钾调节茎用芥菜同化物运输及茎部膨大的作用机理

STUDIES ON MECHANISM OF THE ACTION OF POTASSIUM ON THE ASSIMILATE TRANSPORT AND STEM ESPAND OF STEM MUSTARD (BRASSICA JUNCEA CASS VAR. TUMIDA TSEN ET LEE

1.钾抑制茎用芥菜叶片酸性转化酶活性,削弱蔗糖水解;而促进SPS活性,能增强蔗糖合成,使叶中生产更多的蔗糖。2.对叶细胞内ATP酶超微结构定位发现质膜和液泡膜存在较多的ATP酶;钾促进ATP酶活性,特别在对质膜ATP酶有更明显的促进作用,且表现有基因型的差异,即质膜ATP酶活性高的品种其SPS活性也高。3.钾促进叶中同化物输出,且更多地分配到产品器官一膨大茎中,从而提高产量。可以认为钾对茎用芥菜茎部膨大的作用主要是通过对SPS和ATP酶活性的促进和酸性转化酶活性的抑制,加强叶片内蔗糖的生成和基向运输,从而促进茎部膨大。

The effect of potassium on the assimilate.transport of stem mustard cultivars was studied with field test and pot experiment by measuring the activity of SPS,invertase,ATPase and the export rate of ^(14)C-assi-milate of leaves. The results showed that the export rate of assimilate of leaves was accelerated by potassium and the more assimilate was distributed to the harvest organ-expaneing stem. Potassium depressed the activity of acid invertase significantly, but unaffected the neutral invertase. The SPS activity of leaf was evidently increase and more sucrose were synthesized by higher potassium treatment. The ATPase activity, especially ATPase of plasmalemma was significantly increased in leaves of stem mustard by higher potassium treatment. In normal potassium concentrations, the activity of ATPase of plasmalemma was corresponding to the potassium contents in leaves.The ATPase activity of plasmalemma was increaseed 39.8% by exogenous 50mml K^+ in reaction mixture. The electrograph of ATPase activity in the leaf cells of stem mustard showed that the ATPase activity was located at plasma-lemma, vacuolar membrane, plasmodesma, nucleus, chloroplast, mitochondria and cell wall. The activity of ATPase of leaf in higher potassium treatment was higher than in lower potassium treatment. And the activity of ATPase in plasmalemma and tonoplast was higher than other parts of cell.