UV-B辐射对豌豆伸长生长和细胞壁多糖组分的影响

为探讨紫外线-B（UV—B）辐射引起的豌豆幼苗生长抑制与细胞壁结构组分变化的关系，以豌豆幼苗为对象，研究UV—B辐射对豌豆幼苗株高、细胞壁多糖组分（包括果胶、半纤维素A、半纤维素B和纤维素）中总糖含量与醛酸含量的影响。研究结果表明：自然生长的豌豆幼苗，随着生长天数的增加，幼苗株高增加，但单位长度细胞壁多糖总量降低，两者呈显著负相关（p〈0．05）；UV-B辐射会抑制豌豆幼苗的伸长生长，从而提高了单位长度内细胞壁的多糖总量；在UV—B辐射第5天时，相比对照组，幼苗株高降低了7．35cm，细胞壁多糖增加0．07mg／cm。豌豆幼苗茎细胞壁果胶、半纤维素A、半纤维素B和纤维素中的总糖含量分别比对照提高了22．30％、42．30％、21．47％和12．05％；醛酸含量分别比对照提高6％、33．3％、17．24％和18．08％。提示UV-B辐射调节了细胞壁组分代谢，提高了细胞壁多糖组分总糖与醛酸的含量，使细胞壁增厚，这可能使细胞壁刚性增强、延展性降低，因而限制了细胞伸长生长，抑制了豌豆幼苗生长。

Effects of UV-B radiation on stems elongation and cell wall polysaccharides of pea seedlings

In order to study the relationship between elongation growth inhibition induced by ultraviolet-B （UV-B） radiation and the changes of cell wall polysaccharides fraction, the stems length and contents of total sugar and uronic acid of cell wall polysaccharides fractions （pectin, hemicelluloses A, hemicelluloses B and cellulose） of pea stems irradiated with UV-B were analyzed. The results showed that with the sample of traditional pea, the stem length increased, while the amounts of cell wall polysaccharides per unit length decreased in primary 5 days, which showed a significantly negative correlation （p〈0.05）. However, the elongation growth of stems was inhibited and amounts of cell wall polysaccharides increased with UV-B irradiated sample. Under UV-B radiation, the stem length decreased by 7.35 cm and the amounts of cell wall polysaccharides increased by 0.07 mg/cm compared with control group on the 5th day. Compared with CK, the total sugar of pectin, hemicelluloses A, hemicelluloses B, and cellulose of UV-B irradiated group increased by 22.30%, 42.30%, 21.47%, and 12.05%, respectively, meanwhile the related uronic acid increased by 6%, 33.3%, 17.24%, and 18.08%, respectively. These results can be suggested that the me- tabolism of cell wall polysaccharides may be regulated by UV-B radiation. The changes of cell wall structure may be involved in cell wall thickness, which will lead to the cell wall rigidified. Therefore the extensibility of cell wall is decreased and elongation growth is inhibited.