| Plant secondary metabolites which have a variety of important biological functions provide humanity with an abundance of drugs,spices and industrial raw materials.Plant secondary metabolites have a wide range of species and the structures of them are different.Plant secondary metabolites are usually classified to three main groups such as terpenoids,phenolic compounds and nitrogen compounds according to the chemical structure.Coleus blumei Benth. (lamiaceae) is an ornamental plant,growing all over the world in an enormous number of different cultivars that vary in colour and shape of the leaves.It is used in India,Indonesia and Mexico as a medical plant.Rosmarinic acid, which was reported to have adstringent,antibacterial,antiviral and antioxidant activities,is one of the most prominent secondary compounds in Coleus blumei.As signaling molecules,Methy jasmonate(MJ) can induce the plant defense signal transduction pathways to induce the plant secondary metabolites pathways.Abscisic acid(ABA) can change the expression of many genes throght stress response when the plant is under the biotic and abiotic stress.The tyrosine aminotransferase(TAT) gene of tyrosine metabolic pathway was cloned from the Coleus blumei.This paper discussed the TAT gene transcriptional level expression and the TAT activity changed after MJ and ABA treatment.The TAT activity of different kinds and tissues in Coleus blumei were also determinated.The influence of TAT activity on the production of rosmarinic acid was dicussed.The results were as follows:1.The rosmarinic acid accumulation in different hybrids(K1,K2,K3 ) and tissues of Coleus blumei was estimated by HPLC to analyse the rosmarinic acid distribution in plants.Conditions for HPLC were as follows:column, 150×4.6mm;solvent system,methanol-0.1%phosphate(45:55);flow rate, 0.9mL/min;detection:325nm.The results varied significantly with different hybrids and tissues.One out of three hybrids of Coleus blumei contained more rosmarinic acid(1.56 mg/g of the dry weight,DW) and the leaves of all the hybrids showed higher rosmarinic acid production than roots and stems,followed by stems and roots.2.A proper method was established to determine the TAT activity in different hybrids and tissues of Coleus blumei.The TAT activity have a great difference in different hybrids and tissues of Coleus blumei.The TAT activity in leaves of K2 was the highest,reaching 44.29 Umg-1h-1.The results showed that the RA-content was higher in the hybrids or tissues in which TAT activity was also greater.It implied that the TAT activity would be positive correlation with RA content and the TAT might play an important role in the RA biosynthesis of Coleus blumei.3.TAT gene expression levels were analysed by semi-quantitative RTPCR to discuss the relationship between the expression of TAT gene and rosmarinic acid synthesis.The results showed that the transcript expression level of TAT gene was associated with the Coleus blumei variety.K2 shows highest level of TAT gene expression out of three hybrids while the K2 represent the highest level of RA-content.Stems represent the highest level of TAT gene expression among leaves,roots and stems.RA is not always related to the expression level of TAT mRNA.TAT gene expression can be induced by MJ and ABA,so we speculate that TAT gene might be able to interactions with signaling molecule.4.Both MJ and ABA concentration were related with the TAT activity of Coleus blumei leaves.In the range of 0-500μM MJ concentration TAT activity was increased following the higher MJ concentration,but when MJ concentration reched 600μM,TAT activity declined.The result showed that MJ could increase TAT activity,but the induced-effects have a certain range. When Coleus blumei leaves was treated with different ABA concentration TAT activity was increased then diclined.The highest TAT activity was 82.80mg-1h-1 after 50μM ABA treatment.5.The dynamic changed course of TAT activity were observed after exogenous 500μM MJ and 50μM ABA treatment.The results showed that TAT activity gradually enhanced,then reduced.The highest TAT activity reched 92.85 Umg-1h-1.Similarly to the effects on TAT activity,the ABA also could increase the TAT activity.The effect of MJ to Coleus blumei leaves was greater than ABA,but the response time was longer.6.In order to characterize the relationship between TAT activity and RA biosynthesis in leaf extracts of Coleus blumei,the changes of RA accumulation were analyzed in response to MJ and ABA elicitors.The RA content of the Coleus blumei leaf extracts started to increase gradually after 16 h elicitation with MJ.After 72 h treatment the RA content was enhanced to 3.92 mg/g of the DW treated with MJ elicitor.The leaves treated with 50μM ABA attained 2.81 mg/g RA content of the DW on hour 48 which were 2.1- fold(1.35 mg/g of the DW) of the contents in the control on the same days.The results have shown that the production of RA could be stimulated by MJ and ABA and the MJ-treated leaves RA content was higher than that under ABA-treatment.
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