Abstract
Plants of the genus Salvia produce various types of phenolic compounds and tanshinones which are effective for treatment of coronary heart disease. Salvia miltiorrhiza and S. castanea Diels f. tomentosa Stib are two important members of the genus. In this study, metabolic profiles and cDNA-AFLP analysis of four samples were employed to identify novel genes potentially involved in phenolic compounds and tanshinones biosynthesis, including the red roots from the two species and two tanshinone-free roots from S. miltiorrhiza. The results showed that the red roots of S. castanea Diels f. tomentosa Stib produced high contents of rosmarinic acid (21.77 mg/g) and tanshinone IIA (12.60 mg/g), but low content of salvianolic acid B (1.45 mg/g). The red roots of S. miltiorrhiza produced high content of salvianolic acid B (18.69 mg/g), while tanshinones accumulation in this sample was much less than that in S. castanea Diels f. tomentosa Stib. Tanshinones were not detected in the two tanshinone-free samples, which produced high contents of phenolic compounds. A cDNA-AFLP analysis with 128 primer pairs revealed that 2300 transcript derived fragments (TDFs) were differentially expressed among the four samples. About 323 TDFs were sequenced, of which 78 TDFs were annotated with known functions through BLASTX searching the Genbank database and 14 annotated TDFs were assigned into secondary metabolic pathways through searching the KEGGPATHWAY database. The quantitative real-time PCR analysis indicated that the expression of 9 TDFs was positively correlated with accumulation of phenolic compounds and tanshinones. These TDFs additionally showed coordinated transcriptional response with 6 previously-identified genes involved in biosynthesis of tanshinones and phenolic compounds in S. miltiorrhiza hairy roots treated with yeast extract. The sequence data in the present work not only provided us candidate genes involved in phenolic compounds and tanshinones biosynthesis but also gave us further insight into secondary metabolism in Salvia.
Highlights
Secondary metabolites, which have been used by human for thousands of years, are an important research field in crop breeding and metabolic engineering
The combination of metabolic profile and transcriptome has been widely used for discovery of secondary metabolism-related genes in plants [2,3]. cDNA-amplified fragment length polymorphism is one of the most robust and sensitive transcriptomic technologies for gene discovery [4] and offers an attractive method to identify genes involved in secondary metabolism of non-model plants [5]
Metabolic profiles and cDNA-AFLP analysis of the hydroponic, white and red roots of S. miltiorrhiza, and the red roots of S. castanea Diels f. tomentosa Stib were performed to identify novel genes involved in tanshinones and phenolic compounds biosynthesis
Summary
Secondary metabolites, which have been used by human for thousands of years, are an important research field in crop breeding and metabolic engineering. The differences of secondary metabolites accumulation in these samples indicated that genes involved in biosynthesis of tanshinones and phenolic compounds were probable differentially expressed. Tomentosa Stib were performed to identify novel genes involved in tanshinones and phenolic compounds biosynthesis.
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