Production and characterization of a novel interspecific somatic hybrid combining drought tolerance and high quality of sweetpotato and Ipomoea triloba L.

Abstract Key message A novel interspecific somatic hybrid combining drought tolerance and high quality of sweetpotato and Ipomoea triloba L. was obtained and its genetic and epigenetic variations were clarified. Somatic hybridization can be used to overcome the cross-incompatibility between sweetpotato (Ipomoea batatas (L.) Lam.) and its wild relatives and transfer useful and desirable genes from wild relatives to cultivated plants. However, most of the interspecific somatic hybrids obtained to date can’t produce storage roots and show no good agronomic characters. In the present study, a novel interspecific somatic hybrid, named XT1, was obtained through protoplast fusions between sweetpotato cv. Xushu 18 and its wild relative I. triloba L.. This somatic hybrid was found to produce storage roots and to exhibit significantly higher drought tolerance and quality compared with its cultivated parent Xushu 18. Transcriptome and real-time quantitative PCR (qRT-PCR) analyses showed that the well-known drought stress-responsive genes in XT1 and I. triloba were significantly up-regulated under drought stress. Evidence of genome structural reconstructions between the two genomes of the fusion parents in XT1 was confirmed by genomic in situ hybridization (GISH) and specific nuclear and cytoplasmic DNA markers. Its DNA methylation variations were characterized by methylation-sensitive amplified polymorphism (MSAP). This study not only reveals the significance of somatic hybridization techniques in the genetic improvement of sweetpotato but also provides valuable materials and knowledge for investigating the mechanism of storage root formation in sweetpotato.