The CYP78A Subfamily of Cytochrome P450 Monooxygenases Is Involved in Protonema Growth and Gametophore Formation in the Moss Physcomitrella patens

Abstract

CYP78A is a family of cytochrome P450 monooxygenases highly conserved in land plants. In angiosperms, some CYP78As are reported to regulate plastochron length and organ size, but there have been no reports on the role of CYP78As in non-angiosperms. The moss Physcomitrella patens possesses two CYP78As, CYP78A27 and CYP78A28. To investigate the function of CYP78As in P. patens, we have produced single and double mutants and overexpression lines for CYP78A27 and CYP78A28 by gene targeting. Either cyp78a27 or cyp78a28 single mutant did not show any obvious phenotype in the protonema stage and the gametophore formation. On the other hand, the double mutant exhibited severe retardation of protonemal growth and gametophore development. In addition, endogenous levels of some plant hormones were altered in the double mutant. Transgenic lines that overexpress CYP78A27 or CYP78A28 showed delayed and reduced gametophore formation. Our results suggest that CYP78A is an important factor of growth regulation in P. patens.