Colletotrichum species associated with anthracnose of Pyrus spp. in China

Colletotrichum species are plant pathogens, saprobes, and endophytes on a range of economically important hosts. However, the species occurring on pear remain largely unresolved. To determine the morphology, phylogeny and biology of Colletotrichum species associated with Pyrus plants, a total of 295 samples were collected from cultivated pear species (including P. pyrifolia, P. bretschneideri, and P. communis) from seven major pear-cultivation provinces in China. The pear leaves and fruits affected by anthracnose were sampled and subjected to fungus isolation, resulting in a total of 488 Colletotrichum isolates. Phylogenetic analyses based on six loci (ACT, TUB2, CAL, CHS-1, GAPDH, and ITS) coupled with morphology of 90 representative isolates revealed that they belong to 10 known Colletotrichum species, including C. aenigma, C. citricola, C. conoides, C. fioriniae, C. fructicola, C. gloeosporioides, C. karstii, C. plurivorum, C. siamense, C. wuxiense, and two novel species, described here as C. jinshuiense and C. pyrifoliae. Of these, C. fructicola was the most dominant, occurring on P. pyrifolia and P. bretschneideri in all surveyed provinces except in Shandong, where C. siamense was dominant. In contrast, only C. siamense and C. fioriniae were isolated from P. communis, with the former being dominant. In order to prove Koch's postulates, pathogenicity tests on pear leaves and fruits revealed a broad diversity in pathogenicity and aggressiveness among the species and isolates, of which C. citricola, C. jinshuiense, C. pyrifoliae, and C. conoides appeared to be organ-specific on either leaves or fruits. This study also represents the first reports of C. citricola, C. conoides, C. karstii, C. plurivorum, C. siamense, and C. wuxiense causing anthracnose on pear.

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Recent Outbreak of Soybean Sudden Death Syndrome Caused by Fusarium virguliforme and F. tucumaniae in Argentina

Plant Disease ◽

10.1094/pdis.2004.88.9.1044c ◽

2004 ◽

Vol 88 (9) ◽

pp. 1044-1044 ◽

Cited By ~ 6

Author(s):

M. Scandiani ◽

D. Ruberti ◽

K. O'Donnell ◽

T. Aoki ◽

R. Pioli ◽

...

Keyword(s):

United States ◽

Phylogenetic Analyses ◽

The United States ◽

Positive Control ◽

Koch’S Postulates ◽

First Report ◽

Molecular Phylogenetic ◽

Soil Infestation ◽

Pathogenicity Tests ◽

Koch's Postulates

Sudden death syndrome (SDS) of soybean was detected initially in Argentina during 1991-1992 in the Pampas Region and 1992-1993 in the Northwest Region. The first report of the fulfillment of Koch's postulates of SDS caused by Fusarium solani f. sp. glycines in Argentina was published in 2003 (3). Subsequently, analyses have shown that F. solani f. sp. glycines represents several morphologically and phylogenetically distinct species, including F. tucumaniae in Argentina and F. virguliforme in the United States (1). Isolations were made from plants that exhibited typical SDS symptoms (interveinal foliar chlorosis and necrosis leading to defoliation of the leaflets but not the petioles) from fields in Santa Fe and Buenos Aires provinces in 2001, 2002, and 2003. To determine which species are responsible for SDS in Argentina, cultures of eight slow growing isolates that developed bluish pigmentation and produced abundant macroconidia in sporodochia on potato dextrose agar were subjected to morphological and molecular phylogenetic analyses and pathogenicity tests. Morphological analyses demonstrated that three of the isolates were F. virguliforme and five were F. tucumaniae. Isolates of F. tucumaniae produced long and narrow sporodochial conidia while F. virguliforme produced diagnostic comma-shaped conidia. Molecular phylogenetic analyses of DNA sequences from multiple loci confirmed morphology-based identifications and showed that the soybean SDS pathogen in the United States, F. virguliforme, was also present in Argentina. To our knowledge, this is the first report of F. virguliforme in Argentina and of this pathogen outside the United States. Five isolates of F. tucumaniae and three isolates of F. virguliforme were used for pathogenicity tests. F. virguliforme isolate 171 provided by J. Rupe (University of Arkansas, Fayetteville) was used as a positive control. Soybean cultivars Ripley, RA 702, Pioneer 9492RR, Spencer, and A-6445RG were inoculated with each of the isolates tested in a greenhouse assay using soil infestation and toothpick methods (2). All eight isolates produced typical foliar SDS symptoms 15 to 25 days after inoculation. Severity of foliar symptoms averaged 3.3 for F. virguliforme, 2.6 for F. tucumaniae, and 3.3 for the positive control using a disease severity scale in which 1 = no symptoms and 5 = severely infected or dead plants. Under these conditions, F. virguliforme appeared to be more virulent than F tucumaniae. Noninoculated plants remained symptomless. Koch's postulates were confirmed with soybean cultivars RA 702 and A6445RG. Isolates recovered from symptomatic plants inoculated by the soil infestation and toothpick methods were identical to those used to inoculate the plant. Strains were recovered at frequencies of 100 and 60% from plants inoculated by the toothpick and soil infestation methods, respectively. To our knowledge, this is the first report of the fulfillment of Koch's postulates for F. tucumaniae and F. virguliforme in Argentina. References: (1) T. Aoki et al. Mycologia 95:660, 2003. (2) K. W. Roy et al. Plant Dis. 81:1100, 1997 (3) M. Scandiani et al. Plant Dis. 87:447, 2003.

