镉引起小麦苗逆境乙烯的产生及其和镉的吸收、分布的关系

Stress Ethylene Production Induced by Cadmium in wheat Seediings and its Relation to Cadmium Uptake and Distribution

溶液培养小麦幼苗转移至含Cd^(2+)的营养液中,根系乙烯产生较快地增加,约在12h达高峰,然后下降;ACC含量亦呈先升后降的趋势。未和Cd^(2+)溶液直接接触的地上部乙烯亦增加,至36h达高峰,此后急剧下降,而ACG和 MAGC含量持续上升。地上部乙烯的增加,主要是由通过根系运往地上部的镉直接作用的结果,不是根部合成ACG运往地上部后再产生的。电镜观察表明,地上部乙烯产生和ACC含量变化的时间进程,可以与镉进入叶细胞内的部位及其对细胞膜和细胞器的影响相联系。

The hydroponic wheat seedlings were trans-ferred to solutions containing Cd^(2+) with variousconcentrations. Ethylene production in rootsincreased rapidly, peaked at 12 hours of exposureto 1 and 5 mmol/L CdCl_2 and decreased thereaf-ter. The change of ACC contentin roots showeda similar pattern, i.e.it increased at first and thendecreased. In shoots which were not directlyexposed to Cd^(2+), ethylene production began torise after 12 hours of exposure to 5 and 10 mmol/L, peaked at 36 hour and then declined sharply.However, ACC and MACC content in shootsincreased continually during the period of treat-ment with 10 mmol/L CdCl_2.The results in-dicated that the increase of ethylene productionin shoots induced by cadmium mainly resultedfrom the direct action of Cd^(2+) transported fromroots to shoots, not the conversion of ACC, whichhad been synthesized in roots and transported toshoots, to ethylene. The electronmicroscopic ob-servation of Cd^(2+) distribution and accumulationin wheat leaf cells showed that the time course ofchanges of ethylene production and ACC con-tent in shoots was correlated to Cd-bound sitein leaf cells and effects of Cd^(2+) on plasma membrane and organelles.