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(p0.05).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 metabolism 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.