A citrus abscission agent induces anoxia- and senescence-related gene expression in Arabidopsis.

The mechanisms of negative effects of 5-chloro-3-methyl-4-nitro-1H-pyrazole (CMNP), a pyrazole-derived plant growth regulator used as a citrus abscission agent, were explored in Arabidopsis by integrating transcriptomic, physiological, and ultrastructural analyses. CMNP promoted starch degradation and senescence-related symptoms, such as chloroplast membrane disruption, electrolyte leakage, and decreased chlorophyll and protein content. Symptoms of plant decline were evident 12 h after CMNP treatment. Microarray analysis revealed that CMNP influenced genes associated with stress, including those related to anoxia, senescence, and detoxification. Sucrose treatment arrested CMNP-induced plant decline. The results demonstrate that the plant response to CMNP shares common elements with various stresses and senescence at physiological and molecular levels.