影響稻米味度及黏度特性之數量性狀基因座定位分析

Mapping Quantitative Trait Loci Conferring Palatability and Viscosity of Rice

曾盟群(Meng-Chun Tseng)

指導教授 ： 林彥蓉

國立臺灣大學/生物資源暨農學院/農藝學研究所/碩士(2012年)

https://doi.org/10.6342/NTU.2012.00549

摘要

在稻米品質之育種上，若以白米理化特性作為評估指標可有效節省人力，並應用於早世代族群之選拔，可增進育種效率。然而米質性狀為數量性遺傳，且受到栽培環境的影響很大，故定位及選殖影響米質理化特性之遺傳因子有其必要性，利於後續之分子輔助育種、提升選拔精準度。是以，本研究利用稉稻臺農78號與秈稻臺中秈17號所建立之190個重組自交系為材料，在2010年二期作及2011年一期作兩個栽培期下進行試驗，進行白米味度計分析以及7個快速黏度分析特性，期望能找出在兩期作中穩定表現之QTLs，作為後續米質育種及遺傳研究之參考，並探討環境對米質之影響。
本試驗中之米質味度值、尖峰黏度、熱糊黏度、冷糊黏度、破裂黏度、回升黏度、尖峰時間、成糊溫度等八個理化特性皆呈現連續性分佈，且彼此之間多具有高度之正相關性。除味度與回升黏度於兩期作表現差異不大外，其餘六個特性易受環境影響，於兩期作顯著差異表現。以涵蓋12染色體之133個分子標幟，建立總長度為1501.6 cM、平均為11.4 cM的連鎖圖譜，其中59個標幟偏離預期之分離比、呈現分離偏差， 55個標幟偏向臺中秈17號之基因型，並造成第十二條染色體之標幟順序與物理圖譜不一致。以複合區間定位法進行QTL定位分析，在兩期作之試驗中共得到34個QTLs，分布於第2、3、4、5、6、7、9、10條染色體上，外表型變異解釋量從1.2~78 %不等，並在第3、6、7、10條染色體上觀察到除成糊溫度外之七個性狀QTLs群聚。其中有20個(10對)QTLs在兩期作中皆顯著，qHPV6、qBDV6、qCPV6、qSBV6、qPKV7、qCPV7、qSBV7與其他試驗結果相符，顯示這些QTLs在不同之試驗族群及環境下皆可穩定表現。其中位於第六對染色體Wx標幟附近之QTLs具有最大之效應，對味度值、熱糊黏度、破裂黏度、冷糊黏度、回升黏度、尖峰時間皆具有影響，外表型變異解釋量為29~78 %，此QTL可能為控制直鏈澱粉生合成之基因Waxy。對六個澱粉合成基因進行單點分析，除Wx外，SBE4對於熱糊黏度；PUL基因對於冷糊黏度及回升黏度在兩期作間具有顯著之影響。且在特定之Wx背景及交感組合下可偵測到更多顯著之遺傳因子，如在Wxb背景下之PUL:SBE4交感組合在味度、尖峰黏度、熱糊黏度、尖峰時間具有顯著之效應。

關鍵字

味度分析 ； 快速黏度分析 ； 數量性狀基因座 ； 重組自交系 ； 稻米品質

並列摘要

Physiochemical properties of milled rice could be employed as a selection index of grain quality in early generations of rice breeding programs, which could reduce labor costs and improve breeding efficiency. However, grain qualities of rice are inherited quantitatively and influenced severely by environment. It is imperative to QTL map and clone genes conferring physiochemical properties in prior for marker assisted breeding to promote selection accuracy of grain quality. A total of 190 RILs derived by japonica cultivar TNG 78 crossed with indica cultivar TCS 17 were planted in two cropping seasons, the 2nd crop in 2010 and 1st crop in 2011. The palatability and 7 RVA characteristics were measured of rice grains of each RIL harvested from these two seasons. The objectives herein were to find QTLs expressed stably in two cropping seasons for further grain quality breeding and genetic research, and to study the environmental effects on rice grain quality.
Eight physiochemical properties, included palatability (PLS), peak viscosity (PV), hot paste viscosity (HPV), cool paste viscosity (CPV), brekdown viscosity (BDV), setback viscosity (SBV), peak time (PeT), and pasting temperature (PaT), exhibited continuous distribution, and displayed significant positive correlation between any two traits. Significant differences between two cropping seasons were observed in most traits except palatability and setback viscosity. By using 133 molecular markers covering 12 chromosomes, the linkage map of a total length of 1501.6 cM with an average of 11.4 cM were established. A toal of 59 markers showed segregation distortion which 55 markers skewed to homozygote of TCS 17 genotype, leading marker order of linkage map in chromosome 12 inconsistent to the order of the physical map. We employed composite interval mapping to uncover QTLs associated these eight traits measured in the two cropping seasons, 34 QTLs were obtained with phenotypic variance explanation (PVE) ranged from 1.2% to 78%. The QTLs were mapped on chromosomes 2, 3, 4, 5, 6, 7, 9, and 10; in addition, QTLs conferring 7 traits except pasting temperature were clustered on chromosomes 3, 6, 7, and 10. Twenty (10 pairs) QTLs were detected significantly in two environments, and qHPV6, qBDV6, qCPV6, qSBV6, qPKV7, qCPV7 and qSBV7 identified in this study were conservative with previous studies, suggesting these QTLs expressed stably not only in different environments but experimental populations. The QTLs nearby Wx, which regulates biosynthesis of amylopectin, displaying the largest effect on traits PLS, HPV, BDV, CPV, SBV and PeT, with phenotypic variance explanation ranged from 29% to 78% . The effect of six starch biosynthesis-related genes on these 8 traits was performed a single point analysis and revealed, besides Wx, that SBE4 displayed significant effect on hot paste viscosity, PUL displayed significant effect on cold paste viscosity and setback viscosity. We also proposed that more genes are found carrying significant effects at specific Wx gene haplotypes or interaction combination. Such as PUL:SBE4 interaction exhibits significant effects at PLS, PKV HPV and PeT.

並列關鍵字

Palatability analysis ； Rapid visco analysis ； Quantitative trait loci ； Recombinant inbred lines ； Rice grain quality

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