs). Both GA3 and Ca treatments significantly influenced root architecture and maintained optimal osmotic potential. The chloride-dominated salinity exerted inhibitory effects on all three genotypes’ (Shekhar, Sheela, and Kartika) root growth parameters while applying GA3 and Ca successfully mitigated these effects, enhancing root growth.
... Gibberellin (GA) is a group of tetracyclic diterpene plant hormones that belongs to one of the five major plant hormones and participates in the whole growth process of plants (Liu et al., 2018), playing a pivotal role in secondary growth (Hu et al., 2022). Early studies have shown that gibberellin combined with auxin pathway to promote xylem development and affect xylem fiber differentiation (Shininger, 1971;Aloni et al., 1990). ...
... GA 3 treatment significantly enhanced xylem development in stems and roots of Eucalyptus, and altered the expression of hormones and secondary growth-related genes. It can be found that GAs may crosstalk with other hormones to regulate the expression of genes involved in secondary cell wall biosynthesis and initiate xylogenesis (Liu et al., 2018). In addition, gibberellin and brassinosteroid also have a crosstalk relationship in plant secondary growth. ...
... Asterisk (*) indicates a significant difference between WT and PmCAD-OE at p < 0.05, while double asterisk (**) indicates a highly significant difference between WT and PmCAD-OE at p < 0.01. treatment can significantly promote the xylem development of birch, eucalyptus and other plants, thus promoting the secondary growth of plants (Guo et al., 2015;Liu et al., 2018). And a total of 24 DEGs were identified to be involved in the promotion of branch formation through the gibberellin signal transduction in Eucalyptus urophylla (Yang et al., 2022). ...
... It has been reported that gibberellic acid (GA3) is indispensable in plant growth. Qian et al. [22] emphasised the pivotal role of gibberellins in plant growth facets, encompassing cell elongation, cell expansion, and xylem differentiation. Their research revealed that exogenous GA3 application significantly promoted xylem development in both stem and root tissues. ...
... Similarly, the fruit weight per plant substantially increased from 71.8 g in the control treatment to 215.2 g in the 200-ppm treatment. Qian et al. [22] indicated that exogenous GA3 application induced alterations in the transcript levels of genes involved in the GA biosynthetic pathway, GA signalling, and genes related to auxin, cytokinin, and secondary cell wall biosynthesis. This suggests that GAs may interact with other hormones, such as auxin and cytokinin, to modulate the expression of genes related to secondary cell wall biosynthesis and trigger xylogenesis in eucalyptus plants. ...
In newly reclaimed sandy lands, plants face substantial environmental challenges, affecting their productivity, yield, and quality. Gibberellic acid (GA3) is a plant growth regulator physiologically involved in plant responses to abiotic stresses. As agricultural activities expand in desert regions, applications of GA3 could help address adverse plant growth and developmental effects. Here, we investigated the impact of exogenously applied GA3 on the growth of Cape gooseberry (Physalis peruviana L.) in newly reclaimed sandy lands in the arid Nubaria region of the West Delta of Nile, Egypt. Different GA3 concentrations of 100, 150, 200, and 250 ppm were foliar-applied to the plants. The application of GA3 in our study significantly improved the vegetative growth, plant height, leaf and branch count, and the fresh weight and yield of Cape gooseberry plants. Fruit weight, quality soluble solids, and leaf chlorophyll content were also improved. The most pronounced effects were achieved with concentrations of GA3 at 200 and 250 ppm, with the 200-ppm concentration displaying superiority in most parameters. Notably, GA3 treatments enhanced relative water content (RWC), an indicator of water status in arid conditions. Maintaining optimal RWC is crucial for essential processes like photosynthesis, promoting growth, and productivity. This research underscores GA3’s potential in enhancing Cape gooseberry growth, yield, and quality, providing a practical strategy for mitigating environmental challenges in arid regions, a concern exacerbated by climate change.
... In previous studies, it has been reported that auxin and GA induce the division of the cambium [37]. Results from Eucalyptus grandis and Populus tremula L. × tremuloides Michx showed that the application of GA would stimulate polar auxin transport [28,38]. These reports indicate that GA 3 may strengthen the function of IAA in inducing cambium activity in the present study. ...
