Identification Of Stylo Colletotrichum Fungus And The Cytobiology Of Infecting Process To Stylo

Stylo anthracnose is one of the main diseases of stylosanthes. In order to know the disease harmness and carry out the disease control mechanism. This study investiaged the anrhracnose pathogen species of stylo in Hainan island, and studied the infection process of Colletotrichum, carried out the following results:Investigating the rate of anthracnose, years and terran of cultivating, disease cite of plant. The rate of anthracnose order of investigated sites as following:Wenchang> Linshui>Changjiang>Dongfang>Danzhou. Wenchang and Liushui which located in the the east of Hainan island, had higher anthracnose rate than other sites which located in the west of Hainan island. The weather of west island is more moist, higher tempreter and has more rainfull and much btetter for anthracnose happening. The disease necrosis shape was irregular diamond, the symtom unually appeared from the tip of leaves and then spreaded to the petiole.There were58anthracnose separated and identificated from the disease tissue, including55C. gloeosporioides,3C.boninese. It was the first report of C.boninese infecting stylo. The size of C.bonineses pores was11～12μm×5～7μm, more short and narrow than the size of C. gloeosporioides. The fangi colony of C.bonineseis was about0.8cm, slower than that of C. gloeosporioides. The homology of ITS sequence of these two fungus was93.24%. Using the two fangus inoculated stylo leaves at the same time, measure the disease spot size after5d, the disease scale inoculated by C.bonineses was bigger than that inoculated by. C.gloeosporioides. C.bonineses formed a lot of appressorium, penetration pegs at12hours after inoculating, formed a lot of hyphae at48hours after innochutating. However, C. gloeosporioides formed a lot of appressorium, penetration pegs at24hours after inoculating, began to form hyphae at48hours after innochutating, slower than C.bonineses. In conclusion, C.bonineses had faster infecting speed and more powerful pathogenicity than than of C. gloeosporioides.Microscopic observed of the leaves of Reyan2innoculated Colletotrichum revealed the infecting process and the plant symptoms. Spores germinated and a few spores formed appressorium at4h. Most of spores germinated at6h, and a large quantity of geminating spores formed appressorium at12h and began to form penetration pegs. The inoculated spores began to produce hyphae at36h, a lot of hyphae formed and staggered into a mesh on the surface of the leave at48h. The geminating spores began form conidiophores at60h. A lot of new spores began to produce at72h. Parts of inoculated spores have finished disease cycle in72h. In the same time, plants appeared disease symptom gradually:leaves color became yellow, the host cell membrane rupture at24h, brown necrosis appeared at48h, then dead line, sclerotinite, mycelium appeared on the leaves surface at72h. The host cell began to collapse at96h.5) We collected leaves of Reyan2and907at0,12,24,48,72h, determinated Resistance physiological indexes. The results showed:The CAT,POD,SOD and PAL activity of both stylo species went up after inoculated Colletotrichum, and CAT activity peaked at24h, POD and SOD activity reached the maximum at48h, PAL activity went up, Reyan2reached the maximum at72h,907reached the maximum at48h. The POD and PAL activities of907were significant higher than that of Reyan2, and this maybe related to the symptom of plants.