Expression Pattern of Ethylene-Related Genes in Response to Preharvest Chemical Treatments during Development and Ripening of Mangosteen Fruit (Garcinia mangostana L.)

The expression of ethylene associated genes based on development stage from fruit set until harvest in mangosteen has not been studied yet in some previous studies. The objective of this study was to investigate the expression pattern of genes involved in ethylene biosynthesis, Gm-ACS, and Gm-ACO, and perception, Gm-ETR, from the stages of fruit set (Period I), fruit development (Period II), and maturation until ripening or harvesting (Period III). The results showed that ethylene biosynthetic genes on the Gm-ACO gene were correlated with ethylene production's climacteric pattern. Gm-ACO was up-regulated at the beginning of the fruit set and then decreased. Fruit at age 2 - 10 weeks after anthesis showed a decrease in the Gm-ACO gene's mRNA levels. Then, Gm-ACO expression re-appeared and increased at the fruitage 11 - 12 after the fruit set. At the harvest-stage, the fruit showed down-regulation at the lowest level of the Gm-ACO expression. Ethephon treatment at or beyond 24 h (threshold time) increased the mRNA levels of Gm-ACS, Gm-ACO, and Gm-ETR. In contrast, the 1-Methylcyclopropene (1-MCP) treatment under the threshold time resulted in undetectable expression in all ethylene-related genes. These data would be beneficial to elucidate the molecular mechanisms in the mangosteen fruit ripening process. In addition, preharvest application of ethephon or 1-MCP can induce or inhibit the gene expression of ethylene biosynthesis and perception.