Genetic changes in F1 hybrids of the genetically divergent Solanum L., Solanum melongena L. x Solanum aethiopicum L.

Distant hybridization constitutes an important process in plant evolution. Outbreeding of Solanum plants can produce hybrid progeny with heterobeltiosis in terms of growth, development, and resistance. In this study, the genomic characteristics and genetic variation of reciprocal cross F1 hybrids of cultivars 177 (Solanum melongena L.) and Y11 (Solanum aethiopicum L.) were quantified to analyze the relationship between heterosis and genomic characteristics. While no significant phenotypic differences existed between the F1 hybrids, their phenotypes were closer to those of the Y11 parent. Using whole-genome resequencing, large numbers of single-nucleotide polymorphisms, insertion or deletions, structural variations, and copy number variation (CNV) were found. The variation rate of the Y11 parent was the highest, while those of the F1 hybrids were similar to each other but closer to that of Y11. These results reflect the fact that the genome of the heterozygous progenies was stable at the chromosome level; nevertheless, considerable variation sites were produced, which may underlie the increased phenotypic diversities compared to that found in the cultivated parent plants. Mining and functional annotation of variant genes with different variant types revealed that the highest number of variant genes were caused by CNVs. Moreover, the variant genes were significantly enriched in pathways associated with glucose metabolism, protein synthesis, and phytohormone signaling, indicating that CNVs may be responsible for the heterosis observed in the progeny of outbred crosses. These data can provide a reference for future heterosis research, molecular marker development, genetic engineering, high-density linkage map construction, and genome-wide association analysis.

Automated summary

This study analyzed the genomic characteristics and genetic variation of reciprocal cross F1 hybrids of cultivated eggplant and bitter gourd. The results showed stable genomes at the chromosome level but considerable variation sites in the hybrids, which may explain the increased phenotypic diversities compared to the cultivated parent plants. Copy number variation genes were significantly enriched in pathways associated with glucose metabolism, protein synthesis, and phytohormone signaling, suggesting their role in the heterosis observed in the hybrids.