Cloning of an ADP-ribosylation factor gene from banana (Musa acuminata) and its expression patterns in postharvest ripening fruit.

A full-length cDNA encoding an ADP-ribosylation factor (ARF) from banana (Musa acuminata) fruit was cloned and named MaArf. It contains an open reading frame encoding a 181-amino-acid polypeptide. Sequence analysis showed that MaArf shared high similarity with ARF of other plant species. The genomic sequence of MaArf was also obtained using polymerase chain reaction (PCR). Sequence analysis showed that MaArf was a split gene containing five exons and four introns in genomic DNA. Reverse-transcriptase PCR was used to analyze the spatial expression of MaArf. The results showed that MaArf was expressed in all the organs examined: root, rhizome, leaf, flower and fruit. Real-time quantitative PCR was used to explore expression patterns of MaArf in postharvest banana. There was differential expression of MaArf associated with ethylene biosynthesis. In naturally ripened banana, expression of MaArf was in accordance with ethylene biosynthesis. However, in 1-methylcyclopropene-treated banana, the expression of MaArf was inhibited and changed little. When treated with ethylene, MaArf expression in banana fruit significantly increased in accordance with ethylene biosynthesis; the peak of MaArf was 3 d after harvest, 11 d earlier than for naturally ripened banana fruits. These results suggest that MaArf is induced by ethylene in regulating postharvest banana ripening. Finally, subcellular localization assays showed the MaArf protein in the cytoplasm.
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