Genetic basis of ABA-GA hormonal cross-talk in the control of flowering time in Arabidopsis

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Breve resumo:
Abscisic acid (ABA) and Gibberellins (GA) are two key plant hormones mediating environmental responses. Both hormones play an important role in plant growth and development. Mutants deficient in the production of ABA and GA share phenotypic similarities such as a dwarf phenotype, the production of dark green leafs, and a late flowering phenotype, which suggests that is possible that both hormones share the same influence in the DELLA degradation process and have similar molecular targets. On the other hand literature suggests that ABA and GA are antagonist, for example Gibberellins promotes germination and ABA inhibits it. ABA is commonly related to osmotic/drought stress and the regulation of water balance, but how these effects are integrated with GA is still poorly understood. GA signaling is mediated by DELLA proteins, belonging to a plant specific family of putative transcription regulators, that act as repressors of GA responses. The current model of GA action proposes that DELLA proteins restrain plant growth whereas the GA promotes growth by overcoming DELLA-mediated growth restraint. To understand the basis of the hormonal cross-talk between ABA and GA, mutants of Arabidopsis DELLA genes 鈥 GAI, RGA, RGL1, RGL2 and RGL3 鈥 and mutants involved in ABA biosynthetic and signaling pathways 鈥 ABA1 and ABI1 鈥 were crossed and verified by PCR. In parallel, Western Blot essays were preformed to study the accumulation of DELLA proteins in ABA deficient and signaling mutants. Related to this cross-talk, previous literature shows that there is an accumulation of DELLA proteins in ABA-defective mutants 鈥 ABA1. The present study suggests that this accumulation also happens in ABI-defective mutants 鈥 ABI1. Therefore, this supports the idea that ABA has an important role in DELLA function, perhaps through the control of its degradation.​



Info Adicional:
Abscisic acid (ABA) and Gibberellins (GA) are two key plant hormones mediating environmental responses. Both hormones play an important role in plant growth and development. Mutants deficient in the production of ABA and GA share phenotypic similarities such as a dwarf phenotype, the production of dark green leafs, and a late flowering phenotype, which suggests that is possible that both hormones share the same influence in the DELLA degradation process and have similar molecular targets. On the other hand literature suggests that ABA and GA are antagonist, for example Gibberellins promotes germination and ABA inhibits it. ABA is commonly related to osmotic/drought stress and the regulation of water balance, but how these effects are integrated with GA is still poorly understood. GA signaling is mediated by DELLA proteins, belonging to a plant specific family of putative transcription regulators, that act as repressors of GA responses. The current model of GA action proposes that DELLA proteins restrain plant growth whereas the GA promotes growth by overcoming DELLA-mediated growth restraint. To understand the basis of the hormonal cross-talk between ABA and GA, mutants of Arabidopsis DELLA genes 鈥 GAI, RGA, RGL1, RGL2 and RGL3 鈥 and mutants involved in ABA biosynthetic and signaling pathways 鈥 ABA1 and ABI1 鈥 were crossed and verified by PCR. In parallel, Western Blot essays were preformed to study the accumulation of DELLA proteins in ABA deficient and signaling mutants. Related to this cross-talk, previous literature shows that there is an accumulation of DELLA proteins in ABA-defective mutants 鈥 ABA1. The present study suggests that this accumulation also happens in ABI-defective mutants 鈥 ABI1. Therefore, this supports the idea that ABA has an important role in DELLA function, perhaps through the control of its degradation.



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