CHARACTERIZATION OF DOMAIN REARRANGED METHYLATION-2 INVOLVED IN METHYLATION DURING BANANA (MUSA ACUMINATA) RIPENING FOR POSTHARVEST TREATMENT DEVELOPMENT

• Main Author: Azzahra Putri, Mita
• Format: Final Project
• Language: Indonesia
• Online Access: https://digilib.itb.ac.id/gdl/view/76613
• Institution: Institut Teknologi Bandung

Indonesia ranks sixth as country with highest banana production. However, post-harvest losses are still the main problem, reaching 25-50%. Chitosan coating can solve the post-harvest loss issue by inhibiting fruit ripening. This study focuses on the epigenetics of banana fruit natural ripening and chitosan post- treatment. Epigenetics are mechanisms that regulate gene expression that is tightly linked to the dynamics of chromosome structures and can be influenced by DNA nucleotide methylation. Some studies have suggested that DNA methylation also plays a role in regulating gene expression during fruit ripening. Hence, this research aims to perform in silico characterization of the methylation-related genes in bananas and determine the expression pattern of the identified methylation-related gene during natural ripening and post-treatment with 1.25% chitosan coating. One of DNA methylation genes identified through in silico study is the Musa acuminata DOMAIN REARRANGED METHYLATION 2 (MaDRM2). The MaDRM2 was identified based on conserved domains, the DNA_methylase. There are three MaDRM2 found having the DNA_methylase domain, which is distributed in three chromosomes, i.e., chromosome 3 (MaDRM2-A), chromosome 8 (MaDRM2-B) and chromosome 11 (MaDRM2-C). MaDRM2-A has the highest cis-acting elements responsive to salicylic acid. MaDRM2-B has moderately cis-acting elements. Meanwhile, MaDRM2-C has a high frequency of cis-acting elements in each category, indicating that it is predicted to be regulated under various conditions. Fruit physiological assessment was conducted on day 0, day 3, and day 7 in three treatment groups: control, 1.25% chitosan, and chitosan solvent (acidic) as a negative control. The physiological analysis showed that bananas treated with 1.25% chitosan had the lowest brown spot area on day 7. Significant differences were observed in the CO2 rate but not in the ethylene rate. Meanwhile, the firmness, total soluble solids, and starch content did not differ significantly among the three treatment groups. Nevertheless, the firmness and total soluble solids of bananas treated with chitosan consistently showed the lowest values. The gene expression patterns analyzed using qPCR showed that MaDRM2-A and MaDRM2-B were expressed in both naturally ripened and 1.25% chitosan-coated banana fruit, with higher expression levels found in the chitosan-coated bananas. On the other hand, expression of MaDRM2-C observed neither in natural ripened nor chitosan-coated bananas. It can be concluded that MaDRM2-A and MaDRM-B have been characterized with an increased expression pattern during natural ripening processes and were identified to be slower and higher during chitosan treatment.