Variation inBotryosphaeriaceaefromEucalyptusplantations in YunNan Province in southwestern China across a climatic gradient

TheBotryosphaeriaceaeaccommodates many important pathogens of woody plants, includingEucalyptus. Recently,Botryosphaeriaceaewere isolated from diseased plant parts from surveys ofEucalyptusplantations in the YunNan Province, China. The aims of this study were to identify theseBotryosphaeriaceaeisolates and to evaluate their pathogenicity toEucalyptus. A total of 166 isolates ofBotryosphaeriaceaewere obtained from six regions in the YunNan Province, of which 76 were fromEucalyptus urophyllaxE. grandishybrids, 49 fromE. globulustrees, and 41 isolates were from other unknownEucalyptusspecies or hybrids. Isolates were identified by comparing DNA sequences of the internal transcribed spacer ribosomal RNA locus (ITS), partial translation elongation factor 1-alpha (tef1), beta-tubulin 2 (tub2) and DNA-directed RNA polymerase II subunit (rpb2) genes, and combined with their morphological characteristics. Eleven species were identified, includingBotryosphaeria fusispora,B. wangensis,Lasiodiplodia pseudotheobromae,Neofusicoccum kwambonambiense,N. parvum, and six novel species described asB. puerensis,N. dianense,N. magniconidium,N. ningerense,N. parviconidiumandN. yunnanense. The dominant species across the regions wereN. yunnanense,N. parvumandB. wangensis, representing 31.3, 25.3 and 19.9% of the total isolates, respectively. Species diversity and composition changed across the different climatic zones, despite their relatively close geographic proximity and the fact that some of the species have a global distribution. All theBotryosphaeriaceaespecies were pathogenic to one-year-old plants of anE. urophyllaxE. grandisclone andE. globulusseed-derived plants, but showed significant inter- and intra-species variation in aggressiveness amongst isolates. The study provides a foundation for monitoring and management ofBotryosphaeriaceaethrough selection and breeding ofEucalyptusin the YunNan Province of southwestern China.