【作者】 徐春英；

【导师】 梅旭荣；

【作者基本信息】 中国农业科学院 ， 作物气象学， 2008， 博士

【摘要】 生物节水是节水农业的重要发展方向,耐旱和高水分利用品种、生理节水调控和节水型农作制度是生物节水的核心内容,提高水分利用效率是生物节水的终极目标,其中培育耐旱和高水分利用效率的抗旱节水高产新品种是关键,因此建立可行、科学、稳定的小麦抗旱、高WUE品种选育的鉴定指标是最终实现生物节水的首要诉诸手段。为了探索氨基酸代谢与小麦抗旱性之间的关系,以及是否氨基酸代谢可以作为小麦抗旱育种的鉴定指标,本研究首先根据碳同位素判别值及实际抗旱情况选取冬小麦试验材料;其次应用氮稳定同位素示踪技术,利用GC-MS、GC-C-IRMS等仪器分析了拔节期土壤含水量85%供水条件下不同抗旱性小麦氨基酸氮同位素丰度的动态变化,以此来推断氨基酸合成代谢的动态变化,比较了不同品种氨基酸合成代谢的差异;最后比较了对照品种和施用氮同位素肥料碳稳定同位素的变化。通过对冬小麦籽粒碳稳定同位素的分析以及不同抗旱性小麦拔节期土壤含水量85%供水条件下的氮同化及氨基酸代谢等方面的研究与分析,主要得出以下结论:(1)不同基因型冬小麦籽粒碳稳定同位素分辨率(△‰)不同,大体分布范围在18‰至21‰之间,并且强抗旱品种和弱抗旱品种的△‰有极显著差异。(2)通过对拔节期土壤含水量85%供水条件下不同小麦品种,氮同化和氨基酸代谢的动力学的研究,结果表明:从施入氮同位素肥料后的10min-24h整个时间段来看,强抗旱品种对氮的同化效率要极显著高于中等抗旱和弱抗旱品种,而中等抗旱和弱抗旱品种之间在本研究中没有明显的规律;强抗旱品种的氮吸收速率极显著高于中等抗旱和弱抗旱品种,强抗旱品种间也存在差异,中等抗旱品种和弱抗旱品种之间的氮吸收速率在本研究中没有显著差异;强抗旱品种和中等抗旱品种氨基酸δ15N 24h内呈线性增长,而弱抗旱品种在3h-24h基本维持稳定;24h内蛋白质氨基酸的含量处于升高-降低的动态平衡之中;三个强抗旱品种百农9310、临汾50744、W98中18的谷氨酸/谷氨酰胺、天冬氨酸/天冬酰胺、丝氨酸、甘氨酸δ15N在施入15NH4+24h内的升高要远远超过中等抗旱品种和弱抗旱品种,而中等抗旱品种要高于弱抗旱品种;缬氨酸、亮氨酸、异亮氨酸、蛋氨酸、脯氨酸、苯丙氨酸、酪氨酸、赖氨酸等那些合成比较缓慢的氨基酸δ15N的改变程度也是强抗旱品种要高于中等抗旱和弱抗旱品种。(3)通过分析不同小麦品种拔节期施用(15NH4)2SO4肥料后叶片碳同位素组成的动态变化,以及分析北农5号施用(15NH4)2SO4肥料和(NH4)2SO4肥料后叶片氨基酸碳同位素组成的动态变化,结果发现:同一品种在10min-24h内叶片的δ13C值有一个波动范围,但是没有显著变化趋势;不同品种δ13C值的变化是不同的;从本研究δ13C值表征的WUE的变化来看,小麦品种的抗旱性强弱和瞬时WUE的高低并不是完全相吻合的,也就是单个叶片的δ13C值与瞬时WUE的相关性较差;北农5号施入(15NH4)2SO4肥料和(NH4)2SO4肥料其氨基酸δ13C值变化呈现相反的趋势,并且变化范围也不同;缬氨酸δ13C值极显著升高,而施用14N-肥料δ13C的增加只有施用15N-肥料δ13C的增加值的34.7%。从上述研究结果可以看出,强抗旱、中等抗旱、弱抗旱冬小麦品种在拔节期土壤含水量85%供水条件下其氨基酸的合成代谢动态具有显著差异,因此,氨基酸代谢动态可以作为拔节期冬小麦抗旱性的鉴定指标,这个指标的确定对于小麦抗旱品种的早期筛选具有重要的理论意义和现实意义。更多还原

【Abstract】 The relationships between drought-resistance and amino acids metabolism in wheat were studied for exploring whether amino acids metabolism can be an indicator to evaluate the drought-resistance of wheat, different drought-resistant winter wheat varieties were selected based on their carbon isotope discrimination and actual drought information at first. These varieties were planted in pots, and the soil moisture was controlled under the condition of 85% in the jointing stage, the 15N-labelled fertilizer was applied in the stage. The dynamics of amino acids nitrogen isotope composition of leaves is analyzed by GC-MS and GC-C-IRMS for these varieties. The dynamics and difference of amino acids metabolism are also investigated among the different wheat varieties according to the dynamics change of amino acids nitrogen isotope composition. Finally, the change of carbon isotope composition was compared between control varieties and treated varieties by application of 15N-labelled fertilizer.The following conclusions are drawn:(1) The different genotypes of winter wheat grain have different carbon stable isotope discriminations (△‰), which are generally fallen in the range of 18‰to 21‰. Furthermore, there is a very significant difference of△‰between strong and weak drought-resistant wheat varieties in this research.(2) The dynamics of nitrogen assimilation and amino acids metabolism are studied for different wheat varieties which grew in the conditions of soil moisture content 85% during the jointing stage. The results are as following: From the whole time of 10min-24h after the application of 15N-labelled fertilizer, the strong drought-resistant varieties have very significantly higher nitrogen assimilation efficiency and nitrogen uptake efficiency than weak and middling drought-resistant varieties wheat, while there are no distinct difference between weak and middle drought-resistant varieties in this research, however, there are still difference between the three strong varieties for nitrogen uptake efficiency.δ15N of amino acids shows linear accumulation in the strong and middle drought-resistant varieties in the 24 hours, and the strong varieties increase more quickly and fast, whileδ15N of amino acids almost keep stable during 3h-24h for the weak drought-resistant varieties, which is the most difference among them. No significant change is observed on the content of protein amino acid, although which is changeable either increased or decreased. The increase ofδ15N is significantly bigger in the strong drought-resistant wheat varieties such as Bainong9310, Linfen50744, W98zhong18 than in the middle or weak drought-resistant wheat varieties, including Glu/Gln, Asp/Asn, Ser, Gly, and it is bigger too in the middle drought-resistant varieties than weak drought-resistant varieties after 15NH4+ treatment within 24h. On the other hand, those amino acids which synthesize relatively slow or late including Val, Leu, Ile, Met, Pro, Phe,Tyr etc, change more greatly in the strong drought-resistant varieties than middle and weak drought-resistant varieties.Based on our results, we can make a conclusion that there is significant difference of amino acids metabolism between strong drought, middle and weak resistant wheat varieties in the jointing stage under the 85% soil moisture condition. Therefore, the dynamics of amino acids metabolism can be used as an index to identify the drought character of winter wheat in the jointing stage, which could play a great theoretical and practical role for selecting drought-resistant wheat varieties.更多还原