Mechanisms of Response of Plant Cell Walls to Temperature Signal

水稻(Oryza sativa L.cv.)Koshihikari)和小豆(Vigna angularis Ohwi et Ohashi cv.Takara)幼苗在不同温度条件下生长，并对其生长速率差异的机理进行了分析。将在30℃黑暗中生长的两株幼苗转移到10-50℃的温度范围内进一步生长时，水稻胚芽鞘和红小豆上胚轴的生长速率分别在40℃和30℃时达到最大。细胞壁伸长率在该温度下也最高，且随着温度的升高或降低而变小。两种材料的生长速度与延伸率之间存在着密切的相关性。在生长速率较高的温度下，水稻胚芽鞘和红小豆上胚轴的细胞渗透浓度较低。这些结果表明，植物新梢的生长速率主要由中等PhysIOL…中细胞壁的力学性质决定在水稻胚芽鞘中，单位长度的细胞壁多糖含量最高，而半纤维素多糖的相对分子质量在40℃时最低。(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，在水稻胚芽鞘中，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延伸性。另一方面，在赤小豆上胚轴中，单位长度上胚轴的细胞壁多糖水平、果胶或HC-I多糖的相对分子质量没有明显的变化，与温度无关。但在30℃时，HC-II多糖的相对分子质量最低。红小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，红小豆上胚轴在中等温度下，生理范围主要是通过影响木聚糖酶的降解活性来调节细胞壁的伸长性。较少

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