Study On Latent Infection Mechanism Of Black Spot Disease Of Korla Fragrant Pear

Korla fragrant pear is the advantage fruit of Xinjiang, is one of the characteristics of the fruit. Because of the latent infection of black spot disease in the growth period, it is cause the fruit quality and commodities in the storage, cause certain economic losses. In this paper, by morphology and molecular biology of appraisal and determine the types of bacteria infection, the bacteria biological characteristics, infection time and infect way. Study on the relationship between the fruit phenolic, enzymes and black spot disease. The purpose is to analyze the cause of the latent infection of black spot disease, to effective prevention and control black spot disease. It is important to improve the quality of the fruit store.The rotten pear as the research object in cold storage, through the traditional morphological observation to determine the germs spores. Combined with the molecular biology research, through to the bacteria and SrDNA D1/D2area the determination of sequence. Matching with the GeneBank nucleic acid database. It is determined that the chain alternate (A. alternata).is the disease of fragrant pear.The purified chain as the material in biological characteristics research. Researched the spore germination and growth in different temperature (5℃-40℃),different pH and different humidity (18%100%).conditions. The results showed that hypha growth the fastest in temperature25℃-28℃, relative humidity above98%, pH for pH7-pH8conditions.Statistics the chain alternate pathogen rate of fragrant pear in growth and flower times. The results show that Alternata through style extended to flowering ovary tissue. The young fruit can latent infection Alternata, the rate was7%. The rate was greatly increased38%in swollen, harvest is44%. Alternata were invaded in flowering and growth time.On the fruit after blooming period each interval after30days; determine the total phenolic content and resistance enzyme activity of the fruit of postharvest inoculation of Alternaria interval of24hours and storage period every30days, analysis the effect of total phenolic content and resistance enzyme activity changes in fruit disease resistance. The results show that: in the different phases of the fruit growth, PPO, POD, PAL, CAT enzyme activity in blooming period to recovery period were gradually decreased, and finally to maintain stability, CHT, GLU enzyme activity was increase after the blooming period, to reach the maximum value in enlargement period, and to achieve a relatively stable state in fruit maturation period. In storage period, with the extension of storage time, because of the fruit characteristics became to weakness, resistance enzymes activity in slow decline. The pear fruit inoculation of the pathogen, after48h the fruit total phenolic content increased gradually, higher than that of stabbing unvaccinated fruit significantly (P<0.05), fruit under the environmental damage or pathogen the content increased, promote cell wall lignification, also induced some resistance substance content increases, inhibiting bacteria extension.