Physiological studies on some isolates of Phytophthora palmivora and P. megakarya
Physiological studies were made of six isolates of Phytophthora from cocoa, three of the A2 mating type of P. palmivora (71, 78, and 29) and three of the A1 mating type of the recently described P. megakarya (9A, 75, and 10B). Many of these studies revealed a clear differentiation between the two species. In all experiments the growth rate of the isolates of P. palmivora was higher than that of P. megakarya. Sporulation was also found to be more efficient in P. palmivora. Sporangial initials appeared in cultures after a 24-h incubation at 25 centigrade grade in P. palmivora isolates and after a 72-h incubation in P. megakarya isolates. The period required for the full development of sporangia in all isolates was 48 h. Of the seven carbon compounds tested, glucose was best utilized by all the isolates. Phytophthora megakarya isolates grew better on lactose while those of P. palmivora grew better on glucose, sucrose, and maltose. Sporulation was not as efficient in isolates of P. megakarya as in those of P. palmivora; no sporulation on starch and sorbose occurred in 9 A and very little in 75. On the six nitrogen compounds, isolates of P. palmivora generally grew better than those of P. megakarya. Glycine was preferred for growth by 9 A and 71, while casein hydrolysate was favoured by 75 and 78. For sporulation, asparagine proved to be the best for P. palmivora and ammonium tartrate for P. megakarya. Glutamic acid was not suitable for sporangial production in the isolates of P. megakarya; on the other hand in the isolates of P. palmivora sporangia developed freely on this compound. Solid media was used to detect the production of the extracellular enzymes. Amylase and urease were detected only in the isolates of P. palmivora, while lipase, DNAase, protease, and phosphatase were detected in all the isolates tested
| Main Authors: | , , , |
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| Format: | biblioteca |
| Published: |
1981
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| Subjects: | THEOBROMA CACAO, PHYTOPHTHORA PALMIVORA, PHYTOPHTHORA MEGAKARYA, ENFERMEDADES FUNGOSAS, AISLAMIENTOS, PODREDUMBRES, TIPOS COMPATIBLES, ESPORULACION, MEDIO DE CULTIVO, TEMPERATURA, ESPORAS, TASA DE CRECIMIENTO, |
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