J Integr Plant Biol. ›› 2014, Vol. 56 ›› Issue (5): 480-491.DOI: 10.1111/jipb.12135

• Research Articles • Previous Articles     Next Articles

Functional analyses of an E3 ligase gene AIP2 from wheat in Arabidopsis revealed its roles in seed germination and pre-harvest sprouting

Dong-Yao Gao1,2†, Zhao-Shi Xu1†, Yi He1, Yong-Wei Sun1, You-Zhi Ma1* and Lan-Qin Xia1*   

  1. 1Institute of Crop Sciences/The National Key Facility for Crop Gene Resources and Genetic Improvement, the Chinese Academy of Agricultural Sciences (CAAS), Beijing, China
    2Agricultural and Sideline Base, Unit 65426 of the People's Liberation Army, Hegang, China
  • Received:2013-06-17 Accepted:2013-11-16 Published:2014-05-01
  • About author:These authors contributed equally to this work.
    **Correspondence: E-mail: xialanqin@caas.cn, mayouzhi@caas.cn

Abstract:

Pre-harvest sprouting (PHS) seriously affects wheat yield and quality of the grain. ABI3 is a key factor in the activation of seed development and repression of germination in Arabidopsis. An ABI3-interacting protein (AIP2) could polyubiquitinate ABI3, impair seed dormancy and promote seed germination in Arabidopsis. In this study, two wheat AIP2 genes, TaAIP2A and TaAIP2B, were isolated. Subcellular localization assay and yeast two-hybrid analysis revealed that TaAIP2A and TaAIP2B may function through interaction with wheat Viviporous-1 (TaVp1). The transcripts TaAIP2A and TaAIP2B were more abundant in wheat PHS susceptible cultivars than that of resistant ones, and decreased gradually following seed development. Expression of TaAIP2A and TaAIP2B in Arabidopsis aip2-1 mutant lines resulted in earlier flowering, promotion of seed germination, and reduced ABA sensitivity, respectively, somehow mimicking the phenotype of the wild type, with TaAIP2B having a stronger role in these aspects. Furthermore, the expression of upstream genes ABI1 and ABI2 were upregulated, whereas that of downstream genes ABI3 and ABI5 were downregulated in both TaAIP2A and TaAIP2B complemented lines upon ABA treatment. These results suggested that wheat AIP2s could negatively regulate the ABA signaling pathway and play important roles in seed germination, and thus wheat PHS resistance finally.

Key words: ABA responsiveness, AIP2, Arabidopsis, E3 ligase, functional analysis, pre-harvest sprouting, Triticum aestivum L.

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