Transcriptome sequencing, data-based screening, and functional investigation of MdWRKY75d and MdWRKY75e in disease-resistant apples

Abstract

‘Sushuai’ is a disease-resistant apple variety. Transcriptome sequencing revealed differentially expressed genes mainly in the metabolism, biosynthesis of secondary metabolites, plant–pathogen interactions, and plant signaling transduction pathways. The jasmonate/ethylene signaling pathway and WRKY transcription factors (especially WRKY75 genes) played important roles in improving Alternaria alternata resistance in ‘Sushuai’. An investigation of the effect of biotic and abiotic stresses on the expression of MdWRKY75s revealed that MdWRKY75d and MdWRKY75e expression was upregulated by A. alternata and methyl jasmonate treatments, while their expression was downregulated by salicylic acid treatment. Transient MdWRKY75d and MdWRKY75e expression improved apple resistance to A. alternata. The analysis, prediction, and validation of the transcriptome data revealed that MdLAC7, MdRFK1, and MdWFK1 are the most likely target genes of MdWRKY75d and MdWRKY75e. Our study provides a basis for investigating mechanisms of resistance to A. alternata.

Keywords

• transcriptome sequencing
• mdwrky75d
• mdwrky75e
• transient expression
• disease resistance
• target gene