Nitric oxide production in Olea europaea L. pollen during in vitro germination

The presence of high levels of NO has been described in several pollen grains, where their presence has been shown to regulate pollen tube growth and orientation. Here we have assessed the production of NO during in vitro germination in the olive pollen by using exogenous NO donors like sodium nitroprusside and S-nitrosoglutathione. Both chemical induced a remarkable inhibition of pollen germination and tube growth, which were partially reverted by the addition of the specific NO-scavenger carboxy-PTIO (cPTIO). The presence and localization of NO was determined either by using a fluorimetric assay and by confocal microscopy using the fluorescent probe diaminoflurescein-2 diacetate (DAF-2DA). As olive pollen is also a highly allergenic source, the putative role of NO in eliciting the hypersensitive response in humans is discussed.