It is concluded from a review of the literature that plant cell culture itself generates genetic variability (somaclonal variation). Extensive examples are discussed of such variation in culture subclones and in regenerated plants (somaclones). A number of possible mechanisms for the origin of this phenomenon are considered. It is argued that this variation already is proving to be of significance for plant improvement. In particular the phenomenon may be employed to enhance the exchange required in sexual hybrids for the introgression of desirable alien genes into a crop species. It may also be used to generate variants of a commercial cultivar in high frequency without hybridizing to other genotypes.

Somaclonal variation — a novel source of variability from cell cultures for plant improvement

Plant secondary metabolites are unique sources for pharmaceuticals, food additives, flavors, and industrially important biochemicals. Accumulation of such metabolites often occurs in plants subjected to stresses including various elicitors or signal molecules. Secondary metabolites play a major role in the adaptation of plants to the environment and in overcoming stress conditions. Environmental factors viz. temperature, humidity, light intensity, the supply of water, minerals, and CO2 influence the growth of a plant and secondary metabolite production. Drought, high salinity, and freezing temperatures are environmental conditions that cause adverse effects on the growth of plants and the productivity of crops. Plant cell culture technologies have been effective tools for both studying and producing plant secondary metabolites under in vitro conditions and for plant improvement. This brief review summarizes the influence of different abiotic factors include salt, drought, light, heavy metals, frost etc. o...

https://www.tandfonline.com/doi/pdf/10.4161/psb.6.11.17613

Influence of abiotic stress signals on secondary metabolites in plants

In the growth condition(s) of plants, numerous secondary metabolites (SMs) are produced by them to serve variety of cellular functions essential for physiological processes, and recent increasing evidences have implicated stress and defense response signaling in their production. The type and concentration(s) of secondary molecule(s) produced by a plant are determined by the species, genotype, physiology, developmental stage and environmental factors during growth. This suggests the physiological adaptive responses employed by various plant taxonomic groups in coping with the stress and defensive stimuli. The past recent decades had witnessed renewed interest to study abiotic factors that influence secondary metabolism during in vitro and in vivo growth of plants. Application of molecular biology tools and techniques are facilitating understanding the signaling processes and pathways involved in the SMs production at subcellular, cellular, organ and whole plant systems during in vivo and in vitro growth, with application in metabolic engineering of biosynthetic pathways intermediates.

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Stress and defense responses in plant secondary metabolites production

Plant cell and organ cultures have emerged as potential sources of secondary metabolites, which are used as pharmaceuticals, agrochemicals, flavors, fragrances, coloring agents, biopesticides, and food additives. In recent years, various strategies have been developed to assess biomass accumulation and synthesis of secondary compounds in cultures. Biomass accumulation and metabolite biosynthesis are two-stage events, and the parameters that control the growth and multiplication of cultured cells/organs and biomass accumulation are controlled in the first stage. Parameters that assist with the biosynthesis of metabolites are controlled in the second stage. The selection of high-producing cells or organ clones; optimization of medium parameters such as suitable medium, salt, sugar, nitrogen, phosphate, and plant growth regulator levels; and physical factors such as temperature, illumination, light quality, medium pH, agitation, aeration, and environmental gas (e.g., oxygen, carbon dioxide, and ethylene) are controlled in the first stage of the culture process. Elicitation, replenishment of nutrient and precursor feeding, permeabilization, and immobilization strategies assist with the accumulation of metabolites and can be applied in the second stage of the culture process. By following stage-specific strategies, it is possible to produce large amounts of biomass with an increase in the accumulation of secondary compounds.

Production of secondary metabolites from cell and organ cultures: strategies and approaches for biomass improvement and metabolite accumulation

An excellent new medium was developed for the production of shikonin derivatives by suspension cultures of Lithospermum erythrorhizon. We investigated the effects of all the components of White's medium on the production of these derivatives. Nitrate, phosphate, copper, sulfate and sucrose had especially marked effects. With the new, M-9, medium produced from these studies the yield of shikonin derivatives was 1400 mg/l and the yield for dried cells was about 12%, whereas it was 120 mg/l, or about 2% with White's medium.

Production of shikonin derivatives by cell suspension cultures of Lithospermum erythrorhizon : II. A new Medium for the production of shikonin derivatives.

Hajime Mizukami

Papers

Pigment formation in callus cultures of Lithospermum erythrorhizon

Effect of nutritional factors on shikonin derivative formation in Lithospermum callus cultures

Variation in pigment production in Lithospermum erythrorhizon callus cultures

Formation of stereoisomeric mixtures of naphthoquinone derivatives in Echium lycopsis callus cultures

Geographical Variation in the Furanocoumarin and Polyacetylenic Compound Compositions of Wild Glehnia littoralis Plants