cDNA sequence of E2 gene family in Arabidopsis thaliana and data of statistical analysis

<p>E2 ubiquitin-conjugating enzymes act as a heart role in the ubiquitination process and are responsible for catalysis ubiquitin transfer. Although the function of ubiquitin-protein ligases (E3s) in plant response to diverse abiotic stress by targeting specific substrates has been well studied, the E2s' involvement in environmental responses and their downstream targets are not well understood. Here, we demonstrated that the E2 ubiquitin-conjugating enzyme 18 (UBC18) regulates the stability of FREE1 to modulate iron deficiency stress. UBC18 affects the ubiquitination of FREE1 and promotes its degradation, overexpression of<em> UBC18</em> in plants decreases their sensitivity to iron deficiency by reducing the level of FREE1, and high accumulation of FREE1 in<em> </em>the<em> ubc18</em> mutant resulted in sensitivity to iron deficiency. In addition, we demonstrated the lysine residues K227, K295, K315, and K540 are required for FREE1 ubiquitination and stability regulation, and mutation of these lysines of FREE1 residues resulted in sensitivity to iron starvation in plants. Taken together, our findings reveal a mechanism of UBC18 in response to iron deficiency stress by altering the abundance of FREE1, and further elucidate the role of ubiquitination sites in FREE1 stability regulation and the plant iron deficiency response.</p>