The expression of chili defense gene due to oviposition of fruit fly (Bactrocera dorsalis)

Abstract

Ovipositions of fruit flies typically leave some wounds on the chili fruits. These punctures might allow some pathogenic microorganisms to get into the fruits and eventually cause the secondary infections. Taking this into account, this study aimed at determining the expression of chili defense gene (CaRGA2) due to pathogenic fungus infection which occurred following the fruit fly oviposition activities. The research was carried out from April to October 2018 in two research facilities located in West Java, Indonesia, i.e. the Molecular Laboratory of IVEGRI (West Bandung) and the Molecular Biology Laboratory of the Biotechnology and Bioindustry Research Center (Bogor). Chili fruits of three chili varieties with different levels of resistance againts fruit fly infestations (i.e. susceptible, moderately resistant, and resistant) were used in this study. Moreover, the RNA of each of the varieties was isolated before and after the fruit fly oviposition. The chili defense gene of CaRGA2 was tested in this study whereas the housekeeping gene used was Actin. The gene was amplified by using the RT-PCR method and afterwards, the data from the amplification were analyzed by employing the Livak method. The results showed that chili defense gene expression increased significantly in the susceptible chili variety, but did otherwise in both the moderately resistant and resistant varieties. Eventually, this result supported the previous studies that revealed the increased fungal pathogen infections in host plants due to the injuries caused by fruit fly oviposition.