Heat shock transcriptional factors (HSFs) are expressed in response to hydrogen peroxide production in grapevines inoculated with Colletotrichum Species

Abstract

Heat shock transcriptional factors (HSFs) are expressed in plants due to external stress, high temperatures, or pathogenic infections. This study was undertaken to analyze the expression of HSF genes in grapevines inoculated with pathogens. Spores of Colletotrichum acutatum and C. gloeosporioides were inoculated on the leaves, and on immature and mature fruits of ‘Campbell Early’ and creeping grapevine (Vitis flexuosa). The real-time PCR of RNA isolated from infected leaves and fruits showed specific upregulation of HSF11, HSF12, HSF14, and HSF15 subsequent to both high temperature and pathogen infections. However, HSF16 and HSF17 were up-regulated specifically by pathogenic infections only and showed different expression patterns in response to wounding. Among the hydrogen peroxide-related genes, the expression of catalase (CAT) and superoxide dismutase (SOD) was up-regulated by pathogen infections. Concurrently, expression of six HSFs (HSF11, HSF12, HSF14, HSF15, HSF16, and HSF17) dose-dependently increased with accumulation of hydrogen peroxide in the leaves and fruits of grapevines. The expression of selected HSF genes was up-regulated differentially as a defense reaction in ‘Campbell Early’ and V. flexuosa grapevine in response to external stress (such as wounding) and pathogen inoculation. This indicates that expression of some HSFs is regulated through the hydrogen peroxide-mediated pathways in response to pathogens. Further studies determining the mechanism of HSF gene expression induced by external stress are required.