【作者】 金千瑜；

【导师】 张国平；

【作者基本信息】 浙江大学 ， 作物学， 2006， 博士

【摘要】 水稻是我国最主要的粮食作物,同时又是耗水最多的农作物,越来越受到干旱缺水的制约和困扰。开展水稻抗旱节水研究,具有重大意义。水稻生产以取得高额经济产量为目标,研究其抗旱节水,应着眼于在水分胁迫条件下植物体能保持高水势的水分状态,实现抗旱增产。水稻在遭遇干旱胁迫时保持高水势水分状态的机理主要有:一是限制和减少体内水分丢失,主要在叶片,二是维持水分供应和更多的吸水,主要在根系。有关水稻叶片卷曲对抗旱性的作用,国外虽有一些报道,但结果不尽一致,而国内很少有过研究;有关根系穿透力对水稻抗旱性的作用,近年来在国外受到了广泛关注,而国内尚未见有报道。以各种遗传群体为材料,研究水稻抗旱性根、叶与产量性状QTL的定位已有大量研究,但多数研究在一种环境下进行,且报道的结果很不一致。本研究选用13个不同类型、来自不同生态区的水稻品种,研究在干旱胁迫下水稻不同品种叶片卷曲和根系穿透力及其对抗旱性的作用机理,同时利用珍汕97B×密阳46RILs群体构建的遗传连锁图谱,对干旱胁迫环境与水田(对照)环境下叶片发育动态和产量构成及相关性状进行QTLs定位分析,探讨在水分胁迫环境下水稻抗旱性及其对生育、产量形成影响的遗传基础。主要研究结果如下: 1.土壤干旱胁迫下水稻叶片卷曲的品种间差异及其与蒸腾、光合特性的关系 在水稻分蘖盛期土壤断水后干旱胁迫处理下,13个参试品种(组合)在叶片卷曲动态上差异明显。依据其叶片卷曲发生的时间先后及卷曲程度,可分为3种类型:①敏感型,在干旱胁迫后叶片最先出现明显卷曲,且卷曲速度快、程度大,这一类品种(组合)有秀水11、武运粳7号、中旱1号和中旱3号;②中间型,干旱胁迫后叶片明显卷曲的速度较慢,达到最大程度卷曲的时间较长,如浙733、中早1号、汕优63、协优9308、旱稻8号、旱稻502、云陆29等;③钝感型,干旱胁迫到一定程度后最后出现叶片卷曲,且卷曲速度慢,复水后叶片展开也慢,有巴西陆稻、早稻227。 在干旱胁迫条件下,随着水稻叶片卷曲度(LRI)的增大,叶片的气孔导度(SC)、蒸腾速率(TR)和净光合速率(Pn)均随之降低,但叶片卷曲对气孔导度、蒸腾速率、净光合速率的影响过程与程度以及SC、TR与Pn的相互关系,不同卷叶敏感性的品种间存在着一定的差异。中旱1号(敏感型品种)的更多还原

