Identification of heat tolerance loci in broccoli through bulked segregant analysis using whole genome resequencing
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Most broccoli cultivars are sensitive to high temperatures during the early stages of floral development causing a severe decline of head quality or even complete lack of head formation under superoptimal crop production temperatures. Several heat tolerant lines have been developed in recent years but there have been few studies of the genetic basis of this complex, polygenic trait. A doubled haploid population of broccoli was evaluated for head quality across two summer field trials with the phenotypic extremes validated in two additional summer fields. Whole-genome resequencing of the bulked segregants was used for a quantitative trait loci (QTL)-seq analysis of heat tolerance. Two novel QTL, which differ from previously reported QTL, were identified. Nonsynonymous SNPs were found in a block of flowering time genes within QHT_C09.2 and may explain the significant negative correlation between time to head maturity and heat tolerance. Breeding further genetic gains in this complex, polygenic trait could be expedited through marker assisted selection and gene pyramiding using markers developed from the QTL identified herein.
KeywordsBroccoli Heat tolerance Bulked segregant analysis QTL-seq Brassica oleracea
This study was funded by the United States Department of Agriculture, Project No. 6080-21000-018-00 and the National Institute of Food and Agriculture, Project No. 2010-51181-21062. The authors would like to thank Zachary J. Stansell and David M. Couillard for their technical assistance.
Compliance with ethical standards
Conflict of interest
The authors declare that they have no conflict of interest.
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