Abstract
SummaryKernel size is an important trait determining cereal yields. In this study, we cloned and characterized TaDA1, a conserved negative regulator of kernel size in wheat (Triticum aestivum). The overexpression of TaDA1 decreased the size and weight of wheat kernels, while its down‐regulation using RNA interference (RNAi) had the opposite effect. Three TaDA1‐A haplotypes were identified in Chinese wheat core collections, and a haplotype association analysis showed that TaDA1‐A‐HapI was significantly correlated with the production of larger kernels and higher kernel weights in modern Chinese cultivars. The haplotype effect resulted from a difference in TaDA1‐A expression levels between genotypes, with TaDA1‐A‐HapI resulting in lower TaDA1‐A expression levels. This favourable haplotype was found having been positively selected during wheat breeding over the last century. Furthermore, we demonstrated that TaDA1‐A physically interacts with TaGW2‐B. The additive effects of TaDA1‐A and TaGW2‐B on kernel weight were confirmed not only by the phenotypic enhancement arising from the simultaneous down‐regulation of TaDA1 and TaGW2 expression, but also by the combinational haplotype effects estimated from multi‐environment field data from 348 wheat cultivars. A comparative proteome analysis of developing transgenic and wild‐type grains indicated that TaDA1 and TaGW2 are involved in partially overlapping but relatively independent protein regulatory networks. Thus, we have identified an important gene controlling kernel size in wheat and determined its interaction with other genes regulating kernel weight, which could have beneficial applications in wheat breeding.
Highlights
Common wheat (Triticum aestivum L., AABBDD) is a major staple crop in the world
TaDA1 was identified as the closest homolog of AtDA1 and ZmDA1, and its homoeologs were located on chromosomes 2A, 2B, and 2D (Table S1; Figure S1)
TaDA1 negatively regulate kernel size with TaGW2 1331 conservation suggests that TaDA1 may have similar biological functions to AtDA1 and ZmDA1
Summary
Common wheat (Triticum aestivum L., AABBDD) is a major staple crop in the world. With growing global population and increasing demand for wheat, wheat yields must be further improved. Grain weight and size are major components of wheat yield and are key targets for the further improvement of this crop (Li and Yang, 2017; Mohler et al, 2016; Xie et al, 2015). Based on the knowledge of their counterparts in rice (Oryza sativa), these genes are predicted to function in diverse signalling pathways, including proteasomal degradation, phytohormone signalling, and starch biosynthesis (Zuo and Li, 2014). They are known to regulate grain size or grain filling, the interactions between these different regulators and the overall regulatory network underlying grain development remain to be elucidated
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