Fine Structure of Phytophthora Parasitica Zoospores

SUMMARY

The fine structure of the zoospores of phytophthora parasitica var. nicotiana has been studied. The zoospores have two kinetosomes, one for each flagellum. No vestigial kinetosomes were observed. Each kinetosome has one short and one long rootlet. The long rootlet, composed of 8 microtubules, transverses one-half of the zoospore in the longitudinal direction forming a “backbone.” From it microtubules emerge on both sides, at a 90° angle to the rootlet's long axis, in a rib-like fashion. An interconnecting fiber lies between the two kinetosomes. Other microtubules originate near the proximal end of the kinetosomes and radiate out into the cytoplasm. Details of other cell organelles and substructure of the mastigonemes are discussed.