ShuaiFei Chen

Fungal Planet description sheets: 154–213

Novel species of microfungi described in the present study include the following from South Africa: Camarosporium aloes, Phaeococcomyces aloes and Phoma aloes from Aloe, C. psoraleae, Diaporthe psoraleae and D. psoraleae-pinnatae from Psoralea, Colletotrichum euphorbiae from Euphorbia, Coniothyrium prosopidis and Peyronellaea prosopidis from Prosopis, Diaporthe cassines from Cassine, D. diospyricola from Diospyros, Diaporthe maytenicola from Maytenus, Harknessia proteae from Protea, Neofusicoccum ursorum and N. cryptoaustrale from Eucalyptus, Ochrocladosporium adansoniae from Adansonia, Pilidium pseudoconcavum from Greyia radlkoferi, Stagonospora pseudopaludosa from Phragmites and Toxicocladosporium ficiniae from Ficinia. Several species were also described from Thailand, namely: Chaetopsina pini and C. pinicola from Pinus spp., Myrmecridium thailandicum from reed litter, Passalora pseudotithoniae from Tithonia, Pallidocercospora ventilago from Ventilago, Pyricularia bothriochloae from Bothriochloa and Sphaerulina rhododendricola from Rhododendron. Novelties from Spain include Cladophialophora multiseptata, Knufia tsunedae and Pleuroascus rectipilus from soil and Cyphellophora catalaunica from river sediments. Species from the USA include Bipolaris drechsleri from Microstegium, Calonectria blephiliae from Blephilia, Kellermania macrospora (epitype) and K. pseudoyuccigena from Yucca. Three new species are described from Mexico, namely Neophaeosphaeria agaves and K. agaves from Agave and Phytophthora ipomoeae from Ipomoea. Other African species include Calonectria mossambicensis from Eucalyptus (Mozambique), Harzia cameroonensis from an unknown creeper (Cameroon), Mastigosporella anisophylleae from Anisophyllea (Zambia) and Teratosphaeria terminaliae from Terminalia (Zimbabwe). Species from Europe include Auxarthron longisporum from forest soil (Portugal), Discosia pseudoartocreas from Tilia (Austria), Paraconiothyrium polonense and P. lycopodinum from Lycopodium (Poland) and Stachybotrys oleronensis from Iris (France). Two species of Chrysosporium are described from Antarctica, namely C. magnasporum and C. oceanitesii. Finally, Licea xanthospora is described from Australia, Hypochnicium huinayensis from Chile and Custingophora blanchettei from Uruguay. Novel genera of Ascomycetes include Neomycosphaerella from Pseudopentameris macrantha (South Africa), and Paramycosphaerella from Brachystegia sp. (Zimbabwe). Novel hyphomycete genera include Pseudocatenomycopsis from Rothmannia (Zambia), Neopseudocercospora from Terminalia (Zambia) and Neodeightoniella from Phragmites (South Africa), while Dimorphiopsis from Brachystegia (Zambia) represents a novel coelomycetous genus. Furthermore, Alanphillipsia is introduced as a new genus in the Botryosphaeriaceae with four species, A. aloes, A. aloeigena and A. aloetica from Aloe spp. and A. euphorbiae from Euphorbia sp. (South Africa). A new combination is also proposed for Brachysporium torulosum (Deightoniella black tip of banana) as Corynespora torulosa. Morphological and culture characteristics along with ITS DNA barcodes are provided for all taxa.

Novel species of Calonectria associated with Eucalyptus leaf blight in Southeast China

Leaf blight caused by Calonectria spp. is an important disease occurring on Eucalyptus trees grown in plantations of Southeast Asia. Symptoms of leaf blight caused by Calonectria spp. have recently been observed in commercial Eucalyptus plantations in FuJian Province in Southeast China. The aim of this study was to identify these Calonectria spp. employing morphological characteristics, DNA sequence comparisons for the β-tubulin, histone H3 and translation elongation factor-1α gene regions and sexual compatibility. Four Calonectria spp. were identified, including Ca. pauciramosa and three novel taxa described here as Ca. crousiana, Ca. fujianensis and Ca. pseudocolhounii. Inoculation tests showed that all four Calonectria spp. found in this study were pathogenic on two different E. urophylla × E. grandis hybrid clones, commercially utilised in eucalypt plantations in China.

