PEG胁迫对抗旱性不同的小麦幼苗光合关键酶活性的影响

Effects of Osmotic Stress on Activities of Key Photosynthetic Enzymes in Seedlings of Wheats with Different Drought Resistance

为了解小麦幼苗叶片C4途径酶对干旱胁迫的响应,以小麦节水耐旱品种西农1043和水地品种陕253为材料,通过水培实验,分析了20%PEG胁迫后小麦幼苗叶片的叶绿素含量、相对含水量及C3、C4光合途径酶活性的变化。结果表明,随着PEG胁迫时间的延长,小麦叶片叶绿素含量、相对含水量和C3途径关键酶Rubisco活性均下降,且陕253的降幅相对较大,而C4途径关键酶活性均呈先升后降趋势。PEG胁迫下,C4途径酶CA、PEPC、NADP-MDH、NADP-ME、NAD-ME和PPDK活性最大增幅分别达到19.3%(P<0.05)、34.7%(P<0.05)、52.3%(P<0.01)、93.7%(P<0.01)、56.6%(P<0.01)和91.3%(P<0.01),且西农1043的C4途径关键酶活性较陕253增加明显。说明干旱胁迫下小麦幼苗叶片高活性的C4途径相关酶可能在光合固碳及耐旱生理机制中起着重要作用。

Drought is the one of the most important environmental stresses that reduces crop yield.Though wheat is C3plants,there is C4pathway photosynthetic enzymes,which playing an important role under drought stress particularly.To understand the effects of drought stress on C4pathway enzymes in wheat seedling leaves,two wheat varieties(Triticum aestivum L.)with different sensitivity to drought were chosen,and treated with 20% PEG in hydroponic experiment.The chlorophyll content,relative water content and the activity of C3and C4pathway enzymes in wheat seedling leaf were investigated at 0,6,12and 24hafter 20%PEG stress.The results showed that chlorophyll content,relative water content(RWC)and Rubisco activity(C3pathway key enzyme)all declined with the duration of PEG stress,and a larger reduction was observed in the drought sensitive variety Shaan 253.There was no significant difference in the activity of Rubisco declined(P>0.05)between two cultivars at 6hafter stress,and then significant difference was observed(P<0.05)along with the duration of stress,a reduction of 43.6%(P<0.01)and 54.6%(P<0.01)at 24hwas found in Xinong1043and Shaan 253,respectively.The activities of C4pathway enzymes in the leaves increased with the duration of stress time and then decreased.The maximum increase of the activities of carbonic an-hydrase(CA),phosphoenolpyruvate carboxylase(PEPC),NADP malic dehydrogenase(NADPMDH),NADP malic enzyme(NADP-ME),NAD malic enzyme(NAD-ME)and Pyruvate-Pi-dikinase(PPDK)was 19.3%(P<0.05),34.7%(P<0.05),52.3%(P<0.01),93.7%(P<0.01),56.6%(P<0.01)and 91.3%(P<0.01),respectively.The increase of the activities of C4pathway enzymes in the leaves of Xinong 1043was more than that of Shaan 253.The results suggested that high activities of C4pathway enzymes might play an important role in photosynthetic carbon fixation and physiological mechanism of drought-resistant of wheat seedlings.