玉米抗旱突变体edt1抗旱机制的初步解析

Dissection of drought tolerance mechanism in maize EMS mutant edt1

为了选育玉米抗旱新品种,并进一步探究玉米应对干旱胁迫的分子调控机制,本研究采用田间抗旱筛选得到的抗旱突变体edt1,分别进行中度和重度2种干旱胁迫处理,并测定相关参数。结果表明:在中度干旱胁迫下,edt1的净光合速率(P_n)显著高于野生型‘郑58’,PSII基因psb A、lhcb3和lhcb4的表达与‘郑58’相比显著增强;在重度干旱胁迫下,edt1的质膜受损程度较轻,PSⅡ的最大光化学效率(F_v/F_m)、叶片相对含水量及活性氧清除均显著高于‘郑58’,抗氧化酶活基因Mn-sod3、apx、cat2及cat3的表达较‘郑58’中均显著增加。以上结果说明,干旱胁迫下,edt1具有较强的光合能力与活性氧清除能力,这与PSII反应中心、捕光复合体及抗氧化酶基因的表达调控密切相关。

To screen and identify drought-tolerant maize varieties, and determine the mechanism of drought-tolerance in maize（Zea mays）, a drought-tolerant mutant edt1 which was obtained from drought-tolerance screening in the field was treated with moderate and severe drought. The results showed that the net photosynthesis（P_n） of edt1 were higher than ‘Zheng58＇ significantly, and the relative expression of PSII gene psb A, lhcb3, andlhcb4 increased more significantly than ‘Zheng58＇ under moderate drought. Under severe drought treatment, the membrane of edt1 was only damaged slightly. In addition, the maximal efficiency of PSII photochemistry（F_v/F_m）, the relative leaf water concent and the ability of reactive oxygen species（ROS） scavenging were significantly higher than those in ‘Zheng58＇ respectively. We furtherly found that the relative expression of antioxidant enzyme genes including Mn-sod3, apx, cat2 and cat3 increased more significantly than those in ‘Zheng58＇ during severe drought condition. These results together provided a direct evidence that the edt1 mutant was drought-toletant and possesses more efficient ROS scavenging mechanism than ‘Zheng58＇. Our data indicated that modulation of the expression of genes related to PSII active center, light-harvesting complex and antioxidant enzyme contributes to its drought tolerance in edt1.