Elicitors abiotic

Callus tissue was mixed, divided into 12 equal portions, and placed in incubation vials containing Gamborg s modified medium (19-20) and indicated concentrations of abiotic elicitor. Vials were Incubated for 24 hours. Callus was separated from medium, extracted with MEK, and medicarpin concentration determined by HPLC analysis of extracts (19). 

Abiotic elicitors, examples, 48 Abscisic acid, plant-growth hormone inhibitor, I6f Active defense, definition, 37 Alfalfa, phytoalexins, 56 Allelochemicals... 

The use of elicitors can significantly enhance the production of metabolites. The elicitors are divided mainly in two groups. The biotic elicitors which are compounds of biological origin (e.g. fungal spores, fungal cell wall fractions, cellulase, chitosane) and the abiotic elicitors which include metal ions, high salt concentrations, UV radiations, sonication. Treatment of Hyoscyamus muticus hairy roots with 50-500 jig/ml of chitosane resulted in a 5-fold increase in the accumulation of hyoscyamine [84]. Similar results were obtained by Halperin and Flores [85] who obtained, with hairy roots of the same species, hyoscyamine up to 6-fold when elicited with mannitol. 

Elicitors are probably the best-studied exogenous signals in plants. They are connected with microbial infections and induce plant defense responses. Among others, the production of certain secondary metabolites (phytoalexins) is induced by biotic or abiotic elicitors (e.g., see reviews in refs. 326-328). 

The abiotic elicitor vanadyl sulfate increases alkaloid production (ajmali-cine, catharanthine) in C. roseus cell cultures (340,341). The effect is dependent on the age of the cells, the strongest effect being found during the stationary phase. According to Kargi and Potts (341), the treatment results in more excretion of the alkaloids to the medium. 

If the biosynthetic pathway it is known, the addition of precursors may stimulate the product formation. Also, the addition of biotic and abiotic elicitors is a strategy for the enhancement of secondaiy metabolites production. 

Advanced technology of a benchtop bioreactor has facilitated continuous extraction of secondary metabolites, which is designed for Catharanthus roseus L. (G.) and Santalum album in plant cell suspension cultures. C. roseus cells were exposed by biotic elicitors (Aspergillus niger, crude chitin), abiotic elicitors (mannitol, MJ), and induced the alkaloid production (Valluri 2009). 

Various biotic and abiotic elicitors have been used to increase colchicine production. Application of methyl jasmonate as a biotic elicitor in the media showed increase in growth of the root cultures of Gloriosa superba. Higher concentration of methyl jasmonate decreased growth but enhanced intracellular colchicine content of the root cultures. However, such treatments with methyl jasmonate did not release colchicine into the medium [22],... 

Different strategies, using in vitro systems, have been studied extensively with the objective of improving the production of colchicine, like media manipulation establishment of cell culture, organ culture, and root culture of colchicine-producing plants elicitation with biotic and abiotic elicitors etc. Instead of these progresses, production of colchicine at commercial scale is yet not achieved. 

As has been described previously, V. vinifera cell cultures have been used to the production of trans-R [22, 25]. The main advantage of these cultures is that genetic modification of cells is not necessary because grapevine cells produce trans-R constitutively, or in response to stress, so grapevine cell cultures can be directly exploited. Therefore, the use of biotic or abiotic elicitors could be considered one of the most effective strategies to increase the productivity of this compound. 

Biotic and abiotic elicitors are associated to different mechanisms of elicitation and, when used in combination, could enhance metabolite production in plant cell cultures. Indeed, the combined effect of elicitors is a widely used strategy to increase trans-R and stilbene-related production [48]. 

Broeckling CD, Huhman DV, Farag MA, Smith JT, May GD, Mendes P, Dixon RA, Sumner LW (2005) Metabolic profiling of Medicago truncatula cell cultures reveals the effects of biotic and abiotic elicitors on metabolism. J Exp Bot 53 323-326. doi 10.1093/jxb/eri058... 

Zhao JL, Zhou LG, Wu JY (2010) Effects of biotic and abiotic elicitors on cell growth and tanshinone accumulation in Salvia miltiorrhiza cell cultures. Appl Microbiol Biotechnol... 

Salt-soluble protein with enzymatic activity Glycoprotein cell fusion hormone Abiotic elicitor (ribonuclease)... 

The type and structure of elicitors vary greatly. Elicitors can be classified into abiotic elicitors or biotic elicitors on the basis of their nature . The classification of elicitors is presented in Table 6.4. Abiotic elicitors are substances of non-biological origin, predominantly inorganic salts like Cu, Cd, and Ca, as well as physical factors, osmotic stress, synthetic organic compounds, and so on. Biotic elicitors are substances of biological origin. They... 

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