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The production of plant secondary metabolites by in vitro culture is one of the most challenging and thrilling field of recent scientific researches. In the few last years, pharmaceutical and food industry demand in phytochemicals has increased steadily. Therefore, the establishment of in vitro plant protocols has to be monitored by phytochemical investigation of their selected extracts in order to supply standardized raw material. In this chapter, the advantages and disadvantages of some modem techniques have been described for the sampling, extraction and analysis ofthe invitro plants and derivatives. Depending on the volatile or nonvolatile substances produced by in vitro plant raw material, different kinds of laboratory facilities are needed for the extraction and quali-quantitative analysis. Recent extraction technology such as accelerated solvent extraction or microwave assisted extraction in combination with hyphenated techniques such as gas chromathography-mass spectrometry (GC-MS) and liquid chromatography-mass spectrometry (LC-MS) represent a modern approach to perform fast and reproducible analytical methods for the quality control of secondary metabolite production in 'in vitro' plant material.

The recent biotechnology boom has triggered increased interest in plant cell cultures, since a number of firms and academic institutions investigated intensively to rise the production of very promising bioactive compounds. In alternative to wild collection or plant cultivation, the production of useful and valuable secondary metabolites in large bioreactors is an attractive proposal; it should contribute significantly to future attempts to preserve global biodiversity and alleviate associated ecological problems. The advantages of such processes include the controlled production according to demand and a reduced man work requirement. Plant cells have been grown in different shape bioreactors, however, there are a variety of problems to be solved before this technology can be adopted on a wide scale for the production of useful plant secondary metabolites. There are different factors affecting the culture growth and secondary metabolite production in bioreactors: the gaseous atmosphere, oxygen supply and CO2 exchange, pH, minerals, carbohydrates, growth regulators, the liquid medium rheology and cell density. Moreover agitation systems and sterilization conditions may negatively influence the whole process. Many types ofbioreactors have been successfully used for cultivating transformed root cultures, depending on both different aeration system and nutrient supply. Several examples of medicinal and aromatic plant cultures were here summarized for the scale up cultivation in bioreactors.

Hairy roots (HRs) are differentiated cultures of transformed roots generated by the infection of wounded higher plants with Agrobacterium rhizogenes. This pathogen causes the HR disease leading to the neoplastic growth of roots that are characterized by high growth rate in hormone free media and genetic stability. HRs produce the same phytochemicals pattern of the corresponding wild type organ. High stability and productivity features allow the exploitation of HRs as valuable biotechnological tool for the production of plant secondary metabolites. In addition, several elicitation methods can be used to further enhance their accumulation in both small and large scale production. However, in the latter case, cultivation in bioreactors should be still optimized. HRs can be also utilised as biological farm for the production of recombinant proteins, hence holding additional potential for industrial use. HR technology has been strongly improved by increased knowledge of molecular mechanisms underlying their development. The present review summarizes updated aspects of the hairy root induction, genetics and metabolite production.