Occurrence of a parasexual cycle following the transfer of isolated nuclei into protoplasts of Phytophthora parasitica

1998 ◽  
Vol 34 (2) ◽  
pp. 120-123 ◽  
Author(s):  
Yu-Huan Gu ◽  
W.-H. Ko
Keyword(s):  
Phytophthora Parasitica ◽  
Parasexual Cycle ◽  
Isolated Nuclei

Segregation following interspecific transfer of isolated nuclei between Phytophthora parasitica and P. capsici

2000 ◽  
Vol 46 (5) ◽  
pp. 410-416 ◽  
Author(s):  
Y H Gu ◽  
W H Ko
Keyword(s):  
Nuclear Transfer ◽  
Phytophthora Capsici ◽  
Selective Medium ◽  
Crossing Over ◽  
Phytophthora Parasitica ◽  
Parasexual Cycle ◽  
Different Types ◽  
Average Success Rate ◽  
Fusion Products ◽  
Interspecific Transfer

Nuclei isolated from metalaxyl-resistant (MR) protoplasts of Phytophthora parasitica were transferred into chloroneb-resistant (CnR) protoplasts of Phytophthora capsici and vice versa, with an average success rate of 2.6 × 10-4 (protoplasts with donor nuclei/regenerated protoplasts), using a selective medium containing only the fungicide tolerated by the nuclear donor. No colonies appeared when self-fusion products of donor nuclei or recipient protoplasts were exposed to the selective medium. Colonies produced by the nuclear transfer formed sectors commonly, and differed from the parental types in appearance. All the zoospores produced by the nuclear hybrids were of normal size, and one-fifth of them contained both MR and CnR genes. Since zoospores are mostly uninucleate, these results indicated the occurrence of chromosome re-assortment or mitotic crossing-over following the production of transitory tetraploids, followed by diploidization during zoosporogenesis, thus suggesting the completion of events leading to a parasexual cycle. Hyphal fragment cultures from a nuclear hybrid tested showed considerable variation in growth rate, mycelial morphology, and level of resistance to metalaxyl, indicating uneven distribution and continuous segregation of different types of nuclei in mycelia during vegetative growth.Key words: interspecific nuclear transfer, parasexual cycle, karyogamy, Phytophthora parasitica,Phytophthora capsici.

Creation of hybrid vigor through nuclear transplantation in Phytophthora

2001 ◽  
Vol 47 (7) ◽  
pp. 662-666 ◽  
Author(s):  
Yu-Huan Gu ◽  
Wen-Hsiung Ko
Keyword(s):  
Protoplast Fusion ◽  
Fungicide Resistance ◽  
Phytophthora Capsici ◽  
Hybrid Vigor ◽  
Nuclear Transplantation ◽  
Phytophthora Parasitica ◽  
Isolated Nuclei ◽  
Donor Cells ◽  
Potential Applications ◽  
Fusion Products

When isolated nuclei of a diploid oomycete, Phytophthora parasitica, were fused with protoplasts of another strain of the same species, the regenerated nuclear hybrids grew faster than the parental isolates. Such a phenomenon did not occur in hybrids regenerated from mitochondrion–protoplast or protoplast–protoplast fusion products between these two strains. These results indicate that hybrid vigor is the result of the interaction between two different kinds of nuclei, but not between mitochondria, and they suggest that the presence of mitochondria from nuclear donor cells represses the expression of increased vigor. The nuclear hybrids also expressed increased fungicide resistance and propagule production. Increased vigor in growth was also observed in the interspecific nuclear hybrids when isolated nuclei of P. parasitica were transferred into protoplasts of Phytophthora capsici, and vice versa. This phenomenon may have potential applications, such as the creation of superior fungal strains and plant cultivars with improved commercial traits for usage in industry and agriculture.Key words: hybrid vigor, nuclear transplantation, Phytophthora parasitica, Phytophthora capsici.

Insulin stimulates accumulation and efflux of macromolecules in isolated nuclei from H35 hepatoma cells

Diabetes ◽  
1992 ◽  
Vol 41 (2) ◽  
pp. 194-201 ◽  
Author(s):  
A. P. Soler ◽  
R. M. Smith ◽  
L. Jarett
Keyword(s):  
Hepatoma Cells ◽  
Isolated Nuclei
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