MicroRNA profiling of tomato leaf curl new delhi virus (tolcndv) infected tomato leaves indicates that deregulation of mir159/319 and mir172 might be linked with leaf curl disease

Afsar R Naqvi,Qazi Mr Haq,Sunil K Mukherjee

doi:10.1186/1743-422x-7-281

Abstract

BackgroundTomato leaf curl virus (ToLCV), a constituent of the genus Begomovirus, infects tomato and other plants with a hallmark disease symptom of upward leaf curling. Since microRNAs (miRs) are known to control plants developmental processes, we evaluated the roles of miRNAs in Tomato leaf curl New Delhi virus (ToLCNDV) induced leaf curling.ResultsMicroarray analyses of miRNAs, isolated from the leaves of both healthy and ToLCNDV agroinfected tomato cv Pusa Ruby, revealed that ToLCNDV infection significantly deregulated various miRNAs representing ~13 different conserved families (e.g., miR319, miR172, etc.). The precursors of these miRNAs showed similar deregulated patterns, indicating that the transcription regulation of respective miRNA genes was perhaps the cause of deregulation. The expression levels of the miRNA-targeted genes were antagonistic with respect to the amount of corresponding miRNA. Such deregulation was tissue-specific in nature as no analogous misexpression was found in flowers. The accumulation of miR159/319 and miR172 was observed to increase with the days post inoculation (dpi) of ToLCNDV agroinfection in tomato cv Pusa Ruby. Similarly, these miRs were also induced in ToLCNDV agroinfected tomato cv JK Asha and chilli plants, both exhibiting leaf curl symptoms. Our results indicate that miR159/319 and miR172 might be associated with leaf curl symptoms. This report raises the possibility of using miRNA(s) as potential signature molecules for ToLCNDV infection.ConclusionsThe expression of several host miRNAs is affected in response to viral infection. The levels of the corresponding pre-miRs and the predicted targets were also deregulated. This change in miRNA expression levels was specific to leaf tissues and observed to be associated with disease progression. Thus, certain host miRs are likely indicator of viral infection and could be potentially employed to develop viral resistance strategies.

Highlights

Tomato leaf curl virus (ToLCV), a constituent of the genus Begomovirus, infects tomato and other plants with a hallmark disease symptom of upward leaf curling
PCR- and Rolling Circle Amplification (RCA) - based detection of virus in tomato tissues Using the agroinfiltration technique, we were able to induce the expression of leaf curl disease in tomato cv Pusa Ruby
The accumulation of the viral DNA (~2.5 kb) was detected by carrying out rolling circle amplification (RCA) of the genomic DNA obtained from the agroinfiltrated plants; while such amplification was not found in the healthy controls

Summary

Introduction

Tomato leaf curl virus (ToLCV), a constituent of the genus Begomovirus, infects tomato and other plants with a hallmark disease symptom of upward leaf curling. Tomato leaf curl New Delhi virus (ToLCNDV) is a member of begomovirus genus infecting tomato crop and it causes severe yield loss. The mature miRNA enters into a multi-protein complex termed RNA-induced silencing complex (mi-RISC) and guides it to the target mRNAs with complementary sequences. This leads to the target cleavage [8,11] and/or inhibits translation of the targets [12]. It is apparent that ToLCNDV induced leaf curling in tomato can be utilized as a model system to study the influence of miRNA-mediated biological actions on leaf deformations

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Conclusion