【作者】 崔克辉；

【导师】 张启发； 彭少兵；

【作者基本信息】 华中农业大学 ， 生物化学与分子生物学， 2001， 博士

【摘要】 目前，水稻产量潜力的增加主要依赖于形态改良和杂种优势的利用。近年来，主要农作物的产量增加速率明显下降。这可能与人们对作物生长和产量的生理基础了解不多有关。近年来，新的信息和方法被用来解决禾谷类作物的产量问题和寻找产量相关基因。本研究利用源于我国的珍汕97和明恢63杂交组合的重组自交系(F₁₀、F₁₁)，分别于1999年和2000年在国际水稻研究所（IRRI）进行室内和田间实验，对产量及其构成因子与其它相关性状的关系进行形态生理分析，对幼苗活力及相关生理指标、穗部性状、产量及其构成因子、叶片特征等性状进行了QTL定位分析和上位性检测。主要结果如下： 1 较强的幼苗活力对作物建成和生长而言是重要的。种子萌发速率和幼苗生长被用来量化幼苗活力，淀粉酶活性、根氧化活力、还原糖含量等也被测量。总体上，幼苗活力（如萌发速率、幼苗干重、最大根长等）和几个生理性状（淀粉酶活性、根氧化活力、还原糖含量、种子大小等）间存在着显著的相关性。QTL定位分析表明四个染色体区域（第三染色体上的RZ403-C1087-RG393，第五染色体上的C1447-RM26-C246和C734b-RG360-R3166-R830，第六染色体上的C952-Waxy-C1496）与水稻幼苗活力相关。控制淀粉酶活性、根活力和还原糖含量的几个QTL分别与萌发速率、幼苗干重和最大根长的QTL定位在相似区段。结果表明部分QTL和二位点互作对同时对多个性状有效应，表现出多效性。六对QTL与QTL间的互作也被检测到（根干重和总淀粉酶活性各有一对、还原糖含量有两对、种子大小有二对）。 2 水稻植株高度、分蘖数、抽穗期是三个重要的农艺性状。本研究对播种14天时幼苗高度、移栽后35天和株系成熟期时的高度、移栽后35天和株系成熟期时分蘖数、抽穗期进行了QTL定位和二位点互作分析。在水稻的两个发育阶段（移栽后35天和株系成熟期），株高与分蘖数都呈负相关。抽穗期分别与植株成熟时的高度和分蘖数紧密相关。共有65个分别对两个时期（移栽后35天和株系成熟期）的株高和分蘖数、抽穗期有效应的单标记位点（p≤0.01）在两年都能检测到，其中部分标记位点与多个性状显著相关。对所研究的性状共定位了32个QTL。在定位的控制移栽后35天和株系成熟期时高度、分蘖数、抽穗期的28个QTL中有11个能在两年都检测到。第六染色体上的RG424-RZ667对抽穗期、成熟时的植株高度和分蘖数都有大的效应。由于它的效应，推迟大约六天抽穗可导致成熟时分蘖数减少一个和植株高度增加约六厘米。对除幼苗高度外其它性状而言，共有549个互作对在两年都能检测到（p≤0.01），其中55对对多个性状有效应。总体上，控制成熟时植株高度和分蘖数的QTL和互作对不同于移栽后35天时所检测到的QTL和互作对，这表明在不同的发育时期，不同的基因和基因互作控制着同一性状的表达。 3 通过增加每穗总颖花数来增加库的大小可能是增加产量潜力的一条途径。每穗总颖花数与其它穗部性状如第一次、第二次枝梗数、穗长等显著相关。大体上，第二次枝梗数、每一个二次枝梗上的颖花数、颖花密度紧密联系着总颖花数。通径分析也表明第二次枝梗数、第二次枝梗数上的颖花数、颖花密度对总颖花数有较大的直接效应。两年中共检测到53个对10个穗部性状和其衍生性状有效应的QTL，其中23个QTL能在两年同时检测到。部分QTL表现出多效性。五个染色体区段（第一染色体上G359-RG532和C567-RG236、第二染色体上R712-RM29、第六染色体上P-RG424、第十染色体上C1633附近区域）被发现对多个穗部性状有效应。大量的二位点互作被检测到，其中18.2％的互作对能在两年同时检测到。两年共有互作对的比例高低与性状有关，每个第二次枝梗上颖花数有8.7％，而穗长则为32.6％。两年共有互作对的比例与不同环境中性状表现的一致性相联系，与性状遗传率正相关。上位性分析表明大部分QTL的侧翼标记都参与到二位点互作，且两年共检测到六对同一性状内QTL间的互作。两年同时检测到的互作对中，26.7％的二位点组合对多个性状有效应，表现出多效性。 4 作物的形态特征对籽粒产量的影响是通过对产量构成因子的影响来体现的。水稻千粒重和结实率受源和库特征的共同影响。在本研究中，水稻旗叶、倒二叶、倒三叶的叶面积和相对厚度与结实率显著负相关而与千粒重不相关，然而这三片叶的面积与每穗总颖花之比与千粒重显著正相关而与结实率不相关。总颖花数和第二次枝梗上的颖花数分别与结实率和千粒重呈负相关。大的茎维管束数与总颖花数之比分别与结实率和千粒重呈正相关。通径分析表明：对籽粒大小而言，旗叶和倒二叶的大小、相对厚度、叶面积与每穗总颖花数比等特征表现出正效应，而多的二次枝梗数及在二次枝梗数上的颖花表现出负效应；大而厚的倒二、倒三叶、多的枝梗数、第二次枝梗上多的颖花等特征对结实率有较大的负的直接效应;总体上，高的旗叶面积与总颖花数比、高的茎维管束数与总颖花数之比对结实率和千粒重都有正的效应。5在生产中经常观察到环境因素影响到水稻的干物质生产和籽粒生产.在本研究中，籽粒产量与每平方米面积上的总粒数、总穗数、结实率、收获指数呈正相关，而与抽穗时间、成熟时植株高度呈负相关更多还原

