First Report of Wilt of Eucalyptus Caused by Ceratocystis fimbriata in China

Abstract

Eucalyptus spp., most of which are native to Australia, are one of the world's most commonly planted forestry crops, and have been widely planted in the tropics and subtropics. Eucalyptus trees are distributed in more than 600 counties in 19 provinces/regions throughout China, especially in the southern regions of the country (1). From April of 2013 to May of 2014, eucalyptus trees were noted to be wilting and dying rapidly in Kunming, Yunnan Province (25°02′ N, 102°42′ E), southwest China. Symptomatic trees typically have many wilted or dead leaves hanging throughout the tree or on some major branches, sometimes followed by death of the whole tree. Dark brown to black discoloration can be seen in the woody xylem, and elongated cankers were also present on some affected trees. A fungus was consistently isolated from the leaves and cankers when symptomatic tissue was incubated between two slices of fresh carrot root. Spore masses were removed from the apices of perithecia, transferred to malt extract agar medium (MEA), and incubated at 25°C. Perithecia developed on the medium, and were black, globose, 212.5 to 242.4 × 207.5 to 254.2 μm, and possessed a long black neck (952.3 to 1,303.3 μm). Ascospores had the typical “hat” morphology and were 4.3 to 5.2 × 3.0 to 3.8 μm. Cylindrical endoconidia (11.2 to 22.2 × 3.9 to 6.1 μm) were found. Chlamydospores produced on media were ovoid and smooth, and were 7.8 to 9.7 × 9.9 to 12.8 μm. Chains of barrel-shaped conidia were not found. PCR amplification and sequencing of the ITS region of rDNA were carried out for one isolate, E2-2, using the procedures of Thorpe et al. (3). Analysis of ITS sequence data (GenBank Accession No. KJ511481) showed that the isolates were 99% homologous to the isolate of C. fimbriata from diseased Colocasia esculenta in Cuba, China, and Hawaii (AY526304 to 06) by BLAST analysis. Thus, the fungus was identified as C. fimbriata based on morphological and molecular characteristics. Pathogenicity tests were made on 1-year-old E. grandis seedlings as follows. A conidial suspension of each isolate was diluted to 106 conidia/ml, and 0.2 ml was injected into wounds on three petioles on each of five healthy plants of E. grandis, and control seedlings were injected with sterile water that had been placed on MEA plates. The seedlings were incubated at 25°C in moist chambers. After 3 days, all inoculated E. grandis plants showed dark brown to black discoloration in the leaf axils. After 5 days, leaf wilting was present. C. fimbriata was re-isolated from all inoculated symptomatic tissue. No symptoms were visible in the control plants and no fungus was isolated from them. Ceratocystis wilt was first observed in eucalyptus in 1997 in the state of Bahia. This was followed by a report of C. fimbriata causing wilt of E. grandis in the Republic of Congo, Uganda, and Uruguay (2). Chen et al. reported two species of Ceratocystis, C. acaciivora and a previously undescribed species C. chinaeucensis, from eucalyptus plantations in Guangdong Province in China (1). To our knowledge, this is the first report of C. fimbriata causing wilt of eucalyptus in China. References: (1) S. F. Chen et al. Fungal Diversity 58:267, 2011. (2) F. A. Ferreira et al. Fitopatol. Bras. 24:284, 1999. (3) D. J. Thorpe et al. Phytopathology 95:316, 2005.

New Ceratocystis species from Eucalyptus and Cunninghamia in South China

“…There are only six previous reports of Ceratocystis species from China and all species reside in the South American Clade. These species include C. manginecans from recently harvested stumps of Eucalyptus in GuangDong Province (Chen et al 2013;Fourie et al 2015), and C. fimbriata s.l, causing a disease on Eucalyptus (Li et al 2014b), Ipomoea batatas (sweet potato; Sy 1956), Punica granatum (pomegranate; Huang et al 2003;Xu et al 2011), Colocasia esculenta (taro; Huang et al 2008) and Eriobotrya japonica (loquat; Li et al 2014a). Considering the number of Ceratocystis species found in other countries, and the small number of studies on species of Ceratocystis and other Ceratocystidaceae found in China, the discovery of C. cercfabiensis and C. collisensis suggests that many other species in the genus and family remain to be discovered in this geographic area.…”

“…The recent description of a disease of Eucalyptus in China, caused by C. fimbriata s.l. (Li et al 2014b), and reports of disease and death of Eucalyptus species caused by species of Ceratocystis in Africa (Roux et al 1999(Roux et al , 2000 and South America (Barnes et al 2003;Rodas et al 2008;Van Wyk et al 2012), however, suggest that these fungi could become important to Eucalyptus forestry in China. They clearly deserve further study in the future.…”

“…These have been treated in various previous studies (Roux et al 2000(Roux et al , 2001Harrington 2004;Tsopelas and Angelopoulos 2004;van Wyk et al 2007a;Engelbrecht et al 2007;Roux and Wingfield 2009;Li et al 2014aLi et al , 2014b. Some examples include C. albifundus that causes a canker and wilt disease of Australian Acacia mearnsii trees in Africa (Morris et al 1993;Roux et al 2005), C. manginecans that causes a serious wilt of mango in Oman and Pakistan (van Wyk et al 2007a), C. cacaofunesta that causes a lethal wilt disease of cacao (Theobroma cacao) in the Caribbean and Central and South America (Engelbrecht et al 2007) and C. platani, that causes a canker stain and die-back of Platanus spp.…”

“…Despite the growing importance of Eucalyptus and other plantation species in China, information regarding fungal diseases affecting these plantations is limited (Zhou and Wingfield 2011). This is also true regarding the possible occurrence and impact of Ceratocystis species associated with trees in these plantations, where there have been only two previous studies treating this topic (Chen et al 2013;Li et al 2014b). …”

Molecular phylogenetics and microsatellite analysis reveal a new pathogenic Ceratocystis species in the Asian‐Australian clade

“…In addition, isolates of Ceratocystis from Eriobotrya japonica (loquat; E2‐2) and Eucalyptus (PY1‐1, PY2‐1) have been reported from YunNan Province in China and broadly treated as C. fimbriata s.l . (Li et al ., ,b). However, the ITS sequences of the latter isolates have 99% similarity to those of C. uchidae , a newly described species in the AAC group (Li et al ., ) and 100% similarity to those of the undescribed Ceratocystis sp.…”