Dear Editor,The ubiquitin proteasome system (UPS) is a highly regulated mechanism of intracellular protein degradation in eukaryotes.The UPS comprises three key enzymes:ubiquitin-activating enzyme E1,ubiquitin-conjugating enzyme E2,and ubiquitin ligase enzyme E3.There are nearly 1500 E3 ligase genes in rice and Arabidopsis genomes that target substrates for many biological processes for plant growth and tolerance to abiotic and biotic stresses.