Transfer of a Cytoplasmic Factor by Micro-injection in Verticillium

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Abstract
Preparations of protoplasm, nuclei and mitochondria were introduced into living Verticillium [V. albo-atrum and V. dahliae] cells. Most of the hyphae of auxotrophs injected with protoplasm obtained from complementary auxotrophs survived micro-injection (80%). Of these, 21% formed artificial heterokaryons from which both parental genotypes were recovered by conidial analysis. Reciprocal injections of protoplasm were made between auxotrophic strains with darkly-pigmented resting structures (Hyl+) and hyaline strains lacking resting structures (Hyl). Conidial analysis resulted in the recovery of all auxotrophic markers. The majority of phenotypes having darkly-pigmented resting structures were of the Hyl+ type (92-96%) but a few were partially or completely hyaline. Reciprocal injections between Hyl+ or Hyl+ sooty (Sot) strains and Hyl or Hyl Sot+ strains (hyaline strains induced by UV irradiation from Sot auxotrophs) revealed the cytoplasmic inheritance of the Hyl marker in contrast to the nuclear inheritance of the Sot marker. The survival of recipient cells injected with preparations of nuclei was 30-40% on complete medium but conidial analyses indicated that heterokaryons were not produced. The survival of hyphae injected with mitochondrial preparations was 40-45%; these colonies showed considerable morphological instability which was overcome during 2-3 wk incubation. Conidial analyses of Hyl recipients injected with Hyl+ mitochondrial preparations resulted in 13-21% darkly-pigmented variants. One or more factors controlling darkly-pigmented structures were apparently present in the mitochondrial preparations from the Hyl+ donor cytoplasm.

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