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Eight Colletotrichum Species, Including a Novel Species, Are Associated With Areca Palm Anthracnose in Hainan, China

Plant Disease ◽

10.1094/pdis-10-19-2077-re ◽

2020 ◽

Vol 104 (5) ◽

pp. 1369-1377

Author(s):

Xueren Cao ◽

Xiangming Xu ◽

Haiyan Che ◽

Jonathan S. West ◽

Daquan Luo

Keyword(s):

Species Complex ◽

Novel Species ◽

Management Strategies ◽

Pathogenic Fungi ◽

Fruit Trees ◽

Common Species ◽

Type Locus ◽

Colletotrichum Species ◽

Pathogenicity Tests ◽

A New Species

Genus Colletotrichum is one of the most important genera of plant-pathogenic fungi affecting numerous species, particularly tropical and subtropical crops and fruit trees. In this study, 43 Colletotrichum strains were isolated from areca palm leaves with anthracnose symptoms in 11 areca palm plantations in eight counties of Hainan, China. Based on the morphology, phylogenetic analysis of six loci (internal transcribed spacer, actin, chitin synthase 1, glyceraldehyde-3-phosphate dehydrogenase, β-tubulin, and mating type locus MAT1-2), and pathogenicity tests, eight Colletotrichum species were distinguished, comprising five previously known species (C. cordylinicola, C. fructicola, C. gloeosporioides, C. siamense, and C. tropicale), one unidentified Colletotrichum species, a new species (C. arecicola) in the gloeosporioides species complex, and C. karstii in the boninense species complex. C. siamense was the most common species found in areca palm in Hainan, followed by C. arecicola. Pathogenicity tests showed that all eight species could cause anthracnose symptoms on areca palm leaves using a wound inoculation method and that the isolates from the gloeosporioides species complex caused larger lesions than the isolates from the boninense species complex. Further research is needed to understand the epidemiology of these pathogenic species on areca palm in order to develop management strategies.

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Diaporthalean fungi associated with canker and dieback of trees from Mount Dongling in Beijing, China

MycoKeys ◽

10.3897/mycokeys.59.38055 ◽

2019 ◽

Vol 59 ◽

pp. 67-94 ◽

Cited By ~ 2

Author(s):

Haiyan Zhu ◽

Meng Pan ◽

Guido Bonthond ◽

Chengming Tian ◽

Xinlei Fan

Keyword(s):

Plant Pathogens ◽

Novel Species ◽

Phylogenetic Analyses ◽

Gene Sequences ◽

Morphological Comparison ◽

Disease Symptoms ◽

Wide Range ◽

Plant Families ◽

Beijing China

Diaporthales is a fungal order comprising important plant pathogens, saprobes and endophytes on a wide range of woody hosts. It is often difficult to differentiate the pathogens in this order, since both the morphology and disease symptoms are similar among the various species. In the current study, we obtained 15 representative diaporthalean isolates from six tree hosts belonging to plant families Betulaceae, Fagaceae, Juglandaceae, Rosaceae, and Ulmaceae from Mount Dongling in China. Six species were identified residing in four families of Diaporthales (Diaporthaceae, Erythrogloeaceae, Juglanconidaceae and Melanconidaceae). Based on morphological comparison and the phylogenetic analyses of partial ITS, LSU, cal, his3, rpb2, tef1-α and tub2 gene sequences, we identified five known species (Diaporthe betulina, D. eres, D. rostrata, Juglamconis oblonga and Melanconis stilbostoma) and one novel species (Dendrostoma donglinensis). These results represent the first study of diaporthalean fungi associated with canker and dieback symptoms from Mount Dongling in Beijing, China.

