- 學位論文
利用分子標誌輔助回交改良酒米品種之抽穗期及千粒重
Improvement of a Sake-Brewing Rice Variety on Days to Heading and Thousand-Grain Weight Using Marker-Assisted Backcross Selection
摘要
由於臺灣常有稻米產銷失衡的問題，釀造清酒為解決途徑之一，然而臺灣目前並無適合釀造清酒之專用稻米品種，直接引進日本的酒米品種則會因為過早抽穗而導致產量下降。因此，本研究的目的為將臺灣的稉稻品種臺南16號所具有之晚抽穗及高千粒重基因以分子輔助回交育種的方式導入引進之日本酒米品種美山錦中，希望能改良引進酒米品種之抽穗期及千粒重。本研究以臺南16號為供給親及美山錦為輪迴親雜交獲得18株F1，並先後分別對130株BC1F1、33株BC2F1及92株BC3F1植株進行前景選拔，最後獲選1株具有目標性狀基因之BC3F1植株，將其自交產生93株BC3F2，再對其進行前景選拔和抽穗期、千粒重及稔實率等外表性狀調查。本研究成功將2個晚抽穗(qDTH10-1/qDTH10-2和qDTH3-1)及1個高千粒重(qGwt9-1)基因座導入美山錦品種中，改良後的BC3F2個體之抽穗期可延長約20天，而千粒重則可提升約1.14克，且穀粒產量亦隨之提升28.11%，顯示以分子標誌選拔目標性狀可達到預期目標。同時，本研究也對BC2F1及BC3F1前景選拔獲選之植株進行遺傳背景分析，輪迴親遺傳背景比例分別約為80%及85%，顯示輪迴親遺傳背景所佔比例低於理論值。此外，本研究亦發現抽穗期與千粒重兩目標性狀間呈現顯著負相關，即過度延遲抽穗期將因增加穀粒數而使千粒重降低，且可能導致植株過高增加倒伏風險，並可能因生育期過長而影響輪作制度及節水效益，因此後續品系之抽穗期選拔將以效應較大之qDTH10-1/qDTH10-2基因為主，而以效應較小的qDTH3-1基因為輔。此外，本研究亦使用帶有gs3對偶基因的臺南16號品種為供給親且同樣以美山錦品種為輪迴親進行回交，並先後分別對32株BC1F1及47株BC2F1進行前景選拔，試圖在除了上述抽穗期及千粒重基因外導入可增大粒型(千粒重)的gs3對偶基因，以期間接增加產量。綜合而言，本研究利用分子標誌輔助回交育種已成功改良優良酒米品種之抽穗期及千粒重等性狀，並已初步獲選具潛力之個體/品系，期望後續品系評估後可推薦適合臺灣栽培環境之優良酒米新品種。
並列摘要
Since the balance between rice production and sales often can not be kept very well in Taiwan, brewing sake is one of the ways to solve the problem. There are not any sake-brewing rice varieties bred in Taiwan so far. In Taiwan, rice varieties introduced from Japan have low yield due to early flowering. To improve days to heading and 1000-grain weight of an introduced sake-brewing rice variety Miyamanishiki (Mi), QTL related to the two traits were transferred from a Taiwanese japonica variety Tainan No. 16 (TN16) to Mi using marker-assisted backcross selection. In this study, TN16 was crossed with Mi to obtain 18 individuals of F1 and foreground selection was applied sequentially to 130 individuals of BC1F1, 33 individuals of BC2F1, and 92 individuals of BC3F1 populations. One individual with target QTL from BC3F1 was selected and self-pollinated to breed 93 individuals of BC3F2 for conducting foreground selection and phenotypic investigation (days to heading, 1000-grain weight, and fertility, etc.). In this study, we have successfully transferred two QTL with longer days to heading (qDTH10-1/qDTH10-2 and qDTH3-1) and one QTL with higher 1000-grain weight (qGwt9-1) to Mi. In comparison with Mi, the selected BC3F2 plants had about 20 days longer in days to heading, 1.14 grams increased in 1000-grain weight, and 28.11% increased in grain yields. The results showed that foreground seletions using molecular markers were successful. Also, the genetic background of selected plants was evaluated with SSR markers, and about 80% and 85% were found to be background of recurrent parent in the BC2F1 and BC3F1 generations, respectively. The observed values were less than expected ones. Besides, days to heading was found to be significantly and negatively correlated with 1000-grain weight, which indicated that extending days to heading might lead to a lower 1000-grain weight caused from the increase of grain numbers. It might also result in higher lodging risks and a longer growth period. Thus, seletions should be relied mainly on QTL qDTH10-1/qDTH10-2 and supplied with qDTH3-1 to select lines with days to heading in further breeding program. In addition to the above targeted QTL, one gs3 allele was transferred from a TN16-gs3 line to Mi for increasing 1000-grain weight. Foreground selection was completed in 32 individuals of BC1F1 and 47 individuals of BC2F1 populations, respectively. Overall, days to heading and 1000-grain weight of sake-brewing rice variety were successfully improved with marker-assisted backcross selection in this study, and several individuals/lines with potential were selected preliminarily. These individuals/lines are expected to adapt to the environments in Taiwan and become superior rice varieties for brewing sake.
參考文獻
延伸閱讀
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