Study of sel/non-selfrecognition system in sel/cross incompatibility of wild type and cultivated sweet potato

野生型甘薯（Ipomoea trifida）具有孢子体自交不亲和（SSI）系统，但该系统不像芸苔属植物那样以SPII/SCR和SRK系统为基础。为了鉴定Ipomoea SSI系统的S基因，从多个S单倍型（包括自亲和突变体Sc）中分离并分析了S位点基因组区域。对4个s -单倍型的s -座基因组区域进行鸟枪测序，发现s -座基因组区域的长度与s基因的显性-隐性层次平行；显性较长，隐性较短。在Sc突变系中，所有s候选基因；男为AB2，女为SE2和SEA；AB2和SEA基因存在重复，其中2个SEA基因在男性生殖器官中呈异位表达。可以认为SEA基因的这种异位表达使Sc系具有自亲和性。野生型和栽培型三叶草的s -候选基因分析表明，三叶草的S_3单倍型在三叶草中是保守的。这一结果表明，栽培甘薯的自交不亲和性与单株甘薯的自交不亲和性基于相同的分子机制。

Wild type sweet potato (Ipomoea trifida) has sporophytic self-incompatibility (SSI) system, but this system is not based on the SPII/SCR and SRK system, which is observed in Brassica. To identify S genes of Ipomoea SSI system, S-locus genomic regions from several S-haplotypes, including self-compatible (Sc) mutant, were isolated and analyzed. According to the shotgun sequencing of S-locus genomic regions from four S-haplotypes, the length of the S-locus genomic region was parallel to the dominant-recessive hierarchy of S-genes ; longer in dominants, shorter in recessives. In the Sc mutant line, all S-candidate genes ; AB2 for male, and SE2 and SEA for female ; were located in the Sc-S-locus, however, AB2 and SEA genes were duplicated, and two SEA genes indicated ectopic expression in the male reproductive organs. It is possible to consider that this ectopic expression of SEA genes make Sc line as self-compatible. S-candidate gene analyses of wild type (I.trifida) and cultivated (I.batatas) indicated that S_3 haplotype ofLtrifzda is conserved in the I.batatas. This result indicates that the self/cross-incompatibility in cultivated sweet potato is based on the same molecular mechanism as in the self-incompatibility of I.trifida.