Objective The ethylene responsive factor (ERF) gene in cassava, MeERF1, was cloned for functional analysis.

Method ERF crucially related to the growth, development, abiotic stress response, and antioxidant regulation of cassava SC8 cultivar was cloned. CDS sequence of MeERF1 gene was obtained by PCR, functional annotation and structural prediction performed by bioinformatics methods, subcellular localization detected by Agrobacterium-mediated transient transformation, and relative expressions in tissues at different sampling times after abscisic acid (ABA) treatment of tubers determined.

Result The 1,425bp long CDS sequence of MeERF1 as determined was perfectly consistent with what is shown for the reference in the Phytozome database (accession number: Manes.13G148300). An acidic protein, it was composed of 474 amino acids with a molecular weight of 52.7kDa and a pI of 6.28. Structurally, the protein contained 90.30% of irregular coils, 6.96% of α-helixes, and 2.74% of extended strands. It mainly aggregated in the nuclear region, indicating a high possibility of being a transcription factor. In addition, the multiple sequence alignment and phylogenetic analysis showed its inclusion of a key AP2/ERF conserved family domain specifically bound to GCC/box like a transcription factor. It also shared the highest similarity at 80.33% on amino acid sequence with the ERF protein of Brazilian rubber tree. In various tissues of a cassava plant, the expression of MeERF1 was significantly higher in the hairy fine roots, followed by the stems, than in other organs. And the expression peaked after 12h of ABA induction.

Conclusion The cloned MeERF1 belonged to the AP2/ERF transcription factor that was tissue-specific and responded to ABA. It was plausible that it involved in the regulation of post-harvest physiological deterioration of cassava roots.