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Identification and characterization of Colletotrichum species associated with Camellia sinensis anthracnose in Anhui province, China

Plant Disease ◽

10.1094/pdis-11-20-2335-re ◽

2020 ◽

Author(s):

Lei Zhang ◽

Xianghan Li ◽

YuanYuan Zhou ◽

Genjia Tan ◽

Lixin Zhang

Keyword(s):

Camellia Sinensis ◽

Phylogenetic Analyses ◽

Morphological Characteristics ◽

Anhui Province ◽

Tea Plantation ◽

Colletotrichum Species ◽

Pathogenicity Tests ◽

Colletotrichum Spp ◽

Identification And Characterization

Recent advances in Colletotrichum taxonomy have led to the need to conduct fresh surveys of Colletotrichum species associated with important crops. Anthracnose caused by Colletotrichum spp., is one of the destructive diseases on Camellia sinensis. In this study, a total of 22 representative Colletotrichum isolates were obtained from diseased leaves of Ca. sinensis cultivated in four tea plantation regions in Anhui province of China. The isolates were identified based on multi-locus (ITS, ACT, CAL, CHS-1, TUB2, GAPDH) phylogenetic analyses, and their morphological characteristics were also analyzed. Twenty-one isolates belonging to C. gloeosporioides complex were identified as C. camelliae, C. fructicola and C. siamense. One isolate belonging to C. boninense complex was identified as C. karstii. Pathogenicity tests revealed that the isolates of C. camelliae and C. fructicola were highly virulent when inoculated on the leaves of detached twigs of Ca. sinensis cv. Shuchazao. Furthermore, it was found that the interspecies virulence was less distinct and individual isolates showed varied virulence when inoculated on different varieties of Ca. sinensis. To our knowledge, this is the first report of C. fructicola, C. siamense and C. karstii causing anthracnose on Ca. sinensis in Anhui province, China.

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Cylindrocladiella peruviana and Pleiocarpon algeriense causing stem and crown rot on avocado (Persea americana)

European Journal of Plant Pathology ◽

10.1007/s10658-020-02082-x ◽

2020 ◽

Vol 158 (2) ◽

pp. 419-430

Author(s):

Dalia Aiello ◽

Giorgio Gusella ◽

Alessandro Vitale ◽

Vladimiro Guarnaccia ◽

Giancarlo Polizzi

Keyword(s):

Morphological Characterization ◽

Persea Americana ◽

Crown Rot ◽

Koch’S Postulates ◽

Fungal Isolates ◽

Pathogenicity Tests ◽

Old Trees ◽

Koch's Postulates

Abstract During the winter of 2018, 3-years-old trees of avocado (Persea americana) cv “Hass” from Trapani province (Sicily, Italy) showed symptoms of stem and crown rot. Two different fungi were consistently isolated from infected tissues. Morphological characterization and multi-locus phylogenies using five genomic loci (ITS, tef1, tub2, his3, and rpb2) identified these fungi as Cylindrocladiella peruviana and Pleiocarpon algeriense. Pathogenicity tests on healthy 5-months-old seedlings and 3-year-old trees of avocado reproduced similar symptoms as those observed in nature, and Koch’s postulates were fulfilled for both pathogens. Moreover, the tested fungal isolates revealed a different pathogenic behaviour among two species. Two isolates of Pleiocarpon algeriense resulted more aggressive than Cylindrocladiella peruviana isolates causing major lesions on young seedlings. This study is the first to report of stem and crown rot on avocado caused by Cylindrocladiella peruviana and Pleiocarpon algeriense.

