| Bemisia tabaci(Gennadius)is a species complex comprising dozens of cryptic species.Among them,MEAM1 whitefly has become one of the main pests in China due to its ability to rapidly spread and displace indigenous whitefly.Whitefly ingests plant phloem sap with its piercing-sucking mouthparts.In the long-term evolution,plant has also developed a resistance mechanism to deal with adverse factors.Many of the defense responses are based on secondary metabolites and defense proteins.Notably,the synthesis of these chemicals are tightly regulated by transcriptional control and sometimes miRNA.However,the response of plants transcriptome and miRNA expression has not been explored in whitefly-tobacco interactions.In this study,we identified and analyzed the expression of miRNAs and their target genes in tobacco upon MEAM1 whitefly infection.We also performed functional analysis on genes that might be involved in the resistance of tobacco to MEAM1 whitefly.The main results are as follows:(1)Pre-infestation of tobacco by the whitefly can enhance tobacco resistanceFirst,this study explored the effect of tobacco pretreated by MEAM1 whitefly.We released500 MEAM1 whiteflies to feed on tobaccos for 6 hours,and set untreated tobaccos as control.Then released five female MEAM1 whiteflies and five male MEAM1 whiteflies on tobaccos.After three days,the survival rate and fecundity of whiteflies were counted.We demonstrate that pre-infestation of tobacco by the whitefly reduce the fitness of subsequent whitefly.Therefore,we analyze pre-infestation by the whitefly enhanced the defense response of tobacco.(2)Functional characterization of genes that are involved in the defense of tobacco against whiteflyIn this study,high-throughput sequencing technology was used to sequence the transcriptome of two differently treated tobaccos.In total,5014 differentially expressed genes were identified,among which 3244 genes were up-regulated and 1770 genes were downregulated.By performing GO enrichment and KEGG analysis,we found that most differential genes concentrated on pathways of plant-pathogen interaction,plant hormone signal transduction and protease activity.Next,we selected five significantly differentially expressed genes and used virus-induced gene silencing(VIGS)and transient overexpression technique to verify their roles in tobacco.Down-regulation of XTH24,EAS and PTI5 increased the fitness of MEAM1 whiteflies.(3)Expression of miRNAs of tobacco in response to whitefly infestationWe identified 1291 differentially expressed miRNAs.Among them,30 were up-regulated and 17 were down-regulated.Based on GO enrichment and KEGG analysis,we found that 13 differentially expressed miRNAs may be involved in the defense of tobacco against whitefly.Specifically,mi R6025 may be involved in the SA signaling pathway and mi R3627 may play a positive role in tobacco by regulating F-BOX.(4)Analysis of degradome of tobacco upon whitefly infestationUsing degradome sequencing,we found 289 mRNAs that were degraded and 296 degradation sites within them.Based on GO enrichment,KEGG and KOG anlysis,6 target genes were further analyzed.We found that the mRNA of several proteins associated with plant defenses against biotic stresses such as VDE,MTII,RPP13,Vipp1 and SMG1 were degraded by miRNA in tobacco upon whitefly infestation.Taken together,this study first explored the effects of pre-infestation of whitefly in tobacco plants on whitefly-tobacco interactions,and then analyzed the mRNA transcriptome and miRNA expression in tobacco plants upon whitefly infestation.Our analyses revealed 5 tobacco genes that might be involved in plant defenses against whitefly.Moreover,this study determined several genes that were targetd by miRNA upon whitefly infestation.Our findings may not only help to understand the regulation of plant immune response,but also facilitate the development of crops resistant to insects. |
PDF Full Text Request