Identification, characterisation and expression analysis of MADS-box genes in sweetpotato wild relative Ipomoea trifida

Abstract

MADS-box transcription factors (TFs) participate in various biological processes, including stress response, plant growth and development. The storage root of sweetpotato (Ipomoea batatas) is an important staple food crop in Asian and African areas, and leafy sweetpotato is a popular and healthy vegetable in China. However, the function of the MADS genes remains largely unknown in sweetpotato and the other Ipomoea species. In this study, we carried out a genome-wide gene family analysis of MADS in Ipomoea trifida which is currently considered as the most potential ancestor of sweetpotato. A total of 37 ItfMADS genes that encode 42 proteins were identified. The evolutionary relationship was analysed for MADS proteins in 37 species. According to the tree topology of phylogeny, the ItfMADS genes are classified into Mα, Mβ, Mγ, MIKCC and MIKC* groups. Gene structure analysis revealed that the majority of ItfMADS in the same clade displayed similar exon–intron distribution. Furthermore, the expression patterns of ItfMADS genes were investigated through RNA-seq data and confirmed by qRT-PCR. The expression of ItfMADS genes varied among different tissues, and induced or repressed under different abiotic stresses, thereby suggesting their potential functions under abiotic stresses. Our findings lay a solid foundation for further elucidating the ItfMADS function and promoting sweetpotato molecular breeding.