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Importance of Molecular Data to Identify Fungal Plant Pathogens and Guidelines for Pathogenicity Testing Based on Koch’s Postulates

Pathogens ◽

10.3390/pathogens10091096 ◽

2021 ◽

Vol 10 (9) ◽

pp. 1096

Author(s):

Chitrabhanu S. Bhunjun ◽

Alan J. L. Phillips ◽

Ruvishika S. Jayawardena ◽

Itthayakorn Promputtha ◽

Kevin D. Hyde

Keyword(s):

Fungal Pathogens ◽

Plant Pathogens ◽

Molecular Data ◽

Plant Diseases ◽

Koch’S Postulates ◽

Disease Symptoms ◽

Fungal Plant Pathogens ◽

Bradford Hill ◽

Pathogenicity Testing ◽

Koch's Postulates

Fungi are an essential component of any ecosystem, but they can also cause mild and severe plant diseases. Plant diseases are caused by a wide array of fungal groups that affect a diverse range of hosts with different tissue specificities. Fungi were previously named based only on morphology and, in many cases, host association, which has led to superfluous species names and synonyms. Morphology-based identification represents an important method for genus level identification and molecular data are important to accurately identify species. Accurate identification of fungal pathogens is vital as the scientific name links the knowledge concerning a species including the biology, host range, distribution, and potential risk of the pathogen, which are vital for effective control measures. Thus, in the modern era, a polyphasic approach is recommended when identifying fungal pathogens. It is also important to determine if the organism is capable of causing host damage, which usually relies on the application of Koch’s postulates for fungal plant pathogens. The importance and the challenges of applying Koch’s postulates are discussed. Bradford Hill criteria, which are generally used in establishing the cause of human disease, are briefly introduced. We provide guidelines for pathogenicity testing based on the implementation of modified Koch’s postulates incorporating biological gradient, consistency, and plausibility criteria from Bradford Hill. We provide a set of protocols for fungal pathogenicity testing along with a severity score guide, which takes into consideration the depth of lesions. The application of a standard protocol for fungal pathogenicity testing and disease assessment in plants will enable inter-studies comparison, thus improving accuracy. When introducing novel plant pathogenic fungal species without proving the taxon is the causal agent using Koch’s postulates, we advise the use of the term associated with the “disease symptoms” of “the host plant”. Where possible, details of disease symptoms should be clearly articulated.

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Discovery of Cytospora species associated with canker disease of tree hosts from Mount Dongling of China

MycoKeys ◽

10.3897/mycokeys.62.47854 ◽

2020 ◽

Vol 62 ◽

pp. 97-121 ◽

Cited By ~ 2

Author(s):

Haiyan Zhu ◽

Meng Pan ◽

Jadson D.P. Bezerra ◽

Chengming Tian ◽

Xinlei Fan

Keyword(s):

Plant Pathogens ◽

Novel Species ◽

Phylogenetic Analyses ◽

Gene Sequences ◽

Morphological Comparison ◽

Canker Disease ◽

Worldwide Distribution ◽

Wide Range

Members of Cytospora encompass important plant pathogens, saprobes and endophytes on a wide range of woody hosts with a worldwide distribution. In the current study, we obtained seven representative isolates from six tree hosts of Betulaceae, Juglandaceae, Rosaceae, Tiliaceae and Ulmaceae in Mount Dongling of China. Based on morphological comparison and phylogenetic analyses using partial ITS, LSU, act, rpb2, tef1-α and tub2 gene sequences, we identified two known species (Cytospora leucostoma and C. pruinopsis) and two novel species (C. coryli and C. spiraeicola). These results represent the first study on Cytospora species associated with canker disease from Mount Dongling of China.

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High diversity of Diaporthe species associated with pear shoot canker in China

Persoonia - Molecular Phylogeny and Evolution of Fungi ◽

10.3767/persoonia.2020.45.05 ◽

2020 ◽

Vol 45 (1) ◽

pp. 132-162 ◽

Cited By ~ 2

Author(s):

Y.S. Guo ◽

P.W. Crous ◽

Q. Bai ◽

M. Fu ◽

M.M. Yang ◽

...

Keyword(s):

New Species ◽

Phylogenetic Analyses ◽

Geographical Location ◽

Koch’S Postulates ◽

Important Crop ◽

Wide Range ◽

Crop Diseases ◽

High Degree ◽

Koch's Postulates ◽

High Diversity

Species of Diaporthe (syn. Phomopsis) are important endophytes, saprobes and pathogens, infecting a wide range of plants and resulting in important crop diseases. However, the species occurring on pear remain largely unresolved. In this study, a total of 453 Diaporthe isolates were obtained from branches of Pyrus plants (including P. bretschneideri, P. communis, P. pyrifolia and P. ussuriensis collected from 12 provinces in China) showing shoot canker symptoms. Phylogenetic analyses based on five loci (ITS, TEF, CAL, HIS, and TUB) coupled with morphology of 113 representative isolates revealed that 19 Diaporthe species were isolated, representing 13 known species (including D. caryae, D. cercidis, D. citrichinensis, D. eres, D. fusicola, D. ganjae, D. hongkongensis, D. padina, D. pescicola, D. sojae, D. taoicola, D. unshiuensis and D. velutina) and six new species described here as D. acuta, D. chongqingensis, D. fulvicolor, D. parvae, D. spinosa and D. zaobaisu. Although Koch's postulates confirmed all species to be pathogenic, a high degree of variation in aggressiveness was observed. Moreover, these species have a high diversity, plasticity, and prevalence related to the geographical location and pear species involved.

