Different Camellia Species The Mechanism Of Resistance To Anthracnose And Rapd Analysis

The mechanisms of Camellia gloeosporioides resistance for different varieties of Camellia oleifera were studied on the basis of pathology, biochemistry, and molecular biology. The following results are obtained.Among the 8 varieties of Camellia oleifera investigated and tested, 4 varieties, such as Camellia yuhsienensis - huizhoudahong and shuchengdahong, are Camellia gloeosporioides resistant ones, which incidence were less than 10%; two varieties (ShuChengDaQing and HuiZhouXiaoQing) are susceptible to the disease, which incidence were over 50%. The incidences of the disease for other two varieties were between 10% and 50%.The result from the relative swelling of peel demonstrated that the variety with great relative swelling was usually susceptible to the disease, such as ShuChengDaQing, HuiZhouXiaoQing and HuiZhouXiaoQing which relative swelling were all round 70%. The Colletotrichum gloeosponoides-resistant varieties were usually low relative swelling, such as Camellia yuhsienensis and HuiZhouXiaoHong which relative swelling were about 50%. In addition, this experiment showed that the Colletotrichum gloeosporioides-resistant varieties had high water content, such as HuiZhouDaHong which water content reached 76%. It is probably correlated to the chemical composition of peel, and the difference in fruit maturity because of fruit collection in the same time.The effects of peel extracts on spore germination and hypha growth differed significantly among varieties. The extracts from high-resistant variety had a strong restraint of spore germination and hypha growth; but had no or lower resistant of spore germination for QingGuo-type varieties, which spore germination reached over 80%, particularly 100% for HuiZhouDaQing. This indicates that the extracts contained a lot of matter fitting for spore germination. The experiment of inoculation of spore in juice culture medium showed that there existed significant difference between Colletotrichum gloeosporioides-resistant and -susceptible varieties, which was similar to the result from the experiment of spore germination.Of the 6 phenols in peel measured, the contents of catechol and nipa were closely correlated to the disease resistance. The contents of catechol and nipa in disease-resistant varieties were 5-10 times higher than those in disease-susceptible varieties.Within 8 varieties measured, the variety with higher content of havonids was not susceptible to the disease. My result showed that PPO activity in healthy peel for disease-resistant varieties was 4 times as high as that for disease-susceptible ones. There existed great difference in PAL activity among varieties. PAL activity averaged 12096 OD/g for disease-resistant varieties, which was significantly higher than that for disease-susceptible varieties with an average of 8021 OD/g.The result from molecular biological experiment revealed that the DNA concentration of Camellia oleifera was about 918ug/ml fulfilling the requirement of RAPD analysis. Moreover, UPGMA analysis demonstrated that the 17 DNA samples from the whole country could be divided into 5 groups, of which the disease-resistant and disease-susceptible groups were evident. This result suggests that there is similar DNA fragment in genes for the same group.