Classification Research On Colletotrichum Species On Kinds Of Fujian Economic Crops

Anthracnose disease is one of the plant major diseases.This disease can infect many kinds of economic crops,especially in tropical and subtropical areas with warm and humid environmental conditions.It can cause severe economic loss and threaten to food security.Colletotrichum is the pathogen.But some Colletotrichum species exist in plants as endophytes.There are many species in Colletotrichum and its classification has been in a state of confusion.Recently,DNA barcode and phylogenetic analyses have provided methods for accurate identification and classification of Colletotrichum species.In this study,systematic study for Colletrichum from economic crops in Fujian province was carried out.55 Colletotrichum strains were obtained from leaves,stems,and fruits on 28 economic crops,including tea,citrus,litchi,pepper,mango and others in 10 areas.The identification of these strains was confirmed by morphological observation(pure culture character and spore morphology)and multi-loci(ITS,TUB22,GAPDH,ACT,CAL,SOD2,CHS-1)phylogenetic analyses.Moreover,the main Colletotrichum species,their diversity and relationships were investigated.9 Colletotrichum species were identified from 55 obtainted strains.They belong to 5 Colletotrichum species complex,i.e.,C.gloeosporioides,C musae,C.fructicola and C.siamense from C.gloeosporioides complex,C karstii from C.boninense complex,C.gigasporum from C gigasporum complex,C.fioriniae and C.scovillei from C acutatum complex,C.eleusines from C.graminicola complex.Morphological characters for the 9 Colletotrichum species were described,and compared with previous reports.C.karstii isolated from Fatsia japonica was confirmed as new record on the host.On the other hand,C.siamense was also new record for Cucumis sativus and Citrus limon(L.)Burm.f.C.fructicola was suspected new record for Citrus maxima(Burm.)Merr.In addition,7-gene sequences of the 55 strains were used for phylogenetic analysis.The results showed that ITS gene is unable to distinguish species of the five Colletotrichum species complex,similar to GAPDH and ACT genes.For the C.gloeosporioides species complex,only phylogenetic tree constructed by CAL sequences has higher bootstrap values and posterior probabilities to distinguish this species complex.For the C.acutatum species complex,only phylogenetic tree constructed by CHS-1 sequences has higher bootstrap values and posterior probabilities to distinguish this species complex.For C.boninense species complex,the best genes are TUB2 and ACT,which is different from other two species complex.Therefore,different candidate genes should be used for analyzing different Colletotrichum species complex.Colletotrichum species diversity in Fujian was also discussed from their hosts and tissues used for isolation.The results showed that the major species are C.siamense and C.fructicola from C.gloeosporioides complex,accounting for 30.9%(17 strains)and 21.8%(12 strains)from the obtained 55 strains,respectively.C.siamense was isolated from 16 plant species,belonging to 12 families,including both monocotyledon and dicotyledon,while C.fructicola were isolated from 10 plant species.Most of the strains were isolated from host leaves,which showed anthracnose is an important leave disease.The results of this study can provide a theoretical basis for further study of the biological characteristics of Colletotrichum,as well as the prevention and treatment of anthracnose in Fujian.