Genome-wide association study revealed that the TaGW8 gene was associated with kernel size in Chinese bread wheat

Abstract

Using Wheat 90 K SNP assay, kernel-related traits of Chinese bread wheat were used to perform association mapping in 14 environments by GWAS. Results indicated that 996 and 953 of 4417 and 3172 significant SNPs for kernel length and thousand-kernel weight were located on the chromosome 7B. Haplotype analysis of these SNPs on 7B generated the block containing the predicted TaGW8-B1 gene. TaGW8-B1 gene was further cloned by sequencing in bread wheat and a 276-bp InDel was found in the first intron. TaGW8-B1 without and with the 276-bp InDel were designated as TaGW8-B1a and TaGW8-B1b , respectively. Analysis of agronomic traits indicated that cultivars with TaGW8-B1a possessed significantly wider kernel width, significantly more kernel number per spike, longer kernel length, higher thousand-kernel weight and more spikelet number per spike than cultivars with TaGW8-B1b . Furthermore, cultivars with TaGW8-B1a possessed significantly higher yield than cultivars with TaGW8-B1b . Therefore, TaGW8-B1a was considered as a potentially superior allele. Meanwhile, TaGW8-B1a possessed a significantly higher expression level than TaGW8-B1b in mature seeds by qRT-PCR. It possibly suggested that the high expression of TaGW8-B1 was positively associated with kernel size in bread wheat. Distribution of TaGW8-B1 allele indicated that TaGW8-B1a has been positively selected in Chinese wheat.

Molecular Mapping and Genomics of Grain Yield in Durum Wheat: A Review

“…Recently, four QTLs were identified on chromosomes 2A, 5A and 7B, explaining between 5.5% and 6.8% of the kernel width variance [ 30 ]. The QTLs for KL (at 20.75 cM) and KW (at 66.36 cM) identified on chromosome 7B were localized in the same regions as the TaCYP78A3 and TaGW8 genes reported by Ma et al [ 72 ] and Yan et al [ 73 ], respectively, on chromosome 7 of common wheat. Sun et al [ 17 ] performed an association study for kernel-related traits in a worldwide collection of durum wheat germplasm.…”

“…Moreover, Simmonds et al [ 118 ] reported that null mutants for TaGW2-A1 were associated with an increase in the TKW (6.6%), KW (2.8%) and KL (2.1%) in tetraploid and hexaploid wheat compared to the wild type allele. Additionally, Alemu et al [ 30 ] identified two QTLs for KL (at 20.75 cM) and KW (at 66.36 cM) on chromosome 7B, which were localized in the same regions as the TaCYP78A3 and TaGW8 genes reported by Ma et al [ 72 ] and Yan et al [ 73 ], respectively, on chromosome 7 of common wheat. Moreover, Sun et al [ 17 ] annotated a total of 54 candidate genes for kernel-related traits in a worldwide collection of durum wheat germplasm, which were divided into several categories, where most of them encoded metabolism-related enzymes, and some of them were involved in kernel development.…”

Appraising the Genetic Architecture of Kernel Traits in Hexaploid Wheat Using GWAS

“…Most of the SNPs for TKW were located on 7A. Similarly, SNPs for TKW located on chromosome 7A have been previously reported in several studies [76,77,85]. In our study, we retrieved high-confidence candidate genes surrounding (±200 kb) the peak SNPs, based on the annotated wheat reference genome IWGSC RefSeq v1.0 [86].…”

Gene editing of the wheat homologs of TONNEAU1‐recruiting motif encoding gene affects grain shape and weight in wheat

“…Our data suggested that only one of the TaGW7 haplotypes or its close derivatives reached high frequency in domesticated and cultivated wheats. This observation can potentially explain the lack of overlap between the TaGW7 gene and previously identified QTL for yield component traits (Rasheed et al ., ; Zanke et al ., ; Yan et al ., ). It is possible that wheat populations have been nearly fixed for the beneficial alleles of TaGW7 precluding the identification of their phenotypic effects using genome‐wide association mapping.…”

“…Yield component traits affecting grain size, shape and weight have been the subject of extensive genetic studies in a number of crops aimed to identify genes controlling these traits (Song et al ., ; Takano‐Kai et al ., ; Segami et al ., ; Wang et al ., ; Wang et al ., ; Xie et al ., ; Wang et al ., 2018b). Recently, several genes contributing to grain size and/or weight including TaGW2 (Wang et al ., 2018a,b), TaCKX2 (Zhang et al ., 2012a), TaGASR7 (Zhang et al ., ), TaTGW‐7A (Hu et al ., ), and TaGW8 (Yan et al ., ) have been identified providing insights into the complexity of biological pathways that underlie regulation of grain size and weight in wheat. Many genes identified in wheat have rice homologs with similar function indicating that these developmental pathways are conserved among related grass species (Li and Li, ; Li et al ., ).…”