KARAKTERISASI GEN DEMETILASI YANG BERPERAN DALAM EPIGENETIKA PEMATANGAN BUAH PISANG UNTUK PENGEMBANGAN PERLAKUAN PASCA PANEN

• Main Author: Prabhandiya, Sekar
• Format: Final Project
• Language: Indonesia
• Online Access: https://digilib.itb.ac.id/gdl/view/79078
• Institution: Institut Teknologi Bandung

Bananas are fruits of high economic value but with a short shelf life. Chitosan edible coating treatment and gene expression regulation through epigenetics have potential as means to manage post-harvest losses. Chitosan can form biofilms that inhibit fruit respiration as well as act as a biodegradable and non-toxic antimicrobial agent. Epigenetic mechanisms of DNA demethylation play a role in gene activation during plant development, including ripening. This study aims to characterize the DNA demethylation gene in bananas using the in silico identification and characterization method and to measure expression differentiation at different ripening stages in vitro using qPCR. In silico characterization includes gene structure prediction, gene localization, analysis of cis-acting regulatory elements (CARE), protein motif and domain analysis, and physicochemical characterization of proteins. In the in vitro analysis, 3 treatment groups were assigned into control group coated with water, chitosan group coated with chitosan, and acid group coated with pH 5.5 acetic acid, which were then observed for 7 days, with sampling on the 3rd (Day-3) day and the 7th day (Day-7). The physiological parameters of bananas at each sampling point included peel color, firmness, TSS content, starch content, ethylene rate, and CO2 rate measured in vitro. From the in silico analysis, three DNA demethylation genes were found in bananas, namely MaDML-A on chromosome 3, and MaDML-B and MaROS1 on chromosome 10. The three genes have similar gene structures as shown by 18 exons in similar positions. CARE analysis showed MaROS1 and MaDML-B were more responsive to hormones while MaDML-A was more responsive to environmental conditions. 10 conserved motifs were found, 4 of them with functions affected by demethylation. All three proteins have the same 4 domains, namely ENDO3c, FES, Perm-CXXC, and RRM_DME. The physicochemical properties of the three proteins, namely molecular weight, pI, aliphatic index, and GRAVY are in a similar range of values. Subcellular localization predictions indicated that all three proteins were located in the nucleus, consistent with their presumed function in DNA demethylation activity. In the physiological analysis, differences were observed between treatment groups, and the largest differences were observed in CO2 respiration rate and firmness. The level of demethylation gene expression in the normal ripening process of the control group increased on Day-3 and then decreased on Day-7. Post-harvest treatment caused differences in gene expression in the chitosan and acid groups which increased continuously from Day-0 to Day-7. The genes with the highest to lowest expression levels were MaROS1, MaDML-A, and MaDML-B, consecutively. In conclusion, bananas undergo changes in physiology and DNA demethylation gene expression during ripening, with potential for postharvest treatments through chitosan and epigenetic regulation.