Quantitative Trait Locus Mapping and Identification of Candidate Genes Controlling Flowering Time in Brassica napus L.

Yu Xu,Kaifeng Zuo,Mengfan Qin,Ning Ma,Bingbing Zhang,Aixia Xu,Xia Liu,Zhen Huang,Miao Zhang,Kai Wang,Xiang Liu,Na Guo,Yan Zhang

doi:10.3389/fpls.2020.626205

Abstract

Flowering time plays a vital role in determining the life-cycle period, yield, and seed quality of rapeseed (Brassica napus L.) in certain environments. Quantitative trait locus (QTL) mapping to identify the genetic architecture of genes controlling flowering time helps accelerate the early maturity breeding process. In this study, simple sequence repeats (SSR) and specific-locus amplified fragment sequencing (SLAF-seq) technologies were adopted to map the QTLs for flowering time in four environments. As a result, three target intervals, FTA09, FTA10, and FTC05 were identified. Among this, FTA09 was considered as a novel interval, FTA10 and FTC05 as stable regions. Based on the parental re-sequencing data, 7,022 single nucleotide polymorphisms (SNPs) and 2,195 insertion-deletions (InDels) between the two parents were identified in these three target regions. A total of 186 genes possessed genetic variations in these intervals, 14 of which were related to flowering time involved in photoperiod, circadian clock, vernalization, and gibberellin pathways. Six InDel markers linked to flowering time were developed in the three target intervals, indicating that the results were credible in this study. These results laid a good foundation for further genetic studies on flowering-time regulation in B. napus L.

Highlights

Rapeseed (Brassica napus L.), one of the most important oilseed crops, is adaptive to different geographical environments by adjusting flowering time (FT; Shah et al, 2018)
The results indicated that these traits were quantitative traits and the corresponding loci were presented in two parents
The results indicated the six InDel markers in the three target intervals were associated with the flowering time, and these candidate genes around the six InDel markers were reliable to some extent

Summary

Introduction

Rapeseed (Brassica napus L.), one of the most important oilseed crops, is adaptive to different geographical environments by adjusting flowering time (FT; Shah et al, 2018). Flowering time of rapeseed plays a critical role in determining the life-cycle period, yield, and seed quality. Understanding these regulatory factors of FT assists in improving yield and adaption and contributes to accelerating the early maturity breeding process. Random gene loss and genetic drift have differentiated both the composition of the segments and the orthologous gene copies within the A and C genome. The multiple relevant gene copies hamper the study of some gene expressions and limit the understanding of trait-controlling mechanisms, especially for quality traits

Methods

Results

Discussion

Conclusion