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The ultrastructure of the dimorphic infection cells of Haptoglossa heteromorpha illustrates the developmental plasticity of infection apparatus structures in a nematode parasite

Lookup NU author(s): Dr Sally Glockling, Dr Gordon Beakes


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The nematophagous fungus Haptoglossa heteromorpha Glockling and Beakes is unusual in this genus, as it consistently produces two morphologically distinct infection cells that develop respectively from the large and small aplanospores. The large infection cells are typical 'gun cells' and are uninucleate with over half the cytoplasmic volume occupied by the basal vacuole. However, the small infection cells are considerably modified in their structure. They have an elongate tapered morphology with a bilobed base. Small infection cells are binucleate and contain both apical and basal vacuolar regions. The inverted injection tube is highly modified and originates at a raised padlike region on the mid ventral side of the cell. This protruding pad is associated with a diffuse covering of fibrillar material. The bore region extends deep into the cell and the highly compressed missile chamber is located beneath the hindmost nucleus, near the base of the cell. Finally, there is a more typical tube tail segment, which winds between the nuclei and eventually terminates beneath the anterior vacuole. The differences with gun cells of previously described Haptoglossa species are documented. The functional and biological significance of these two different infection cells is discussed. Only the large gun cells were observed to discharge to form sporidia. It seems unlikely that the highly modified smaller cells can infect in this way. It may be that the two different cell types have evolved to infect different hosts, but no direct confirmation of this could be obtained.

Publication metadata

Author(s): Glockling SL, Beakes GW

Publication type: Article

Publication status: Published

Journal: Canadian Journal of Botany

Year: 2000

Volume: 78

Issue: 8

Pages: 1095-1107

Print publication date: 01/01/2000

ISSN (print): 0008-4026

ISSN (electronic):

Publisher: NRC Research Press


DOI: 10.1139/b00-074


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