Gibberellin Metabolism and its Regulation

Abstract

Bioactive gibberellins (GAs) are diterpene plant hormones that are biosynthesized through complex pathways and control diverse aspects of growth and development. Biochemical, genetic, and genomic approaches have led to the identification of the majority of the genes that encode GA biosynthesis and deactivation enzymes. Recent studies have highlighted the occurrence of previously unrecognized deactivation mechanisms. It is now clear that both GA biosynthesis and deactivation pathways are tightly regulated by developmental, hormonal, and environmental signals, consistent with the role of GAs as key growth regulators. In some cases, the molecular mechanisms for fine-tuning the hormone levels are beginning to be uncovered. In this review, I summarize our current understanding of the GA biosynthesis and deactivation pathways in plants and fungi, and discuss how GA concentrations in plant tissues are regulated during development and in response to environmental stimuli.

New insight in the Gibberellin biosynthesis and signal transduction

“…Yi Chen 1 and Bao-Cai Tan 2, * 1 School of Life Sciences; The Chinese University of Hong Kong, Shatin, NT, Hong Kong; 2 Key laboratory of Plant Cell Engineering and Germplasm Innovation;…”

“…GA biosynthesis is believed to occur in 3 compartments within the cell. 1 The first phase from geranylgeranyl diphosphate (GGDP) to ent-kaurene occurs in plastids; the second phase from ent-kaurene to GA 12 in the plastid envelope and endoplasmic reticulum (ER); and the final phase from GA 12 to bioactive GAs in the cytosol (Fig. 1).…”

Attenuation of low-temperature stress in rice seedlings

“…At 7 and 14 DAS, significant differences were found only in the 'Puita Inta CL' cultivar, with an increase in H 2 O 2 production in the roots of plants treated with GA 3 . Gibberellins are effective in stimulating mesocotyl elongation, promoting a rapid development of the seedling shoot (Yamaguchi 2008, Dai & Xue 2010. However, when shoot growth becomes excessive, the seedling moves its metabolites to nourish the organ at the expense of root development.…”

Physiological, morphological and biochemical characteristics of the sexual propagation of Piper aduncum (Piperaceae)

“…In these species, light can regulate the content of GA-modulated expression of genes encoding enzymes that participate in the biosynthesis and deactivation of GA (Sawada et al. , Yamaguchi 2008, Seo et al 2009). Perhaps the seeds of P. aduncum are not responsive to the application of GA 3 but to other gibberellins, such as GA 1 as in lettuce seeds (Sawada et al 2008) or GA 4 and GA 7 as in seeds of Taxus mairei (Chien et al 1998).…”

“…At high temperatures, termo-inhibition may occur due to induction of ABA synthesis and repression of GA (Toh et al 2008) and in addition the growth potential of the embryo is markedly reduced (Nonogaki 2006). On the other hand, endogenous levels of GA are increased at low temperatures (Penfield 2008, Yamaguchi 2008. Thus, there is a relationship between requirement for light, temperature and levels of GA (Seo et al 2009).…”