The sensitivity of pollen from various coniferous and broad–leaved trees to combinations of acidity and trace metals

Abstract

SUMMARYThe effects of acidic and trace element components of polluted rain on pollen germination and tuhe growth iv vitro are described. The sensitivity of pollen to pH in vitro was related to the species' position in canopy and was different for conifers and hroad-Ieaved trees. Most pollen assayed revealed significant inhibition of germination and germ tuhe growth in response to pHs currently observed in rain samples in eastern Canada. Acer saccharum Marsh and Betula alleghaniensis Britt. pollen m vitro showed a high sensitivity to pH in comhination with copper. The pollen of Popiilus tremuloides L. was shown to he highly sensitive to pH, and a synergism hetween pH and copper on pollen function in this species was also demonstrated. This was in contrast to the general antagonistic interaction of pH and copper noted in the other species tested in which copper by itself either did not affect pollen function or was stimulatory. Zinc has little or no effect, whereas lead at the concentrations used significantly inhibited both germination of Pinus strobus L. pollen at pH 5-6-.3-6 and tube growth of hoth P. strobus and Pinus resinosa Ait. The increase in pollen mortality in response to air pollution at the time of pollination raises certain implications for reproduction and breeding. These implications are also discussed in the light of the significant genetic overlap hetween pollen and sporophytes of higher plants.

Response of Pollen Germination and Tube Growth to Cadmium with Special Reference to Low Concentration Exposure

“…Whether overcorrection or overcompensation is involved, hormesis might be associated with organism sensitivity to toxic substances; like response to inhibitory doses, response of organisms to stimulatory doses of toxic substances might also be related to their tolerance to stresses, in view of the stimulation being a disruption to homeostasis as well. There has been evidence that pollen exhibiting hormesis usually has higher LD values when exposed to copper (Cox, 1988). In Mimulus guttatus, clones whose sporophytes are tolerant to copper exhibit pollen hormesis, whereas those that are nontolerant do not display pollen hormesis (Searcy and Mulcahy, 1985).…”

“…Therefore 2-h incubations were used in the present study (Table 1). The incubations were terminated by the addition of 50 L 50% acetic acid to the culture solution (Cox, 1988). Slides were examined under a microscope.…”

“…Pollen germination and pollen tube growth are considered to be among the sensitive botanical indicators of air pollution (Feder, 1968;Wolters and Martens, 1987;Cox, 1988). It has been found, for example, that inhibitory e!ects of sulfur dioxide on pollen germination and tube elongation have occurred at concentrations lower than those at which foliar e!ects have been recorded (Varshney and Varshney, 1980).…”

Parietaria judaica flowering phenology, pollen production, viability and atmospheric circulation, and expansive ability in the urban environment: impacts of environmental factors

“…For instance, it was reported that copper is extremely important for the development of normal pollen (Graham 1975), that wheat pollen is nonviable under copper-deficiency conditions (Graham 1986), and that temporary copper deficiencies significantly reduce wheat pollen viability (Graham 1975). Also, Read et al (1993) found that Cu-(II) salts play an important role in pollen-tube development in a Nicotiana species, and Cox (1988) reported a synergistic effect of pH and Cu on pollen function of Populus tremuloides; the latter author reported that lead significantly inhibits both pollen germination and tube growth of Pinus species, whereas zinc has little or no effect.…”

Evaluating the impact of pollution on plant-Lepidoptera relationships

“…Several degenerative processes in the pollen cells of plants growing on polluted soils have been reported (Cox, 1988a;Micieta and Murin, 1999;Koscinska-Pajak, 2000). Under controlled conditions, pollen mother cells clearly show genotoxic effects of heavy-metal ions, being even more sensitive than the widely used micronucleus tests with meristematic root tip cells (Steinkellner et al, 1998).…”