Novel and major QTL for branch angle detected by using DH population from an exotic introgression in rapeseed (Brassica napus L.)

Abstract

A high-density SNP map was constructed and several novel QTL for branch angle across six environments in Brassica napus were identified. Branch angle is a major determinant for the ideotype of a plant, while the mechanisms underlying this trait in Brassica napus remain elusive. Herein, we developed one doubled haploid population from a cross involving one Capsella bursa-pastoris derived B. napus intertribal introgression line with the compressed branches and wooden stems, and constructed a high-density SNP map covering the genetic distance of 2242.14 cM, with an average marker interval of 0.73 cM. After phenotypic measurements across six environments, the inclusive composite interval mapping algorithm was conducted to analyze the QTL associated with branch angle. In single-environment analysis, a total of 17 QTL were detected and mainly distributed on chromosomes A01, A03, A09 and C03. Of these, three major QTL, qBA.A03-2, qBA.C03-3 and qBA.C03-4 were steadily expressed, each explaining more than 10% of the phenotypic variation in at least two environments. Compared with other results on rapeseed branch angle, these major QTL were newly detected. In QTL by environment interactions (QEI) mapping, 10 QTL were identified, and the QTL average effect and QEI effect were estimated. Of these, 7 QTL were detected in both single-environment analysis and QEI mapping. Based on the physical positions of SNPs and the functional annotation of the Arabidopsis thaliana genome, 27 genes within the QTL regions were selected as candidate genes, including early auxin-responsive genes, small auxin-up RNA, auxin/indoleacetic acid and gretchenhagen-3. These results may pave the way for deciphering the genetic control of branch angle in B. napus.

Major Co-localized QTL for Plant Height, Branch Initiation Height, Stem Diameter, and Flowering Time in an Alien Introgression Derived Brassica napus DH Population

“…A B. napus YW-DH population encompassing 208 lines was used as a mapping population (Shen et al, 2018 ). The parents of this doubled-haploid (DH) population were B. napus introgression Y689 and cultivar Westar.…”

“…Y689 was derived from a partial intertribal hybrid between B. napus cv. Zhongyou 821 and Capsella bursa-pastoris (L.) Medic (2n = 4x = 32) (Chen et al, 2007 ; Zhang et al, 2013 ; Shen et al, 2018 ). Westar is a spring-type canola that is widely used in experiments involving the role of genetic architecture in resistance to Sclerotinia sclerotiorum and timing of flowering (Zhao et al, 2009 ; Nelson et al, 2014 ).…”

“…For PH, BIH, and SD, data from the five plants were averaged to represent the phenotype of a plot, and data from replicated plots were averaged to represent the phenotype of a DH line. Broad-sense heritability ( h 2 ) and correlations among the four traits were analyzed using SAS GLM and CORR packages, respectively (Shen et al, 2018 ; SAS v9.3, SAS Institute, Cary, NC, USA).…”

“…In the present study, QTL mapping for PH, BIH, SD, and FT were performed, based on a high-density SNP map constructed from a DH population developed from a cross involving one Capsella bursa - pastoris derived B. napus intertribal introgression line with compressed branches and wooden stems (Shen et al, 2018 ). Additive QTL and the QTL by environment interactions (QEI) were detected across multiple environments.…”

Mapping of QTLs Detected in a Broccoli Double Diploid Population for Plant Height and Leaf Characteristics

“…To date, based on different molecular markers, researchers have constructed multiple genetic linkage maps and successfully mapped them to multiple QTL sites of Brassica crops [25][26][27]. Shen et al [28] used 208 DH populations to locate 17 rape branch angle QTLs. Each of the three main QTLs could explain approximately 10% of the phenotypic variation, and 27 candidate genes were obtained in the QTL interval.…”