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Endophytic Colletotrichum Species from Aquatic Plants in Southwest China

Journal of Fungi ◽

10.3390/jof8010087 ◽

2022 ◽

Vol 8 (1) ◽

pp. 87

Author(s):

Hua Zheng ◽

Zefen Yu ◽

Xinwei Jiang ◽

Linlin Fang ◽

Min Qiao

Keyword(s):

Aquatic Plants ◽

Species Complex ◽

Plant Pathogens ◽

Fruits And Vegetables ◽

Southwest China ◽

Phylogenetic Analyses ◽

Its Region ◽

Morphological Characterization ◽

Colletotrichum Species ◽

Species Complexes

Colletotrichum species are plant pathogens, saprobes, and endophytes in many economically important hosts. Many studies have investigated the diversity and pathogenicity of Colletotrichum species in common ornamentals, fruits, and vegetables. However, Colletotrichum species occurring in aquatic plants are not well known. During the investigation of the diversity of endophytic fungi in aquatic plants in southwest China, 66 Colletotrichum isolates were obtained from aquatic plants there, and 26 of them were selected for sequencing and analyses of actin (ACT), chitin synthase (CHS-1), glyceraldehyde-3-phosphate dehydrogenase (GAPDH), the internal transcribed spacer (ITS) region, and β-tubulin (TUB2) genomic regions. Based on morphological characterization and multi-locus phylogenetic analyses, 13 Colletotrichum species were recognized, namely, C. baiyuense sp. nov., C. casaense sp. nov., C. demersi sp. nov., C. dianense sp. nov., C. fructicola, C. garzense sp. nov., C. jiangxiense, C. karstii, C. philoxeroidis sp. nov., C. spicati sp. nov., C. tengchongense sp. nov., C. vulgaris sp. nov., C. wuxuhaiense sp. nov. Two species complexes, the C. boninense species complex and C. gloeosporioides species complex, were found to be associated with aquatic plants. Pathogenicity tests revealed a broad diversity in pathogenicity and aggressiveness among the eight new Colletotrichum species.

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Survey Reveals a Broad Range of Fungal Pathogens and an Oomycete on Peonies in the United States

Plant Health Progress ◽

10.1094/php-09-19-0065-s ◽

2019 ◽

Vol 20 (4) ◽

pp. 250-254

Author(s):

Andrea R. Garfinkel ◽

Gary A. Chastagner

Keyword(s):

United States ◽

Fungal Pathogens ◽

Plant Pathogens ◽

Large Subunit ◽

Ornamental Plants ◽

The United States ◽

Cut Flowers ◽

Koch’S Postulates ◽

Colletotrichum Spp ◽

Koch's Postulates

Peonies, Paeonia lactiflora and hybrids, are popular ornamental plants grown in landscapes and as cut flowers. As with many ornamental plants, the information on the etiology of peony diseases is incomplete with varying amounts of detailed descriptive material; sometimes validation of Koch’s postulates is also lacking. In a survey to identify the range of diseases of peony in the United States, samples were obtained from 12 states. Fungal and oomycete plant pathogens recovered from symptomatic, diseased tissue were identified by morphology and BLAST identification of the internal transcribed spacer, glyceraldehyde 3-phosphate dehydrogenase, the 28s large subunit, and/or cytochrome c oxidase subunit 1 gene nucleotide sequences for representative isolates. Ten fungal or oomycete genera were identified, and Koch’s postulates were confirmed for selected plant pathogens found during this survey. New disease reports are generated for several states, including five genera never previously reported on peonies in the United States: a Botryosphaeria sp., multiple Colletotrichum spp., Mycocentrospora acerina, a Phoma sp., and Pilidium concavum. The information gained from this survey will provide plant disease diagnosticians and growers a more comprehensive resource for understanding the regional prevalence of peony diseases and subsequently making better disease management decisions.

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