The ALOG family members OsG1L1 and OsG1L2 regulate inflorescence branching in rice.

The architecture of the rice inflorescence is an important determinant of crop yield. The length of the inflorescence and the number of branches are among the key factors determining the number of spikelets, and thus grains, that a plant will develop. Especially the timing of the identity transition from indeterminate branch meristem to determinate spikelet meristem regulates the complexity of the inflorescence. In this context, the ALOG gene TAWAWA1 (TAW1) has been shown to delay the transition to determinate spikelet development in rice. Recently, by combining precise laser microdissection of inflorescence meristems with RNA-seq we observed that two ALOG genes, Oryza sativa OsG1-like 1 (OsG1L1) and OsG1L2, have an expression profile similar to TAW1. Here we report that osg1l1 and osg1l2 loss-of-function CRISPR mutants have similar phenotypes as the previously published taw mutant, suggesting that these genes might act on related pathways during inflorescence development. Transcriptome analysis of the osg1l2 mutant suggested interactions of OsG1L2 with other known inflorescence architecture regulators and the datasets were used for the construction of a gene regulatory network (GRN) proposing interactions among genes potentially involved in controlling inflorescence development in rice. We selected in this GRN the homeodomain-leucine zipper transcription factor encoding gene OsHOX14 for further characterisation. The spatio-temporal expression profiling and phenotypical analysis of CRISPR loss-of-function mutants of OsHOX14 suggests that the proposed GRN indeed serves as a valuable resource for the identification of new players involved in rice inflorescence development.