Effects Of Feeding Rice With Rhizoctonia Solani On Biological Characteristics Of Brown Planthopper And Defense Enzyme Activities Of Rice Plants

Based on the relationship among different insect-resistant genes of rice,Rhizoctonia solani infection and brown planthopper damage(Nilaparvata lugens(St?l)),the differences about biological characteristics and behavioral responses of brown planthopper(BPH)in rice plants infected with Rhizoctonia solani and non-infected,as well as the changes of important defense enzyme activities in rice plants infected with Rhizoctonia solani and non-infected after brown planthopper infested were studied.The physiological and ecological mechanism of the virulence variation about brown planthopper(BPH)induced by rice plants infected with Rhizoctonia solani,and the scientific basis for revealing the phenomenon of "rice burning" in rice plants would be elucidated.The results are as follows:(1)The effects of growth,development and reproduction of brown planthopper(BPH)fed with infected rice plants were studied by single tube feeding.The results showed that,continuous feeding for 1-3 generations,on the TN1 variety(non-insect-resistant gene)and Utri Rajapan variety(insect-tolerant gene),whether the nymphs of brown planthopper were infected with Rhizoctonia solani or not had no effect on the stage of nymphs.Brown planthopper(BPH)fed the rice plants with Rhizoctonia solani infected on IR26,IR36,IR56(insect-resistant gene Bph1,bph2,Bph3)had significantly longer nymphal stage than healthy plants with non-infected Rhizoctonia solani.The nymphs survival rate of brown planthopper(BPH)decreased significantly after fed the infected plants TN1 and IR26.On IR36,IR56,and Utri Rajapan varieties,whether the nymphs of brown planthopper(Nilaparvata lugens(St?l))fed on the rice infected with Rhizoctonia solani or not had no significant effects on the survival rate of brown planthopper(BPH).Furthermore,the life span of female and male adults,egg production and egg hatching rate of brown planthopper were significantly different between brown planthopper fed different insect-resistant rice plants infected with Rhizoctonia solani and non-infected.(2)The screening behavior of brown planthopper nymphs against rice plants infected with Rhizoctonia solani and non-infected was measured by Y type olfactometer.The results showed that in different insect-resistant rice varieties,the screening behavior of brown planthopper nymphs at different ages had significantly differences when fed with Rhizoctonia solani infected rice plants and normal rice plants.In insect-sensitive and insect-tolerant rice varieties,young nymphs selected rice plants with Rhizoctonia solani infected,but elderly nymphs had no obvious selectivity.In insect-resistant rice varieties,the older nymphs selected healthy plants without Rhizoctonia solani infected,and the young nymphs had no selectivity.(3)The changes of important defense enzyme activities in rice plants infected with Rhizoctonia solani and brown planthopper were measured by enzyme kit.The results showed that,under the damage of brown planthopper for 24 hours,48 hours and 72 hours,the activities of superoxide dismutase(SOD),peroxidase(POD),catalase(CAT),phenylalanine ammonia lyase(PAL)and polyphenol oxidase(PPO)changed greatly in different insect-resistant rice plants with Rhizoctonia solani infected.Among them,the activities of superoxide dismutase(SOD)and peroxidase(POD)were increased in the resistant varieties containing the insect-resistant gene Bph3.In other varieties,the activities of superoxide dismutase(SOD)and peroxidase(POD)decreased or changed unobviously.CAT activity almost unchanged or decreased in different insect-resistant varieties.The activity of PAL was opposite to the activity of CAT,and it almost unchanged or increased,The activity of PPO did not change obviously in insect-susceptible and insect-resistant varieties,but it increased significantly in insect-resistant varieties.