SDG128 is involved in maize leaf inclination.

Maize leaf angle is one of the complex quantitative traits, controlled by developmental signals, hormones, and environmental factors. However, the connection between histone methylation and leaf angles in maize remains unclear. Here, we reported SET domain protein 128 (SDG128) is involved in leaf inclination in maize. Knockdown of SDG128 using RNA interference approach resulted in expand architecture, less large vascular bundles, more small vascular bundles, and larger spacing of large vascular bundle in auricle. SDG128 interacts with ZmGID2 in vitro and in vivo. Knockdown of ZmGID2 also showed the larger leaf angle with less large vascular bundle and larger spacing of vascular bundle. In addition, the transcription level of cell wall expansion family genes ZmEXPA1, ZmEXPB2, and GRMZM2G005887, and transcriptional factor genes Lg1, ZmTAC1, and ZmCLA4, and auxin pathway genes ZmYUCCA7, ZmYUCCA8, and ARF22 were reduced in SDG128 and ZmGID2 knockdown plants. SDG128 directly targets ZmEXPA1, ZmEXPB2, LG1, and ZmTAC1 and required for H3K4me3 deposition at these genes. Together, this study suggested that SDG128 and ZmGID2 are involved in the maize leaf inclination.