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Rht18 semidwarfism in wheat Is due to increased GA 2-oxidaseA9 expression and reduced GA content


Ford, BA and Foo, E and Sharwood, R and Karafiatova, M and Vrana, J and MacMillan, C and Nichols, DS and Steuernagel, B and Uauy, C and Dolezel, J and Chandler, PM and Spielmeyer, W, Rht18 semidwarfism in wheat Is due to increased GA 2-oxidaseA9 expression and reduced GA content, Plant Physiology, 177, (1) pp. 168-180. ISSN 1532-2548 (2018) [Refereed Article]

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Copyright 2018 American Society of Plant Biologists. All Rights Reserved.

DOI: doi:10.1104/pp.18.00023


Semidwarfing genes have improved crop yield by reducing height, improving lodging resistance, and allowing plants to allocate more assimilates to grain growth. In wheat (Triticum aestivum), the Rht18 semidwarfing gene was identified and deployed in durum wheat before it was transferred into bread wheat, where it was shown to have agronomic potential. Rht18, a dominant and gibberellin (GA) responsive mutant, is genetically and functionally distinct from the widely used GA-insensitive semidwarfing genes Rht-B1b and Rht-D1b. In this study, the Rht18 gene was identified by mutagenizing the semidwarf durum cultivar Icaro (Rht18) and generating mutants with a range of tall phenotypes. Isolating and sequencing chromosome 6A of these "overgrowth" mutants showed that they contained independent mutations in the coding region of GA2oxA9. GA2oxA9 is predicted to encode a GA 2-oxidase that metabolizes GA biosynthetic intermediates into inactive products, effectively reducing the amount of bioactive GA (GA1). Functional analysis of the GA2oxA9 protein demonstrated that GA2oxA9 converts the intermediate GA12 to the inactive metabolite GA110. Furthermore, Rht18 showed higher expression of GA2oxA9 and lower GA content compared with its tall parent. These data indicate that the increased expression of GA2oxA9 in Rht18 results in a reduction of both bioactive GA content and plant height. This study describes a height-reducing mechanism that can generate new genetic diversity for semidwarfism in wheat by combining increased expression with mutations of specific amino acid residues in GA2oxA9.

Item Details

Item Type:Refereed Article
Keywords:gibberellins, plant hormones, semidwarfism
Research Division:Biological Sciences
Research Group:Plant biology
Research Field:Plant physiology
Objective Division:Plant Production and Plant Primary Products
Objective Group:Environmentally sustainable plant production
Objective Field:Environmentally sustainable plant production not elsewhere classified
UTAS Author:Foo, E (Associate Professor Eloise Foo)
UTAS Author:Nichols, DS (Dr David Nichols)
ID Code:126868
Year Published:2018
Web of Science® Times Cited:66
Deposited By:Central Science Laboratory
Deposited On:2018-06-29
Last Modified:2021-08-17

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