Abstract
BackgroundKernel weight and morphology are important traits affecting cereal yields and quality. Dissecting the genetic basis of thousand kernel weight (TKW) and its related traits is an effective method to improve wheat yield.ResultsIn this study, we performed quantitative trait loci (QTL) analysis using recombinant inbred lines derived from the cross ‘PuBing3228 × Gao8901’ (PG-RIL) to dissect the genetic basis of kernel traits. A total of 17 stable QTLs related to kernel traits were identified, notably, two stable QTLs QTkw.cas-1A.2 and QTkw.cas-4A explained the largest portion of the phenotypic variance for TKW and kernel length (KL), and the other two stable QTLs QTkw.cas-6A.1 and QTkw.cas-7D.2 contributed more effects on kernel width (KW). Conditional QTL analysis revealed that the stable QTLs for TKW were mainly affected by KW. The QTLs QTkw.cas-7D.2 and QKw.cas-7D.1 associated with TKW and KW were delimited to the physical interval of approximately 3.82 Mb harboring 47 candidate genes. Among them, the candidate gene TaFT-D1 had a 1 bp insertions/deletion (InDel) within the third exon, which might be the reason for diversity in TKW and KW between the two parents. A Kompetitive Allele-Specific PCR (KASP) marker of TaFT-D1 allele was developed and verified by PG-RIL and a natural population consisted of 141 cultivar/lines. It was found that the favorable TaFT-D1 (G)-allele has been positively selected during Chinese wheat breeding. Thus, these results can be used for further positional cloning and marker-assisted selection in wheat breeding programs.ConclusionsSeventeen stable QTLs related to kernel traits were identified. The stable QTLs for thousand kernel weight were mainly affected by kernel width. TaFT-D1 could be the candidate gene for QTLs QTkw.cas-7D.2 and QKw.cas-7D.1.
Highlights
Kernel weight and morphology are important traits affecting cereal yields and quality
Using a recombinant inbred line (RIL) population derived from ‘PuBing 3228 (P3228) × Gao8901 (G8901)’, the objectives of this study were to (i) identify stable and major quantitative trait loci (QTL) for thousand kernel weight (TKW), kernel length (KL), kernel width (KW) and kernel width (KL/W) under different field conditions; (ii) reveal the contribution of the other kernel traits to TKW using conditional QTL analysis; (iii) predict candidate gene(s) for targeted QTLs interval based on reference genome annotation information; (iv) develop Kompetitive Allele-Specific PCR (KASP) markers of the candidate gene(s) and verified by ‘PuBing3228 × Gao 8901’ recombinant inbred lines (PG-RIL) and a natural population consisted of 141 cultivar/lines for markerassisted selection in high-TKW wheat breeding
After screening PG-RIL and a natural population consisted of 141 cultivar/ lines using these KASP markers, we found that the KASP marker of TaFT-D1 was co-segregated with single nucleotide polymorphism (SNP) marker AX-111184541
Summary
Kernel weight and morphology are important traits affecting cereal yields and quality. Dissecting the genetic basis of thousand kernel weight (TKW) and its related traits is an effective method to improve wheat yield. Wheat yield is determined by thousand kernel weight (TKW), kernel number per spike, and effective tiller number [1]. Exploring the genetic variation of TKW and its related traits is an effective approach to increase wheat yield [4]. TaGW2 and TaDA1, which encode an E3 RING ligase [13,14,15] and a ubiquitin receptor [16], respectively Both of them are conserved component of the ubiquitin-proteasome pathway and negatively regulate wheat kernel size. Genes involved in starch and sucrose metabolism pathways affect wheat kernel size, such as the cell wall invertase TaCwi-A1 [19], the sucrose synthases TaSus and TaSus2 [20], ADP-glucose pyrophosphorylase TaAGP-S1-7A and TaAGP-L-1B [21]
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