Genetic dissection of a major QTL for kernel weight spanning the Rht-B1 locus in bread wheat
Genetic dissection uncovered a major QTL QTKW.caas-4BS corresponding with a 483 kb deletion that included genes ZnF, EamA and Rht-B1. This deletion was associated with increased grain weight and semi-dwarf phenotype.
Previous studies identified quantitative trait loci (QTL) for thousand kernel weight (TKW) in the region spanning the Rht-B1 locus in wheat (Triticum aestivum L.). We recently mapped a major QTL QTKW.caas-4BS for TKW spanning the Rht-B1 locus in a recombinant inbred line (RIL) population derived from Doumai/Shi 4185 using the wheat 90K array. The allele from Doumai at QTKW.caas-4BS significantly increased TKW and kernel number per spike, and conferred semi-dwarf trait, which was beneficial to improve grain yield without a penalty to lodging. To further dissect QTKW.caas-4BS, we firstly re-investigated the genotypes and phenotypes of the RILs and confirmed the QTL using cleaved amplified polymorphic sequence (CAPS) markers developed from flanking SNP markers IWA102 and IWB54814. The target sequences of the CAPS markers were used as queries to BLAST the wheat reference genome RefSeq v1.0 and hit an approximate 10.4 Mb genomic region. Based on genomic mining and SNP loci from the wheat 660K SNP array in the above genomic region, we developed eight new markers and narrowed QTKW.caas-4BS to a genetic interval of 1.5 cM. A 483 kb deletion in Doumai corresponded with QTKW.caas-4BS genetically, including three genes ZnF, EamA and Rht-B1. The other 15 genes with either differential expressions and/or sequence variations between parents were also potential candidate genes for QTKW.caas-4BS. The findings not only provide a toolkit for marker-assisted selection of QTKW.caas-4BS but also defined candidate genes for further functional analysis.
Cleaved amplified polymorphic sequence
Derived cleaved amplified polymorphic sequence
Genome-wide association study
Inclusive composite interval mapping
Kompetitive allele-specific PCR
Kernel number per spike
Logarithm of odds
Open reading frame
Quantitative trait locus
Recombinant inbred line
Spike number per square meter
Single nucleotide polymorphism
Simple sequence repeat
Thousand kernel weight
The authors are grateful to Prof. R. A. McIntosh, Plant Breeding Institute, University of Sydney, for review of this manuscript. This work was funded by the National Key Research and Development Programs of China (2016YFD0101802), National Key Technology R & D Program of China (2014BAD01B05) and CAAS Science and Technology Innovation Program.
Compliance with ethical standards
Conflict of interest
The authors declare no conflicts of interest in regard to this manuscript.
We declare that these experiments comply with the ethical standards in China.
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