不同氮肥用量下水稻產量及米質相關基因之表現

Abstract

氮肥用量會直接影響水稻產量與品質，本研究目的為探討水稻在不同氮肥用量對產量及米質之影響，以及在不同氮肥用量下產量及米質相關基因之表現。本研究利用台中秈10號與越光雜交所衍生之124個重組自交系族群，分析兩種氮肥用量(80及200公斤/公頃)處理對水稻產量、株高、抽穗期、白堊質發生率、白堊質面積、白堊質指標、蛋白質含量、直鏈性澱粉含量及食味值等9個重要性狀之影響。結果顯示，不同氮肥用量間族群之產量、蛋白質含量及食味值等性狀有顯著差異，而株高則具有顯著之基因型與氮肥用量之交感效應，顯示氮肥用量處理對產量及米質相關性狀具有不同程度之影響。高氮肥與低氮肥用量處理下有部分性狀間維持一致相關趨勢，但亦有性狀間之相關性隨不同氮肥用量處理而改變，顯示氮肥用量的差異可能改變部分基因之表現程度。利用91個SSR與2個InDel分子標誌建立水稻連鎖圖譜，並以綜合區間定位法測定兩種氮肥用量處理下水稻產量及米質之數量性狀基因座(QTL)。結果於第1對、第5對、第6對、第8對、第10對、第11對及第12對染色體上測得相關之QTL，其中控制株高之q-PH6、白堊質發生率之q-CR5、蛋白質含量之q-PC10以及控制食味值之q-TV10在兩種氮肥環境下皆偵測到基因對性狀有顯著影響，顯示這4個QTL較不受氮肥用量影響。而影響水稻株高之q-PH11、抽穗期之q-HD5與q-HD12、蛋白質含量之q-PC12、直鏈性澱粉含量之q-AC1及食味值之q-TV12等6個QTL僅在低氮肥環境下測得；影響產量之q-Y8、白堊質指標之q-CI5、蛋白質含量之q-PC5與q-PC11及食味值之q-TV5與q-TV11等6個QTL僅在高氮肥環境下測得。這些單一氮肥環境下測得相關之QTL容易受氮肥用量影響，也易造成不同氮肥環境下選種及栽培差異。此外，影響食味值之QTL皆與影響蛋白質含量之QTL位於相同之染色體區間，顯示出不同氮肥環境對食味值影響主要為蛋白質含量改變所致。本研究探討不同氮肥環境下測定影響重要農藝性狀基因之位置及其表現，並比較這些基因在不同環境下之表現差異，除了可提供水稻栽培氮肥用量之參考外，並且可以做為分子標誌輔助改良產量及品質之參考。

Rice yield and grain quality could be directly influenced by different nitrogen levels. In order to reveal the quantitative trait loci (QTL) controlling rice yield and grain quality at different nitrogen levels, a recombinant inbred line (RIL) population consisting of 124 lines derived from a cross from varieties Taichung Sen 10 (TCS-10) and Koshihikari was used as materials. In this study, two nitrogen fertilization levels (80 and 200 kg/ha) were applied and nine traits were evaluated, including yield(Y), plant height(PH), days to heading(HD), chalkiness rate(CR), chalkiness area(CA), chalkiness index(CI), protein content(PC), amylose content(AC) and taste value(TV). The results indicated that significant in yield, PC and TV between two nitrogen levels were observed. Furthermore, PH had significant interaction between line (genotype) and nitrogen level. The effects of nitrogen levels on RILs were mainly based on traits. The correlations between traits were deviated under different nitrogen levels. It implied that expression of some QTL controlling rice yield and quality were probably influenced by different nitrogen levels. According to results of CIM (composite interval mapping) with a linkage map composed of 91 SSR and 2 InDel DNA markers, 16 QTL located on rice chromosomes 1, 5, 6, 8, 10, 11 and 12 were detected at two nitrogen levels. Four QTL including q-PH6, qCR5, q-PC10 and q-TV10 were detected at both nitrogen levels, indicating the expression stability of these QTL. However, QTL q-PH11, q-HD5, q-HD12, q-PC12, q-AC1 and q-TV12 were only detected at low nitrogen level; q-Y8, q-CI5, q-PC5, q-PC11, q-TV5 and q-TV11 were only detected at high nitrogen level. The QTL detected in single nitrogen level are easily affected by nitrogen levels, and it will be resulted in selection and cultivation difference under various nitrogen levels. Moreover, QTL controlling protein content and taste value were detected in the same chromosome regions, showing that difference in taste value between nitrogen levels were mainly caused by the change of protein content. This study not only could provide information for nitrogen fertilization application, but also for maker-assisted selection (MAS) on rice breeding.