A novel small open reading frame gene, IbEGF, enhances drought tolerance in transgenic sweet potato

Small open reading frames (sORFs) can encode functional polypeptides or act as cis-translational regulators in stress responses in eukaryotes. Their number and potential importance have only recently become clear in plants. In this study, we identified a novel sORF gene in sweet potato, IbEGF, which encoded the 83-amino acid polypeptide containing an EGF_CA domain. The expression of IbEGF was induced by PEG6000, H2O2, abscisic acid (ABA), methyl-jasmonate (MeJA) and brassinosteroid (BR). The IbEGF protein was localized to the nucleus and cell membrane. Under drought stress, overexpression of IbEGF enhanced drought tolerance, promoted the accumulation of ABA, MeJA, BR and proline and upregulated the genes encoding superoxide dismutase (SOD), catalase (CAT) and peroxidase (POD) in transgenic sweet potato. The IbEGF protein was found to interact with IbCOP9-5 alpha, a regulator in the phytohormone signalling pathways. These results suggest that IbEGF interacting with IbCOP9-5 alpha enhances drought tolerance by regulating phytohormone signalling pathways, increasing proline accumulation and further activating reactive oxygen species (ROS) scavenging system in transgenic sweet potato.

Automated summary

The study identified a novel sORF gene IbEGF in sweet potato, which encodes an 83-amino acid polypeptide and is induced by various stresses. Overexpression of IbEGF in transgenic sweet potato enhances drought tolerance, promotes phytohormone signaling pathways, and increases proline accumulation to activate ROS scavenging system. IbEGF protein interacts with IbCOP9-5 alpha, suggesting a role in regulating stress responses in plants.