Studies on plasma membrane proteins which are specifically induced by cold acclimation in plants.

本研究的目的是鉴定小麦(Triticum aestivum L.)在冷驯化过程中特异诱导的质膜蛋白。以遗传力差异较大的春小麦13EA(中国春)和冬小麦(诺斯塔)为试验材料。在冷室中生长4周后，冬小麦地上部的耐寒性提高到-18ﾟC，而春小麦地上部的耐寒性仅提高到-8ﾟC。在低温环境下生长后，两个品种的根的耐寒性都略有提高。冷锻炼使质膜蛋白的电泳谱发生了明显的变化，这种变化依赖于C13EA细胞和组织。两个品种的根和地上部质膜中分子量在22~31 kDa之间的多肽含量普遍减少。在这些多肽中，28和26 kDa的多肽在冷硬化一周后突然减少。而相对分子质量为89、83、23、18和17 kDa的多肽在冬小麦地上部的含量显著增加。23、18和17 kDa多肽的增加与抗冻性的发展成正比。对冬小麦茎细胞质膜的冷冻断裂电子显微镜观察表明，冷驯化后冬小麦断裂面上的膜内颗粒数量显著减少，而春小麦的减少较少。这些结果可能表明，质膜在冷驯化过程中经历了分子重组，从而稳定了质膜对冷冻诱导的脱水胁迫的抵抗力。

The objective of this study was to identify plasma membrane proteins which are specifically induced by cold acclimation in wheats (Triticum aestivum L.). Two cultivars with a marked difference in the genetic capability to harden, namely spring wheat13EA\ : (cv Chinese Spring) and winter wheat (cv Norstar) were used as the experimental materials. After four weeks of growth in a cold chamber, the freezing tolerance in the shoots of winter wheat increased to -18ﾟC, whereas only to -8ﾟC in the shoots of spring wheat. In roots from both cultivars, the freezing tolerance increased very slightly after the growth under the cold environment. Cold hardening induced remarkable changes in electrophoresis patterns of plasma membrane proteins depending on c13EA\ : ultivars and tissues. Polypeptides with molecular masses ranged from 22 to 31 kDa decreased commonly in the root and shoot plasma membranes from both cultivars. of these polypeptides, 28 and 26 kDa polypeptides decreased abrupty after one week of th13EA\ : e cold hardening. On the other hand, polypeptides with molecular masses of 89, 83, 23, 18 and 17 kDa increased specifically in the shoots of winter hardy wheat. The increases of the 23, 18 and 17 kDa polypeptides were proportional to the development13EA\ : of freezing tolerance. A freeze-fracture electronmicroscopy of plasma membranes from shoot cells revealed that the intramembrane particle number on the fracture faces decreased significantly in winter wheat after cold acclimation, but less in sprin13EA\ : g wheat. These results may suggest that the plasma membrane undergoes a molecular reorganization during cold acclimation in such manner that they are stabilized against freeze-induced dehydration stress.