白粉病菌对不同甜瓜品种幼苗生理生化指标的影响

Effect of Powdery Mildew on Physiological and Biochemical Indexes of Different Melon Varieties

为研究甜瓜白粉病菌对不同甜瓜品种生理指标的影响,本研究以高抗甜瓜白粉病品种‘16-6’、中抗甜瓜白粉病品种‘04-38’和高感甜瓜白粉病品种‘15B-42’幼苗为材料,测定病原菌接种1、3、5、7、9 d后甜瓜幼苗叶片中抗氧化防御性功能酶活性、丙二醛(malondialdehyde,MDA)、可溶性蛋白、叶绿素以及光合指标的变化。结果表明,接种白粉病菌后,除了超氧化物歧化酶(SOD)活性,3个甜瓜品种幼苗叶片中过氧化物酶(POD)、过氧化氢酶(CAT)、抗坏血酸过氧化物酶(APX)、多酚氧化酶(PPO)以及苯丙氨酸解氨酶(PAL)5个防御性酶的活性以及MDA含量均呈先升高后降低的变化趋势,且整体升高幅度表现为抗病品种大于感病品种;3个甜瓜品种幼苗叶片的可溶性蛋白和叶绿素含量以及净光合速率(net photosynthetic rate,Pn)、气孔导度(stomatal conductance,Gs)、胞间CO2浓度(intercellular CO2 concentration,Ci)、蒸腾速率(transpiration ratio Tr)和气孔限制值(stomatal limitation value,Ls)5个光合指标均有不同程度的下降,且抗病甜瓜品种的下降幅度明显小于感病品种。

In order to study the effect of melon powdery mildew on the physiological indexes of different melon varieties, high resistant to melon powdery mildew variety ’16-6’, medium resistant to melon powdery mildew variety’04-38’, and highly susceptible melon powdery mildew variety ’15 B-42’ were used as materials. The activities of antioxidant defense system enzymes, the contents of malondialdehyde(MDA), soluble protein and chlorophyll,and the photosynthetic indicators in leaves of melon seedlings were assayed after inoculated with powdery mildew 1, 3, 5, 7 and 9 d. The results showed that after inoculation with powdery mildew, except for superoxide dismutase(SOD) activity, the defense enzyme activities, including peroxidase(POD), catalase(CAT), ascorbic acid peroxidase(APX), phenylalanine ammonialyase(PAL) and polyphenol oxidase(PPO) and the MDA content in leaves of the three melon varieties showed a trend of first increase and then decrease, and the increment amplitude of the resistant lines was larger than that of the susceptible lines;the contents of chlorophyll and soluble protein, and the five photosynthetic indicators, including the net photosynthetic rate(Pn), the stomatal conductance(Gs), the intercellular CO2 concentration(Ci), the transpiration rate(Tr) and the stomatal limitation(Ls) of leaves of the three melon varieties decreased with different amplitude after inoculation, and the decrement amplitude of the resistant lines was smaller than that of the susceptible lines.