Arabidopsis E3 SUMO ligase controls vegetative growth and development including responses to nutrient deficiency and environment stresses. Here, we analyzed seed proteins of its mutant siz1-2. Proteomic analysis showed that the amount of three major nutrient reservoir proteins were decreased in siz1-2 mutants. However, quantitative real-time RT-PCR showed that their transcript levels were significantly high in siz1-2 mutants compared to wild-type plants, which means that these proteins are stabilized by E3 SUMO ligase. In addition, yeast two hybrid assay showed that they interact with E3 SUMO ligase, suggesting that they must be sumoylated by E3 SUMO ligase. Furthermore, tthe analysis of amino acid composition by HPLC showed that the contents of amino acids were a bit high in siz1-2 mutants. Our data indicate that AtSIZ1 plays an important function for accumulation of seed storage proteins through its ligase activity

• Sung-Il Kim(Department of Plant Science, Research Institute for Agriculture and Life Sciences, and Plant Genomics and Breeding Institute)
• Kim Joo Yong(Department of Plant Science, Research Institute for Agriculture and Life Sciences, and Plant Genomics and Breeding Institute)
• Hak Soo Seo(Department of Plant Science, Research Institute for Agriculture and Life Sciences, and Plant Genomics and Breeding Institute)