The increase in the atmospheric carbon dioxide concentration promotes its accumulation in trees by regulating the synthesis and transportation genes for endogenous hormones, such as IAA and GA, which are key factors in regulating various life activities, including growth rings. To explore the impact of changes in endogenous hormone levels such as IAA and GA on the growth of tree rings, and to provide a basis for improving the management of hybrid larch clonal forests, we investigated the effects of exogenous indole-3-acetic acid (IAA), gibberellic acid 3 (GA3), and their combination on tree-ring growth in hybrid larch. IAA, GA3, and a combination treatment were sprayed on the leaves of one clone of a hybrid larch seedling every three days. Small blocks were collected at the base stems for sequential anatomical observations. The phytohormone type, instead of the concentration, had a more significant effect on wood formation. Specifically, IAA treatment at 300 mg L−1 significantly increased latewood (LW) layers until 90 days after treatment (DAT). The 500 mg L−1 treatment significantly increased the wall radial thickness (WRT) of latewood (LW) cells. GA3 treatment at 100 mg L−1 significantly decreased the layers and width of total wood (TW), LW, and earlywood (EW). The 300 mg L−1 treatment significantly increased the WRT of EW. The IAA 100 mg L−1 + GA3 100 mg L−1 combination treatment significantly increased the layers and width of TW and LW by inducing cambium activity and increasing the rate of wood cell development. The WRT and lumen radial diameter (LRD) of EW or LW in this treatment were similar to those observed with the corresponding single phytohormone treatment. These results indicate that combination treatment at 100 mg L−1 + 100 mg L−1 was a better way to promote tree-ring growth. Our study suggests that changes in phytohormone levels and ratios are important factors that affect tree-ring formation. Hormone levels and ratios should be regarded as important indicators to guide the improvement of management practices in hybrid larch clonal plantations.
... In fact, in Eucalyptus, GAs activate isopentenyl transferase 3 (IPT3), a key enzyme of metabolism of cytokinin (Q. Y. Liu et al., 2018). Thus, the role of ZEA in sunflower seed germination is consistent with the already known role of the different CKs in germination. ...
Sunflower (Helianthus annuus L.) seed dormancy at harvest is an undesirable characteristic regarding productive systems. From a commercial point of view, the dormancy generates production and marketing problem with a negative impact on crop yields. To overcome this problem, we studied different treatments, including the application of growth regulators. In addition, as the interaction of various hormones in different sunflower fruit parts is not fully understood regarding regulation of dormancy and germination processes, we also (1) characterized the dormancy level of sunflower seeds of Xi3 and X274 inbred lines; (2) assessed the effect of exogenous growth regulators on dormancy release; (3) evaluated the endogenous content of abscisic acid (ABA), gibberellins (GAs), 12‐oxo‐phytodienoic acid (OPDA), jasmonic acid (JA), salicylic acid (SA), auxins, and cytokinins (CKs) in embryonic axis, cotyledons, pericarp, and seed coat‐endosperm; and (4) analyzed the kinetics of the accumulation of these phytohormones in Xi3 embryonic axis during early imbibition (3 to 12 h) of cypselas treated, or not, with growth regulators effective in the dormancy release. We were able to classify the two sunflower lines studied according to dormancy level: The Xi3 line was dormant and X274 line was non‐dormant at harvest. The results showed that the dormancy of Xi3 seeds is associated with a high level of ABA, OPDA, and JA, while germination of X274 dry seeds at harvest time is related to high levels of GA1. Exogenous treatment with GA3 and Ethephon overcame Xi3 seed dormancy through the changes in endogenous hormonal profiles of the embryonic axis. The exogenous application of GA3 induced JA, SA, and CKs accumulation and to modify the ABA/GA1 ratio, whereas Ethephon treatments mediated the ABA/GA1 ratio with the consequent Xi3 seed germination. Thus, the interplay of different phytohormones during early imbibition time seems to be the responsible for breaking sunflower seed dormancy.
... A previous study demonstrated that exogenous application of GA 3 on female papaya increased its height, peduncle length and inflorescence branch number [9]. While plant phenotype is a consequence of complex interactions between plants and environment, aboveground, the vegetative growth and yield were improved by GA 3 application [9,10]. Belowground, however, the responses of roots and rhizosphere (the soil adjacent to the roots) of papaya to the exogenous application have not been studied. ...
