Heterosis prediction of wheat based on SNP genetic distance and combining ability

Heterosis, as a means of increasing crop yield. has been used as part of long-tenn strategies to meet the demand for global food security. Molecular markers have been widely used to predict the outcome of crop heterosis. However. there is little research on genomic single-nucleotide polymorphism (SNP) prediction for heterosis in wheat (Triticum aestivum L.). In this study, we genotyped 30 wheat cultivars (lines) using wheat 660 K SNP chip technology and constructed the hybrid Population of 419 F-1 using diallel design. Yield component traits (YCT) in three environments, combining ability effect, and the genetic distance of 660 K SNP array were used to predict heterosis. As expected, general commercial heterosis (CH), mid-parent heterosis (MPH), and high-parent heterosis (HPH) were observed in wheat YCT. The combining ability effect, here composed of the general combining ability (GCA) and special combining ability (SCA), was varied due to the parents or traits. For GCA, Bainong4199 had the smallest influence on plant height (PH), while BNS366 and CL0438 had the greatest influence on thousand kernel weight (TKW) and spike length (SL), respectively. Chinese spring showed the highest GCA on PH, spike number per plant (SNPP), and grain yield per plant (GYP), and SN055525 showed the highest GCA of spikelet number per spike (SNS), grain number per spike (GNS), and kernel weight per spike (KWPS). More importantly, SN055525. Chinese Spring, and CL0438 were found to be better restorer lines for male sterile lines BNS and BNS366. In addition, when BNS. BNS366, and Zhoumai18 in the Huanghuai wheat region were crossed with Yunnanmai and MR168 in the Southwest wheat region or foreign varieties Ciava and CL0442, SCA occurred more frequently for SNPP, SL, GNS, KWPS, and GYP. GCA and SCA showed a positive correlation with hybrid yield. CH, MPH, and HPH (P < 0.01). Genotyping 30 parents with 660 K chips showed the genetic distance of these SNPs to be positively correlated with GYP, GCA. and CH (P < 0.01). The genetic distance of SNP was greater in superior combination, and consistent with the GCAs of parents, SCA and CH in 35.71% and 61.90% among the top 10% combinations, respectively. According to the clustering results of parental SNP, YCT, and GCA, these parents were clustered into three major groups. The cultivars from the Huanghuai wheat region clustered into groups A, B1, and C2; the cultivars from the Southwest wheat region clustered in groups B2 and C1; and foreign varieties clustered in group C2. Based on the genetic distance of SNP, combining ability, and superiority combination in the Huanghuai wheat region, we propose three wheat heterotic patterns: Huanghuai group BI/Southwest group B2. Huanghuai group B1/foreign group C2, and Huanghuai group C2/group B. The male sterile lines and restorer lines can be improved based on these heterotic groups of different wheat regions, which provide an important reference for parental selection of wheat hybrids and the production and use of hybrid wheat in the Huanghuai wheat region.