Characterization of Putative NPR1-dependent Aphid Resistance Factors in Tomato
A. GALLA (1), C. Avila (2), F. Goggin (1) (1) University of Arkansas, U.S.A.; (2) Department of Horticultural Science , Texas A& M University, U.S.A.

The suppressor of prosystemin-mediated responses2 (spr2) mutant in tomato (Solanum lycopersicum), which carries a loss-of-function mutation in Fatty Acid Desaturase 7 (FAD7), displays enhanced aphid resistance when compared to wild-type plants.  Aphid resistance in this mutant requires salicylic acid (SA) accumulation and expression of NONEXPRESSOR OF PATHOGENESIS-RELATED PROTEINS1 (NPR1), a major transporter of SA. To investigate the basis of aphid resistance in spr2, we have used RNA-seq analysis to compare aphid-responsive gene expression in spr2 and wild-type plants with normal or compromised NPR1 expression.  This approach identified numerous transcripts that were highly upregulated in the spr2 mutant upon aphid infestation, but that were down regulated when NPR1 was silenced. These candidates, which may contribute to NPR1-dependent aphid resistance in spr2, include genes encoding nucleotide-binding, leucine-rich repeat (NB-LRR) proteins, receptor kinases, membrane transporters, transcription factors, and cell death-associated factors. To characterize the biological significance of these candidate genes in resistance mechanisms, we are currently using Virus Induced Gene Silencing (VIGS) with a Tobacco Rattle Virus (TRV)-based vector to suppress their expression, and are we assaying how silencing these genes affect the survival, growth and fecundity of aphids. The results from this study should identify defense genes that act downstream of NPR1 to impart aphid resistance; furthermore, this project should shed light on SA-responsive signaling nodes that are modulated by fatty acid metabolism.

Abstract Number: P17-525
Session Type: Poster