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Sweetpotato, origin, gene conversion, domestication, T-DNA, HPA
Abstract:
Abstract:
The hexaploid sweetpotato (Ipomoea batatas (L.) Lam.) is one of the most important root crops worldwide. However, its genetic origin remains controversial, and its domestication history remains unknown. In this study, we employed a range of genetic evidence and a newly developed haplotype-based phylogenetic analysis to identify two probable progenitors of sweetpotato. The diploid progenitor is likely closely related to I. aequatoriensis and has contributed the B1 subgenome, the IbT-DNA2 and the lineage 1 type of chloroplast genome to sweetpotato. On the other hand, the tetraploid progenitor of sweetpotato is most likely I. batatas 4x, which has donated the B2 subgenome, IbT-DNA1 and the lineage 2 type of chloroplast genome. Sweetpotato most likely originated from reciprocal crosses between the diploid and the tetraploid progenitor, followed by a subsequent whole genome duplication. Additionally, we detected biased gene exchanges between subgenomes; the rate of B1 to B2 subgenome conversions was nearly three times higher than the B2 to B1 subgenome conversions. Our analyses reveal that the genes involved in storage root formation, maintenance of genome stability, biotic resistance, sugar transport, and potassium uptake have been selected during the speciation and domestication of sweetpotato. This study sheds lights on the evolution of sweetpotato and paves the way for the improvement of the crop.
