ABSTRACT
OBJECTIVE: To investigate the effect of elicitors on secondary metabolites accumulation at different proliferation stages of thyme. METHODS: The thyme was induced by jasmonic acid methyl ester, salicylic acid and chitosan respectively after being culture on 1/2 MS basal medium for 20, 30 and 40 d, and secondary metabolites were extracted and examined by GC-MS. RESULTS: Forty-six compounds were identified in the solution. It was found through comparison of 12 compounds with contents more than 1% that three inducers significantly increased the contents of aromatic compounds represented by thymol, oxidation terpenoids and terpenes compounds represented by benzene, 1-methyl-3-(1-methylethyl) and 1,4-cyclohexadiene 1-methyl-4-(1-methylethyl). CONCLUSION: The secondary metabolites of thyme are affected significantly by elicitors.
ABSTRACT
The defence mechanisms that are activated by methyl jasmonate (MJ) in fruits are not well understood. In this work, we studied the expression of defence genes in papaya fruit that are induced by the exposure to MJ and/or low temperatures. The papaya fruits Maradol were randomly divided into two groups: one group was the untreated control and the other was treated with 10-4 M of MJ. Half of the fruits from each of the two groups were stored after treatment for 5 days at 5ºC and 2 days at 20ºC. We studied the expression levels of the pdf1.1 and pdf1.2 genes by amplification from expression libraries created from the pulp and skin tissues of the papaya fruit. As a reference, the mRNA level of the 18s ribosomal gene was used. In the skin tissue, the expression levels of the pdf1.1 and pdf1.2 genes were higher immediately after MJ treatment compared to the control. Furthermore, the expression of pdf1.2 remained high after MJ treatment and subsequent storage compared to the control. It was therefore concluded that the activation of the pdf1.1 and pdf1.2 genes forms part of the molecular defence mechanism in fruits that is activated by exposure to MJ. To our knowledge, this is the first study that analyzes the gene expression in papaya fruit that is induced by the exogenous application of methyl jasmonate and cold treatment.