Expression and localization of calreticulin in tobacco anthers and pollen tubes.

The developmental expression pattern and localization of calreticulin were studied in Nicotiana tabacum L. anthers, pollen and pollen tubes. High transcript and protein levels were detected throughout anther development.

KINKY POLLEN encodes a SABRE-like protein required for tip growth in Arabidopsis and conserved among eukaryotes.

In higher plants, pollen tubes and root hairs share an ancient growth process named tip growth. We have isolated three allelic Arabidopsis mutant lines showing kinky-shaped pollen tubes and, when homozygous, showing shorter and thicker root hairs. The ultrastructure of pollen tubes in these kinky pollen (kip) mutants is similar to that of the wild type; however, time-lapse studies suggest that aberrant pollen tube shape is caused by periodic growth arrests alternated with phases of tube axis reorientation.

Characterization and localization of the transmitting tissue-specific PELPIII proteins of Nicotiana tabacum.

The class III pistil-specific PELP proteins (PELPIII) of Nicotiana tabacum includes at least two members of highly soluble glycoproteins containing glucan modules that are characteristic for arabinogalactan proteins (AGPs). PELPIII accumulates in the style transmitting tissue (TT) during pistil development and, at flower anthesis, is present in the intercellular matrix (IM) of non-pollinated pistils. After pollination, PELPIII appears to be directly and completely translocated from the IM into the pollen tube callose walls, no significant accumulation was observed in the primary wall in the tip.

Brefeldin A effects on tobacco pollen tubes.

Pollen germination and pollen tube growth were clearly affected by the drug brefeldin A: both processes could be stopped completely. Notable thickening of the cell wall was not observed in non-growing pollen tubes, and plasma streaming remained vigorous in the presence of brefeldin A. Over time, the tip region became filled with a dense cytoplasm that lacked large organelles.

Exocytosis in non-plasmolyzed and plasmolyzed tobacco pollen tubes : A freeze-fracture study.

Exocytosis occurring during deposition of secondary wall material was studied by freeze-fracturing ultrarapidly frozen non-plasmolyzed and plasmolyzed tobacco pollen tubes. The secondary wall of tobacco pollen tubes shows a random orientation of microfibrils. This was observed directly on fractures through the tube wall and indirectly as imprints of microfibrils on fracture faces of the plasma membrane of non-plasmolyzed tubes.