Characterization Of The Populations Of Diaporthe Species On Citrus In Jiangxi Province,China

Melanose,one of the most common fungal diseases of citrus worldwide,occurs in many citrus growing regions of China,such as Jiangxi,Zhejiang,Guangxi,Guangdong,Shaanxi,Fujian,Hunan,Chongqing,Shanghai and so on.Diaporthe spp.(anamorph Phomopsis spp.)is the causal agents of this disease.The genus Diaporthe shows high species diversity.Until recently,22 Diaporthe(Phomopsis)species have been reported to be isolated from citrus cultivars worldwide.This study was conducted to identify species of Diaporthe causing melanose diseases on citrus in Jiangxi province of China.Totally,802 single-spore isolates identified as Diaporthe spp.were collected from two citrus varieties(Citrus sinensis(L.)Osbeck and Citrus reticulata cv.nanfengmiju)in 12 orchards of Jiangxi province.Among them,420,309 and 73 isolates were obtained from fresh leaves,fruits and twigs with typical melanose symptoms,respectively.One hundred and forty isolates were randomly selected from 802 isolates by basal of characterization and morphological were difference on PDA agar media.To identify isolates to species level,the molecular identification was performed based on five locus nuclear ribosomal internal transcribed spacer regions(ITS),translation elongation factor 1-α gene(TEF),beta-tubulin gene(TUB),calmodulin gene(CAL)and histone-3 gene(HIS).Totally,27 Diaporthe species were identified from 140 isolates in Jiangxi province.Among them,5 new Diaporthe species(species names werenot established in this study)were identified.Thirteen species of D.apiculata,D.lagerstroemiae,D.mali,D.momicola,D.penetriteum,D.perniciosa and D.sennicola,D.eucalyptorum,D.longicicola,D.passifloricola,D.podocarpi-macrophylli,D.sackstonii,D.tectonendophytica,that had been reported on other host plants,were firstly found on citrus crops.Six of them,i.e.D.eucalyptorum,D.longicicola,D.passifloricola,D.podocarpi-macrophylli,D.sackstonii,D.tectonendophytica,were firstly recorded in China.For difference citrus varities,19 and 16 Diaporthe species were identified on Citrus reticulata cv.nanfengmiju and C.sinensis(L.)Osbeck,respectively.For different citrus tissue,the number of Diaporthe species identified on leaves,fruits and twig were 21,11 and 8,respectively.D.citri was the dominant species on different citrus varieties and tissues.