Studies On Biological Characteristics Of Colletotrichum Spp From Diverse Hosts And The Resistance Mechanism Of Pepper To Anthracnose

In this paper,different isolates of Collectotrichum spp were theresearch objects. The comparative research on biological characteristics and thepathogenicity to pepper , the esterase isozyne of Collectotrichum spp from differenthosts, the biochemical mechanisms of pathogenicity and pepper resistance toCollectotrichum capsici,and screening of effective mix-fungicides were studiedsystematically.The results were as follows:1.Study on the biological characteristics of Collectotrichum.spp According to the classification criteria of Collectotrichum edited by Sutton, 8isolates of Collectotrichum from different hosts were cultured. Their culturalcharacteristics,morphological features, suitable temperature and diverse nutrimentswere studied and analyzed. The results were consistent with Sutton in culturalcharacteristics and morphological features. Up to now, many researches on biological characteristics of Collectotrichum.spphad been reported, but the comparative research on them was not reported. Thisexperiment about biological characteristics of Collectotrichum.spp was conductedsystematically. Their optimum temperature was 25℃³0℃,the temperature range forthe growth and development was 10-35℃. The colony diameters of diverse isolates atdifferent illumination conditions were not significantly different,the results showedthat the growth of diverse anthracnose pathogens were not strict with light conditions. The isolates could utilized many carbohydrates ,but the utilization effects ofdiverse carbon sources were different. The best carbon sources were sucrose , glucoseand maltose, the worst carbon source was lactose. The gradation of 8 isolates frombigness to smallness in colony diameter was GL, YM ,BL, Z, LJ, PG, PP and XBC atthe same level of carbon sources. The utilization effects of diverse nitrogen sources was significantly different. 8isolates could utilize Arginine, KNO₃ and NaNO₃, But H₂NCONH₂,NH₄NO₃ and(NH₄)₂SO₄ suppressed the mycelia growth.While the suppression of (NH₄)₂SO₄ wasthe most strong. The gradation of 8 isolates from bigness to smallness in colonydiameter was BL,GL,LJ,Z,YM,PG,PP and XBC at the same level of nitrogen sources.2.Electrophoretic Analysis of Esterase Isozyne of Collectotrichum spp. Polyacrylamicide gel electrophoretic analysis of isozymes of 9 isolates ofColletotrichum spp from different hosts include apple, watermelon, corn,pepper,grape and other plants was studied. Fuzzy cluster of date from isozymesequivalence matrix grouped the 9 isolates into five groups. PP, BL, PT, PG and LJwere composed into one group; XG, YM,GL and XBC were singly composed into onegroup. Therefore, if the conditions are controlled strictly, the EST Isozyne spectra ofCollectotrichum can possibly become one of the classification and identification ofCollectotrichum.3. The mechanism of pathogenicity of Collectotrichum fungi The pathogenicity of Collectotrichum spp. from diverse hosts to pepper wasstudied. The result showed Collectotrichum spp from methon,loquat, grape,mongliansnakeground had no pathogenicity to pepper,but the rest(XBC,Z,BL,YM,LJ) hadsome difference pathogenicity to pepper. The pathogenicity order from strength toweakness was XBC, BL, LJ, Z, YM. Activities of the cell wall-degrading enzymes(CWDEs) produced by 5 differentCollectotrichum species in mature green pepper fruits were studied. activities ofCx,PMG and PMTE rose after inoculation then dropped gradually with increase ofinfection and the disease expansion,while that of CK had not changed. There was apositive correlation between the activity peak value and pathogenicity. The resultsprimarily demonstrated that Cx,PMG and PMTE played roles during the infection.4.The resistance identification of pepper cultivars to anthracnose The seventeen main pepper cultivars from anhui province were inoculated withCollectotrichum capsici by pricking mature green fruits and red fruits. Among 17pepper cultivals, 6 cultivals were found to be resistant,3 cultivals susceptible and therest 8 cultivals middle-resistant.5. The physiological an...