Response Of Nilaparvata Lugens To Chilo Suppressalis-Damaged Rice Plants And The Mechanisms

Background: Rice(Oryza sativa)is the paramount grain crop in the world,which dominates more than half of the world's population.Howerver,various biological and non-biological stresses result the reduction of output.The herbivores belong to biological factors affect the yield of rice,which exists a mutual-benefit,lateral-benefit and competition relation between them.Objectives: This article is to elucidate the ecology relationship of rice(including Bt rice)-Chilo suppressalis(Bt rice target pests)-Nilaparvata lugens(Bt rice non-target insects).The prime target is to reveal the effect of the Bt rice planting on N.lugens populations dynamics and the corresponding ecological mechanisms,and clarify the rice mediated interspecific relationship of C.suppressalis and N.lugens from different aspects,as biology,ecology,and omics technology.Major conclusion:(1)The feeding response of N.lugens to C.suppressalis-damaged rice plants in the laboratory experiments research.It was found that both Mudgo(resistant rice variety to N.lugens)and Taichung Native 1(sensitive rice variety to N.lugens),N.lugens life parameters(survival rate,development time,body weight and body length)did not differ significantly on healthy or damaged plants,although N.lugens have significant preference to the damaged rice plants.Honeydew on damaged Mudgo plant was significantly lower than on healthy plant,but no differences in weight gain.N.lugens nymphae hatchability had no significant difference on damaged or healthy Mudgo.The mechanism of N.lugens preference to C.suppressalis-damaged needs further study.(2)Field surveys indicate that Bt rice harbours had fewer rice planthoppers than non-Bt rice although planthoppers are not sensitive to the Bt proteins produced by Bt rice.The ecological mechanisms of this phenomenon remain unknown.Here we show that the low numbers of planthoppers on Bt rice is associated with reduced caterpillar damage.In laboratory and field-cage experiments,N.lugens had no feeding preference for undamaged Bt or non-Bt plants but exhibited a strong preference for C.suppressalis-damaged plants whether Bt or non-Bt.Under open field conditions,rice planthoppers were more abundant on C.suppressalis-damaged non-Bt rice than on neighbouring healthy Bt rice.Our results suggest that Bt rice provides ecological resistance to planthoppers.Non-Bt rice planted as a refuge to delay the evolution of Bt resistance is thus likely to divert planthoppers away from Bt rice and may therefore restrain planthopper outbreaks.(3)In order to reveal the molecular mechanism of N.lugens preference to C.suppressalis-damaged rice,using omics technology analysis of the physiology reaction mechanism of rice damaged by C.suppressalis.We found plant transcriptome has changed significantly,2,342 genes differentially expressed,mainly involves the basal metabolism of amino acid metabolism,carbohydrate metabolism,and lipid metabolism,and secondary metabolite biosyntheses,such as terpenoids and ketone.Among the differences gene expression,most genes are up-regulated.The metabolomic analysis discovered 119 different compounds,mainly related to the secondary metabolism substance synthesis,phenylpropanoid biosynthesis,amino acid and carbohydrate metabolism.The change of these substances can cause changes in plant nutrition of N.lugens feeding.At the same time,the transcriptome analysis discovered N.lugens resistance genes significant differences expression of damaged rice,which may also be a cause of N.lugens preference to C.suppressalis-damaged rice.