Exogenous GAs have an indeterminate effect on root development. Our current study used female papaya to reveal how the roots and rhizosphere respond to the exogenous application of GA3 by investigating the transcriptome profile in roots, metabolic profile and microbial community in both roots and rhizosphere of GA3-treated and control female papaya. The results demonstrated that exogenous GA3 treatment enhanced female papaya lateral root development, which gave plants physical advantages of water and nutrient uptake. In addition, it was likely that GA3 spraying in papaya shoot apices increased the level of auxin, which was transported to roots by CpPIN1, where auxin upregulated CpLBD16 and repressed CpBP to promote the lateral root initiation and development. In papaya roots, corresponding transporters (CpTMT3, CpNRT1:2, CpPHT1;4, CpINT2, CpCOPT2, CpABCB11, CpNIP4;1) were upregulated and excretion transporters were downregulated such as CpNAXT1 for water and nutrients uptake with exogenous GA3 application. Moreover, in GA3-treated papaya roots, CpALS3 and CpMYB62 were downregulated, indicating a stronger abiotic resistance to aluminum toxic and phosphate starvation. On the other hand, BRs and JAs, which involve in defense responses, were enriched in the roots and rhizosphere of GA3-treated papayas. The upregulation of the two hormones might result in the reduction of pathogens in roots and rhizosphere such as Colletotrichum and Verticillium. GA3-treated female papaya increased the abundance of beneficial bacteria species including Mycobacterium, Mitsuaria, and Actinophytocola, but decreased that of the genera Candidatus and Bryobacter for that it required less nitrate. Overall, the roots and rhizosphere of female papaya positively respond to exogenous application of GA3 to promote development and stress tolerance. Treatment of female papaya with GA3 might result in the promotion of lateral root formation and development by upregulating CpLBD16 and downregulating CpBP. GA3-treated papaya roots exhibited feedback control of brassinolide and jasmonate signaling in root development and defense. These findings revealed complex response to a growth hormone treatment in papaya roots and rhizosphere and will lead to investigations on the impact of other plant hormones on belowground development in papaya.
... We found that PBZ downregulated gibberellin synthesis in P. heterophylla, consistent with a previous study in Eucalyptus grandis [22]. In addition, we found that exogenous gibberellin reversed the PBZinduced decreases in gene expression and secondary metabolite levels in root tubers. ...
Background：Pseudostellaria heterophyllais one of the most well-known traditional Chinese medicines, and its secondary metabolites play an important medicinal role. Paclobutrazol (PBZ), an antagonist of the plant hormone gibberellin, is widely used to increase the yield of P. heterophylla. Whether PBZ affects the synthesis and accumulation of the plant’s secondary metabolites is unclear. Here we investigated the effects of PBZ on the production of polysaccharides, saponins and heterophyllin B in the root tubers of P. heterophylla, and further explored its molecular mechanisms.
Results：We found that PBZ promoted the yield of P. heterophylla, but reduced the accumulation of polysaccharides, saponins and heterophyllin B. PBZ dramatically downregulated genes associated with gibberellin synthesis and reduced concentration of the hormone in root tubers. Inhibition of gibberellin signaling by PBZ altered the expression of genes involved in synthesis and metabolism of polysaccharides, saponins and heterophyllin B.Exogenous gibberellin reversed these effects.
Conclusion：These results suggest that PBZ suppresses the synthesis of saponins, polysaccharides and heterophyllin B by antagonizing gibberellin signaling in P. heterophylla, providing important guidance for its cultivation.
... In recent years, it has been found that GA promotes cambial activity [56] and xylogenesis in trees [55,57]. Furthermore, the expression of three CELLULOSE SYNTHASE (CESA) genes in Eucalyptus (CESA3, CESA4, and CESA7), which are involved in xylem development, was induced by GA treatment [58]. Similarly, in birch, application of GA promoted xylem development and induced the expression of genes related to xylogenesis and cellulose production, such as MYB, CESA, and PHENYLALANINE AMMONIA-LYASE (PAL) [59]. ...
Gibberellins have been classically related to a few key developmental processes, thus being essential for the accurate unfolding of plant genetic programs. After more than a century of research, over one hundred different gibberellins have been described. There is a continuously increasing interest in gibberellins research because of their relevant role in the so-called "Green Revolution", as well as their current and possible applications in crop improvement. The functions attributed to gibberellins have been traditionally restricted to the regulation of plant stature, seed germination, and flowering. Nonetheless, research in the last years has shown that these functions extend to many other relevant processes. In this review, the current knowledge on gibberellins homeostasis and mode of action is briefly outlined, while specific attention is focused on the many different responses in which gibberellins take part. Thus, those genes and proteins identified as being involved in the regulation of gibberellin responses in model and non-model species are highlighted. The present review aims to provide a comprehensive picture of the state-of-the-art perception of gibberellins molecular biology and its effects on plant development. This picture might be helpful to enhance our current understanding of gibberellins biology and provide the know-how for the development of more accurate research and breeding programs.
