Enhanced expression of a thaumatin-like gene, involved in Pseudoperonospora cubensis and abiotic stresses, induced by DNA introgression from a wild relative, Cucumis hystrix

Abstract

Introgression of alien DNA from wild relatives into cultivated plant genomes by means of interspecific hybridization is a method which has been widely used in breeding. However, the effects of introgression on the patterns of gene transcription of the host genome have rarely been studied. In the present study, in order to understand the molecular defense response of an introgressed line (IL5211S) with introgression from a wild cucumber, Cucumis hystrix, a thaumatin-like gene, referred to as CsPR5, was successfully isolated from IL5211S. The gene was 1504 bp in length with a putative open reading frame of 726 bp, encoding 241 amino acid residues. Open reading frame sequences of CsPR5 from IL5211S and backcross parents were identified. It was also observed that the expression of the CsPR5 gene was enhanced remarkably by DNA introgression of C. hystrix using real-time quantitative PCR (RT-qPCR). In addition, the expressions of CsPR5 in response to Pseudoperonospora cubensis and four different abiotic stresses stimuli (namely salicylic acid, methyl jasmonate, abscisic acid, and hydrogen peroxide) were further analyzed at different time points. These stimuli triggered a significant induction of CsPR5 within 72 h after treatment. These findings indicate that the expression of the CsPR5 gene was enhanced by alien DNA introgression from C. hystrix. This may play a role in the molecular defense of IL5211S against pathogen invasion, and aid in protecting against environmental stresses.