Effect of low oxygen, temperature and 1-methylcyclopropene on the expression of genes regulating ethylene biosynthesis and perception during ripening in apple

Ethylene initiates and controls ripening in climacteric fruit which is developmentally regulated. During this process, ethylene production generates a strong signaling process inducing/suppressing various target genes that are associated with several attributes of fruit ripening. In apple, low temperature, low oxygen and 1-methylcyclopropene (1-MCP) treatments have been used to increase shelf life. In the present study, effort has been made to understand the molecular basis of the increase in shelf life under the influence of temperature, low oxygen and 1-MCP in Granny Smith apple. The apple fruit were exposed to these treatments either individually or in combination and levels of ethylene as well as transcript accumulation of the genes responsible for ethylene biosynthesis and ethylene receptors were measured. A tight regulation of the ethylene production was observed through differential expression of MdACS1 and MdERS1 genes. The ethylene levels were highly dependent on temperature, oxygen concentration and 1-MCP and effects of each were not only additive but associated with the expression of MdACS1 and MdERS1.