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Title: Gibberellin hormone signal perception: down-regulating DELLA repressors of plant growth and development

Author
item NELSON, SVEN - Washington State University
item Steber, Camille

Submitted to: Annual Plant Reviews
Publication Type: Book / Chapter
Publication Acceptance Date: 1/1/2016
Publication Date: 2/10/2016
Citation: Nelson, S.K., Steber, C.M. 2016. Gibberellin hormone signal perception: down-regulating DELLA repressors of plant growth and development. Annual Plant Reviews. 49:153-188.

Interpretive Summary: The plant hormone GA (gibberellin, gibberellic acid) controls many developmental transitions that are important for crop plant health and yield. GA stimulates seed germination. Understanding this is important for controlling preharvest sprouting and good seedling emergence, a key trait for obtaining good yield. GA also stimulates plant stem elongation. GA-insensitive semi-dwarf mutants led to the increase in yield called the green revolution by preventing plants from getting spindly and falling over in response to modern fertilizers. Finally, GA stimulates the transition to flowering (flowering time) and fertility. These are both yield-determining traits. The chapter reviews how the GA hormone signal is perceived in the plant, and mechanisms leading to changes in plant growth and development.

Technical Abstract: The gibberellin (GA) hormone signal is perceived by a receptor with homology to hormone sensitive lipases, GID1 (GA-INSENSITIVE DWARF1). This leads to GA-stimulated responses including stem elongation, seed germination, and the transition to flowering. GA-binding enables GID1 to interact with and block the function of the DELLA (Asp-Glu-Leu-Leu-Ala) repressors of GA responses. DELLA repression can be blocked both by proteolytic and non-proteolytic mechanisms triggered by the formation of a GID1-GA-DELLA complex. DELLA is down-regulated by the SLEEPY1/GID2 F-box proteins via the ubiqutin-proteasome pathway, and can be regulated by other posttranslational modifications. This chapter reviews the structural requirements for GA-binding by GID1 and for GID1-GA-DELLA protein complex formation, and reviews the current understanding of the mechanisms regulating DELLA repressors.