No evidence for Fabaceae Gametophytic self-incompatibility being determined by Rosaceae, Solanaceae, and Plantaginaceae S-RNase lineage genes

Background: Fabaceae species are important in agronomy and livestock nourishment. They have a long breeding history, and most cultivars have lost self-incompatibility (SI), a genetic barrier to self-fertilization. Nevertheless, to improve legume crop breeding, crosses with wild SI relatives of the cultivated varieties are often performed. Therefore, it is fundamental to characterize Fabaceae SI system(s). We address the hypothesis of Fabaceae gametophytic (G)SI being RNase based, by recruiting the same S-RNase lineage gene of Rosaceae, Solanaceae or Plantaginaceae SI species.
Results: To address if Fabaceae GSI is RNase based we first looked for the presence of SSK1 like genes (described only in species having RNase based GSI), in the Trifolium pratense, Medicago truncatula, Cicer arietinum, Glycine max, and Lupinus angustifolius genomes. Since we find these genes in Fabaceae species, we characterize the S-lineage T2-RNase genes in these genomes. Except for T. pratense, all species ar...