玉米幼苗抗氧化酶活性、脯氨酸含量变化及与其耐寒性的关系

研究了黄C（耐寒型）和Mo17（低温敏感型）两种耐寒性不同的玉米自交系幼苗在低温逆境（5 ℃，3 d）下，根、中胚轴和胚芽鞘3个部位过氧化氢酶（CAT）、过氧化物酶（POD）活性和脯氨酸（Pro）含量变化及与其耐寒性的关系.结果表明，低温期间，黄C的中胚轴、胚芽鞘相对生长率显著高于Mo17；黄C的根、中胚轴、胚芽鞘3个部位的CAT、POD活性和Pro含量变化率（其中，中胚轴分别为39.02%、-31.35%和86.86%）均高于Mo17（中胚轴变化率分别为1.86%、-48.67%和12.01%）；黄C 3个部位的质膜透性（中胚轴为22.05%）均低于Mo17（中胚轴为29.11%）.逐步回归分析表明黄C低温期间积累的干物质主要与Pro含量有关，而Mo17主要与POD活性有关，玉米幼苗中胚轴对低温反应最敏感，中胚轴Pro含量变化率与玉米耐寒性关系最密切.

Antioxidant enzyme activities and proline content in maize seedling and their relationships to cold endurance

This paper studied the catalase (CAT) and peroxidase (POD) activities and proline (Pro) content in the seedling's root, mesocotyl (including coleoptile node) , and coleoptile (including infancy leaf) of two maize inbred lines Huang C (cold-endurance) and Mo17 (cold-sensitive), and their relationships to cold endurance under low temperature stress (5 degrees C, 3 d). The results showed that under the low temperature stress, Huang C had a significantly higher relative growth rate of mesocotyl and coleoptile than Mo17, and the change rates of CAT and POD activities and Pro content in the root, mesocotyl and coleoptile of Huang C were higher than those of Mo17. The plasma membrane permeability of the three segments of both inbred lines was significantly increased, but Huang C had significantly lower plasma membrane permeability than Mo17. Compared with those under normal temperature, the seedlings under low temperature stress had higher CAT activity and Pro content, and the increment was higher in Huang C than in Mo17. The POD activity in the three segments of the seedlings under low temperature stress was reduced, and the decrement was lower in Huang C than in Mo17. Stepwise regression analysis showed that under low temperature stress, the dry matter accumulation in cold-endurance line Huang C was mainly related to Pro content, while that in cold-sensitive line Mo17 was mainly related to POD activity. Mesocotyl was the most responsive tissue to low temperature. The change rate of Pro content in mesocotyl was more closely correlated with the cold endurance of maize inbred lines than the other physiological parameters.