Cloning and characterization of the UBC gene from lotus (Nelumbo nucifera).

Protein ubiquitination is extensively involved in the regulation of a considerable number of physiological processes in plant cells. E2 (ubiquitin-conjugating enzyme, UBC), one of the essential enzymes of eukaryotic ubiquitination, catalyzes protein ubiquitination together with E1 and E3. In this study, we cloned four full-length cDNA NnUBCs of Nelumbo nucifera. With the same coding sequence length of 459 bp and coding 153 amino acids, these four genes are highly homologous with the AtUBC1 and AtUBC2 of Arabidopsis thaliana. Quantitative fluorescence polymerase chain reaction showed that these four genes exhibited different expression patterns in different tissues of N. nucifera. Overall, the expression of NnUBC3 was the highest in all plant tissues. Tests of different stress treatments showed that NnUBC3 plays an important role in response to heat, salt, and drought stresses in N. nucifera. Moreover, transgenic Arabidopsis plants (Atubc1-1Atubc2-1 mutant) expressing NnUBC3 presented a wild-type phenotype, indicating that NnUBC3 performs the same function as AtUBC1 and AtUBC2.