Scientists from the University of the Philippines Los Banos were able to successfully isolate and analyze the gene involved in the developmental control of ripening in banana. Named as MaMADS2, the gene cloned from the cDNA of ripe banana fruit, was found to have putative sequence that shares structural sequences with Type II MADS-box transcription factors. MADS-box gene transcription factors are regulating genes which controls flower development and organogenesis. Promoter region analysis showed the presence of known binding sites for MADS-box, hinting at possible autoregulation of MaMADS2 gene transcription.

The gene expression of MaMADS2 was compared with a known-MaMADS1 gene in the pulp and tissue of ripening banana. They found that MaMADS2 expression starts to increase before the climacteric in both pulp and peel of bananas while MaMADS1 expression increased only after the ethylene peak was attained. The increase in MaMADS2 expression was earlier in fruits stored at low humidity showing that the gene is expressed in response to stress resulting in developmental shift and earlier ripening. MaMADS1 expression appears to be ethylene- induced while MaMADS2 acts upstream of the ethylene pathway and is involved in the developmental shift to ripening.

This is the first report of the presence of the MaMADS2 gene from banana, a climacteric fruit. The results show the involvement of a regulatory gene that acts upstream of the ethylene pathway, which has been the target of many climacteric ripening control experiments. The identification of the developmental factor in banana shows another avenue for regulatory pathways in ripening that could also control the endogenous ethylene pathway. These findings provide critical information in development of research strategies in prolonging the shelf-life of banana.

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