Apple host defence reactions against decay.
Wild, B. L.; Wilson, C. L.;
Proceedings of the Australasian postharvest horticulture conference 'Science and technology for the fresh food revolution', Melbourne, Australia, 18-22 September, 1995. Year: 1996 Pages: 393-398 Ref: 15 ref.
1996
บทคัดย่อ
A host defence reaction was detected in apples which reduced decay development in fruit that had been challenged by the apple blue mould pathogen Penicillium expansum. The reaction was negated by the application of the protein synthesis inhibitor cycloheximide, which when applied to inoculated fruit resulted in >700% increase in decay. The defence response was temp. dependant and was optimised by holding damaged fruit at 22 deg C for 72 h before inoculation. Decay development under these conditions was reduced from 96% to 37%. Inoculation of apples with the citrus green mould pathogen, P. digitatum, does not normally result in decay. However, when the defence reaction was prevented by the application of cycloheximide, mould development occurred. Isolation of the organism at the lesion margin showed P. digitatum to be responsible for the rot. Comparative measurements of lesion development in apples inoculated with P. expansum and P. digitatum showed that once the citrus green mould became establi
shed in the apple, it progressed at c. twice the rate of the apple blue mould. It was also found that if mould resulting from P. digitatum infection progressed through an apple and came in contact with a previously damaged section, it progressed around that damaged site, leaving a halo of uninfected tissue of up to 1 cm in diameter. It is proposed that this area is where the host defence reaction is occurring and it has been visualised by P. digitatum development. The compounds formed within this halo area are being examined to see if a natural 'fungicide' can be isolated that will prevent citrus green mould development. Further studies also showed that synergism existed between these 2 organisms in the infection process. Apple blue mould decay increased from 30% to 84% when P. digitatum spores were present. This emphasised the need for sanitizing field bins that may be used by both the citrus and pome fruit industries.