| According to the Sutton s classification system, the genus of Colletotrichum is consisted of 19 species and 3 populations of species. The orchid often are infected by pathogenic fungi of Colletotrichum. Especially the anthracnose is very serious in the plants of Cymbidium sinense. The symptoms of anthracnose firstly appear chlorotic blots in the tips in the leaves of C. sinense. Afterwards the diseases expand to the other sites of leaves. There were few systemic studies on the anthracnose in C. sinense. For this reason, we studied the incidental patterns of the anthracnose in C. sinense in Guangdong district.At the same time, the pathogenic fungus was separated from the leaves of C. sinense and determinated.Its biological characteristics were studied. Being inoculating the spores of Colletotrichum gloeosporioides on the leaves of tissue-cultured seedings of C. sinense, the infecting processes and the relations of the occurrence of diseases and changes in activities of the five protective enzymes, such as phenylalanine ammonialyase (PAL), peroxidase(POD), superoxide dismutase(SOD), chitinase and -1, 3-glucanase in leaves of C. sinense were studied. Through spreaded salicylic acid(SA), methyl jasmonate(MeJA) and two kinds of antibiotics, such as kasugamycin and wuyinycin, in the leaves of C. sinense,ve hoped to understand the disease resistance of C. sinense to anthracnose and the changes of activities of POD. Moreover, the effects of the inhibitions of the antimicrobial peptides that were expressed by antimicrobial peptides genes in E. coli or Pichia pastoris were studied on C. gloeosporioides. Finally, we preliminarily researched the agrobacterium-mediated antimicrobial peptides genes transfer. The major results are as follows: 1. The continuous rainfall and poor managements were two main reasons of the serious occurrence of anthracnose in Guangdong.The rates ofdiseases and index of diseases fast rose during March to May and March to October, respectively. Many diseased leaves of C. sinense and hydrops on ground around pots cause a fast propagations of spores of C. gloeosporioides. On the other hand, many varieties of C. sinense belong to the susceptibilities to the pathogens of C. gloeosporioides.2. Identified by Dr. Zhou Erxun,the pathogens causing anthracnose in C. sinense were C. gloeosporioides. The ranges of temperature for the mycelial growths of C. gloeosporioides were 12~37, optimum being 25. Among the range of pH2. 0~14. 0, the mycelia of C. gloeosporioides might grow. It was showed that the culture mediax carbon resources and light conditions effected on the spores germination of C. gloeosporioides during the experiment.3. The results showed that the activities of PAL increased significantly after 36 h after inoculation and reached the highest activities at 84 h. POD activities in leaves appeared two peaks at 12 h and 60 h, respectively. The first peak surpassed the second peak. SOD activities rose quickly after inoculation, and reached the highest level at 12 h,then fell. The activities of chitinase and -\, 3-glucanase significantly increased after inoculation. The increases in the activities of PAL, P0D, SOD, chitinase and -\, 3-glucanase showed that these five enzymes play an important role on resisting the infection of C. gloeosporioide.4. The resistance of the leaves of C. sinense to the infection of C. gloeosporioide significantly increased after spreading two inductors of SA or MeJA. Comparing to the controls, the time of appearing symptoms of anthracnose were delayed, and the numbers of lesions were few, and lesions slowly expand in the leaves of C. sinense. The index of diseases was lower than that of the controls. Moreover, the two appeared peaks of activities of POD were higher than that of the controls after spreading SA, but only one peak after treatments was higher than that of controls at 60h inMeJA. The results showed inducting mechanisms of two inductors to thediseases resistance of C. sinensemaybe were different. The kasugamycin andwuyinycin might decrease the rates of diseases and...
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