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Integrative Study on Proteomics, Molecular Physiology, and Genetics Reveals an Accumulation of Cyclophilin-Like Protein, TaCYP20-2, Leading to an Increase of Rht Protein and Dwarf in a Novel GA-Insensitive Mutant (gaid) in Wheat

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journal contribution
posted on 06.08.2010, 00:00 by Beibei Li, Wenzhong Xu, Yunyuan Xu, Yuanyuan Zhang, Tai Wang, Yue Bai, Chenggui Han, Aimin Zhang, Zhihong Xu, Kang Chong
Dwarfism with a “Green Revolution” phenotype is a desirable agronomic trait for crop cultivators as associated with increased yield, improved lodging resistance and higher fertility. Few dwarf mutants of hexaploid wheat (Triticum aestivum), except for Rht-B1 and Rht-D1, have been identified. Here, we report on a novel dwarf natural wheat mutant, which is identified as a gibberellic acid (GA)-insensitive dwarf (gaid) mutant for its semidominant blocking GA signaling pathway. Physiological and morphological investigations showed that the shoot elongation of gaid mutant plants is insensitive to exogenous GA3 treatment. Expression of TaGA20ox1 in the gaid mutant was enhanced after GA3 treatment. The short stem of gaid resulted from reduced cell elongation. The transcript expression of Rht, encoding a DELLA protein negatively regulating GA signaling in wheat, displayed similar patterns between gaid and wild type. Contrarily, the degradation of Rht induced by GA3 treatment was suppressed in the mutant. 2-DE screening assay showed that the expression patterns of the mutant, as well as their responses to GA3, were changed as compared with the wild type. In the mutant, one of enriched proteins was identified as TaCYP20-2 by Q-TOF MS approach and immunoblotting. TaCYP20-2 was localized in the chloroplast and cell plasma membrane. The transcript of TaCYP20-2 was higher in gaid than that in wild type. Molecular genetic data showed that overexpression of TaCYP20-2 in wheat resulted in a dwarfism similar to that of gaid. It suggests that TaCYP20-2 is a new member that regulates wheat stem development mediated by DELLA protein degradation of GA signaling pathway.