1-MCP treatment modulated physiological, biochemical and gene expression activities of guava during low-temperature storage

Guava fruits remain biologically active even after harvest as they continue respiration and other physioligical activites. Being climacteric in nature, guava fruits senesce fast duringstorage. To extend the storage life of guava fruits, they were treated with 1-MCP 500 ppb and found that 1-MCP could extend the storage life of guava. 1-MCP-treated fruits retained greater fruit texture (2.17 N) with reduced respiration (54.57 CO 2 mg/kg/h), ethylene (5.02 µl/kg/h) and pectin methylestaerase activity (1.21 units/ml) after 21 days of storage period when compared to untreated fruits. To determine the effects of 1-MCP on ripening, various physiological, biochemcial and gene expression parameters were studied. The results showed that 1-MCP delayed respiration and ethylene peak by maintaining the quality parameters like ascorbic acid content (129.24 mg/100 g), antioxidant activity (199.2 AAE/100 g), phenols (528.93 GAE/100 g) and sugar acid ratio (16.05% acid) in the fruits. RNA isolation protocol was developed using Tris saturated phenol and sodium dodecyl sulfate. This rapid protocol allowed us to isolate quality RNA from guava pulp. Further, RT-qPCR gene expression analysis of expansin and ACC synthase genes reveled that the texture and ethylene production were significantly down regulated with 1-MCP treatment. The present reserach work highlighted the effect of 1-MCP in extending the shelf life of guava fruits by regulating physiological and biochemical processes during friut ripening, and their validation through gene expression studies provide insights for manipulaiton of genes involved in climacteric fruit ripening.