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To investigate the regulation of 14-3-3 proteins in banana ( Musa acuminata L. AAA group, cv. Brazilian) fruit postharvest ripening, four cDNAs encoding 14-3-3 proteins were isolated from banana and designated as Ma- 14- 3- 3a, Ma- 14- 3- 3c, Ma- 14- 3- 3e, and Ma- 14- 3- 3i, respectively. Amino acid sequence alignment showed that the four 14-3-3 proteins shared a highly conserved core structure and variable C-terminal as well as N-terminal regions with 14-3-3 proteins from other plant species. Phylogenetic analysis revealed that the four 14-3-3 genes belong to the non-ε groups. They were differentially and specifically expressed in various tissues. Real-time RT-PCR analysis indicated that these four genes function differentially during banana fruit postharvest ripening. Three genes, Ma- 14- 3- 3a, Ma- 14- 3- 3c, and Ma- 14- 3- 3e, were significantly induced by exogenous ethylene treatment. However, gene function differed in naturally ripened fruits. Ethylene could induce Ma- 14- 3- 3c expression during postharvest ripening, but expression patterns of Ma- 14- 3- 3a and Ma- 14- 3- 3e suggest that these two genes appear to be involved in regulating ethylene biosynthesis during fruit ripening. No obvious relationship emerged between Ma- 14- 3- 3i expression in naturally ripened and 1-MCP (1-methylcyclopropene)-treated fruit groups during fruit ripening. These results indicate that the 14-3-3 proteins might be involved in various regulatory processes of banana fruit ripening. Further studies will mainly focus on revealing the detailed biological mechanisms of these four 14-3-3 genes in regulating banana fruit postharvest ripening. [ABSTRACT FROM AUTHOR]