Cumulative and different genetic effects contributed to yield heterosis using maternal and paternal backcross populations in Upland cotton

Abstract

Heterosis has been utilized in commercial production, but the heterosis mechanism has remained vague. Hybrid cotton is suitable to dissect the heterosis mechanism. In order to explore the genetic basis of heterosis in Upland cotton, we generated paternal and maternal backcross (BC/P and BC/M) populations. Data for yield and yield-component traits were collected over 2 years in three replicated BC/P field trials and four replicated BC/M field trials. At single-locus level, 26 and 27 QTLs were identified in BC/P and BC/M populations, respectively. Six QTLs shared in both BC populations. A total of 27 heterotic loci were detected. Partial dominant and over-dominant QTLs mainly determined yield heterosis in the BC/P and BC/M populations. QTLs for different traits displayed varied genetic effects in two BC populations. Eleven heterotic loci overlapped with QTLs but no common heterotic locus was detected in both BC populations. We resolved the 333 kb (48 genes) and 516 kb (25 genes) physical intervals based on 16 QTL clusters and 35 common QTLs, respectively, in more than one environment or population. We also identified 189 epistatic QTLs and a number of QTL × environment interactions in two BC populations and the corresponding MPH datasets. The results indicated that cumulative effects contributed to yield heterosis in Upland cotton, including epistasis, QTL × environment interaction, additive, partial dominance and over-dominance.

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

“…However, fiber micronaire (FM) showed significant negative correlation with FL and FS in the populations. This result was similar to the previous research (Liang et al , 2013; Shang et al , 2016d; Ma et al , 2019).…”

“…The parental backcross (BC/P) population was obtained by backcrossing the original male parent (GX100-2) to 177 RI lines, respectively. The maternal backcross (BC/M) population referred to the previous study (Ma et al 2017; Ma et al 2019). The control set was performed in each experimental trial, including GX100-2, “Xinza 1”, GX1135 and a competition hybrid “Ruiza 816” in Yellow River Region.…”

“…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).…”

“…In addition, 32 QTLs at five stages and 24 conditional QTLs at four intervals were detected for plant height in different years or populations or stages (Ma et al 2018a). And 26 and 27 QTLs including heterotic loci were identified in TC/P and TC/M populations, respectively (Ma et al 2019). In addition, 10 and 16 clusters improved more than one trait for fiber quality and yield and yield-components, respectively (Ma et al 2017; Ma et al 2019).…”

“…And 26 and 27 QTLs including heterotic loci were identified in TC/P and TC/M populations, respectively (Ma et al 2019). In addition, 10 and 16 clusters improved more than one trait for fiber quality and yield and yield-components, respectively (Ma et al 2017; Ma et al 2019). In order to identify and validate genetic components related fiber quality traits, we further developed BCF 1 progenies population based on RIL population by backcrossing with the paternal parent of ‘Xinza 1’.…”