【作者】 苏芳；

【导师】 李勃；

【作者基本信息】 兰州大学 ， 生物学·植物学， 2019， 硕士

【摘要】 玉米作为重要的粮食作物,又兼具饲料和生物燃料的功能,其产量关系国计民生。玉米属于盐敏感植物,它的生长和产量受到盐胁迫的极大限制。德美亚2号(DMY2)和金穗3号(JS3)作为本研究的实验材料,是我国华北和西北地区(土壤盐渍化多发地区)长期种植的玉米品种。在水培系统中进行的盐胁迫下玉米苗期生理学实验鉴定显示:相比金穗3号,德美亚2号的抗盐性和离子排除能力较强。至少在中度盐胁迫下,德美亚2号叶中K~+和Na~+两种离子的比值相对于金穗3号约高10倍,显示了更强的排Na~+保K~+的能力。同时,德美亚2号叶中的Cl~-含量也显著低于金穗3号。德美亚2号在盐处理下抗盐性指标(如ST,salt tolerance index)的变化表明其在盐胁迫下的生长保持在更接近正常水平的状态,这一结果完全符合其盐胁迫下对Na~+和Cl~-较强的离子排除(salt exclusion)能力。金穗3号相比之下抗盐性较低,其在盐胁迫下生物量的减少也最大。盐胁迫下金穗3号根冠的生物量之比几乎没有变化,说明其对盐胁迫的主动适应机制相对不足,这也与其较弱的排盐能力相一致。在分子生物学层面,本研究利用同源克隆对两个可能参与介导和调节玉米组织水平Cl~-转运的转运蛋白(GRMZM2G104542和GRMZM2G122251)进行了初步的功能分析。结果显示:在B73背景下,两个基因在根中有较高、较特异的表达,并受到盐胁迫的显著抑制;生物信息学分析和亚细胞水平定位实验显示两个基因编码的产物很可能定位在质膜上;酵母异源表达实验结果显示两个基因编码的蛋白可能对Cl~-没有转运活性,对其蛋白的进一步转运功能研究(如电生理学研究)亟待开展。更多还原

【Abstract】 As an important food crop,maize also serves as animal feed and biofuel.Therefore maize production has attracted heavy attention in the scope of national economy and people’s livelihood.Maize is a salt sensitive plant species whose growth and yield are limited by salt stress.DMY2 and JS3 as experimental materials for this study,are long-term grown in Northern and Northwestern China,where soil salinezation is commom to observe.The physiological evaluation in the hydroponic experimental system showed that the salt tolerance and ion exclusion ability of DMY2were significantiy higher than JS3.Under moderate salt stress,the K~+/Na~+ratio in leaves of DMY2 was maintained about 10 times higher than JS3,shows a stronger ability to discharge Na~+to protect K~+.At the same time,the Cl~-content of DMY2was also significantly lower than that of JS3.The ST(salt tolerance index)values of DMY2 under salt treatment indicated that its growth remained at a state closer to that under normal conditions.This result is consistent with its strong exclusion of Na~+and Cl~-from accumulating under salt stress.In contrast,JS3 is more salt sensitive,and its biomass reduction is the largest under salt stress among the cultivars tested.The root-to-shoot ratio of JS3 remained the same when plant was treated with salt stress,indicating that the active adaptation mechanism to salt stress was insufficient in JS3.This is also consistent with its weaker salt exclusion capacity.At the molecular biology level,this study used homologous cloning to perform a preliminary functional analysis of two putatitive Cl~-transporters(GRMZM2G104542 and GRMZM2G122251)that may be involved in mediating and regulating of tissule level Cl~-transport in maize.The results showed that in the B73 background,the two genes have quite specific expression in the roots and their expression was strongly inhibited by salt stress.Bioinformatics analysis and subcellular localization experiment showed that the products of the two genes are likely to be localized on the plasma membrane.The results of heterologous expression in yeast showed that the proteins encoded by the two genes may have no transport activity for Cl~-.Further study of protein transport function,such as electrophysiological studies,is needed.更多还原