Transcriptome-wide identification and stress properties of the 14-3-3 gene family in cotton (Gossypium hirsutum L.).

14-3-3s are a class of conserved proteins in eukaryotes involved in almost all cellular processes. Published studies have shown that this family plays a role in response to stress conditions. In this study, comparative genomics identified thirty-one 14-3-3 cDNAs encoding 25 unique proteins with transcripts that were sufficiently divergent in the coding regions to define different 14-3-3 members. Phylogenetic analysis indicated that the cotton 14-3-3 family was similar to the family in the plant model species Arabidopsis and rice. The multiple copies of 14-3-3 genes in cotton are suggested to be the result of a recent duplication event after the divergence of cotton from its progenitor species. 14-3-3s are differentially expressed in a range of cotton organs as well as under different environmental conditions. Salinity and drought stress significantly induced the altered expression of 14-3-3 genes, suggesting that 14-3-3s play a role in cotton response to environmental abiotic stress. The 14-3-3 gene CGF14-4 was more sensitive to both drought and salinity stress with a 10.2-fold change under 1% of PEG treatment, while other 14-3-3s responded only to either drought or salinity stress. These results implied that specific isoforms of 14-3-3s play different regulatory roles in stress response besides their role in development. 14-3-3s were more sensitive to abiotic stress in roots than in leaves, suggesting that the root is more sensitive to stress treatment than leaves. The differential expression pattern of 14-3-3s also suggests the occurrence of functional divergence among specific isoforms.