Altered Expression of Micro<scp>RNA</scp>s and Target m<scp>RNA</scp>s in Tomato Root and Stem Tissues upon Different Viral Infection

Abstract

Abstract Micro RNA s (mi RNA s) are post‐transcriptional regulators that are involved in numerous biological processes in both plants and animals. In plants, root and stem tissues play essential roles in their anchorage to soil as well as in nutrient and water uptake and transfer. We have quantified the expression alterations of eleven mi RNA s and their target m RNA s in tomato root and stem tissues after infection with C ucumber mosaic virus ( CMV )‐ F ny, CMV ‐ F nyΔ2b (a CMV ‐ F ny 2b‐deletion mutant), CMV ‐ F ny‐ sat T 1 ( CMV ‐ F ny plus an aggressive satellite ( sat ) RNA variant sat T 1) and T omato aspermy virus ( TAV )‐ B j. From 21 days postinoculation onwards, we found the stem tissues were ‘hollow’ in CMV ‐ F ny‐ sat T 1 infected tomatoes, and a ‘fibrosis’ phenotype was observed in stems of TAV ‐ B j infected plants. In addition, this phenotype was associated with the decreasing of tomato lateral root numbers upon the two infections. Consistence with these phenotypic alterations, tomato mi RNA /m RNA levels upon different viral infections were changed by different degrees. Based on our results, the interference of different viral infections with tomato mi RNA pathways were analysed and the correlations between mi RNA s/m RNA s expression alterations and tomato symptoms were discussed.