Functional Diversification of Genes in Panicle Architecture Determination.

Grain yield, which is one of the most important traits in rice breeding, is controlled in part by panicle branching patterns. Numerous genes involved in the control of panicle architecture have been identified through mutant and QTL characterization. Previous studies suggested the importance of several AP2/ERF transcription factor-encoding genes in the control of panicle development, including the () genes. The gene was specifically considered to be a key regulator of shoot and floral development in . However, the likely importance of paralogous genes in the regulation of meristem identities and activities during panicle architecture development has not to date been fully addressed in rice. In this study, we observed that the rice genes displayed divergent temporal expression patterns during the branching stages of early panicle development, with spatial localization of expression in meristems for two of these genes. Moreover, a functional analysis of rice -related genes using genome editing revealed their importance in the control of panicle architecture, through the regulation of axillary meristem (AM) establishment and meristem fate transition. Our study suggests that the paralogous genes have become partially diversified in their functions, with certain opposing effects, since they arose from ancestral gene duplication events, and that they act in regulating the branching of the rice panicle.