外源H2O2处理对小麦渗透性调节物的影响

以小麦品种西旱2号和宁春4号为材料,研究了不同浓度H₂O₂处理对其幼苗叶绿素、渗透性调节物质量分数及脯氨酸代谢相关酶活性的影响.与对照相比,50,100,200μmol/LH₂O₂处理下西旱2号幼苗叶片叶绿素a质量分数显著降低,而叶绿素b和叶绿素总量无显著变化;对宁春4号来说,不同浓度的H₂O₂处理使幼苗叶片叶绿素a,叶绿素b和叶绿素总量均显著降低.此外,外源H₂O₂处理诱导西旱2号幼苗叶片可溶性糖质量浓度和脯氨酸质量分数均显著增加,却使宁春4号可溶性糖质量浓度降低,且仅在200μmol/L H₂O₂处理下脯氨酸质量分数明显增加,但H₂O₂处理对两种小麦可溶性蛋白质质量浓度无影响.50,100μmol/L H₂O₂处理下西旱2号幼苗鸟氨酸转氨酶活性降为对照的78%,83%,200μmol/LH₂O₂处理使脯氨酸脱氢酶活性增加为对照的116%;而H₂O₂处理诱导宁春4号幼苗脯氨酸脱氢酶,鸟氨酸转氨酶活性均显著提高.结果表明:与宁春4号相比,西旱2号小麦幼苗叶片的光合色素在H₂O₂胁迫下受到较轻的破坏,却积累了较多的可溶性糖和脯氨酸,从而对H₂O₂胁迫表现出较强的耐受能力;H₂O₂处理诱导西旱2号幼苗叶片的脯氨酸积累与轻微变化的脯氨酸脱氢酶活性有关,而在宁春4号脯氨酸积累与H₂O₂诱导的鸟氨酸转氨酶活性升高有关.

Effects of exogenous H2O2 on the osmotic regulations in wheat

Two kinds of wheat,cv.Xihan 2 and Ningchun 4,were employed to study the changes of chlorophyll and osmotic regulation contents and proline metabolism activities in the leaves of seedlings under hydrogen peroxide treatment.Compared to the control,a significant decrease in chlorophyll content and no changes in the amount of chlorophyll b and total chlorophyll were observed in Xihan 2 seedlings when they were exposed to 50, 100 and 200μmol/L H₂O₂,but remarkable reductions in Chl a,Chl b and in the total chlorophyll occurred in the leaves of Ningchun 4 seedlings treated with different H_O2 concentrations.Exogenous H_O2 led to significant elevations in the levels of soluble sugar and proline in the leaves of Xihan 2,but a decrease in soluble sugar content in Ningchun 4.Also,a proline accumulation was found in Ningchun 4 seedlings treated with 200μmol/L H_O2, but no significant change in soluble protein content was exhibited in the two kinds of wheat treated by H_O2.In Xihan 2 seedlings,OAT activity decreased by 78%and 83%of the control value under 50 and 100μmol/L H_O2 treatment,respectively;200μmol/L H_O2 led to about 16%elevation in PDH activity.Significant enhancement in the activities of PDH and OAT was found in Ningchun 4 under H_O2 treatment.Exogenous H_O2 treatment resulted in slight destruction of photosynthetic pigment but significant accumulation of soluble sugar and proline in Xihan 2 seedlings in comparison with Ningchun 4 seedlings,Xihan 2 was more tolerant to oxidative stress. Also,the elevation of proline content was associated with a slight change in PDH activity in Xihan 2 seedlings, and with significantly increased OAT activity in Ningchun 4 seedlings treated with exogenous H₂O₂.