酸雨对水稻不同生育期叶片叶绿体ATP酶的影响

酸雨对植物生长发育具有显著影响。然而,不同生长阶段植物对逆境胁迫的响应存在差异。以模拟酸雨胁迫水稻(Oryza sativa)(孕穗期、灌浆期),利用植物生理生化方法测定了水稻叶肉细胞叶绿体Mg2+-ATPase活性及其基因表达量、光合磷酸化活性、ATP含量、植株相对生长速率(RGR)和叶片净光合速率(Pn),研究酸雨胁迫下孕穗期、灌浆期水稻叶绿体ATP酶的变化及其对植物光合作用影响的机理。结果表明,p H=4.5酸雨使孕穗期水稻RGR、Pn、叶片ATP质量比和光合磷酸化活性均显著提高,灌浆期上述指标变化不明显;p H=3.5和p H=2.5酸雨使上述指标均下降,且随酸雨p H值降低,变幅增加。p H=4.5酸雨使孕穗期、灌浆期水稻ATP合酶基因表达量及Mg2+-ATPase活性升高;p H=3.5和p H=2.5的酸雨使孕穗期、灌浆期水稻ATP酶基因表达量减少,造成Mg2+-ATPase活性降低,且随酸雨p H值降低变幅增加。可以认为,酸雨通过影响ATP酶转录水平,改变Mg2+-ATPase活性、光合磷酸化活性和叶片ATP质量比,进而影响Pn,并最终影响植物生长发育。酸雨胁迫对孕穗期水稻生长发育及光合作用有低促高抑的剂量效应,而低强度酸雨对灌浆期水稻影响不明显。与灌浆期相比,孕穗期对酸雨胁迫较敏感,表明植物不同生长发育阶段对酸雨胁迫响应存在差异,此发现应成为评价酸雨影响植物的一个因素。

Effect of acid rain on chloroplast ATP enzyme in rice at different growth stages

The paper would like to present its exploration results of the effects of the acid rain on the rice growth in terms of chloroplast ATP enzyme in different growth stages (the booting stage and the filling stage) by making the growing rice treated with the simulated acid rain in comparison with the control rain.As is known,acid rain has proven to be effective on the rice plant growth,though its response to the rain can be various at the different stages of its growth.Therefore,the paper tries to focus our attention on identifying and determining the mechanism of the effect of the acid rain on the change in the chloroplast ATP synthase of the photosynthesis in the rice.As a matter of fact,the acid rain stress and the difference of the growing rice response to it can be made between the booting stage and the filling stage of the rice,which can be tested and measured by the activities and the gene expressions of the chloroplast ATP synthase and the photosynthetic phosphorylation in the ATP content in the leaves,the relative growth rate (RGR) and the net photosynthetic rate (Pn)through a ultraviolet spectrophotometry,a fluorescence quantitative polymerase chain reaction,and some other ways of physiology and biochemistry.The results of our investigation demonstrate that the RGR,Pn,the photosynthetic phosphorylation activity and the ATP content in the rice leaves treated with the acid rain at pH =4.5 at the booting stage have been found significantly increased by 9.14％,9.32％,7.22％ and 4.68％,as compared with those of the control rain,respectively.However,the acid rain has been found no obvious effect on the above indices during the filling stage.But,in contrast,the above indices at the booting stage and filling stage can be noticeably decreased after the stress of the acid rain at pH =3.5 and pH =2.5,whereas the decreasing degree has been aggravated with the decrease of the pH value of the acid rain.For example,the acid rain at pH =4.5 can increase the expression of six subunits of chloroplast ATP synthase and promote the activity of chloroplast ATP synthase during the two said stages.To be sure,the acid rain at pH =3.5 and pH =2.5 tends to inhibit the expression of the six subunits of chloroplast ATP synthase and decrease the activity of the chloroplast ATP synthase,with the changing degree increased with the decrease of the pH value.It means that the acid rain can change the photophosphorylation activity,the ATP content in leaves and the Pn by transcribing the activity of chloroplast ATPase,and finally has made effect on the plant own growth.On the other hand,the acid rain stress has also had promotive effects at the low acidity and inhibitive effects at the high acidity on the rice growth and photosynthesis at the booting stage,though the effect of the lowacidity acid rain has been found neglected on the rice growth at the filling stage.Thus,as compared with the filling stage,the change of indices at the booting stage turn out more obvious,implying that there exist differences in the resistance of rice to the acid rain stress in the two stages.Thus,it can be concluded that this finding can be expected to be made known as a significant factor in the evaluation of the acid rain effects on the growing plants.