Overexpression of SUMO1 located predominately to euchromatin of dividing cells affects reproductive development in maize

Abstract

Post-translational modification of proteins by small ubiquitin-like modifier (SUMO) plays essential roles in a large variety of cellular and developmental processes. While SUMO conjugation to target proteins has been reported in numerous studies in animals and human, and partly also in the model plant Arabidopsis, little is known about the specific roles of SUMO in crop plants. Here, we report about the maize SUMO family and show that the highly conserved core isoform SUMO1 predominately locates to the nucleus where it marks euchromatin rather than heterochromatin. Moreover, SUMO1 is especially present in nuclei of small dividing cells. Strong overexpression of SUMO1 caused a severe dwarf phenotype and abnormalities in floral organ structures. Defects in anther development and female gametogenesis occurred similar to null-mutant phenotypes reported in Arabidopsis . Taken together, these studies imply that precise and fine-tuned conjugation of the highly conserved plant SUMO1 isoform to target proteins is required for vegetative and reproductive development. Mis-regulation by overexpression or knock-out is deleterious, strongly affecting fertility in both dicots and monocots, including the crop plant maize.

Plant SUMO E3 Ligases: Function, Structural Organization, and Connection With DNA

“…In plants, the genome-wide location of SUMO E3 ligases is unknown and only one study looked at the global distribution of SUMO on DNA (Han et al, 2020). The presence of SUMO on chromatin correlates with active chromatin markers, in accordance with fluorescence microscopy experiments showing that maize SUMO1 associate more with euchromatin than heterochromatin (Chen et al, 2019). Upon heat stress induction, SUMO rearranges to upregulate heat stress genes while downregulating growth genes (Han et al, 2020).…”