Cotton is one of the most economically important crops in the world, and it is exposed to various abiotic stresses during its lifecycle, especially salt stress. However, the molecular mechanisms underlying cotton tolerance to salt stress are still not fully understood due to the complex nature of salt response. Therefore, identification of salt stress tolerance-related functional genes will help us understand key components involved in stress response and provide valuable genes for improving salt stress tolerance via genetic engineering in cotton. In the present study, virus-induced gene silencing of GhWRKY5 in cotton showed enhanced salt sensitivity compared to wild-type plants under salt stress. Overexpression of GarWRKY5 in Arabidopsis positively regulated salt tolerance at the stages of seed germination and vegetative growth. Additionally, GarWRKY5-overexpressing plants exhibited higher activities of superoxide dismutase (SOD) and peroxidase (POD) under salt stress. The transcriptome sequencing analysis of transgenic Arabidopsis plants and wild-type plants revealed that there was enriched coexpression of genes involved in reactive oxygen species (ROS) scavenging (including glutamine S-transferases (GSTs) and SODs) and altered response to jasmonic acid and salicylic acid in the GarWRKY5-OE lines. GarWRKY5 is involved in salt stress response by the jasmonic acid- or salicylic acid-mediated signaling pathway based on overexpression of GarWRKY5 in Arabidopsis and virus-induced gene silencing of GarWRKY5 in cotton.
Keywords: Gossypium aridum; RNA-Seq; WRKY; expression patterns; salt stress; virus-induced gene silencing (VIGS).