Phaseolus vulgaris presence

Enzyme induction is an indirect effect of metal toxicity. In consequence, it only appears after in-vivo metal application. Increase in capacity in the presence of toxic concentrations of metals implies that the enzyme involved is insensitive to or well masked from direct metal action. In Silene cucubalus POD and to a lesser extent ICDH were shown to be very tolerant to zinc, copper and cadmium applied in-vitro (Mathys, 1975). MDH extracted from roots of both copper tolerant and non-tolerant clones of Agrostis stolonifera was found to be insensitive in-vitro to copper concentrations up to 180 im. However, in the literature, conflicting results are reported about the effects of in-vitro and in-vivo application of metals on enzymes. In Phaseolus vulgaris, GDH was inhibited by cadmium in-vitro, while an induction was found after in-vivo application of a toxic dose of the same metal (Weigel and Jager, 1980b). 

The enzyme converting Z to DHZ, zeatin reductase, was characterised in Phaseolus vulgaris embryos [26]. The reduction proceeds only in the presence of NADPH and the enzyme is verj specific, with the highest affinity for Z (cZ, ZR, iPA, iPAR are not substrates, see also part 3.1.1. of this article). Taking into account that bases of isoprenoid cytokinins may represent the physiologically active forms of cytokinins [6], the conversion of Z to DHZ by zeatin reductase may prevent the loss of cytokinin activity caused by degradation of Z (but not that of DHZ, cf. part 3.1.5. of this article) by cytokinin oxidase. 

The existence of the enzyme catalysing the conversion between cis- and frany-isomers of zeatin is the prerequisite for possible involvement of tRNA as a source of free cytokinins (c/. part 2.1.3. in this chapter). Indeed, the c/y-rra y-isomerase was isolated and partially purified from the endosperm of immature Phaseolus vulgaris seeds. The reaction may proceed in the presence of FAD or FMN cofactors and light in both directions, but the conversion of the cis- to the frany-isomer is preferred. The enzyme seems to be a glycoprotein and is specific for both free bases (Z, cis-Z) and their ribosides [83,84],... 

Sarret G, Vangronsveld J, Manceau A, Musso M, D Haen J, Menthonnex J-J, Hazemann J-L (2001) Accumulation forms of Zn and Pb in Phaseolus vulgaris in the presence and absence of EDTA. Environ Sci Technol 35 2854-2859... 

In the presence of Mo deficiency, low nitrate reductase activity results in high accumulations of NO," in plants, with many physiological implications. Disorders such as scald disease of beans (Phaseolus vulgaris) (Wilson, 1949) and leaf burn/scorch of clementine (Citrus sinensis) trees (Triboi, 1978 Cassin et al., 1982) have been related to nitrate accumulation in the presence of a short supply of Mo. Premature sprouting of... 

Cytokinin oxidase has been partially purified from Phaseolus vulgaris callus tissue [3]. The enzyme activity could be induced by external application of cytokinin and the cytokinin active urea derivative, Thidiazuron [3]. Thidiazuron also inhibited the activity of cytokinin oxidase. It was also shown [4] that the in vitro activity of the enzyme is enhanced when assayed in the presence of copper-imidazole complexes. 

Phaseolus vulgaris L. 3 Derived by EMS mutagenesis condition nonnodulation, supemodulation, and nodulation in the presence of NOj". Davis et al. (1988) Park and Buttery (1988)... 

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