Abstract:

To explore the biological functions of WRKY transcription factor under drought stress and arbuscular mycorrhizal (AM) fungal influence, transcriptome sequencing was performed on Carex siderosticta inoculated with AM fungi and simultaneously subjected to drought stress. Members of the C. siderosticta WRKY (CsWRKY) gene family were identified, and their physicochemical properties, protein secondary structures, conserved motifs and expression patterns were analysed; candidate genes related to drought stress were screened and verified by qRT-PCR. In total, 41 CsWRKY genes were obtained and classified into three groups: group 1 had 7 members, group 2 had 24 members, and group 3 had 10 members. The encoded proteins contained 99-1 052 amino acids, with theoretical isoelectric points of 4.83-9.84; all members were hydrophilic proteins with negative hydrophilicity values. Gene Ontology (GO) annotation showed enrichment in three major biological functions: transcriptional regulation, regulation of metabolic processes, and regulation of biosynthetic processes. KEGG pathway analysis revealed significant enrichment in the plant MAPK signaling pathway, plant-pathogen interaction, and transcription factors related pathways. After AM fungal inoculation, 26 CsWRKY genes were up-regulated and 12 were down-regulated. By integrating transcriptomic data and homologous alignment, 13 CsWRKY genes were selected as potential participants in drought response. qRT-PCR demonstrated that 10 of these candidates were induced by drought, suggesting positive regulatory roles, whereas three were repressed, implying negative regulatory roles. This study provides valuable candidate genes and a theoretical basis for further investigation of drought-tolerance mechanisms in C. siderosticta.

Key words: Carex siderosticta, WRKY gene family, bioinformatics, drought stress, arbuscular mycorrhizal