Tomato SlERF.A1, SlERF.B4, SlERF.C3 and SlERF.A3, Members of B3 Group of ERF Family, Are Required for Resistance to .

The Ethylene-Responsive Factors (ERFs) comprise a large family of transcriptional factors that play critical roles in plant immunity. Gray mold disease caused by , a typical necrotrophic fungal pathogen, is the serious disease that threatens tomato production worldwide. However, littler is known about the molecular mechanism regulating the immunity to in tomato. In the present study, virus-induced gene silencing (VIGS)-based functional analyses of 18 members of B3 group (also called Group IX) in tomato ERF family were performed to identify putative ERFs that are involved in disease resistance against . VIGS-based silencing of either or had lethal effect while silencing of () significantly suppressed vegetative growth of tomato plants. Importantly, silencing of , or resulted in increased susceptibility to , attenuated the -induced expression of jasmonic acid/ethylene-mediated signaling responsive defense genes and promoted the -induced HO accumulation. However, silencing of also decreased the resistance against pv. () DC3000 but silencing of or did not affect the resistance to this bacterial pathogen. Expression of , or was induced by and by defense signaling hormones such as salicylic acid, methyl jasmonate, and 1-aminocyclopropane-1-carboxylic acid (an ethylene precursor). SlERF.A1, SlERF.B4, SlERF.C3, and SlERF.A3 proteins were found to localize in nucleus of cells and possess transactivation activity in yeasts. These data suggest that SlERF.A1, SlERF.B4, and SlERF.C3, three previously uncharacterized ERFs in B3 group, and SlERF.A3, a previously identified ERF with function in immunity to DC3000, play important roles in resistance against in tomato.