紫花苜蓿对牛角花齿蓟马为害的生理响应研究

为明确紫花苜蓿(Medicago sativa)对牛角花齿蓟马(Odontothrips loti)为害的抗性生理机理,测定了不同牛角花齿蓟马虫口密度下抗蓟马苜蓿无性系R-1、感蓟马苜蓿无性系I-1可溶性蛋白、游离脯氨酸含量及超氧化物歧化酶(SOD)、愈创木酚过氧化物酶(GPX)、过氧化氢酶(CAT)活性的变化.结果表明:受牛角花齿蓟马为害后,R-1无性系在低虫口密度(1, 3头·枝条^-1)下,SOD, GPX活性升高,在高虫口密度(5, 7头·枝条^-1)下,SOD, GPX活性先上升后下降;I-1无性系各接虫处理的SOD, GPX活性均先上升后下降;二者各接虫处理的可溶性蛋白含量均降低,游离脯氨酸含量均增加,CAT活性均下降,且在牛角花齿蓟马为害过程中,R-1无性系各接虫处理可溶性蛋白的减少量、游离脯氨酸的增加量及CAT活性的下降速率均小于I-1无性系.说明SOD, GPX活性的升高是紫花苜蓿对牛角花齿蓟马诱导抗性的一种表现,R-1无性系在低虫口密度下其SOD, GPX活性持续升高而表现为抗蓟马,I-1无性系对蓟马为害的诱导抗性反应滞后于R-1无性系而表现为感蓟马.

Physiological Response of Medicago sativa to Odontothrips loti Damage

In order to clarify the physiological resistance mechanism of alfalfa plant to thrip damage, the soluble protein contents, free proline contents as well as the SOD, GPX and CAT activities of resistant and susceptible alfalfa R-1 and I-1 clones growing under different thrip densities were investigated. The results indicated that the SOD and GPX activities of R-1 clones increased under low insect densities (1, 3 per branch), whereas the SOD and GPX activities of R-1 clones increased firstly and then decreased under high insect densities (5, 7 per branch); The SOD and GPX activities of I-1 treatments increased firstly and then decreased under all tested conditions. The soluble protein contents and CAT activities of R-1 and I-1 treatments decreased, whereas the free proline contents R-1 and I-1 treatments increased under all tested conditions. The CAT activities, soluble protein and free proline contents of R-1 clones changed less than that of I-1 clones under all tested conditions, indicating that the increases of SOD and GPX activities were the physiological response of alfalfa plant to thrip damage. R-1 clone under low thrip densities was resistant to thrip damage that manifested in the continuous increases of SOD and GPX activities, while I-1 clone was susceptible to thrip compared with R-1 clone.