【Abstract】 Raising yield potential in rice depends largely on morphological improvement and heterosis utilization. Rates of grain yield advances through plant breeding programs have apparently declined in recent years. It may partly be because that understanding of morphological and physiological bases for crop growth and yield are rather limited. New information and methodologies such as QTL analysis are employed to approach the grain yield problem and search yield genes in cereals. In the study, a recombinant inbred population derived from ZS97x MH63 cross (F10, F11) was employed for morpho-physiological analyses and molecular dissection of yield-related traits in 1999 and 2000 at International Rice Research Institute (IRRI). The main results are as follows:1 Strong seedling vigor are desirable for crop establishment in rice. Germination rate and seedling growth were measured to quantify seedling vigor Total amylase activity, a-amylase activity, reducing sugar content, root activity, and seed weight were determined. Overall, correlation was observed between the seedling vigor traits (germination rate, seedling dry weight, and root maximum length etc) and physiological traits (amylase activity, root activity, reducing sugar content etc). QTL analysis reveals that the intervals of RZ403-C1087-RG393 on chromosome 3, C1447-M26-C246 and C734b-RG360-R3166 -R830 on chromosome 5, and C952-Waxy-C1496 on chromosome 6 are the four main chromosomal regions controlling seedling vigor. Several QTLs for amylase activities, reducing sugar content, and root activity were localized in the similar region as the QTLs for seedling vigor, respectively. The results show that it is common that single marker, QTL, and digenic interaction have pleiotropic effects, suggesting that pleiotropy of detected single marker, QTL, and digenic interaction should be the molecular basis for relationship among amylase and seedling vigor. Six interactions between QTLs within a trait were detected (one for root dry weight, one for total amylase activity, two for reducing sugar content, two for seed size).2 Plant height, tiller number, and heading date are agronomic traits of importance. We mapped quantitative trait locus (QTLs) for plant height (at seedling stage, at 35 days after transplanting, and at maturity stage) and tiller number (at 35 days after transplanting, and at maturity stage), and for heading date using a recombinant inbred (RI) population. Negative correlations between plant height and tiller number were observed at two growth stages (35 days after transplanting and at maturity stage). Heading date significantly correlated with tiller number and plant height at maturity. At p^O.Ol, a total of 65 single markers associated with studies traits but the seedling height were detected simultaneously in 1999 and 2000. Some markers were observed to be associated with at least two traits. A total of 32 QTLs were detected, 11 of which were identified simultaneously in two years. Several QTLs had pleiotropic effects. Three QTLs for seedling height were located in the similar regions with QTLs for 1000-grain weight, and significantly positive correlation between seedling height and 1000-grain weight were observed, suggesting that seedling height may be closely associated with seed size. The interval of RG424-RZ667 showed its large effects on heading date, plant height and tiller numbers at maturity. Delay of heading date for approximately 6 days due to the effect of the region may result in a reduction in living tiller numbers at maturity by one and an increase in ultimate plant height by approximately 6 cm. A total of 549 digenic interactions for all traits but the seedling height were detected simultaneously in two years by two-way ANOVA. Among them, 55 combinations had pleiotrpic effects by simultaneously affecting two or more traits. The results show that different QTLs and digenic interactions affect plant height and tiller number at different developmental stages, respectively, suggesting selective expression of genes for更多还原