Genomic Heterozygosity and Hybrid Breakdown in Cotton (Gossypium): Different Traits, Different Effects

Hybrid breakdown has been well documented in various species. In the current study, two reciprocal F₂ populations were developed using Gossypium hirsutum cv. Emian 22 and G. barbadense acc. 3-79 as parents to study hybrid breakdown in cotton. A total of 125 simple sequence repeat (SSR) markers were used to genotype the two F₂ interspecific populations. After marker checking, 83 common loci were used to assess the extent of genomic heterozygosity. The only relationships observed between hybrid breakdown and heterozygosity in the (Emian22 × 3-79) F₂ population were for seed index (SI) and boll number per plant (BN). The maternal cytoplasmic environment may have a significant effect on genomic heterozygosity and on correlations between heterozygosity and reproductive traits. These findings may offer new insights into hybrid breakdown in allotetraploid cotton interspecific hybrids, and may be useful for the development of interspecific hybrids for cotton genetic improvement.