Over the past few years, Medicago truncatula has emerged as a model legume for the study of plant functional genomics that incorporates profiling of gene expression (transcriptome), protein expression (proteome), and metabolite expression (metabolome) to better understand the biological processes with legumes and their interaction with the environment. It is an excellent species for fundamental studies on the unique secondary metabolism of legumes. Two classes of secondary metabolites are of particular interest: phenylopropanoids, which have been attributed with health-promoting properties, And another important class of secondary metabolites from M. truncatula are the triterpene saponins, which possess allelopathic, anti-microbial, anti-insect activity, as well as anti-nutritional effects. Profiling and identification of a large variety of natural products from M. truncatula are crucial to metabolomics and functional genomics.
Flavonoids form a group of secondary metabolites ubiquitous in the plant kingdom. These compounds are synthesized in plant tissues on the phenylalanine lyase pathway and may be divided into several groups, differing in their skeleton: flavones, flavonols, isoflavons, flavanons, flavan-3-ols (catechins), anthocyanidins, aurons, and chalcons. All these compounds occurring in plant tissues may be hydroxylated, methylated or sulphated and are substituted with different groups such as sugars or acyls. More than 6000 compounds differing in their chemical and biological properties belong to this group. Fast and precise methods of identification and quantitative analysis of all these plant constituents are necessary because of their important biological functions and different applications of plant products. Instrumental analytical methods used in this purpose are described in the paper. Special concern is directed to particularly useful hyphenated chromatographic techniques such as HPLC C/MS, HPLC/NMR, GC/MS, and CE/MS.
The phenylpropanoid metabolism in plants is an important source of numerous compounds of great importance in development and defense. In particular, flavonoids play a significant role as signal compounds, phytoalexins, UV-protectants, pigments etc. Numerous enzymes (PAL, CHS, CHI, CHR, IFR and many others) are involved in this branched metabolic pathway. The key enzymes of phenylpropanoid biosynthesis are phenylalanine ammonia-lyase (PAL), and chalcone synthase (CHS). Both enzymes (as well as some other of the pathway) are encoded by multigene families. The organospecific expression of different members of these families is presumably the key factor for the regulation of the entire pathway. Several cis-elements, and trans-acting factors have been already described, however it is too early to formulate the conclusive model of the overall transcriptional regulation of the phenylpropanoid metabolism.
This paper reviews information from last decade world literature on the occurence in tissue cultures of some Lamiaceae species of secondary metabolites.The introductory part of paper gives information on the occurence of the biological active secondary metabolites in the native plant species from Lamiaceae family.
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