Novel species of Celoporthe from Eucalyptus and Syzygium trees in China and Indonesia

Many species in the Cryphonectriaceae cause diseases of trees, including those in the genera Eucalyptus and Syzygium. During disease surveys on these trees in southern China, fruiting structures typical of fungi in the Cryphonectriaceae and associated with dying branches and stems were observed. Morphological comparisons suggested that these fungi were distinct from the well known Chrysoporthe deuterocubensis, also found on these trees in China. The aim of this study was to identify these fungi and evaluate their pathogenicity to Eucalyptus clones/species as well as Syzygium cumini. Three morphologically similar fungal isolates collected previously from Indonesia also were included in the study. Isolates were characterized based on comparisons of morphology and DNA sequence data for the partial LSU and ITS nuclear ribosomal DNA, β-tubulin and TEF-1α gene regions. After glasshouse trials to select virulent isolates field inoculations were undertaken to screen different commercial Eucalyptus clones/species and S. cumini trees for susceptibility to infection. Phylogenetic analyses showed that the Chinese isolates and those from Indonesia reside in a clade close to previously identified South African Celoporthe isolates. Based on morphology and DNA sequence comparisons, four new Celoporthe spp. were identified and they are described as C. syzygii, C. eucalypti, C. guangdongensis and C. indonesiensis. Field inoculations indicated that the three Chinese Celoporthe spp., C. syzygii, C. eucalypti and C. guangdongensis, are pathogenic to all tested Eucalyptus and S. cumini trees. Significant differences in the susceptibility of the inoculated Eucalyptus clones/species suggest that it will be possible to select disease-tolerant planting stock for forestry operations in the future.

Diversimorbus metrosiderotis gen. et sp. nov. and three new species of Holocryphia (Cryphonectriaceae) associated with cankers on native Metrosideros angustifolia trees in South Africa

The Cryphonectriaceae includes important tree pathogens, especially on the Myrtales. During a routine disease survey in the Western Cape Province of South Africa, a fungus resembling the Eucalyptus pathogen Holocryphia eucalypti was observed on native Metrosideros angustifolia (Myrtales). The aims of this study were to identify the fungus and to expand surveys for fungi in the Cryphonectriaceae on M. angustifolia. Fungi were identified based on DNA sequence comparisons and morphological features, and their pathogenicity was tested on M. angustifolia under field conditions. Based on morphology and multigene phylogenetic analyses of DNA sequence data from six gene regions, we describe a new genus including a single species and three new species of Holocryphia (Cryphonectriaceae) from M. angustifolia. These fungi are provided with the names Diversimorbus metrosiderotis gen. et sp. nov., Holocryphia capensis sp. nov., Holocryphia gleniana sp. nov., and Holocryphia mzansi sp. nov. We also revise H. eucalypti, the type of the genus, to include only isolates from Eucalyptus in South Africa. Research results indicated that H. mzansi may undergo host shifts between different tree genera in the Myrtaceae. Inoculation tests showed that isolates of all the newly described species can cause lesions on the branches of M. angustifolia, indicating that they are all pathogens of this tree.

