10th INTERNATIONAL VERTICILLIUM SYMPOSIUM 16-20 ...

ETHYLENE PERCEPTION VIA NEVER RIPE AND LEETR4AFFECTS THE RESISTANCE OF TOMATO PLANTS TOVASCULAR INFECTION BY VERTICILLIUM DAHLIAEPANTELIDES I.S., TJAMOS S.E. AND PAPLOMATAS E.J.Department of Plant Pathology, Agricultural University of Athens, 75 Iera Odos, 118 55 Athens,GreeceTo investigate whether impaired perception of ethylene via the ethylenereceptor ETR4 affects the resistance of tomato plants against Verticillium dahliae, aTobacco rattle virus (TRV) based virus induced gene silencing (VIGS) system wasemployed, to knock down the LeETR4 gene expression in tomato plants. The role ofthe ethylene receptor Never ripe (Nr) was assessed in pathogenicity tests of Nr mutantplants with the pathogen. LeETR4-silenced and mutant Never ripe plants wereinoculated with V. dahliae and the disease symptoms were scored. The pathogenicityexperiments revealed that the Verticillium disease severity in the Nr and ETR4-silenced plants was statistically reduced compared to wild-type and control plants,respectively. Quantification of V. dahliae by qPCR showed that the reduction insymptom severity in the Nr plants was associated with significant reduction of thefungal biomass in the vascular tissues of the Nr plants compared to wild-type plants,suggesting that loss of function of the Nr receptor results in increased diseaseresistance. Fungal reduction was evident at each sampling day in the Nr plantscompared to the wild-type plants, whereas the fungal quantification in the ETR4silenced and TRV-only inoculated plants showed similar levels of fungal biomass.64