Few Layer Graphene and graphene oxide affect sexual reproduction of a seed plant.
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GO affects pollen tube growth by lowering extracellular pH and Ca2+ bioavailability.
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Both FLG and GO alter the tip-focused ROS distribution along the pollen tube.
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Low pH and Ca2+ imbalance may interfere with stigma-pollen interactions.
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Reduced GO affects neither pollen germination nor pollen tube elongation.
Abstract
Graphene related materials (GRMs) are currently being used in products and devices of everyday life and this strongly increases the possibility of their ultimate release into the environment as waste items. GRMs have several effects on plants, and graphene oxide (GO) in particular, can affect pollen germination and tube growth due to its acidic properties. Despite the socio-economic importance of sexual reproduction in seed plants, the effect of GRMs on this process is still largely unknown. Here, Corylus avellana L. (common Hazel) pollen was germinated in-vitro with and without 1−100 μg mL−1 few-layer graphene (FLG), GO and reduced GO (rGO) to identify GRMs effects alternative to the acidification damage caused by GO. At 100 μg mL−1 both FLG and GO decreased pollen germination, however only GO negatively affected pollen tube growth. Furthermore, GO adsorbed about 10 % of the initial Ca2+ from germination media accounting for a further decrease in germination of 13 % at the pH created by GO. In addition, both FLG and GO altered the normal tip-focused reactive oxygen species (ROS) distribution along the pollen tube. The results provided here help to understand GRMs effect on the sexual reproduction of seed plants and to address future in-vivo studies.