Mechanisms of Response of Plant Cell Walls to Temperature Signal

水稻（Oryza sativa L. cv.）和红豆（Vigna angularis Ohwi et Ohashi cv）。在不同温度条件下，对青菜幼苗生长速率差异的机理进行了分析。在30℃的暗光条件下生长的两种幼苗，将其转移到10 ~ 50℃的温度范围内继续生长，水稻胚轴和红豆上胚轴的生长速度分别在40℃和30℃达到最大值。在此温度下，细胞壁的延伸性最高，随着温度的升高或降低，细胞壁的延伸性变小。两种材料的生长速率与伸长率之间存在密切的相关关系。另一方面，水稻胚轴和红豆上胚轴的细胞渗透浓度在生长速率高的温度下较低。这些结果表明，在中等、生理或较生理的温度范围内，植物芽的生长速度主要取决于细胞壁的力学特性。在40℃时，单位长度的细胞壁多糖含量最高，而半纤维素多糖的分子量最低。（1→3）、（1→4）-β- d -葡聚糖的降解活性在40℃时最高，在此温度范围内随温度的升高或降低而降低。这些数据表明，在水稻胚芽组织中，温度主要通过影响（1→3）、（1→4）-β-葡聚糖降解活性来调节细胞壁的伸展性。另一方面，在红豆上胚轴中，无论温度如何，上胚轴单位长度的细胞壁多糖水平或果胶或HC-I多糖的分子质量都没有明显的变化。而在30℃时，HC-II多糖的分子量最低。红豆上胚轴降解木葡聚糖的活性在30℃时最高，在此温度范围内随温度的升高或降低而降低。由此可见，在小豆上胚轴温度适中的生理范围内，主要通过影响木葡聚糖降解活性来调节细胞壁的伸展性。少

Rice (Oryza sativa L. cv. Koshihikari) and azuki bean (Vigna angularis Ohwi et Ohashi cv. Takara) seedlings were grown under various temperature conditions and the mechanism inducing the difference in growth rate was analyzed. When both seedlings which had been grown in the dark at 30℃ were transferred to the temperature range of 10-50℃ and grown further, the growth rate of rice coleoptiles and azuki bean epicotyls was maximum at 40℃ and 30℃, respectively. The cell wall extensibility was also the highest at such temperatures, and became smaller as the temperature increased or decreased. There were close correlations between the growth rate and the extensibility of both materials. On the other hand, the cellular osmotic concentration of rice coleoptiles and azuki bean epicotyls was lower at the temperatures where the growth rate was high. These results suggest that the growth rate of plant shoots is mainly determined by the mechanical properties of the cell wall in the moderate, physiol … More ogical temperature range.In rice coleoptiles, the levels of cell wall polysaccharides per unit length were the highest, whereas the molecular mass of the hemicellulosic polysaccharides was the lowest at 40℃. The activity of (1→3), (1→4) -β-D-glucan degradation was the highest at 40℃, and decreased as the temperature increased or decreased from this temperature range. These data suggest that in rice coleoptiles temperature regulates the cell wall extensibility mainly by affecting the activity of (1→3), (1→4) -β-glucan degradation. On the other hand, in azuki bean epicotyls, there were no clear changes in the levels of cell wall polysaccharides per unit length of epicotyls, or the molecular masses of the pectin or the HC-I polysaccharides, irrespective of temperature. However, the molecular mass of the HC-II polysaccharides was the lowest at 30℃. Xyloglucan-degrading activity in azuki bean epicotyls was highest at 30℃, and decreased as the temperature increased or decreased from this temperature range. Thus, in azuki bean epicotyls temperature in the moderate, physiological range was shown to regulate the cell wall extensibility mainly by affecting the activity of xyloglucan degradation. Less