YABBY3-Orthologous Genes in Wild Tomato Species: Structure, Variability, and Expression

Evolution of the genes encoding YABBY transcription factors is believed to be one of the key reasons for flat leaf emergence from the radially symmetrical stem and gynoecium diversity. YABBY genes determine the identity of the abaxial surface of all aboveground lateral organs in seed plants. In the present study, complete sequences of YABBY3-orthologous genes were identified and characterized in 13 accessions of cultivated and wild tomato species with diverse morphophysiology of leaves, flowers, and fruits. The obtained gene sequences showed high homology (95-99%) and an identical exon-intron structure with the known S. lycopersicum YABBY3 gene, and they contained sequences that encode the conserved HMG-like YABBY and Cys2Cys2-zinc-finger domains. In total, in the analyzed YABBY3 genes, 317 variable sites were found, wherein 8 of 24 exon-specific SNPs were nonsynonymous. In the vegetative and reproductive organs of red-fruited and green-fruited tomato species, YABBY3 gene expression was similar to that in S. pimpinellifolium described earlier, but it demonstrated interspecies differences at the leaf-, bud- and flower-specific expression levels.