Effects of zinc and copper on male gametophytes off lowering plants

Abstract

The Effect of Zinc and Copper on Male Gametophytes of FloweringPlants1) The aim of this study was to investigate the effect of heavy metals in the development of male gametophytes in flowering plants. Several experiments were conducted to find the best germination medium for the maximum percent germination and pollen tube growth of pollen. Temperature was also found to be an important factor influencing pollen tube growth.2) Three plant species were used in this study. They were Kalanchoe fedtschenkoi, Brassica rapa and Hippeastrum. The optimum germination medium for the pollen under study was found to be species-specific. 3) The best in vitro germination medium for the maximum percent germination and pollen tube growth for Kalanctioe fedtsclienl<oi was 10% PEG and 10% sucrose, while for Brassica rapa dwf2 it was 15% PEG and 10% sucrose.4) A 5 C difference of germination temperature was shown to alter pollen tube growth length in two cultivars of Brassica rapa.5) Presence of zinc in the germinating medium led to reductions in both percent pollen germination and pollen tube length growth in Kalanctioe fedtsctienkoi at high concentrations of zinc. In contrast, Bnassica rapa dwf2 showed a greater reduction in percent pollen germination than in pollen tube length. 6) There was a large inhibitory effect of copper on both the percent pollen germination and pollen tube length of Brassica rapa dwf2.7) Cytoplasmic streaming was found to be a useful indicator of the possible toxicity of heavy metals. The movements of granules on the cytoplasm in the pollen tube slowed down when pollen was incubated in germination medium containing heavy metals. Thus this approach provides a sensitive assay for the effects of heavy metals such as zinc and copper upon male gametophytes.8) Brassica rapa dwf2 grown in water culture medium containing heavy metals showed a reduction in in vivo pollen tube growth. Thus, metal uptake by plants from the growing medium does result in metal reaching the male gametophyte and can in turn result in reduction of pollen tube germination and growth, thus potentially markedly affecting reproduction. I