BREVIPEDICELLUS and ERECTA mediate expression ofAtPRX17in preventing Arabidopsis callus retardation and browning

Efficient in vitro callus generation is fundamental to tissue culture propagation, a process required for plant regeneration and transgenic breeding for desired phenotypes. Identifying genes and regulatory elements that prevent callus retardation and browning is essential to facilitate the development of vitro callus systems. Here we show thatBREVIPEDICELLUS(BP) andERECTA(ER) pathways inArabidopsiscallus are converged to prevent callus browning and positively regulate an isoperoxidase gene AtPRX17expression in the rapid growth callus. Loss of functions in bothBPandERresulted in markedly increasing callus browning. Transgenic lines withpro35S::AtPRX17in thebp-5 er105double mutant background fully rescued this phenotypic abnormality. Using plantin vitroDNA-binding assays, we observed that BP protein bound directly to the upstream sequence ofAtPRX17to promote its transcription during callus growth. ER is a universally presenting factor required for cell proliferation and growth, we show thatERpositively regulates expression of a transcription factorWRKY6, which also directly binds to an additional site of the AtPRX17promoter for its high expression. Our data reveals an important molecular mechanism in regulating expression of peroxidase isozyme to reduce Arabidopsis callus browning.HighlightBREVIPEDICELLUSandERECTAare involved in regulating Arabidopsis callus browning by controlling expression ofAtPRX17.