【Abstract】 Rice is the most important food crop and water shortage is posing a more severe limiting factor to its production while it consumes the largest amount of water in agriculture. It is utmost important to save water consumption in rice production. As high grain yield is targeted in rice production, studies of water saving should be concentrated on increasing yield with less water consumption, by maintaining high water potential of plants under water stress. The main mechanisms for plants to maintain good water relation when subjected to water stress are as follows: one is to limit or reduce water loss, mainly happened in leaf, and another is to keep high water uptake in root. There have been some reports about the effect of leaf rolling on drought stress, but no consistent agreement has been obtained so far. In recent years, the effect of root penetration in water stress resistance has been widely studied, but there is still less research in China. Meanwhile extensive researches have been done to analyze the QTL of root, leaf and yield traits related to drought resistance in rice by using different genetic populations. However, most researches were done in a single condition (environment), and moreover the results were inconsistent. In the present research, 13 rice varieties with different ecotypes were used to investigate the functions of leaf rolling and root penetration on drought resistance. In addition, a recombinant inbred line (RIL) population developed from the cross Zhenshan 97B and Miyang 46 was used to determine QTLs of leaf development and yield components under both water stress and well-irrigated conditions, so as to illustrate the physiological mechanisms of drought resistance and its effect on growth and yield formation in rice under water stress. The main results are as follows:1. The genotypic difference in leaf rolling of rice under water stress and its relation to transpiration and photosynthesisThere was a distinct difference in the change of leaf rolling across growth stages among 13 rice varieties (hybrid combinations) when they were exposed to water stress through stopping water supply at active tillering stage. Three groups could beclassified according to time and extent of leaf rolling: (1) sensitive one, which showed earlier and severe leaf rolling under water stress. Xiushui 11, Wuyunjing 7, Zhonghan 1 and Zhonghan 3 belonged to this group;(2) intermediate one, which showed slower development of leaf rolling and longer time for the maximum rolling extent, and Zhe733, Zhongzao 1, Shanyou 63, Xieyou 9308, Handao 8, Handao 502, Yunlu 29 belonged to this group. (3) insensitive one, which showed slow and less leaf rolling and slow recovery when re-watering, and IAPAR 9, Handao 227 belonged to this group.With an increase in leaf rolling of rice under water stress, stomatal conductance (SC), transpiration rate (TR) and net photosynthesis (Pn) declined greatly. However, the effect of leaf rolling on these physiological traits and the relationship between them varied with rice genotypes. For Zhonghan 1 (a sensitive variety), leaf rolling index (LRI) had significant negative effect on TR and Pn, mainly mediated by its effect on SC, and SC was significantly and positively correlated with Pn and TR. For Handao 8 (an intermediate variety), LRI also showed the significantly negative effect on TR and Pn, but SC had no correlation with TR, although it was significantly correlated with Pn, suggesting that the negative effect of LRI on TR and Pn was not mediated by its effect on SC. For IAPAR 9 (an insensitive variety), LRI had a significant and negative effect on TR, but no obvious effect on Pn was found. Moreover, there was no correlation between SC and TR.The effect of leaf rolling on water use efficiency (WUE) is dependent on its effect on TR and Pn, and also dependent on genotype. For instance, the effect was caused by the dramatic changes of both TR and Pn for Zhonghan 1, while Handao 8 and IPAR 9, only TR caused the effect. When moderate leaf rolling happened under water stress, Pn showed a slight reduction, while TR had more reduction, and WUE raised with an increased LRI. 2. The genotypic difference in root penetration ability of rice under water stressand its relation to transpiration and photosynthesisThere was a great difference among 13 rice varieties or hybrid combinations in root penetration ability under water stress, with upland rice being higher than paddy rice, hybrid rice higher than conventional variety, and japonica higher than indica.Among genotypes within a same type, as found among 7 upland rice varieties, there was also distinct difference in root penetration, and the difference became larger with the growth. Thus at 45 d after sowing, IAPAR 9, Zhonghan 3, Zhonghan 1 showed higher root penetration ability and the difference among them was small, while at 105 d after sowing, Zhonghan 3 and IAPAR 9 had significantly higher root penetration ability than other genotypes.The relationship between root penetration and some morphological characters varied with growth stage. At active tillering stage (45 d after sowing), root penetration was positively correlated with root thickness and root length, dry weight and ratio of root to shoot. At booting stage (75 d after sowing) root penetration was also correlated with root thickness, root length and dry weight, but no correlation with ratio of root to shoot was found. At maturity (105 d after sowing), root penetration was positively correlated with root thickness and root length, but no related with root dry weight and ratio of root to shoot. With the development, the effect of these root traits on root penetration became smaller.The effect of root penetration on stomatal conductance, transpiration rate and net photosynthesis and WUE also varied with genotypes. Some upland rice varieties, such as IAPAR 9, Yunlu 29 and Zhonghan 1 had higher root penetration, larger difference in SC and smaller difference in TR, while there was no consistency between Pn and WUE in response to root penetration. The two indica varieties had lower root penetration. Although their SC, TR and Pn declined greatly under water stress, WUE was less reduced. Other genotypes had middle root penetration, but they showed different SC, Pn, TR and WUE, with 2 hybrid rices being higher than the conventional varieties. 3. QTL analysis of leaf number and age development under different waterconditionsThe genetic linkage mapping with 207 molecular markers obtained from a RIL of Zhenshan 97B and Miyang 46 was used to determine QTLs of leaf number and age development over the growth under the different water conditions. QTLs related to leaf number of main culm, lasting time of leaf growth, and rate of leaf growth were mainly located on the chromosomes 6 and 9, in particular qtln6.2, qrlg6.2 located onRM197-RZ516 of the chromosome 6 controlled total leaf number and rate of leaf growth, respectively, and their additive effect value and contribution were relatively larger. In addition, a QTL controlling rate of leaf growth in main culm was also detected in the location, which showed additive effect of genotypes and environment interaction. Moreover, five QTLs were detected near to a marker RM197 on the chromosome 6 under both water conditions, and under well-irrigated condition, it was found that three additive locus qtln6.1, qltlg6.1 and qrlg6.1 on the location of RM225-RM197 on the chromosome 6 controlled total leaf number, lasting time of leaf growth, and rate of leaf growth, respectively.By analyzing QTL of leaf age development, 14 additive QTLs were detected under water stress condition. During 13 d to 29 d after sowing, one additive QTL was detected on the marker locations of RM296-RM105 of the chromosome 9 and of RM296-RM105 of the chromosome 6, respectively. However, these two QTLs were no longer found thereafter, suggesting that leaf age development under water stress was caused by the expression of the different genes. 4. QTL analysis of yield components and related traits under different waterconditionsCorrelation and QTL analysis were done on panicle weight of main shoot and nine yield-related characters by using a RIL population under two water conditions. 14 and 32 QTLs, controlling panicle weight of main shoot, plant height, panicle length, panicles per plant, shoot weight of main shoot, grains per panicle, grain-setting percentage and grain weight, were detected under water stress and well irrigated conditions, respectively, and 40 and 38 QTLs of additive X additive effect of gene interaction related to these traits were found under the two water conditions, respectively.By analyzing the performance of yield components and yield-related traits under the two water conditions, it was found that the number of additive QTLs controlling grains per panicle, grain-setting percentage, grain weight and shoot weight was obviously greater under well-irrigated condition than water stress, suggesting some genes expressed under well irrigated condition did not express when the plants were exposed to water stress. Some additive QTLs on the 6 marker locations were detectedin both water conditions., but only 3 additive QTLs expressed in both water conditions for a same trait, i.e. qgnpl.l on the marker location of RM151-RG532 of the chromosome 1, qpl2.1 on the marker location of M6-RM240 of the chromosome 2 and qtgwS.l on the marker location of RZ225-RG435 of the chromosome 5.It was found that gene pleiotropism or gene linkage was commonly present in analysis of QTL for targeting traits under the two water conditions. In analysis of QTL related to total leaf number and age development, 26 QTLs involved in 8 marker locations were detected. In analysis of QTLs related to yield characters, 31 QTLs involoved in 10 marker locations were detected.更多还原