Cloning and Characterization of TaTGW-7A Gene Associated with Grain Weight in Wheat via SLAF-seq-BSA

Abstract

Thousand-grain weight (TGW) of wheat (<i>Triticum aestivum</i> L.) contributes significantly to grain yield. In the present study, a candidate gene associated with TGW was identified through specific-locus amplified fragment sequencing (SLAF-seq) of DNA bulks of recombinant inbred lines (RIL) derived from the cross between Jing 411 and Hongmangchun 21. The gene was located on chromosome 7A, designated as <i>TaTGW-7A</i> with a complete genome sequence and an open reading frame (ORF). A single nucleotide polymorphism (SNP) was present in the first exon between two alleles at <i>TaTGW-7A</i> locus, resulting in a Val to Ala substitution, corresponding to a change from higher to lower TGW. Cleaved amplified polymorphic sequence (CAPS) (<i>TGW7A</i>) and InDel (<i>TG9</i>) markers were developed to discriminate the two alleles <i>TaTGW-7Aa</i> and <i>TaTGW-7Ab</i> for higher and lower TGW, respectively. A major QTL co-segregating with <i>TaTGW-7A</i> explained 21.7-27.1% of phenotypic variance for TGW in the RIL population across five environments. The association of <i>TaTGW-7A</i> with TGW was further validated in a natural population and Chinese mini-core collections. Quantitative real-time PCR revealed higher transcript levels of <i>TaTGW-7Aa</i> than those of <i>TaTGW-7Ab</i> during grain development. High frequencies of the superior allele <i>TaTGW-7Aa</i> for higher TGW in Chinese mini-core collections (65.0%) and 501 wheat varieties (86.0%) indicated a strong and positive selection of this allele in wheat breeding. The molecular markers <i>TGW7A</i> and <i>TG9</i> can be used for improvement of TGW in breeding programs.