【作者】 刘辉；

【导师】 王三根；

【作者基本信息】 西南农业大学 ， 植物学， 2003， 硕士

【摘要】 已有的研究表明植物对低磷胁迫的适应性表现在多方面，如根系分泌有机酸等物质活化难溶无机磷以及一些酶和蛋白质的特异生成，这些酶和蛋白质特异性地为低磷所诱导，并对磷的吸收、活化、转运及利用起重要作用。本试验通过研究低磷胁迫下大麦和小麦的生理生化变化，比较小麦和大麦在磷胁迫下的不同生理生化反应，同时研究内源激素在低磷胁迫下的可能作用，探讨大麦和小麦对低磷胁迫的主动适应机制，以期为提高大麦和小麦的耐低磷胁迫性，增加其对有效磷的吸收提供信息，主要结果如下： 1．对低磷胁迫下大麦和小麦根系形态变化研究表明，低磷胁迫诱导大麦和小麦根的伸长，根系表面积增大，根系活力增加；不同水平的磷胁迫都使大麦和小麦的根／冠比显著大于对照，同时低磷胁迫诱导大麦和小麦根干物重增加。比较大麦和小麦在磷胁迫下根系变化的不同可以看出，在低磷胁迫的初期小麦R／S、根长有较大的增加而大麦则变化不大。 2．对低磷胁迫下大麦和小麦细胞膜脂过氧化研究表明，在低磷胁迫后期，大麦MDA含量远高于对照，小麦在胁迫期间MDA含量变化不大，说明低磷确能引起大麦超氧自由基的积累并引起叶片膜脂过氧化程度的提高，但对小麦膜伤害程度不高；大麦和小麦SOD活性随着胁迫时间的延长而增强，因此可以认为，膜保护酶(SOD)的变化及其对活性氧的清除是植物耐低磷胁迫特性的生理机制之一。 3．对低磷胁迫下大麦和小麦体内蛋白和酶的变化研究表明，大麦和小麦在磷胁迫初期可溶性蛋白含量增加，然后达最小(大麦第5d，小麦第7d)，这可能与植株向外分泌蛋白有关；低磷胁迫诱导小麦和大麦根和叶内的酸性磷酸酶活性增加，从而分解体内多余的有机磷以缓解磷胁迫。对大麦和小麦酸性磷酸酶同工酶谱分析表明，随着胁迫时间的延长，大麦诱导多条特异带，小麦只诱导一条特异带；随着介质磷水平的降低，大麦和小麦酸性磷酸酶酶带活性呈增强趋势。 4．对低磷胁迫下大麦和小麦体内其他变化研究表明，大麦和小麦在低磷胁迫期问脯氨酸含量呈波动变化；胁迫后期低磷促进小麦叶绿素增加，但对大麦叶绿素影响不大：低磷胁迫诱导小麦和大麦有机酸在体内累积，从而有利于根系向外分泌有机酸。根系和地上部分的可溶性糖含量分析表明：低磷胁迫下大麦和小麦可溶性糖含量随着胁迫时间的延长而有不同程度的降低，且低磷胁迫促进了同化物向根系的分配，根系中同化物的含量比对照明显增加。 5．对低磷胁迫下大麦和小麦内源激素变化研究表明，不同程度的磷胁迫都促进了大麦和小麦体内IAA含量的提高，且随着介质磷水平的降低IAA含量增加，iPA含量与之相反；低磷对ABA影响不大，但对GA。含量有影响，特别是胁迫初期对大麦GA。有较大的影响，可能在胁迫初期通过GA。的改变引起其他的代谢反应进而促进根系的变化。对不同激素的比值进行分析表明，低磷条件下大麦和小麦通过体内各种激素平衡的改变来调节其适应低磷胁迫的能力。 6．对低磷胁迫下大麦和小麦磷吸收的研究表明，低磷胁迫下大麦和小麦磷吸收速率显著增加；同时低磷胁迫促使大麦和小麦磷利用效率提高，但在胁迫后期小麦磷利用效率增加较大，大麦则变化较小。 7．对低磷胁迫下大麦和小麦磷吸收速率与有机酸含量、根系活力、ACP活性及根系表面积的相关分析表明，低磷处理小．01P）下大麦和小麦磷吸收速率与ACP活性、根系表面积显著相关，与有机酸含量有很好的相关性，但与根系活力相关性不明显。更多还原

【Abstract】 Under P deficiency stress, a series of physiological and biochemical changes have been studied, such as plant secreted organic acid from roots to activate the unavailable inorganic phosphorus into the available form, some special enzyme and protein which was important to absorb, activate, transport and utilize the phosphorus was induced.This paper studied the growth changes in wheat and barley under P deficiency stress to comparative the variant physiological and biochemical response. And the possible action of endogenous hormones was studied to discuss the initiative mechanism of barley and wheat to adapt low P stress. It can supply some information for the study of enhancing the ability of P deficiency stress tolerance and absorbing valid phosphorus of wheat and barley. The main results were as follows:1.Under P deficiency stress the roots system configuration changes in wheat and barley were studied. The results showed that P deficiency stress induced the roots length elongating, the roots surface area augmenting, the root dry weight and activity of root dehydrogenase increasing. And the root/shoot ratios of wheat and barley were distinct higher than control’s. From the study, it was found that the root/shoot ratio and roots length of wheat increased at the early stage of low P stress, but the barley’s showed little variation.2.Under P deficiency stress, the membrane lipid peroxidation in wheat and barley was studied. The results showed that the MDA content of barley was far higher than control’s at late stage of P deficiency stress, however the wheat’s showed little variation. With the same P concentration, SOD activity in wheat and barley was enhanced with the duration of P stress. It could be concluded that P deficiency stress could increase the membrane lipid peroxidation in barley, it affect little the membrane in wheat. The above results probably indicate that thechange of protective enzyme(SOD) activity and the ability of scavenging O were one of the physiological mechanism of deficiency phosphorus tolerance.3.Under P deficiency stress, the changes of protein content and enzyme activity in wheat and barley were studied. The results showed that the soluble protein content was enhanced at the early stage of P deficiency stress, and then decreased. It may because the soluble secretory protein content increased at some stage of P deficiency stress. The ACP activity in wheat and barley enhanced during the P deficiency stress, which could decompose the remanent organic phosphorus in plant to decrease the P deficiency stress. The results of ACP isozyme zymogram analysis showed that P deficiency stress induced barley producing several special bands, but wheat producing only one. With the decrease in P concentration in medium, the ACP isozyume bands activity presented fortified trend.4.Under P deficiency stress, the other changes in barley and wheat were studied. The results showed that the Pro content change was wavy, during the P deficiency stress. The chlorophyll content in wheat increased, but changed very little in barley at late stage of P deficiency stress. P deficiency induced the organic acid accumulating in barley and wheat, which could help plants to secrete organic acid out of roots. Analysis of soluble sugar content indicated that P deficiency stress changed the distribution of carbohydrate between roots and shoots in barley and wheat.5.Under P deficiency stress, the changes of endogenous hormones in barley and wheat were studied. The results showed that different phosphorus stress induced IAA content increasing and it decreased with the increase in P concentration in medium, however the iPA content changes were reverse to IAA. The ABA content changes showed little variation but GA3 concentration increased considerably at the early stage of P deficiency stress. It’s probably the part reason of other reaction which could induce the roots system configuration changing. The analysis of different hormones ratio showed that barley and wheat adjust the balance of hormones to adapt更多还原