Cold Plasma Up-Regulated Expressions of WRKY1 Transcription Factor and Genes Involved in Biosynthesis of Cannabinoids in Hemp (Cannabis sativa L.)

Abstract

Plasma technology as an eco-friendly efficient strategy has gained much attention in various industries, especially in food, medicine, and agriculture. This study aimed to explore the cold plasma-mediated changes in growth, anatomy, expression of a WRKY1 transcription factor, and transcription rates of four key genes involved in the biosynthesis of cannabinoids (pharmaceutically valuable secondary metabolites) in hemp (Cannabis sativa L.). The seeds were treated with cold plasma (dielectric barrier discharge; 0.84 W cm−2; exposure times of 0, 40, and 80 s). The plasma treatment of 40 s increased biomass in both shoot and roots by an average of 57%, whereas the treatment at 80 s delayed growth and reduced it by 48%. Seed priming with plasma up-regulated the WRKY1 transcription factor (mean = 11.55 folds). Besides, the plasma treatments induced the expression of olivetolic acid cyclase by 42 folds. Furthermore, the plasma-primed seedlings also exhibited higher expression rates of olivetol synthase by 19 folds. With a similar trend, exposure to plasma stimulated transcription of cannabidiolic acid synthase by 12.4 folds. Up-regulations in Δ9-tetrahydrocannabinolic acid synthase also occurred following seed priming with plasma by 25.6 folds. Seed priming with plasma exhibits high potency to up-regulate expressions of genes involved in the productions of secondary metabolites, like cannabinoids. These results imply that the plasma reception and signal transduction can alter expressions of genes at the transcriptional level through which plasma priming may improve plant protection and secondary metabolism.