Vol. 10, Special Issue 10 (2021)

Author(s):
G Adhithya

Abstract:
Gibberellins (GAs) are a family of diterpenoid compounds produced by plants. The major bioactive GAs are GA1, GA4 and most agriculturally used is GA3 which affect wide range of processes during seed germination, plant development, leaf expansion, stem elongation to flower initiation and development of flowers, fruits and seeds. DELLA proteins belong to a subfamily of the plant-specific GRAS protein (GAI, RGA and SCARECROW) and are negative regulators of GA signaling that act immediately downstream of the GA receptor. DELLA repressors have an N-terminal DELLA regulatory domain containing the conserved amino acid sequence Asp-Glu-Leu-Leu-Ala and C- terminal GRAS functional domain. The first DELLA protein isolated was the ga-1(gibberellins deficient mutant) of Arabidopsis as inframe deletion motif and its orthologues in other species encode nucleus-localized proteins that act as transcription factor and appearS to be negative regulators which includes several RGA (repressor-of-ga1-3), RGL1 (RGA-like1), RGL2 and RGL3 in the GA-signal transduction pathway. The role of DELLA mediated GA signaling in relation to the gibberellin- stimulated synthesis and secretion of alpha- amylase in aleurone layers are explained by biochemical and molecular mechanisms.