水稻兩重組自交系族群之遺傳重組分析

Abstract

本研究利用秈稻品種台中秈 10 號(TCS10)與稉稻品種越光(KH)雜交所繁殖之F2後代並以修飾單粒後裔法(modified single seed descendant, modified SSD)培育共有 121 個的重組自交系(recombinant inbred line, RIL)的族群；另一族群使用稉稻品 種越光(KH)與稉稻品種台農 67 號(TNG67)以同樣方法培育 146 個重組自交系的族群，並以 SSR 分子標誌建立兩族群之連鎖圖譜，並與現有物理圖譜(日本晴)比對。本研究結果顯示 TCS10 × KH 族群在連鎖群順序上具有較多錯位、轉置現象，可能與其染色體組成有關，且發現秈稻台中秈 10 號的遺傳貢獻度大於稉稻越光，而同為稉稻之台農 67 號之貢獻度亦大於越光。且發現 TCS10 × KH 族群相較於 KH ×TNG67 族群有更明顯之偏差分離現象，且偏差傾向台中秈 10 號，而兩者間在染色體發生偏差分離的位置相近，顯示偏差分離並非隨機發生。KH × TNG67 族群在重組事件或是雙重互換事件之發生率普遍較 TCS10 × KH 族群高。TCS10 × KH 族群連鎖失衡的衰退也較 KH × TNG67 族群慢，並經由效應衰退距離顯示兩族群所使用之分子標誌數量已足夠，但應盡可能平均分散。綜合以上結果顯示秈稻與稉稻雜交後代較稉型稻間雜交後代需有投入較多的個體數及較多的自交世代，以分別提高其重組機會及基因型之固定。本研究結果未來可供水稻雜交育種選拔之參考。

In this study comparative maps of rice were constructed with a reference physical map (Nippobare) using SSR DNA markers and two recombinant inbred lines (RILs) populations, which were generated by a modified Single Seed Descendent (SSD) method. One population including 121 RILs was generated from an inter-subspecific cross between cultivars Taichung Sen No.10 (TCS10) and Koshihikari (KH). While the other population including 146 RILs was generated from an intra-subspecific cross between cultivar Koshihikari and Tai Nung No.67 (TNG67) with the same method.More misposition and conversion events were found in the linkage groups of the population TCS10 × KH. Besides, the genetic contribution of indica variety TCS10 is larger than that of japonica variety KH in the populations TCS10 × KH, and japonica TNG67 also has larger genetic contribution than KH. In addition, TCS10 × KH has more obvious segregation distortion (SD) were observed in the population TCS10 × KH than in the population KH × TNG67. There were several SD events at the corresponding positions on most chromosomes of the two populations, suggesting that SD events were not taken place in random. The rates of recombination event or double crossing over event are higher in the population KH × TNG67. Also, linkage disequilibrium (LD) decay was slower in the population TCS10 × KH than KH × TNG67. According to LD decay data, the amount of SSR molecular markers were sufficient in both populations; these markers were not sufficiently distributed evenly. To sum up, more projenies and selfing generations in a population developed from a cross between indica and japonica varieties. The results of this study could provide informations for rice breeding.