Differential expression of chitinase and stilbene synthase genes in Florida hybrid bunch grapes to Elsinoë ampelina infection

Abstract

Florida hybrid bunch grape (Vitis spp.) cultivars with commercial value are susceptible to anthracnose disease caused by the fungi, Elsinoe ampelina. The Florida grape industry is keen on improving anthracnose tolerance characteristics of these grape cultivars as the cultivation of European grapes is limited in Southeastern United States due to Pierce’s disease incidence. In this connection, a molecular approach was taken to identify and characterize the gene/s differentially expressed upon infestation with E. ampelina in selected Florida hybrid bunch grape cultivars differing in their disease tolerance level. Variation in gene expressions was monitored by employing Differential Display RT-PCR. The results showed significant up-regulation of transcripts ranging between 200 and 800 bp in anthracnose-tolerant (cvs. Blue Lake and Lake Emerald) grape cultivars compared to anthracnose-susceptible (cvs. Suwannee and Blanc du Bois) cultivars. The transcripts that were uniquely induced in tolerant cultivars were identified as chitinase, stilbene synthase, protein/sugar kinases and transcriptional factor. Expression of chitinase and stilbene synthase genes was validated using real time PCR analysis. The results showed that these genes were more rapidly expressed in tolerant cultivars within a day after inoculating with E. ampelina and peaking by day 3, compared to susceptible cultivars. Induction of these anti-fungal genes appears to enable tolerant cultivars to withstand fungal infestation compared to susceptible cultivars. Rapid expression of chitinase and stilbene synthase genes along with others genes may be partly responsible for anthracnose-tolerance in Florida hybrid bunch grapes. Further analysis may shed light on their specific role in anthracnose tolerance.