Etiology Of Apple Glomeralla Leaf Spot Caused By Colletotrichum And Infection Sources Of Apple Bitter Rot

The apple anthracnose is the main diseases of apple,including apple better rot and Glomerella leaf spot(GLS)induced by Colletotrichum spp..The apple anthracnose causing pre–harvest fruit rot,leaves drop and post–harvest fruit rot.This disease brought huge economic losses to orchardmen.Glomerella leaf spot is a new serious disease for apple in China.And there was not systematic research about pathogenic of Glomerella leaf spot.The pathogenic of apple better rot and Glomerella leaf spot include various specises of Colletotrichum.And these Colletotrichum specises were infected a wide range of hosts.These hosts possible locate in or near apple orchard.The Colletotrichum specises from other host causing apple anthracnose were not confirmed.The aim of this study is to clear the pathogenic of Glomerella leaf spot and the effect of Colletotrichum specises from other host to apple bitter rot.In the study isolates isolated from different hosts from Shaanxi,Henan,Shandong province,the pathogenic species of Colletotrichum were identified systematically and their pathogenicity were analyzed.The main results were summarized as follows.1.The pathogenic species of Colletotrichum from GLS in China were studied systematically.A total of 199 samples from GLS were collected from Shaanxi,Henan,Shandong province,and 76 isolates were isolated.The species of Colletotrichum were identified systematically by characterized morphologically and phylogenetic analysis.All iaolates were grouped into three species: C.fructicola,C.aenigma and new species C.galae.C.fructicola and C.aenigma were new pathogens associated with GLS.The C.fructicola was the predominant pathogen associated with GLS,occupying 76.6% of the total strains.The isolates of C.fructicola and C.galae inoculated different cultivar of apple fruit and leave,the pathogenic tests showed that two species of Colletotrichum spp.could infect apple leaves of cultivar Golden Delicious,as well as Gala,Qinguan,Pink Lady,Pacific Rose,Jinshiji and Honeycrisp,In wound inoculation experiments,C.fructicola and C.aenigma were pathogenic to fruit of Gala,Qinguan,Golden Delicious,Pacific Rose,Starkrimson and Fuji.With non–wounded fruit,C.fructicola was pathogenic to Gala and Golden Delicious,and C.aenigma was pathogenic to Gala.The pathogenicity differentiation was presented for the pathogens on leaves and fruits of different apple cultivars.All susceptible cultivars were parentage with Golden Delicious,therefore the parentage cultivars should choose carefully when breeding cultivation for apple.2.The Colletotrichum specises from other host could be the infecting scource of apple bitter rot was cleared.A total of 329 samples of pepper,grape,kiwi anthracnose were collected from around apple orchard in Shaanxi,Shandong province.and 251 isolates were isolated.Combining morphological characteristic and five gene(ITS,ACT,GAPDH,CHS–1 and TUB2)and ApMat gene phylogenetic,all iaolates of Colletotrichum were grouped into 16 species.The pathogen isolates form pepper grouped into 14 species: C.aenigma,C.coccodes,C.fioriniae,C.fructicola,C.gloeosporioides,C.liaoningense,C.liriopes,C.scovillei,C.duyangense,C.truncatum,C.godetiae,C.salicis.The pathogenic tests showed that all 14 species of Colletotrichum isolates were pathogenic to apple fruit with wounded inoculation.C.fructicola,C.gloeosporioides,C.liriopes were pathogenic to apple fruit with non–wounded inoculation.All isolates of Colletotrichum form pepper could be the infecting scource of apple bitter rot.The isolates of Colletotrichum form pepper included 3 new specises(C.yanglingense,C.dingbianense,C.duyangense),two new record specises(C.godetia,C.salicis),and three new pathogens to pepper(C.liriopes,C.godetiae,C.salicis).The pathogen isolates form kiwi grouped into 3 species: C.conoides,C.fructicola,C.gloeosporioides.The pathogenic tests showed that all 3 species of Colletotrichum isolates were pathogenic to apple fruit with wounded inoculation.C.gloeosporioides was pathogenic to apple fruit with non–wounded inoculation.The isolates of Colletotrichum form kiwi could be the infecting scource of apple bitter rot.The isolates of Colletotrichum form kiwi included two new pathogens(C.conoides,C.gloeosporioides.).The pathogen isolates form grape grouped into 1 species: C.viniferum.The pathogenic tests showed that C.viniferum specise was pathogenic to apple fruit with wounded inoculation and nonpathogenic to apple with non–wounded inoculation.The isolates of Colletotrichum form grape could be the infecting scource of apple anthracnose.The pathogenic tests indicated Colletotrichum specises from other host could be infect apple and causing apple anthracnose.The pathogen isolates of Colletotrichum from these hosts could be cross infect with apple.3.The pathogenicity differentiation of C.fructicola was revealed.In the study,we isolated isolates of C.fructicola from apple(Malus domestica),pepper(Capsicum sp.),kiwi(Actinidia chinensis),pear(Pyrus sp.)and so on.Combining morphological characteristic and phylogenetic analysis indicated that all isolates belong to C.fructicola.The pathogenic texts indicated that the pathogenicity of C.fructicola isolates was significant differentiation on identified hosts(Gala apple,pear fruit).All isolates were grouped into two forma specialis: C.fructicola f.sp.mali,C.fructicola f.sp.pyri.According to pathogenic differentiation of C.fructicola f.sp.mali isolates on different apple varieties,these isolates grouped into two pathological type: bitter rot type and GLS type.The pathogenicity differentiation of C.fructicola indicated that the pathogen from pepper,kiwi,pear,papaya,nectarine couldn't caused apple GLS in China.