干旱胁迫对小麦叶片核糖核酸酶活力及合成的影响

干旱协迫下，抗旱（陕合６号）与干旱敏感（郑引１号）小麦品种叶片中的核糖核酸酶活性均有所增加，增加幅度与其相对含水量变化呈显著负相关。１４Ｃ－Ｌｅｕ掺入后，样品粗提液经ＰＡＧＥ分离并染色，发现干旱处理叶片的两个低分子女（１２ｋＤ、１７ｋＤ）具ＲＮａｓｅ活性的蛋白质的放射性掺入总量低于对照，但占总蛋白的放射性比例高子对照，证明干旱胁迫下存在ＲＮａｓｅ的从头合成（ｄｅｎｏｖｏｓｙｎｔｈｓｉｓ）。讨论了胁迫下ＲＮａｓｅ活性增加的原因。

EFFECT OF DROUGHT STRESS ON THE RNase ACTIVITY AND de novo AYNTHESIS IN WHEAT LEAVES

The RNase activities in wheat leaves of both drought resistant(shanhe-No,6)anddrought sensitive(Zhenyin-No.1)cultivars increased significantly during drought stress andthe increase was negatively related with the RWC of leaves.With the incorporation experi-ment of 14 C-Leu,it was found that the radioactivities of two low moleclar bands(seperatedby native-PAGE) of proteins with RNase activity(MW 12 and 17 kD)in stressed leaves werelower than that of control, but the percent of total radioactivity in leaf proteins was muchhigher,This result gives a direct evidence of existing of de onvo synthesis of RNase indrought stressed wheat leaves.