Ethylene participates in the brassinolide-regulated asymmetric growth of O. sativa root

In this work, brassinosteroid (BR)-induced root asymmetric growth as well as its interaction with ethylene (ETH) were investigated. The results reveal that 2, 4-epibrassinolide (2,4-eBL) can induce asymmetric growth of the primary roots of monocotyledonous Oryza sativa to form root coils and waves under both illumination and dark conditions. Similarly, ETH can also induce asymmetric growth of the primary roots of O. sativa to form hooked structures. Upon adding a concentration of 2 × 10−8 M 2,4-eBL and inhibitors of ethylene simultaneously, silver thiosulfate (STS) and aminooxyacetic acid could completely eliminate the 2,4-eBL-induced asymmetric growth of roots, while the asymmetric growth could also be partly eliminated by CoCl2. Meanwhile, the effect of ETH inhibitors was proven to be reversible, wherein 2,4-eBL can exert its function and induce the asymmetric growth of O. sativa roots after the removal of STS. These conclusions provide a scientific foundation for further investigations of the relationships between BR and ETH.