ZmCYP90D1 regulates maize internode development by modulating brassinosteroid-mediated cell division and growth

Plant height (PH) is associated with lodging resistance and planting density, which is regulated by a complicated gene network. In this study, we identified a spontaneous dwarfing mutation in maize, m30, with decreased internode number and length but increased internode diameter. A candidate gene, ZmCYP90D1, which encodes a member of the cytochrome P450 family, was isolated by map -based cloning. ZmCYP90D1 was constitutively expressed and showed highest expression in basal internodes, and its protein was targeted to the nucleus. A G -to -A substitution was identified to be the causal mutation, which resulted in a truncated protein in m30. Loss of function of ZmCYP90D1 changed expression of hormoneresponsive genes, in particular brassinosteroid (BR) -responsive genes which is mainly involved in cell cycle regulation and cell wall extension and modification in plants. The concentration of typhasterol (TY), a downstream intermediate of ZmCYP90D1 in the BR pathway, was reduced. A haplotype conferring dwarfing without reducing yield was identified. ZmCYP90D1 was inferred to influence plant height and stalk diameter via hormone -mediated cell division and cell growth via the BR pathway. (c) 2023 Crop Science Society of China and Institute of Crop Science, CAAS. Production and hosting by Elsevier B.V. on behalf of KeAi Communications Co., Ltd. This is an open access article under the CC BY -NCND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).