Li S B, Li J Z, Li S C, Lu Z H, Wang J H, Zhang H
Flower Research Institute, Yunnan Academy of Agriculture Science, Kunming 650205, Yunnan, China.
Plant Dis. 2010 May;94(5):641. doi: 10.1094/PDIS-94-5-0641C.
Cupressus funebris Endl. (Chinese weeping cypress) is native to southwestern and central China. In June 2008, blighted shoots of Chinese weeping cypress trees were observed in Yunnan Province (southwestern China). Symptomatic trees were located in an ornamental planting established approximately 8 to 12 years ago. Additional samples were collected from 11 locations in the provinces of Sichuan, Yunnan, Guizhou, and Chongqing. Disease symptoms included yellowing and wilting of leaves on several branches, followed by sudden death within 6 to 8 weeks. Cross sections on trunks and branches revealed darkened zones. Tissue from diseased samples was plated on potato dextrose agar (PDA) and incubated at 25°C. Fungal isolates developed copious, white, aerial mycelium that became dark gray after 4 to 6 days and formed black pycnidia after 25 days. Conidia were hyaline, ellipsoidal to fusiform, externally smooth, thin walled, nonseptate, and measured 12.5 to 18.5 × 4.0 to 6.5 μm. Identity was confirmed by analysis of the rDNA internal transcribed spacer region (ITSI-5.8S-ITS2) and the translation elongation factor 1-alpha (EF1-α). BLAST searches at GenBank showed a high identity with reference sequences (ITS: >99%; EF1-α: 100%). Representative sequences of both regions were deposited in GenBank (ITS: Accession No. FJ842960 and FJ842961; EF1-α: Accession No. GU811148). Morphological and molecular results confirmed this species as Neofusicoccum parvum, reported as the anamorph of Botryosphaeria parva. Pathogenicity tests were conducted by stem inoculation of 2-year-old C. funebris seedlings. Mycelial plugs (4 mm in diameter) of N. parvum from actively growing colonies were applied to same-size bark wounds on the middle point of the stems. Control seedlings were inoculated with sterile PDA plugs. Inoculated and control seedlings (five each) were kept in a greenhouse and watered as needed. After 5 weeks, all C. funebris seedlings showed leaf wilting and dark vascular stem tissue. N. parvum was reisolated from all inoculated, symptomatic tissues, fulfilling Koch's postulates; no symptoms were visible in the control seedlings. N. parvum has previously been reported to cause canker and dieback disease of avocado (3), mango (2), and magenta cherry (Syzygium paniculatum) (1). To our knowledge, this is the first report of N. parvum causing dieback of C. funebris in China. References: (1) R. C. Ploetz et al. Plant Pathol. 58:801, 2009. (2) B. Slippers et al. Mycologia 97:99, 2005. (3) T. Zea-Bonilla et al. Plant Dis. 91:1052, 2007.
柏木原产于中国西南部和中部地区。2008年6月，在中国西南部的云南省发现了柏木的枯枝。有症状的树木位于大约8至12年前种植的观赏植物区。另外从四川省、云南省、贵州省和重庆市的11个地点采集了样本。病害症状包括多个枝条上的叶片发黄和枯萎，随后在6至8周内突然死亡。树干和枝条的横切面显示出变色区域。将患病样本的组织接种在马铃薯葡萄糖琼脂（PDA）上，并在25°C下培养。真菌分离物产生大量白色气生菌丝体，4至6天后变为深灰色，25天后形成黑色分生孢子器。分生孢子透明，椭圆形至梭形，表面光滑，薄壁，无隔膜，大小为12.5至18.5×4.0至6.5μm。通过对核糖体DNA内转录间隔区（ITSI-5.8S-ITS2）和翻译延伸因子1-α（EF1-α）的分析确定了其身份。在GenBank上进行的BLAST搜索显示与参考序列具有高度同源性（ITS：>99%；EF1-α：100%）。这两个区域的代表性序列已存入GenBank（ITS：登录号FJ842960和FJ842961；EF1-α：登录号GU811148）。形态学和分子学结果证实该物种为葡萄座腔菌属小球腔菌，据报道它是小葡萄座腔菌的无性型。通过对2年生柏木幼苗进行茎部接种来进行致病性测试。从活跃生长的菌落中选取直径为4mm的小球腔菌菌丝块，接种到茎中部相同大小的树皮伤口上。对照幼苗接种无菌PDA块。接种和对照的幼苗（各5株）置于温室中，并根据需要浇水。5周后，所有柏木幼苗均出现叶片枯萎和维管束茎组织变黑的症状。从小球腔菌接种的所有有症状组织中重新分离出该菌，满足柯赫氏法则；对照幼苗未出现症状。此前已有报道称小球腔菌可引起鳄梨（3）、芒果（2）和蒲桃（1）的溃疡病和枝枯病。据我们所知，这是小球腔菌在中国引起柏木枝枯病的首次报道。参考文献：（1）R.C.Ploetz等人，《植物病理学》58:801，2009年。（2）B.Slippers等人，《真菌学》97:99，2005年。（3）T.Zea-Bonilla等人，《植物病害》91:1052，2007年。
