利用分子標誌輔助回交改良水稻之食味及米粒外觀品質

Abstract

隨著經濟的發展與生活品質的提升，提高稻米品質成為台灣當前水稻育種目標之一，白堊質為影響稻米品質之重要性狀，本研究藉由與白堊質相關基因座緊密連鎖之分子標誌，選拔低白堊質稻米之優良品系。台南13號水稻品種具有早熟、抗倒伏、抗稻熱病、抗褐飛蝨與高產等優良農藝性狀，但白堊質米粒比例偏高，故本研究期望利用分子標誌輔助回交育種，將水稻品種台南16號的低白堊質相關基因導入台南13號之中。首先以台南13號與台南16號雜交族群之160個F2後代及其56個衍生品系為材料，利用混合DNA分群分析法篩選147組SSR和InDel分子標誌，並利用單一分子標誌分析法驗證與白堊質基因座緊密連鎖之分子標誌，共找到了三組與白堊質性狀基因座緊密連鎖之CH0648、CH0463與RM22155分子標誌，此外加上2組與食味相關性狀基因座緊密連鎖之RM8120與RM14275分子標誌輔助選拔低白堊質與食味佳之優良品系。經過BC1F1、BC2F1、BC3F1與BC3F2世代的前景選拔與背景選拔，共選獲6個優良品系，全部品系之乳白率、腹白率和基白率皆低於親本台南13號，其中#K5-79其白堊質表現幾乎與親本台南16號相同，而#K4-6具有較低之白堊質表現且榖粒較大(有可能提升產量)，為非常有潛力的2個品系，本研究結果初步符合預期的育種目標，此6個獲選品系將種植於試驗田區調查產量、白堊質性狀與其他重要農藝性狀，以再度確認所選出品系之低白堊質、食味佳與產量高之特性。

With the promotion of economy and life quality of human, the improvement of rice quality has became one of rice breeding objectives in Taiwan. The trait of chalky grain plays an important role in rice quality. The purpose of this study was to select superior lines with low chalky grain by molecular markers tightly linked to chalkiness related loci. Tainan No. 13 (TN13) was an early maturing rice variety with great agronomic traits, including resistant to lodging, resistant to rice blast , resistant to brown planthopper and high yield, but with high percentage of chalky grains. Low chalky genes were introduced from rice variety Tainan No. 16 (TN16) to TN13 by marker assisted backcross (MAB). A total of 160 F2 progenies developed from a cross between rice varieties TN13 and TN16, and 56 derived lines (F2:3) to identify marker associated with grain chalkiness from 147 SSR and InDel markers by bulk segregant analysis (BSA) and single marker analysis (SMA). Three markers (CH0463, CH0648 and RM22155) associated with grain chalkiness loci, and two markers (RM14275 and RM8120) associated with eating quality trait were used to select low chalky lines. Through foreground and background selections of BC1F1、BC2F1、BC3F1 and BC3F2 generations, six superior BC3F2 lines were selected. All of these selected lines had lower milky-white, white-belly and white-base rates than the recurrent parent TN13. K5-79, one of six selected line, had the least low chalky rate as TN16 (donor parent). Another promising line, K4-6, with lower chalky grain and larger grain have high yielding potential. The preliminarily results have met our expectation, and the six selected lines will be grown in the experimental fields to investigate grain yield, chalkiness trait, eating quality and other agronomic traits.