Involvement of sweet pepperCaLOX2in jasmonate‐dependent induced defence against Western flower thrips

AbstractInsect herbivory can seriously hinder plant performance and reduce crop yield. Thrips are minute cell‐content‐feeding insects that are important vectors of viral plant pathogens, and are serious crop pests. We investigated the role of a sweet pepper (Capsicum annuum) lipoxygenase gene,CaLOX2,in the defense of pepper plants against Western flower thrips (Frankliniella occidentalis). This was done through a combination ofin‐silico,transcriptional, behavioral and chemical analyses. Our data show thatCaLOX2is involved in jasmonic acid (JA) biosynthesis and mediates plant resistance. Expression of the JA‐related marker genes,CaLOX2andCaPIN II, was induced by thrips feeding. Silencing ofCaLOX2in pepper plants through virus‐induced gene silencing (VIGS) resulted in low levels ofCaLOX2transcripts, as well as significant reduction in the accumulation of JA, and its derivatives, upon thrips feeding compared to control plants.CaLOX2‐silenced pepper plants exhibited enhanced susceptibility to thrips. This indicates thatCaLOX2mediates JA‐dependent signaling, resulting in defense against thrips. Furthermore, exogenous application of JA to pepper plants increased plant resistance to thrips, constrained thrips population development and made plants less attractive to thrips. Thus, a multidisciplinary approach shows that an intact lipoxygenase pathway mediates various components of sweet pepper defense againstF. occidentalis.