Towards a PCR-based procedure for identifying ripening banana mutants : sequence analysis and primer design
2013
Balingit, J.C. | Corales, L.G. | Ocampo, E.T.
Banana is the number one fruit crop in the Philippines in terms of area and volume of production. Although the contribution to the economy by banana exports is considerable at approximately US $ 370 million, the value of the domestic market is thrice this. With increasing demand for banana and its products, there is a need to improve low productivity of domestic varieties that are mainly caused by disease infestation and poor postharvest characteristics. After initiation, banana ripening proceeds at a rapid pace, resulting in fruit deterioration and up to 40% loss in marketable yield. Climacteric ripening in banana is controlled either by ethylene or developmental factors that include the MAD-box genes. MaMADS2, a fruit-specific MADS-box gene, was shown to encode a transcription factor that regulates the developmental competence of banana to ripen. This regulation is thought to act upstream of the ethylene biosynthetic pathway. Based on the full-length cDNA sequence of MaMADS2 gene isoforms in Lakatan, the authors isolated and sequenced the MaMADS2 homolog in Musa balbisiana var Saba (also known as Cardaba). A 531 bp genomic DNA segment in the 3'UTR region was found to contain a single intron that spanned 309 bases. Removal of the intronic sequence showed that the remaining nucleotide sequence was 99% homologous with Musa acuminata MADS2 gene reported in the GenBank, while the amino acid sequence after translation showed 100% homology with Musa acuminata MADS2 protein. Another 721-bp fragment corresponding to the promoter region of MaMADS2 was also isolated. Several sets of primers are being designed from the areas in order to amplify different regions in the MaMADS2 gene. Working primers will be used to screen changes in genomic DNA in MaMADS2 of Saba mutant seedlings that were produced through gamma irradiation.
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