The Arabidopsis ELP3/ELO3 and ELP4/ELO1 genes enhance disease resistance in Fragaria vesca L.

Background: Plant immune response is associated with a large-scale transcriptional reprogramming, which is regulated by numerous transcription regulators such as the Elongator complex. Elongator is a multitasking protein complex involved in diverse cellular processes, including histone modification, DNA methylation, and tRNA modification. In recent years, Elongator is emerging as a key regulator of plant immune responses. However, characterization of Elongator's function in plant immunity has been conducted only in the model plant Arabidopsis thaliana. It is thus unclear whether Elongator's role in plant immunity is conserved in higher plants. The objective of this study is to characterize transgenic woodland strawberry (Fragaria vesca L.) overexpressing the Arabidopsis Elongator (AtELP) genes, AtELP3 and AtELP4, and to determine whether F. vesca carries a functional Elongator complex.

Methods: Transgenic F. vesca and Arabidopsis plants were produced via Agrobacterium-mediated genetic transformation and characterized by morphology, PCR, real-time quantitative PCR, and disease resistance test. The Student's t test was used to analyze the data.

Results: Overexpression of AtELP3 and AtELP4 in F. vesca impacts plant growth and development and confers enhanced resistance to anthracnose crown rot, powdery mildew, and angular leaf spot, which are caused by the hemibiotrophic fungal pathogen Colletotrichum gloeosporioides, the obligate biotrophic fungal pathogen Podosphaera aphanis, and the hemibiotrophic bacterial pathogen Xanthomonas fragariae, respectively. Moreover, the F. vesca genome encodes all six Elongator subunits by single-copy genes with the exception of FvELP4, which is encoded by two homologous genes, FvELP4-1 and FvELP4-2. We show that FvELP4-1 complemented the Arabidopsis Atelp4/elo1-1 mutant, indicating that FvELP4 is biologically functional.

Conclusions: This is the first report on overexpression of Elongator genes in plants. Our results indicate that the function of Elongator in plant immunity is most likely conserved in F. vesca and suggest that Elongator genes may hold potential for helping mitigate disease severity and reduce the use of fungicides in strawberry industry.