Characterization of the AP2/ERF gene family in Fritillaria thunbergii and functional evaluation of FtAP2/ERF-61 in conferring tolerance to drought and salt stress.

Background

The APETALA 2/ethylene-responsive element binding factors (AP2/ERFs) are crucial modulators of plant development and stress responses. Fritillaria thunbergii is an important medicinal herb with considerable therapeutic efficacy. However, despite its importance, no systematic identification and functional characterization of the AP2/ERF gene family in F. thunbergii has been reported to date.

Results

This study identified a total of 71 AP2/ERF genes in F. thunbergii and classified them into 11 subgroups, with genes in the same subgroup exhibiting similar motifs and domains. Expression analysis revealed that these genes displayed distinct expression patterns under salt and drought stress, and Gene Ontology annotation indicated their involvement in stress responses and hormone signaling. Further analysis demonstrated that FtAP2/ERF-61 responded to mannitol, NaCl, ethylene, abscisic acid, and jasmonic acid. The FtAP2/ERF-61 protein consisted of 352 amino acids, contained a conserved AP2/ERF domain, was localized to the nucleus, and possessed transcriptional activation activity. Overexpression of FtAP2/ERF-61 in Arabidopsis thaliana significantly enhanced germination rates and growth status under salt and osmotic stress, while reducing hydrogen peroxide and malondialdehyde accumulation, and upregulating the expression of stress-responsive genes and antioxidant enzyme genes.

Conclusion

This study provided the systematic identification of AP2/ERF family members in F. thunbergii and demonstrated that FtAP2/ERF-61 conferred dual stress tolerance by activating the ROS-scavenging system and stress-responsive genes, thereby offering new genetic resources and a theoretical basis for molecular breeding of stress-tolerant medicinal plants.