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作者	单位
贾少磊，吕金印，刘昌欣，梁泰帅，敬志豪	(1.西北农林科技大学理学院，陕西杨凌 712100； 2.西北农林科技大学生命科学学院，陕西杨凌 712100)

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中文摘要:

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。

英文摘要:

Drought is the one of the most important environmental stresses that reduces crop yield. Though wheat is C₃ plants, 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 C₃ and C₄pathway enzymes in wheat seedling leaf were investigated at 0, 6, 12 and 24 h after 20% PEG stress. The results showed that chlorophyll content, relative water content (RWC) and Rubisco activity (C₃ pathway 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 6 h after 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 24 h was found in Xinong 1043 and 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 anhydrase (CA), phosphoenolpyruvate carboxylase (PEPC), NADP malic dehydrogenase (NADP MDH),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 1043 was 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.

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