Abstract
BackgroundHeterosis has been extensively utilized in different crops and made a significant contribution to global food security. Genetic distance (GD) is one of the valuable criteria for selecting parents in hybrid breeding. The objectives of this study were to estimate the GD between parents using both simple sequence repeat (SSR) markers and single nucleotide polymorphism (SNP) markers and to investigate the efficiency of the prediction of hybrid performance based on GD. The experiment comprised of four male parents, 282 female parents and 1128 F1, derived from NCII mating scheme. The hybrids, their parents and two check cultivars were evaluated for two years. Performance of F1, mid-parent heterosis (MPH), and best parent heterosis (BPH) were evaluated for ten agronomic and fiber quality traits, including plant height, boll weight, boll number, lint percentage, fiber length, fiber strength, fiber uniformity, fiber elongation ratio, micronaire, and spinning consistent index.ResultsHeterosis was observed in all hybrids and, the traits like plant height, boll number, boll weight and lint percentage exhibited higher heterosis than the fiber quality traits. Correlations were significant between parental and F1 performances. The F1 performances between three hybrid sets (Elite×Elite, Exotic×Elite, and Historic×Elite) showed significant differences in eight traits, including boll number, lint percentage, fiber length, fiber strength, fiber uniformity, fiber elongation ratio, micronaire, and spinning consistent index. The correlation of the GD assessed by both SSR and SNP markers was significantly positive. The cluster analysis based on GD results estimated using SNP showed that all the female parents divided into five groups and the F1 performance between these five groups showed significant differences in four traits, including lint percentage, micronaire, fiber strength, and fiber elongation ratio. The correlation between GD and F1 performance, MPH and BPH were significant for lint percentage and micronaire.ConclusionsOur results suggested that GD between parents could be helpful in heterosis prediction for certain traits. This study reveals that molecular marker analysis can serve as a basis for assigning germplasm into heterotic groups and to provide guidelines for parental selection in hybrid cotton breeding.
Highlights
Heterosis has been extensively utilized in different crops and made a significant contribution to global food security
1128 F1 hybrids clustered into five groups based on genetic distance (GD) assessed through single nucleotide polymorphism (SNP) markers and named as group I, II, III, IV and V, having 144, 176, 304, 224 and 280 F1, respectively (Fig. 1)
We could find that Group 1 in simple sequence repeat (SSR) clustering result included the majority crosses which clustered as Group I and Group III by SNP, Group 2 in SSR clustering result was consisted by crosses which clustered as Group III, Group IV, and
Summary
Heterosis has been extensively utilized in different crops and made a significant contribution to global food security. The experiment comprised of four male parents, 282 female parents and 1128 F1, derived from NCII mating scheme. The hybrids, their parents and two check cultivars were evaluated for two years. Utilization of heterosis in cotton has significantly contributed to the yield and fiber quality [3]. The development of hybrid cotton involves the proper selection of parents and the identification of superior heterotic combinations. Various methods have been used to predict the hybrid performance depending on the types of hybrids (single cross or three-way cross) and traits which including parental performance, mid-parent value and the general combining ability [4,5,6,7]
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