Genetic Diversity Of Colletotrichum Spp. Strains Causing Anthracnose Of Capsicum Annuum L. Plants In Hunan

Pepper anthracnose is one of the important disease in pepper production, its restricted pepper production.A total of 73 isolates of Colletotrichum were isolated from pepper fruit anthracnose samples in Changsha,Changde,Huaihua,Yueyang,et al.,Hunan.Combined with the strain morphological features and analysis of rDNA ITS sequence. The result showed that the cause of hunan pepper anthracnose on pathogenic is Colletotrichum gloeosporioides?C. acutatum?C. truncatum?C. brevisporum by Koch's postulation.To analyse the population gentic diversity of the dominant species of anthracnose fungi of chili in Hunan,China, paitial sequence of five genes including actin(ACT),beta-tubulin-2-gene(TUB2),calmoudulin(CAL),glutamine-synthetase(GS)and glyceraldehyde-3-phosphate dehydrogenase(GDPH) were amplified using primers ACT512F/ACT783R,Bt2a/Bt2b,CL1/CL2,GSF1/GSR1,GDF1/GDR1. Phylogenetic trees were constructed by method of neighbor-joining(MEGA 5.0). The result revealed that the genetic differentiation of information of interspecific and intraspecific from different Colletotrichum spp. Clustering analysis showed that the genetic differentiation has associated with geographic structure and the host plant of different Colletotrichum spp in Hunan. Simultaneously, its genetic differentiation also affects biological character such as the morphological characteristics, pathogenic strains and to the chemical fungicide biological properties of itself.Sensitivities of four different Colletotrichum spp. strains to pyraoxystrobin were determined through bioassay of growth rate of mycelium, and then target gene of pyraoxystrobin, cytochrome b(Cytb) of different Colletotrichum species was cloned and analyzed in the study. The result showed that the EC50 range of C. brevisporum YYGXZ07, C. truncatum CZHP03, C. acutatum HHBY48 and C. gloeosporioides CSLL11 to pyraoxystrobin is 0.098 ?g/ml.3.363 ?g/ml,10.156 ?g/ml and 31.982 ?g/mL, respectively. Therefore, the growth rate of mycelium on target is ranked as C. truncatum CZHP03< C. brevisporum YYGXZ07< C. acutatum HHBY48< C. gloeosporioides CSLL11. Simultaneously, the amino acid sequences similarity of Cytb of C. acutatum HHBY48 with C. truncatum CZHP03, C. brevisporum YYGXZ07 and C. gloeosporioides CSLL11 is 82.98%% 88.30% and 87.77% respectively. From the alignment of the amino acids sequence of four Colletotrichum species, we preliminary inferred that the sensitivity differentiation of them in this study maybe was caused by the differences of six amino acids in the Cytb sequences.