Laboratory of Pomology, Graduate School of Agriculture, Kyoto University, Kyoto, 606-8502 Japan.
Japan Science and Technology Agency (JST), PRESTO, Kawaguchi-shi, Saitama 332-0012, Japan.
Plant Cell Physiol. 2018 Jun 1;59(6):1265-1275. doi: 10.1093/pcp/pcy068.
The S-RNase-based gametophytic self-incompatibility (GSI) reproduction barrier is important for maintaining genetic diversity in species of the families Solanaceae, Plantaginaceae and Rosaceae. Among the plant taxa with S-RNase-based GSI, Prunus species in the family Rosaceae exhibit Prunus-specific self-incompatibility (SI). Although pistil S and pollen S determinants have been identified, the mechanism underlying SI remains uncharacterized in Prunus species. A putative pollen-part modifier was identified in this study. Disruption of this modifier supposedly confers self-compatibility (SC) to sweet cherry (Prunus avium) 'Cristobalina'. To identify the modifier, genome re-sequencing experiments were completed involving sweet cherry individuals from 18 cultivars and 43 individuals in two segregating populations. Cataloging of subsequences (35 bp kmers) from the obtained genomic reads, while referring to the mRNA sequencing data, enabled the identification of a candidate gene [M locus-encoded GST (MGST)]. Additionally, the insertion of a transposon-like sequence in the putative MGST promoter region in 'Cristobalina' down-regulated MGST expression levels, probably leading to the SC of this cultivar. Phylogenetic, evolutionary and gene expression analyses revealed that MGST may have undergone lineage-specific evolution, and the encoded protein may function differently from the corresponding proteins encoded by GST orthologs in other species, including members of the subfamily Maloideae (Rosaceae). Thus, MGST may be important for Prunus-specific SI. The identification of this novel modifier will expand our understanding of the Prunus-specific GSI system. We herein discuss the possible functions of MGST in the Prunus-specific GSI system.
基于 S-RNase 的配子体自交不亲和（GSI）生殖障碍对于维持茄科、车前科和蔷薇科物种的遗传多样性非常重要。在具有基于 S-RNase 的 GSI 的植物类群中，蔷薇科李属物种表现出李属特异性自交不亲和（SI）。尽管已经鉴定出雌蕊 S 和花粉 S 决定因素，但李属物种中的 SI 机制仍未阐明。本研究鉴定出一个假定的花粉部分修饰因子。据称，破坏该修饰因子可使甜樱桃（Prunus avium）‘Cristobalina’具有自交亲和性（SC）。为了鉴定修饰因子，完成了涉及来自 18 个品种和 43 个分离群体个体的甜樱桃个体的基因组重测序实验。从获得的基因组读序列中对亚序列（35bp kmers）进行编目，同时参考 mRNA 测序数据，可鉴定出一个候选基因[M 基因座编码 GST（MGST）]。此外，在‘Cristobalina’中，转座子样序列插入假定的 MGST 启动子区域，下调 MGST 表达水平，可能导致该品种的 SC。系统发育、进化和基因表达分析表明，MGST 可能经历了谱系特异性进化，并且编码的蛋白质可能与其他物种（包括蔷薇科 Maloideae 亚科的成员）中 GST 同源物编码的相应蛋白质具有不同的功能。因此，MGST 可能对李属特异性 SI 很重要。该新型修饰因子的鉴定将扩展我们对李属特异性 GSI 系统的理解。我们在此讨论了 MGST 在李属特异性 GSI 系统中的可能功能。
