Identification and Expression Analyses of the Special 14–3-3 Gene Family in Papaya and its Involvement in Fruit Development, Ripening, and Abiotic Stress Responses

Plant 14–3-3 proteins play key roles in regulating growth, development, and stress responses. However, little is known about this gene family in papaya (Carica papaya L.). We characterized eight 14–3-3 genes from the papaya genome and designed them as CpGRF1–8. Based on phylogenetic, conserved motif, and gene structure analyses, papaya CpGRFs were divided into ε and non-ε groups. Expression analysis showed differential and class-specific transcription patterns in different organs. Quantitative real-time polymerase chain reaction analysis showed that most CpGRFs had large changes in expression during fruit development and ripening. This indicated that the CpGRFs were involved in regulating fruit development and ripening. Significant expression changes occurred after cold, salt, and drought treatments in papaya seedlings, indicating that CpGRFs were also involved in signaling responses to abiotic stress. These results provide a transcription profile of 14–3-3 genes in organs, during fruit development and ripening and in response to stress. Some highly expressed, fruit-specific, and stress-responsive candidate CpGRFs will be identified for further genetic improvement of papayas.