链格孢侵染对伽师瓜果皮活性氧代谢的影响

本文以采后伽师瓜果实为试验材料,无损接种链格孢菌(Alternaria alternata),比较伽师瓜无网纹、小网纹、大网纹果皮组织抗病性差异,研究活性氧代谢及关键酶活性变化规律。结果表明:链格孢菌侵染30 d时,伽师瓜果皮无网纹病害发生率77.77%、小网纹84.17%、大网纹88.02%。各实验组超氧阴离子(O_2·~-)产生速率和还原型谷胱甘肽(GSH)含量呈先升高后降低的变化趋势,过氧化氢(H_2O_2)含量呈升高-降低-升高的变化趋势,丙二醛(MDA)含量外果皮呈升高-降低的变化趋势,内果皮一直升高;且侵染期间外果皮O_2·~-产生速率、GSH、H_2O_2和MDA含量高于内果皮。各实验组超氧化物歧化酶(SOD)、过氧化氢酶(CAT)、过氧化物酶(POD)、谷胱甘肽还原酶(GR)均呈先升高后降低的变化趋势;SOD活性无网纹、小网纹、大网纹外果皮峰值为49.19 U、39.29 U、31.81 U,内果皮峰值为32.36 U、24.28 U、19.30 U;CAT活性无网纹、小网纹、大网纹外果皮峰值为485.95 U、393.68 U、220.40 U,内果皮峰值为202.67 U、228.30 U、137.93 U;POD活性无网纹、小网纹、大网纹外果皮峰值为28.62 U、24.84 U、23.13 U,内果皮峰值为14.46U、9.73 U、8.58 U;GR活性无网纹、小网纹、大网纹外果皮峰值为378.32 U、170.24 U、196.15 U,内果皮峰值为70.58 U、45.61 U、66.67 U;抗坏血酸过氧化物酶(APX)活性呈上升趋势,外果皮活性高于内果皮,无网纹活性高于小网纹和大网纹。由此表明,伽师瓜果皮抗病性与活性氧代谢关系密切,外果皮抗病性强于内果皮,无网纹组抗病性强于小网纹组和大网纹组。

Effects of Alternaria alternata Infection on Reactive Oxygen Species Metabolism in Pericarp of Jiashi Muskmelon

Jiashi melon was chose as experimental material. Non-invasive inoculation methods of melon with Alternaria alternata was used. The objective of this study was aimed to compare the resistance difference of no-netted, small-netted and large-netted pericarp to pathogenic bacteria during storage. The relationship between reactive oxygen species (ROS) metabolism and key enzymes activity was investigated. The results showed that, when Jiashi melon was infected by Alternaria for 30 days, the incidence of disease rates of non-netted group, small-netted group and large-netted group were 77.77%, 84.17%, 88.02%, espectively. The superoxide radical (O2·-) production rate and Glutathione (GSH) content of each experimental group increased firstly and then decreased. The content of hydrogen peroxide (H2O2) increased firstly, then decreased, and increased during storage. The content of Malondialdehyde (MDA) of exocarp increased firstly and then decreased. However, the content of MDA of endocarp increased continuously. The O2·- production rate, GSH, H2O2 and MDA content of exocarp were higher than that of endocarp during the infection period. The activity of superoxide dismutase (SOD), catalase (CAT), peroxidase (POD) and glutathione reductase (GR) of each experimental group increased firstly and then decreased. Themaximum of SOD activity in no-netted, small-netted and large-netted of exocarp were 49.19 U, 39.29 U and 31.81 U, respectively, and that of endocarp were 32.36 U, 24.28 U and 19.30 U, respectively. The maximum of CAT activity in no-netted, small-netted and large-netted of exocarp were 485.95 U, 393.68 U and 220.40 U, respectively, and that of endocarp were 202.67 U, 228.30 U and 137.93 U, respectively. The maximum of POD activity in no-netted, small-netted and large-netted of exocarp were 28.62 U, 24.84 U and 23.13 U, respectively, and that of endocarp were 14.46 U, 9.73 U and 8.58 U, respectively. The maximum of GR activity in no-netted, small-netted and large-netted of exocarp were 378.32 U, 170.24 U and 196.15 U, respectively, and that of endocarp were 70.58 U. 45.61 U and 66.67 U, respectively. Ascorbate peroxidase (APX) activity increased continuously during storage. APX activity of exocarp was higher than that of endocarp. APX activity of no-netted group was higher than that of small-netted group and large-netted group. In conclusion, the postharvest disease resistance of Jiashi melon pericarp was closely related to the metabolism of ROS. The disease resistance of exocarp was stronger than that of endocarp. The disease resistance in no-netted group was stronger than that of small-netted group and large-netted group.