Gibberellic acid

About: Gibberellic acid is a research topic. Over the lifetime, 6597 publications have been published within this topic receiving 109294 citations. The topic is also known as: GIBBERELLIN A3.

Physiological response of vicia faba to prohexadione-calcium under saline conditions

Abstract: Changes in the activities of oxidative enzymes (indole acetic acid oxidase, peroxidase and catalase), endogenous hormones (gibberellic acid (GA3), indole acetic acid (IAA), abscisic acid (ABA) and cytokinins (AsZeatin), photosynthetic pigments (chlorophyll a, chlorophyll b and carotenoids), total carbohydrates, total soluble sugars, amino acid proline and vegetative growth parameters were used as indicators to explain the physiological role of the growth retardant prohexadione-calcium on Vicia faba seedlings 40 days after sowing under salinity stress for 30 days. The obtained results show that soaking faba bean seeds prior to sowing at different concentrations of prohexadione-calcium (0, 10, 20 and 30 ppm) significantly increased the activities of indole acetic acid oxidase (IAA-oxidase) and peroxidase enzymes, but decreased the catalase enzyme activity as compared with their respective control. Application of prohexadione-Ca caused markedly decreases in the endogenous contents of gibberellins and indole acetic acid (IAA) but increased the levels of natural growth inhibitor abscisic acid (ABA) and cytokinins in the shoots of faba bean seedlings. All the prohexadione-Ca concentrations increased the contents of amino acid proline, photosynthetic pigments (chlorophyll a, chlorophyll b and carotenoids), total carbohydrates and total soluble sugars in faba bean seedlings grown under salt stress. Application of prohexadione-Ca decreased significantly seedling height and shoot fresh weight but significantly increased shoot dry weight.

Dynamics of endogenous hormone regulation in plants by phytohormone secreting rhizobacteria under water-stress

Abstract: Although the physiological benefits of plant growth promoting rhizobacteria (PGPR) to plants are well known, the precise mechanisms that make these PGPR such wonderful friends of plants under adverse environmental conditions are still under investigation. We have previously reported that one such PGPR, Pseudomonas putida GAP-P45 ameliorates the adverse effects of water deficit in Arabidopsis thaliana by upregulating proline turnover and polyamine biosynthesis (Ghosh et al. Ann Microbiol 67:655–668, 2017; Sen et al. Plant Physiol Biochem 129:180–188, 2018). In this study, we investigated the impact of this phytohormone secreting strain on the regulation of endogenous phytohormone (abscisic acid, auxin, cytokinin and gibberellic acid) modulation in A. thaliana under normal and water stress conditions. We analyzed the content of all four phytohormones secreted by the bacteria in the nutrient medium as well as in the roots and shoots (separately) of the inoculated plants at three different days, post treatments. We observed that, while water stress increased the accumulation of abscisic acid and decreased the content of auxin and cytokinin in shoots and roots; the level of gibberellic acid decreased in shoots but increased in roots due to stress. Inoculation with GAP-P45 under water stress effectively reversed the trends of phytohormone accumulation, making their levels similar to the non-stressed, non-inoculated control plants. This happened despite there being no change in the water-potential of the medium due to GAP-P45 inoculation. We also observed that the pattern of phytohormones secreted by the PGPR varied depending on composition of nutrient media and culture conditions. We conclude that P. putida GAP-P45 alleviates water stress in A. thaliana by altering the endogenous hormone accumulation and re-distribution in both roots and shoots without causing any change to the water-potential of the medium.

Halo-tolerant rhizospheric Arthrobacter woluwensis AK1 mitigates salt stress and induces physio-hormonal changes and expression of GmST1 and GmLAX3 in soybean

Abstract: In the present study rhizospheric bacteria were isolated from sand dune-dwelling Artemisia princeps, Chenopodium ficifolium, Oenothera biennis, and Echinochloa crus-galli and evaluated the ability of the bacterial isolates to produce jasmonic acid (JA) and abscisic acid (ABA) under NaCl-induced salt stress. We observed that 7 of 126 bacterial isolates were capable of producing siderophores, gibberellic acid (GA), indole-3-acetic acid (IAA), phosphate solubilisation, organic acids e.g., quinic acid, succinic acid, acetic acid and butyric acid. A bioassay of the seven selected isolates on rice showed that the isolate AK1 significantly promoted rice growth. Moreover, AK1 produced IAA and ABA in broth spiked with elevated levels of NaCl (100 mM, 200 mM, 300 mM, and 400 mM). The isolate AK1 was further investigated for plant growth promotion and mitigation of NaCl-induced salt stress in soybean grown under 100 mM, 200 mM, and 300 mM stress. Application of AK1 upregulated the expression of GmLAXs, and GmST genes in plants exposed to salt stress as compared to uninoculated plants. Interestingly, the bacteria-treated soybean showed significant increase in growth attributes with or without salinity stress. The endogenous ABA and JA level of inoculated soybean plants declined under elevated salt stress, thus showing an enhanced stress mitigation. A similar ameliorative trend was observed for total proteins, polyphenol oxidase, and peroxidase activity under saline conditions. The isolate AK1 was identified as Arthrobacter woluwensis AK1 based on its 16S rDNA gene sequencing and subsequent phylogenetic analysis.

Stimulation of in vitro shoot proliferation from nodal explants of cassava by thidiazuron, benzyladenine and gibberellic acid

Abstract: Multiple shoots were produced from nodal explants of cassava (Manihot esculenta Crantz) by a two-step procedure: a 6- to 8-day exposure to 0.11–0.22 µM thidiazuron (TDZ) in liquid Murashige and Skoog (MS) medium followed by culture on agar-solidified MS medium supplemented with 2.2 µM 6-benzyladenine (BA) and 1.6 μM gibberellic acid (GA3). TDZ caused the nodal explants to expand and this expansion (growth) continued during culture with BA and GA3. From this expanded explant, clusters of buds and fasciated stems developed continuously and these gave rise to shoots. The shoot proliferation process was open-ended, yielding an average of 31.5 shoots per nodal explant after 10 weeks of culture with genotype CG 1–56. A positive response was also obtained from seven other genotypes evaluated with this protocol.