Inhibitory effects of propiconazole on rice root development and abilities of brassinosteroid and auxin in alleviating its effects

Abstract

Propiconazole is commonly used as a fungicide to minimize crop loss caused by various fungal diseases in many crop plants, including rice. Propiconazole has the potentials to deteriorate the environmental problems due to its chemical properties that it is highly persistent in soil after application, suggesting that the constant use of propiconazole could be problematic. Hence, the evaluation of its effects on plant growth and development is necessary for the assessment of future use of propiconazole. Here, we demonstrated that propiconazole had inhibitory effects on plant growth. Treatments of propiconazole resulted in shoot dwarfism, abnormal leaf morphology, reduced plant biomass, and inhibited root growth, further supporting the importance of brassinosteroid for regulating optimal plant growth and development due to the ability of propiconazole to inhibit brassinosteroid biosynthesis. In addition, propiconazole reduced emerged lateral root density by inhibiting the emergence of lateral root primordia and lateral root elongation. Treatments of 1-naphthaleneacetic acid (NAA), a synthetic auxin, could rescue lateral root density in the propiconazole-treated plants to the untreated level, suggesting that auxin-mediated regulation of lateral root development was defective in the propiconazole-treated plants.