京都大学 / 新制・課程博士 / 博士(農学) / 甲第24653号 / 農博第2536号 / 新制||農||1097(附属図書館) / 学位論文||R5||N5434(農学部図書室) / 京都大学大学院農学研究科農学専攻 / (主査)教授 土井 元章, 教授 田尾 龍太郎, 教授 那須田 周平 / 学位規則第4条第1項該当 / Doctor of Agricultural Science / Kyoto University / DGAM

Rice is one of the most important cereal crops for the world population. Flowering time and seed development of rice are directly related to plant regional and ecological adaptions, and productive yield. In this dissertation, to gain knowledge of seed development in rice, the status of post-translational modifications (PTMs) in developing rice seeds was investigated. Numerous modified lysine sites in developing rice seeds were identified utilizing antibody-based affinity enrichment approaches and nano-HPLC/MS/MS analyses of acetylated, succinylated, crotonylated and 2-hydroxyisobutyrylated peptides. Functional annotation analyses indicated that a wide variety of vital biological processes were targeted by lysine PTMs. A number of modified histone and non-histone proteins were found to harbor multiple PTMs, and our findings showed that many modified histone sites were conserved across plant, human, and animal systems. Comprehensive analyses of lysine modification sites illustrated that the sites were highly sequence-specific for distinct motifs. Overall, this study provides a systematic analysis of lysine PTM proteome in plants, which will serve as the basis for future investigations of the regulatory mechanisms and functions of lysine PTMs. The mechanisms of flowering time variances in response to different photoperiods were further studied in the rice mutant, HSS. QTL-seq analysis identified a major effect on chromosome 6 responsible for the phenotypic divergence between Nipponbare (wild-type) and HSS rice. Sequence and mRNA expression analyses confirmed that allelic variants of Hd1 make HSS plants less sensitive to photoperiod by altering expression level of Hd3a. Diurnal expression pattern analyses revealed that DTH8 transcripts were largely affected by Hd1 expression level in both LD and SD. This result suggested that Hd1 may able to regulate DTH8 and DTH8-Hd1 complex abundance in response to day length in rice flowering time regulation. In addition, we discussed the functions of PTMs in flowering time regulation in rice.