High population diversity and increasing importance of the Eucalyptus stem canker pathogen, Teratosphaeria zuluensis, in South China

Coniothyrium stem canker, caused by Teratosphaeria zuluensis, is one of the most important diseases of plantation-grown Eucalyptus trees in tropical and sub-tropical areas of the world. Previous research on the population structure of T. zuluensis in China, Malawi and South Africa has suggested that T. zuluensis in these countries had independent origins, with the highest genetic diversity found in a population from South China. In this study, the genetic diversity of three T. zuluensis populations from different regions in South China was determined using ten microsatellite markers. Results showed that more than one genotype of T. zuluensis can occur on a single tree in all three populations and that a moderate to high genetic diversity exists within the populations. Population differentiation was evident between populations, and in one population there was evidence for a low level of genetic recombination. Comparisons among the three populations of T. zuluensis from South China suggest that they originated independently of each other.

Identification and Pathogenicity of Chrysoporthe cubensis on Eucalyptus and Syzygium spp. in South China

The genus Chrysoporthe includes important pathogens of plantation-grown Eucalyptus spp. and has been reported from several tree genera in the order Myrtales in tropical and subtropical areas of the world. During disease surveys in South China, fruiting structures typical of Chrysoporthe spp. were observed on cankers on Eucalyptus spp. and Syzygium cumini trees. The aim of this study was to confirm the identity of the Chrysoporthe cubensis infecting the Eucalyptus spp. and S. cumini and to test the pathogenicity of the fungus. Following glasshouse trials to select virulent isolates, field inoculations were undertaken to screen different commercial Eucalyptus genotypes for their susceptibility to the fungus. Isolates were characterized based on their morphology and DNA sequence data for the β-tubulin and internal transcribed spacer regions of the ribosomal DNA. Results showed that the putative pathogen represented the Asian form of C. cubensis, which occurred on numerous different Eucalyptus spp. and hybrid clones as well as S. cumini. Field inoculations showed that all six of the Eucalyptus genotypes tested are susceptible to infection by C. cubensis. Significant differences were observed between them, providing prospects to select disease-tolerant planting stock in the future.

New species, hyper-diversity and potential importance of Calonectria spp. from Eucalyptus in South China

Plantation forestry is expanding rapidly in China to meet an increasing demand for wood and pulp products globally. Fungal pathogens including species of Calonectria represent a serious threat to the growth and sustainability of this industry. Surveys were conducted in the Guangdong, Guangxi and Hainan Provinces of South China, where Eucalyptus trees in plantations or cuttings in nurseries displayed symptoms of leaf blight. Isolations from symptomatic leaves and soils collected close to infected trees resulted in a large collection of Calonectria isolates. These isolates were identified using the Consolidated Species Concept, employing morphological characters and DNA sequence comparisons for the β-tubulin, calmodulin, histone H3 and translation elongation factor 1-alpha gene regions. Twenty-one Calonectria species were identified of which 18 represented novel taxa. Of these, 12 novel taxa belonged to Sphaero-Naviculate Group and the remaining six to the Prolate Group. Southeast Asia appears to represent a centre of biodiversity for the Sphaero-Naviculate Group and this fact could be one of the important constraints to Eucalyptus forestry in China. The remarkable diversity of Calonectria species in a relatively small area of China and associated with a single tree species is surprising.

First Report of Lasiodiplodia citricola and Neoscytalidium dimidiatum Causing Death of Graft Union of English Walnut in California

