Overexpression of the ethylene response factor SlERF1 gene enhances resistance of tomato fruit to Rhizopus nigricans

The tomato SlERF1 gene belongs to a distinct subfamily of the large ERF gene family. It is a downstream component in the ethylene signaling pathway in tomato, and is involved in plant defense and stress responses. Overexpression of the SlERF1 gene (SlERF1-OEs) in tomato dramatically enhanced the resistance of fruit to Rhizopus nigricans. In attempt to elucidate the mechanism basis of this observation, our study revealed a dual modulation. Firstly, SlERF1-OEs fruit showed a remarkable transcript accumulation of PR5 and PAL genes before infection with R. nigricans, which was not observed in wild-type (WT) fruit. Secondly, SlERF1-OEs fruit had higher activitiers of phenylalanine ammonia lyase (PAL) and chitinase (CHI) in response to the fungal stress. These results show that SlERF1 positively modulated the ethylene-dependent pathogenesis defense pathway in tomato. That may be one of the mechanisms by which ERFs enhance plant tolerance to fungal invasion.

► Overexpression of the tomato SlERF1 gene enhanced the resistance of tomato fruit to R. nigricans.
► A substantial transcript accumulation of PR1a, PR5, Chi1 and PAL genes was stimulated by overexpression of the SlERF1 gene.
► We found higher activities of phenylalanine ammonia lyase (PAL) and chitinase (CHI) in response to the fungal stress.
► Ethylene is involved in, but does not play the pivotal role, in fruit resistance to R. nigricans.