Effects of Ca2+ and Mg2+ on Botrytis cinerea and Penicillium expansum in vitro and on the biocontrol activity of Candida oleophila.
Wisniewski, M.; Droby, S.; Chalutz, E.; Eilam, Y.;
Plant Pathology Year: 1995 Vol: 44 Issue: 6 Pages: 1016-1024 Ref: 36 ref.
1995
บทคัดย่อ
ABSTRACT :
Calcium salts have been reported to play an important role in the inhibition of postharvest decay of apples and in enhancing the efficacy of postharvest biocontrol agents. The effects of calcium and magnesium salts on the germination and metabolism of the postharvest pathogens B. cinerea and P. expansum were examined and compared, and the effects of these salts on the biocontrol activity of 2 isolates (182 and 247) on the yeast, Candida oleophila, was determined. Increasing concn of CaCl2 (25-175 mM) resulted in decreased spore germination and germ-tube growth of both pathogens. The greatest effect was observed in the case of B. cinerea. The inhibitory effect could be overcome by the addition of glucose to the germination medium. MgCl2 (25-175 mm) had no effect on the germination or germ-tube growth of either pathogen, indicating that calcium cation rather than the chloride anion was responsible for the inhibition. The pectinolytic activity of crude enzyme obtained from the culture medium of bot
h pathogens was also inhibited by 25-175 mM CaCl2, with the greatest effect on the crude enzyme from P. expansum. The biocontrol activity of isolate 182 was enhanced by the addition of 90 or 180 mM CaCl2, whereas there was no effect on the biocontrol activity of isolate 247. This was apparently due to the inability of isolate 247 to proliferate in apple wounds. It is postulated that the enhanced biocontrol activity of isolate 182 of the yeast C. oleophila in the presence of Ca2+ ions is directly due to the inhibitory effects of calcium ions on pathogen spore germination and metabolism, and indirectly due to the ability of isolate 182 to maintain normal metabolism in the presence of 'toxic' levels of calcium.