Abstract
Thousand-grain weight (TGW) of wheat (Triticum aestivum 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 TaTGW-7A 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 TaTGW-7A locus, resulting in a Val to Ala substitution, corresponding to a change from higher to lower TGW. Cleaved amplified polymorphic sequence (CAPS) (TGW7A) and InDel (TG9) markers were developed to discriminate the two alleles TaTGW-7Aa and TaTGW-7Ab for higher and lower TGW, respectively. A major QTL co-segregating with TaTGW-7A explained 21.7–27.1% of phenotypic variance for TGW in the RIL population across five environments. The association of TaTGW-7A with TGW was further validated in a natural population and Chinese mini-core collections. Quantitative real-time PCR revealed higher transcript levels of TaTGW-7Aa than those of TaTGW-7Ab during grain development. High frequencies of the superior allele TaTGW-7Aa 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 TGW7A and TG9 can be used for improvement of TGW in breeding programs.
Highlights
MATERIALS AND METHODSThousand-grain weight is the most stable component of wheat grain yield (Giura and Saulescu, 1996)
The results indicated that twenty-five polymorphic SLAF tags closely related to thousand-grain weight (TGW) were identified on six hot regions, and located on chromosomes 2A, 3A, 4B, 6A, 7A, and 7B, respectively, through BLAT analysis (Table 1)
Two full-length open reading frame (ORF) were found in the two hot regions by alignment of SLAF tags sequences with wheat genome sequences
Summary
Thousand-grain weight is the most stable component of wheat grain yield (Giura and Saulescu, 1996). TaGW2, encoding an E3 ubiquitin ligase and associated with GW and TGW, was cloned based on the homologous rice gene GW2 (Su et al, 2011). TaCwiA1 associated with TGW (Ma et al, 2012; Jiang et al, 2015), TaGASR7-A1 for GL and yield (Dong et al, 2014), TaGSD1 for GL and TGW (Zhang et al, 2014), and TaTGW6 encoding an indole-3-acetic acid (IAA)-glucose hydrolase (Hu et al, 2016) have been cloned based on rice gene sequences
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