Role of miRNAs expression against Potato virus X (PVX) and the PVX-25K efector protein in Solanum tuberosum

TASSELLI, SABRINA E.; SIMONSINI, SERGIO; GERHARDT, NADIA; MARTIN, ANA PAULA; MARANO, MA. ROSA

Congreso; 11th International Congress of Plant Molecular Biology; 2015

Solanum tuberosum (potato) cv. Pentland Ivory carrying the resistance gene Nb, confers hypersensitive response (HR) to PVX strain ROTH1. The PVX 25-kDa protein (p25) is the effector of Nb-mediated HR. In Nicotiana benthamiana and Arabidopsis thaliana plants, p25 acts as a viral suppressor of RNA silencing (VSRs) via degradation of AGO1 protein through the proteasome pathway. In addition, it has been shown that the accumulation of the miR168 is an early function of VSRs and this activity is associated with the control of the endogenous AGO1 protein level. In this study, we analyzed the expression levels of miR168 against PVX-ROTH1 in resistant (genotype Nb), and susceptible (genotype nb) potato plants in order to identify the role of this miRNA in both, the basal defense layer through RNA silencing and ETI (effector-triggered immunity). Preliminary results have shown no significant differences in the accumulation of miR168 between both pathosystems (incompatible vs compatible), nor differences of ago1 mRNA levels were identified. Agrobacterium-mediated expression assay of p25 gene did not shown significant changes in the accumulation of this microRNA. However, miR398 and miR408, involved in defense pathways, such as ROS accumulation and strengthening of cell wall, respectively, show different expression levels between both systems under study, either using PVX-ROTH1 or p25. Further studies are required to understand the role of miR168 in the Nb-mediated defense responses to PVX or its viral efector p25.