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- Title
Molecular Characterization of Rht-1 Dwarfing Genes in Hexaploid Wheat.
- Authors
Pearce, Stephen; Saville, Robert; Vaughan, Simon P.; Chandler, Peter M.; Wilhelm, Edward P.; Sparks, Caroline A.; Al-Kaff, Nadia; Korolev, Andrey; Boulton, Margaret I.; Phillips, Andrew L.; Hedden, Peter; Nicholson, Paul; Thomas, Stephen G.
- Abstract
The introduction of the Reduced height (Rht)-B1b and Rht-D1b semidwarfing genes led to impressive increases in wheat (Triticum aestiwm0 yields during the Green Revolution. The reduction in stem elongation in varieties containing these alleles is caused by a limited response to the phytohormone gibberellin (GA), resulting in improved resistance to stem lodging and yield benefits through an increase in grain number. Rht-B1 and Rht-D1 encode DELLA proteins, which act to repress GA-responsive growth, and their mutant alleles Rht-B1b and Rht-D1b are thought to confer dwarfism by producing more active forms of these growth repressors. While no semidwarfing alleles of Rht-A1 have been identified, we show that this gene is expressed at comparable levels to the other homeologs and represents a potential target for producing novel dwarfing alleles. In this study, we have characterized additional dwarfing mutations in Rht-B1 and Rht-D1. We show that the severe dwarfism conferred by Rht-B1c is caused by an intragenic insertion, which results in an in-frame 90-bp insertion in the transcript and a predicted 30-amino acid insertion within the highly conserved amino-terminal DELLA domain. In contrast, the extreme dwarfism of Rht-D1c is due to overexpression of the semidwarfing Rht-D1b allele, caused by an increase in gene copy number. We show also that the semidwarfing alleles Rht-B1d and Rht-B1e introduce premature stop codons within the amino-terminal coding region. Yeast two-hybrid assays indicate that these newly characterized mutations in Rht-B1 and Rht-D1 confer "GA-insensitive" dwarfism by producing DELLA proteins that do not bind the GA receptor GA INSENSITIVE DWARF1, potentially compromising their targeted degradation.
- Subjects
DWARFISM; PLANT genetics; WHEAT; GREEN Revolution; PHYSIOLOGICAL effects of gibberellins; PLANTS
- Publication
Plant Physiology, 2011, Vol 157, Issue 4, p1820
- ISSN
0032-0889
- Publication type
Article
- DOI
10.1104/pp.111.183657