Ri T-DNA-transformed carrot roots

Phenolic compounds in plants play a role in disease resistance (Morandi, 1996). Mycorrhizal plants of maize accumulated more phenolic compounds p-hydrocinnamic acid and ferulic acid in roots than non-mycorrhizal plants (Huang, 2003). Mycorrhizal Ri T-DNA transformed carrot roots accumulated more phenolic compounds when challenged by Fusarium oxysporum (Benhamou et al., 1994). All cultivars of pea colonized with G. mosseae accumulated more phenolic acids, and total phenolic accumulation were closely correlated to disease intensity (Singh et al., 2004). 

Benhamou N., Fortin J.A., Hamel C., St.-Amaud M, Shatilla A. Resistance responses of mycorrhizal Ri T-DNA transformed carrot roots to infection by Fusarium oxysporum f. sp. chrysanthemi. Phytopathology... 

Compartment devices have also been used with root-organ cultures to study the contribution of AM hyphae to Cs and U uptake. In one instance, AM fungi and Agrobacterium rhizogenes (Ri-T-DNA)-transformed carrot roots (Declerck et al, 1998) were cultivated in compartmentalized Petri plates, in liquid or gelified media, where hyphal and root uptake were compared. Such devices are very useful to study the potential uptake of elements by AM hyphae in the absence of any other microorganisms, and are very convenient to use. However, it has not been shown whether transformed roots have comparable absorption capacity when compared to normal roots and to whole plants. 

Fig. 3. Uranium activity concentrations in hyphae and spores developing in the hyphal compartment (top) and in the mycorrhizal roots (bottom) developing in the central root compartment for Ri T-DNA transformed carrot (Daucus carota L.) roots grown in association with G. intraradices in a two-compartment system with 0.1 p,M added to the hyphal compartment set at pH 4, 5.5 and 8. Data used with permission from Rufyikiri et al. (2002).

Diop, T.A., Becard, G., Piche, Y., 1992. Long-term in vitro culture of an endomycorrhizal fungus, Gigaspora margarita, on Ri T-DNA transformed roots of carrot. Symbiosis 12, 249-259. 

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