使用Selective Genotyping鑑定已知的水稻種子休眠與穗上發芽數量性狀基因座

Abstract

稻穀在收穫前若遭遇高溫溼熱的氣候，容易發芽，此現象稱為穗上發芽，穗上發芽的程度與個別「基因型/品系」的種子休眠性相關。本論文的目的是在高雄及花蓮兩個育種族群中鑑定出已知的水稻種子休眠與穗上發芽數量性狀基因座。高雄族群由高雄143號與高雄146號的雜交後代組成，而花蓮族群則由臺稉16號與臺農71號的雜交後代組成；高雄143號與臺稉16號在各自的雜交組合中皆為貢獻強種子休眠性的親本。為了進行已知數量性狀基因座的遺傳定位，分子標記位置的選擇是基於十篇文獻所記載的主效數量性狀基因座的位置，而高雄族群與花蓮族群各有十八個與十三個SNP分子標記成功地完成基因型鑑定。本論文並應用selective genotyping以節省基因型鑑定的成本。 結果顯示在花蓮族群偵測到兩個種子休眠數量性狀基因座，分別與位於第一和第四條染色體上的分子標記snp01和snp07連鎖。與snp01分子標記連鎖的數量性狀基因座可解釋較大的外表型變異，其增進種子休眠性的對偶基因來自臺稉16號；此一數量性狀基因座亦與兩個已知的水稻種子休眠數量性狀基因座sd1和Sdr6、以及一個阿拉伯芥種子休眠基因DOG1在水稻的同源基因OsDOG1L-2位於相同的染色體區間。然而，沒有任何已知的數量性狀基因座能在高雄族群中被偵測到。

Rice grains can germinate before harvest in hot and humid weather; this phenomenom is called pre-harvest sprouting. The degree of pre-harvest sprouting relates to seed dormancy of a genotype/line. The object of this thesis was to identify known rice QTLs for seed dormancy and pre-harvest sprouting in two breeding populations － Kaohsiung and Hualian population. Kaohsiung population was made from a cross between Kaohsiung 143 and Kaohsiung 146, and Hualian population was made from a cross between Taiken 16 and Tainung 71. Kaohsiung 143 and Taiken 16 were the donor parents contributing stronger seed dormancy in each cross. For mapping known QTLs, the locations of molecular markers were assigned according to the chromosomal regions of known major QTLs in ten literatures; eighteen and thirteen SNP molecular markers were successfully genotyped in Kaohsiung and Hualien populations, respectively. In addition, selective genotyping was applied to save the cost for marker genotyping. The result showed that two seed dormancy QTLs were identified in Hualien population; they were linked to the snp01 marker and the snp07 marker on chromosome 1 and 4, respectively. The QTL linked to the snp01 marker explained larger phenotypic variance, and its allele from Taiken 16 was able to enhance seed dormancy. This QTL also co-localized with two known rice QTLs for seed dormancy (sd1 and Sdr6) and one rice gene homologous to the Arabidopsis seed dormancy gene DOG1 (OsDOG1L-2). However, no known QTL was identified in Kaohsiung population.