Changes in Homogalacturonan Metabolism in Banana Peel during Fruit Development and Ripening.

Though numerous studies have focused on the cell wall disassembly of bananas during the ripening process, the modification of homogalacturonan (HG) during fruit development remains exclusive. To better understand the role of HGs in controlling banana fruit growth and ripening, RNA-Seq, qPCR, immunofluorescence labeling, and biochemical methods were employed to reveal their dynamic changes in banana peels during these processes. Most HG-modifying genes in banana peels showed a decline in expression during fruit development. Four polygalacturonase and three pectin acetylesterases showing higher expression levels at later developmental stages than earlier ones might be related to fruit expansion. Six out of the 10 top genes in the Core Enrichment Gene Set were HG degradation genes, and all were upregulated after softening, paralleled to the significant increase in HG degradation enzyme activities, decline in peel firmness, and the epitope levels of 2F4, CCRC-M38, JIM7, and LM18 antibodies. Most differentially expressed alpha-1,4-galacturonosyltransferases were upregulated by ethylene treatment, suggesting active HG biosynthesis during the fruit softening process. The epitope level of the CCRC-M38 antibody was positively correlated to the firmness of banana peel during fruit development and ripening. These results have provided new insights into the role of cell wall HGs in fruit development and ripening.

Hypolipidaemic and antioxidant effects of fruits of Musa AAA (Chenkadali) in alloxan induced diabetic rats.

Hypolipidaemic and antioxidant effects of ethanol extract of mature green fruits of Musa AAA (Chenkadali) was evaluated in alloxan induced diabetic rats. The effect of extract at two doses, 500 mg/kg body weight and 1000 mg/kg body weight was analysed and compared with a standard drug, glibenclamide. Rats administered with alloxan showed significantly increased levels of serum triacylglycerol, total cholesterol and alanine amino transferase (ALT) activity. Lipid peroxides increased significantly while reduced glutathione (GSH) decreased considerably in liver and pancreas. Oral administration of the ethanol extract of fruits of Musa AAA (Chenkadali) significantly decreased the levels of serum triacylglycerol, cholesterol and ALT activity. Significant decrease was also observed in the level of lipid peroxides while GSH content increased substantially in liver and pancreas. The effect was dose independent and rats treated with 500 mg/kg body weight showed comparable levels of serum triacylglycerol, cholesterol, ALT activity and liver lipid peroxides to that of normal control and glibenclamide treated groups. Although, there was no significant difference, treatment with 500 mg/kg body weight of the extract showed a higher content of GSH and lower level of lipid peroxides in pancreas compared with glibenclamide. Histopathological examination of pancreas and liver revealed regeneration of islet cells and hepatocytes respectively, which correlate with the biochemical findings. The present study shows that ethanol extract of mature green fruits of Musa AAA (Chenkadali) has antioxidant and hypolipidaemic properties and may be used for treating diabetes mellitus.