Agrostis metal tolerance

There is another important determinant of which species do and can evolve tolerance and those that do not. Symeonidis et al. (1985) screened cultivars of Agrostis capillaris for metal tolerances and demonstrated differential sensitivities to metals, suggesting the existence of non-specific low level tolerances to metals other than those present at toxic levels in soils from which they were derived. Other screening experiments have implicated such constitutive properties in the ability to evolve... 

Turner RG (1970) The subceUular distribution of zinc and copper within the roots of the metal tolerant clones of Agrostis tenuis Sibth. New Phytol 69 725 — 731. 

It has been known for some time that tolerance towards high levels of both essential and toxic metals in a local soil environment is exhibited by species and clones of plants that colonize such sites. Tolerance is generally achieved by a combination of exclusion and poor uptake and translocation. Some species can accumulate large quantities of metals in their leaves and shoots at potentially toxic levels, but without any harmful effects. These metal-tolerant species have been used in attempts to reclaim and recolonize metal-contaminated wastelands. More recently such species have attracted the attention of inorganic chemists. There is abundant evidence that the high metal levels are associated with carboxylic acids, particularly with nickel-tolerant species such as Allysum bertolonii. The main carboxylic acids implicated are citric, mahc and malonic acids (see refs. 30 and 31 and literature cited therein). Complexation of zinc by malic and oxalic acids has been reported in the zinc-tolerant Agrostis tenuis and oxalic acid complexation of chromium in the chromium-accumulator species Leptospermum scoparium ... 

Some plant and microbial species have developed unique and sometimes high tolerance for metals. Plant species of Agrostis, Minuartia, and Silene are known for their tolerance to heavy metals (Sieghardt, 1990 Verkleij et al., 1991). In a study... 

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). 

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