California produces 99% of the English walnuts (Juglans regia) in the USA. In August 2012 in Tulare County, about 5,000 out of 90,000 trees were killed in a walnut nursery by a distinct black canker that developed around the graft union. The cankers appeared to be initiated at the heading cut on the rootstock, and expanded down to the rootstock and through the budded union up to the scion, resulting in mortality of scion. The walnut nursery was located adjacent to a mature walnut orchard. The fungi isolated from the cankers were identified as Lasiodiplodia citricola and Neoscytalidium dimidiatum based on morphological characteristics and DNA sequence comparisons. L. citricola was isolated from one of the 10 graft unions, while N. dimidiatum from the other nine. L. citricola isolates were characterized by white, aerial mycelium on potato dextrose agar that turned gray after 4 days and produced ellipsoidal to ovoid hyaline one-celled conidia that became 2-celled and brown with thick walls and longitudinal striations in the wall (1). N. dimidiatum isolates were characterized by ellipsoid to ovoid, hyaline conidia with a truncate base and an acutely rounded apex, initially 1-celled, and some becoming brown and 2-celled at maturity; no muriform conidia were produced (3). These identifications were confirmed by analyses of the ITS, BT2, and TEF-1α gene regions. The three gene regions were amplified by using the primers and methods described in (4). For L. citricola (isolates 7E78 to 7E80), a DNA sequence BLASTn at GenBank showed 100% identity with accessions GU945354 (ITS) and GU945340 (TEF-1α) of the ex-type specimen (CBS124707, BT2 sequencing data was not available) (3). For N. dimidiatum (isolates 7E61 to 7E63), a BLASTn search showed a high identify (ITS, 100%; BT2, 99%; TEF-1α, 99%) with reference sequence of N. dimidiatum (ITS, GQ330903; BT2, GU251768; TEF-1α, GU251240). Sequences of the studied DNA regions were deposited to GenBank as KC357298 to KC357303 (ITS); KC357304 to KC357309 (BT2); and, KC357310 to KC357315 (TEF-1α). The pathogenicity of L. citricola in comparison with N. dimidiatum in J. regia cvs. Chandler, Tulare, and Vina was evaluated in an orchard at KARE, by using two isolates each of L. citricola (7E78, 7E80) and N. dimidiatum (7E61, 7E63). Pathogenicity tests were performed by inoculating ten 2-year-old branches per isolate in late September 2012 by the method described in (2). After 3 weeks, the average lesion lengths caused by L. citricola on Chandler, Tulare, and Vina were 152, 156, and 188 mm, respectively, and 32, 38, and 34 mm, respectively, caused by N. dimidiatum. The lesion length averages produced on the three cultivars by the four isolates were all significantly (P < 0.05) longer than their respective controls (average length 10 mm on all cultivars). L. citricola, but not N. dimidiatum, killed branches of Chandler, Tulare, and Vina in 10 days. Both L. citricola and N. dimidiatum were reisolated from the inoculated branches and no fungus was isolated from the control, confirming Kochs postulates. These results confirmed that the walnut graft union canker was caused by either L. citricola or N. dimidiatum. To our knowledge, this is the first report of death of newly grafted walnut trees caused by L. citricola and N. dimidiatum worldwide, and also the first report of L. citricola infecting walnut worldwide. References: (1) J. Abdollahzadeh et al. Persoonia. 25:1, 2010. (2) S. F. Chen et al. Plant Dis. 97:994, 2013. (3) D. Pavlic et al. Mycologia. 106:851, 2008. (4) B. Slippers et al. Mycologia. 96:83, 2004.

Novel species of Botryosphaeriaceae associated with shoot blight of pistachio.

Various species of phytopathogenic Botryosphaeriaceae were identified previously from pistachio trees worldwide. Disease symptoms caused by pathogens in Botryosphaeriaceae on pistachio include panicle and shoot blight, leaf defoliation, fruit discoloration and decay. In this study species of Botryosphaeriaceae were collected from blighted pistachio shoots in Arizona, USA, and Greece. The aims of this study were to identify these Botryosphaeriaceae isolates and to test their pathogenicity to pistachio. The fungi were identified based on comparisons of DNA sequence data of the nuclear rDNA internal transcribed spacer region (ITS), a partial translation elongation factor 1-alpha gene (TEF1), a partial β-tubulin gene (TUB2) and morphological characteristics. Results indicated that some isolates collected from pistachio represent two previously undescribed species, which we described here as Lasiodiplodia americana sp. nov. from the United States and Neofusicoccum hellenicum sp. nov. from Greece. Field inoculations of L. americana and N. hellenicum on branches of four pistachio cultivars showed that both L. americana and N. hellenicum are pathogenic on pistachio. The four pistachio cultivars differed in their susceptibility to the Botryosphaeriaceae species. Results of this study suggested that the two new species of Botryosphaeriaceae need to be monitored carefully to determine the distribution of these pathogens and the possible spread to other areas.

