Epistasis together with partial dominance, over-dominance and QTL by environment interactions contribute to yield heterosis in upland cotton

Abstract

QTL mapping based on backcross and RIL populations suggests that epistasis together with partial dominance, over-dominance and their environmental interactions of QTLs play an important role in yield heterosis in upland cotton. A backcross population (BC) was constructed to explore the genetic basis of heterosis in upland cotton (Gossypium hirsutum L.). For yield and yield components, recombinant inbred line (RIL) and BC populations were evaluated simultaneously at three different locations. A total of 35 and 30 quantitative trait loci (QTLs) were detected based on the RILs and BC data, respectively. Six (16.7 %) additive QTLs, 19 (52.8 %) partial dominant QTLs and 11 (30.6 %) over-dominant QTLs were detected by single-locus analysis using composite interval mapping in BC population. QTLs detected for mid-parent heterosis (MPH) were mostly related to those detected in the BC population. No significant correlation was found between marker heterozygosity and performance. It indicated that heterozygosity was not always favorable for performance. Two-locus analysis revealed 46, 25 and 12 QTLs with main effects (M-QTLs), and 55, 63 and 33 QTLs involved in digenic interactions (E-QTLs) were detected for yield and yield components in RIL, BC and MPH, respectively. A large number of M-QTLs and E-QTLs showed QTL by environment interactions (QEs) in three environments. These results suggest that epistasis together with partial dominance, over-dominance and QEs all contribute to yield heterosis in upland cotton.

QTL and genetic analysis controlling fiber quality traits using paternal backcross population in Upland Cotton

“…The intraspecific F 14 recombinant inbred lines (RIL) were inbred for 177 individuals, which were derived from an Upland cotton hybrid “Xinza 1” (GX 1135 × GX 100-2) by single seed descent method (Shang et al 2016a). The parental backcross (BC/P) population was obtained by backcrossing the original male parent (GX100-2) to 177 RI lines, respectively.…”

“…Three BC/P field trials and one maternal BC trial were conducted in 2015 and 2016 in two locations in China, E1: Quzhou Experimental Station in Handan City, and E2: Guoxin Seed Company Ltd in Cangzhou City (Ma et al 2017, 2018a, 2019). The field trials were designed and planted same to the previous study for BC field trials (Shang et al 2016a; Ma et al 2017, 2018a, 2019). Field management followed the local conventional standard field practice.…”

“…The genetic map based on RIL population published before (Shang et al 2016c), in which a total of 653 loci based on SSR markers distributed on 31 linkage groups and anchored on 26 chromosomes, covering 3889.9 cM (88.20%) of cotton genome with average interval of 6.2 cM (Ma et al 2017, 2018a, 2019). The genotype for each maternal F 14 BC 1 was deduced on the basis of the RIL genotype used as the parent for backcross (Shang et al 2016a, b, c).…”

“…All of our raw data are available as Supporting Information Table S6 for phenotype values of fiber quality traits of BC/M population in three field trials in this study, Table S7 for phenotype values of fiber quality traits in field trial of BC/P population in this study, and Supporting Information Table S8A for genotypes of RIL population (Shang et al 2016a), Table S8B for genotypes of BC/M population (Ma et al 2017), and Table S8C for genotypes of BC/P population.…”

“…It is very important to detect novel QTLs and to validate the reported QTLs using diverse populations. In our previous study, serial genetic analyses were performed in multiple segregating populations including F 2 , F 2: 3 , RIL and BC/M population derived from the hybrid ‘Xinza 1’ across multiple years and various locations (Liang et al 2013; Liang et al 2015; Shang et al 2015, 2016a,b,c,d; Ma et al 2017, 2018a, 2019). In previous study, 111 quantitative trait loci (QTLs) were detected for fiber quality using four populations derived from RIL (XZ) and backcross (XZV) hybrids (Shang et al 2016d).…”