Plant cell culture regenerants

As in vitro regeneration of SAM 1 is currently not feasible, MT reactions were often performed with live whole-cell biocatalysts to avoid the need of cofactor supply (i.e., microbial hosts expressing recombinant MTs, see next section). However, a drawback of this strategy is the relatively low intracellular concentration of endogenous SAM 1, which limits methylation capacity and, thus, leads to low product yield. Even in the biosynthesis of natural products in microorganisms, such as methylated antibiotics [69] and triterpenoids [70] or fatty acid methyl esters [71], or in the biotransformation of phenolic compounds by plant cell cultures, for example, of protocatechuic aldehyde to vanillin 28 [72], availability of SAM 1 is rate-limiting. 

Witrzens, B., Scowcroft, W.R., Downes, R.W., and Larkin, P.J., Tissue culture and plant regeneration from sunflower (Helianthus annuus) and interspecific hybrids (H. tuberosus X H. armuus), Plant Cell Tiss. Organ Cult., 13, 61-76, 1988. 

C. Y.Hu Regeneration ofVirus-Free Plants Through in Vitro Culture. - LA. Withers, Low Temperature Storage of Plant Tissue Cultures. - K Tran-Thanh-Van Control of Morphogenesis or What Shapes a Group of Cells ... 

Regeneration of plants from the imidazolinone-resistant cell cultures was invariably the most difficult part of the procedure. Cells in culture for long periods of time lose their morphogenic capacity. Imidazolinones may also affect morphogenic capacity. In addition, regenerated plants were often highly or completely sterile. 

Somaclonal variation in regenerated plants has been observed and reported since cell culture technology was very young (14). 

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