First Report of Lasiodiplodia theobromae Associated with Stem Canker of Almond in California

California is a major almond (Prunus dulcis) producer in the world. In September 2012, 2-year-old almond trees from an orchard in Fresno Co. with stem cankers were submitted for disease diagnosis. In a survey of the orchard, 12 ha (1,500 Nonpareil and 1,800 Monterey almond trees) of 48 ha trees had been killed apparently due to a stem canker. The cankers developed above the graft union, were covered with amber sap, and often girdled the trunk. Isolations made from tissues at the canker margins onto acidified potato dextrose agar (PDA) yielded two fungi, Macrophomina phaseolina (Tassi) Goid and Lasiodiplodia theobromae (Pat.) Griffon & Maubl (1). M. phaseolina and L. theobromae were isolated from eight and two of 10 cankered trees, respectively. No mixed infections were found. M. phaseolina isolates were characterized by gray hyphae that turned black with developing microsclerotia. L. theobromae isolates were characterized by white, aerial mycelium that turned mouse gray after 5 days. Young conidia were ellipsoidal, thick walled, initially hyaline, granular, and nonseptate; aged conidia were brown, 1-septate with longitudinal striations in the wall. Identity was confirmed by analyses of the internal transcribed spacer (ITS), β-tubulin 2 (BT2), and the translation elongation factor 1-alpha (TEF-1α) gene regions. BLAST searches at GenBank showed a high identity with reference sequences of type specimens both for M. phaseolina (isolates 7E64 to 7E69: ITS, 100%; BT2, 99%; TEF-1α, 99%) and L. theobromae (isolates 7E86 to 7E88: ITS, 99%; BT2, 99%; TEF-1α, 100%). Sequences of three gene regions were deposited as GenBank accessions KC357271 to KC357279 (ITS); KC357280 to KC357288 (BT2); and KC357289 to KC357297 (TEF-1α). The pathogenicity of M. phaseolina and L. theobromae to P. dulcis cultivars Butte, Carmel, Nonpareil, and Padre was investigated in an orchard at KARE using four isolates of M. phaseolina (7E64, 7E65, 7E66, and 7E69) and two isolates of L. theobromae (7E86 and 7E88). Ten 2-year-old branches per isolate from 7-year-old trees were inoculated with each isolate in late September 2012, after removing the bark with a 7-mm cork borer and placing a 7-day-old 7-mm-diameter agar plug bearing mycelium of each isolate directly into the fresh wound, mycelium side down. Ten additional branches of each of the four cultivars were inoculated with sterile PDA plugs and served as negative controls. Three weeks after inoculation, the average lesion produced by M. phaseolina on Butte, Carmel, Nonpareil, and Padre was 53, 52, 41, and 37 mm in length, respectively. Lesions produced by L. theobromae were 191, 206, 194, and 103 mm in length on the four cultivars, respectively. No disease lesion, only wounds, were produced on negative controls. Lesions produced by both pathogens were longer (P < 0.05) than wounds on the controls (average length 10 mm on all cultivars). Both L. theobromae isolates killed branches of cultivars Butte, Carmel, and Nonpareil in 2 weeks. M. phaseolina and L. theobromae were reisolated from the inoculated branches, and no fungus was reisolated from controls. Based on pathogenicity results, L. theobromae is more virulent to almond branches than M. phaseolina. To our knowledge, this is the second report of M. phaseolina (2) and the first report of L. theobromae as pathogens of P. dulcis trees in California. References: (1) A. Alves et al. Fungal Diversity 28:1, 2008. (2) P. Inderbitzin et al. Mycologia 102:1350, 2010.