SDG721 and SDG705 are required for rice growth.

H3K4me3 plays important roles in development, transcription, and environmental responses. Here, we report that SDG721 (SET-domain group protein 721) and SDG705 are involved in regulating rice development. SDG721 and SDG705 encode TRITHORAX-like proteins, which appear to modulate H3K4 methylation levels. Loss of SDG721 and SDG705 function resulted in GA-deficient phenotypes, including semi-dwarfism, reduced cell length, and reduced panicle branching. The transcripts levels and H3K4me3 levels of GA biosynthesis genes and GA signaling pathway genes were downregulated in the sdg721 sdg705 plants. Together, these results suggest that SDG721 and SDG705 regulate H3K4 methylation, which is crucial for plant development in rice.