The role of chloroplast-resident RNA helicase ISE2 in defense response against pathogens
E. GANUSOVA (1), T. Burch-Smith (1) (1) University of Tennessee, U.S.A.

The chloroplast resident DEVH-type RNA helicase ISE2 has been identified as a protein playing significant role in regulating the size intercellular trafficking mediated by plasmodesmata (PD). PD are channels connecting each cell to its immediate neighbors and allowing transport of micro- and macromolecules, such as water, ions, metabolites, proteins, and RNA. In addition, PD play a crucial role in the pathogen defense response. It is well known that these cytoplasmic channels facilitate movement of the viruses. In the last few years some discoveries were made that link the PD regulation to the hormonal status of the plants. It is well known, for example, that salicylic acid-dependent defense leads to changes in PD-mediated macromolecule trafficking. In this study we show that overexpression or silencing of ISE2 in Nicotiana benthamiana plants leads not to changes in cell-to-cell macromolecule trafficking but also to changes in the expression of the defense response genes activated by the production of salicylic (SA) or jasmonic acid (JA). Interestingly, both up-regulation and down-regulation of ISE2 expression lead to severe susceptibility of plants to infection by Tobacco mosaic virus (TMV). On the other hand, the level of ISE2 expression does not influence defense response of N. benthamiana against the opportunistic bacterial pathogen (Pseudomonas syringae). Collectively, our data indicate a crucial regulatory role of ISE2 in the triggering innate immune signaling pathways following RNA virus infection.

Abstract Number: P17-526
Session Type: Poster