GWSF-EuSWAP70 gene expression to enhance gray mold resistance in Arabidopsis thaliana

Abstract

Background Eucalyptus, a widely cultivated woody plant, is susceptible to a diverse array of pests and diseases, leading to reduced yields and economic losses. Traditional breeding methods are very time-consuming; therefore, plant genetic engineering has emerged as a promising approach for plant pathogen management. However, the genetic transformation system of eucalyptus is still in its early stages of development, while studies on transgenic eucalyptus and its disease-resistance genes are limited. The SWAP70 gene has been shown to play a crucial role in the defense response of Arabidopsis thaliana and rice. In this study, the model plant A. thalianawas selected for genetic transformation. The aim was to enhance the expression of the EuSWAP70 gene derived from Eucalyptus grandis, and other disease-resistance genes, by utilizing an artificial GWSF promoter. Results The results showed that the EuSWAP70 gene was successfully transformed into A. thaliana, and the PCR assay confirmed the presence of the EuSWAP70 gene in transgenic Arabidopsis plants. The gray mold resistance of the EuSWAP70 transgenic Arabidopsis plants under GWSF and CaMV35S promoters was evaluated against Botrytis cinerea infection. After gray mold infection, Arabidopsisplants were ranked by leaf pore area percentage: wild-type > CaMV35S-EuSWAP70 > GWSF-EuSWAP70. The transgenic plants showed stronger gray mold resistance, and the GWSF-EuSWAP70 transgenic plants were stronger than the CaMV35S-EuSWAP70 transgenic plants. In two transgenic Arabidopsis plants treated with different inducers, the expression levels of ten disease-resistant genes were compared, and there was a significant difference between them. The expression levels of disease-resistance genes, particularly NPR1 and ChiB, were found to be higher in GWSF-EuSWAP70 transgenic Arabidopsis plants than those in CaMV35S-EuSWAP70transgenic plants. GWSF-EuSWAP70 transgenic Arabidopsis plants have stronger disease-resistance gene activity than CaMV35S-EuSWAP70plants under various inducers. The GWSF-EuSWAP70transgenic plants have minimal background expression and a wide range of plant inducer responses. Different inducer treatments had different effects on gene expression levels, B. cinerea treatment resulted in a significant increase in the expression levels of NPR1 and ChiB genes, whereas ethylene and salicylic acid (SA) pre-treatment reduced the expression levels of ChiB genes under B. cinerea treatment. Conclusions The EuSWAP70 gene can be effectively introduced into Arabidopsis plants, induced by two promoters, and potentially improve their B. cinerearesistance.