... Moreover, exogenous GA 3 stimulated the mitotic activity of the apical region and increased the rate and duration of cataphyll, resulting in wider and higher apical meristem formation [46]. However, exogenous GAs activated cell expansion and cell division in the cambial region, while they were not involved in xylem differentiation [47]. The application of GAs to plants under short daylight conditions leads to rapid stem elongation and flower formation [48]. ...
(1) The phytohormones gibberellins (GAs) play a crucial role in plant growth and development, such as seed germination, flowering, fruiting, and stem elongation. Although many biological roles of GAs have been studied intensively, the molecular mechanisms of GAs in woody plants are still unclear. (2) In this study, we investigated the effects of exogenous application of GAs on Neolamarckia cadamba. (3) The height and biomass of N. cadamba increased after 7 days of GA treatment, especially on the second internode. Transcriptome analysis showed that although the majority of genes involved in the GA signaling pathway were up-regulated, the expression of GA20 oxidase (GA20ox) and GA3 oxidase (GA3ox) was down-regulated in the 3 days GA-treated group compared to the CK group. The expression of the cell elongation-related basic helix-loop-helix genes bHLH74 and bHLH49 was up-regulated in the GA-treated group compared with the CK group. Transcriptional expression levels of transcription factors involved in hormone signaling were changed, mainly including bHLH, ethylene response factor (ERF), and WRKY families. In addition, the transcriptional expression level of the key enzymes engaged in the phenylalanine pathway was downregulated after GA treatment. (4) In brief, our findings reveal the physiological and molecular mechanisms of exogenous GA treatment stimulation in N. cadamba.
... This GA-dependent regulation has biological effects, such as gravitropism modulation in Arabidopsis roots via PIN2 stabilization [67,68] or xylogenesis promotion in Populus by means of PIN1 upregulation [69]. In Eucalyptus roots and stems, exogenous GA 3 treatment promotes xylogenesis and alters the expression of genes not only related to GA biosynthesis, but also to auxin and secondary cell wall formation [70]. Xylem differentiation from cambium cells was also reported in hypocotyl cuttings of Pinus radiata seedlings treated with indole-butyric acid (IBA) and GA 3 [71]. ...
... To further complicate their interplay, auxin content and signaling are also influenced by GAs. In Eucalyptus roots, GAs upregulate SUPERROOT2 (SUR2), which is involved in auxin homeostasis [70], while in Arabidopsis GA 3 improves root responses to exogenous IAA through the modulation of auxin transporters (AUX1 and PIN1, PIN2 and PIN3) and signaling, as these effects are not detected in Arabidopsis signaling mutants (tir1-1 and axr1-3) [72]. ...
... In tobacco, Jasmonates reduce GA20ox2 levels, thus lowering GA content [97]. DEFECTIVE ANTHER DEHIS-CENCE 1 (DAD1), which intervenes in jasmonate metabolism, is upregulated by GAs in Eucalyptus [70]. Interestingly, the interaction of JA/GA seems to present a cooperative nature in the formation of flower tissues, at least in model species such as Arabidopsis and rice (Castro-Camba et al., under review). ...
Gibberellins are amongst the main plant growth regulators. Discovered over a century ago, the interest in gibberellins research is growing due to their current and potential applications in crop production and their role in the responses to environmental stresses. In the present review, the current knowledge on gibberellins’ homeostasis and modes of action is outlined. Besides this, the complex interrelations between gibberellins and other plant growth regulators are also described, providing an intricate network of interactions that ultimately drives towards precise and specific gene expression. Thus, genes and proteins identified as being involved in gibberellin responses in model and non-model species are highlighted. Furthermore, the molecular mechanisms governing the gibberellins’ relation to stress responses are also depicted. This review aims to provide a comprehensive picture of the state-of-the-art of the current perceptions of the interactions of gibberellins with other phytohormones, and their responses to plant stresses, thus allowing for the identification of the specific mechanisms involved. This knowledge will help us to improve our understanding of gibberellins’ biology, and might help increase the biotechnological toolbox needed to refine plant resilience, particularly under a climate change scenario.
