PROTEIN-CONTAINING CELLS IN THE NECTARY PHLOEM OF PASSIFLORA WARMINGII

Passiflora warmingii petiolar nectaries are characterized by the presence of large protein-containing phloem parenchyma cells which occupy the bulk of the nectary. Immature, mature, and senescent nectaries, as well as stem tips and petioles from unexpanded and mature leaves, were studied to learn the origin and fate of the protein and to determine if similar protein-containing cells occur in main-path phloem. The protein is present as membrane-limited fibrils in the phloem parenchyma of immature nectaries and in young main-path phloem. In the nectary, it persists until leaf senescence but becomes highly dispersed and barely detectable in mature main-path phloem parenchyma. Although superficially resembling P-protein it is always surrounded by a membrane, has smaller dimensions than is reported for P-protein, appears to be derived from RER, and is found in association with typical P-protein in the same cell. Possible functions for this material are suggested.