Материал из Антэкология /// Anthecology
Pollen-stigma Interaction in the Seagrass Posidonia australis
Submarine pollination of the seagrass Posidonia australis has been studied under controlled conditions. Once released from the anther, the filiform pollen produces precocious pollen tubes when adjacent to the female flower, prior to contacting the stigma. Once in contact with the stigma a bond is formed between the pollen grain and stigma surface coatings. At the site of pollen tube emergence, the pollen grain wall is eroded and the tube wall initiated. The pollen tube penetrates the stigma surface between the receptive cells and a collar of stigma wall material surrounds the tube at this point. Deposition of callose is induced in the stigma cells and stylar transmitting tissue cells adjacent to the pollen tube. A callose plug blocks the tube where it enters the stigma. These features are compared with previous observations made on other hydrophilous angjosperms. The classification of the seagrass stigma is reconsidered and a new form of pollen-stigma interaction proposed.