scholarly journals Species Diversity, Mating Strategy and Pathogenicity of Calonectria Species from Diseased Leaves and Soils in the Eucalyptus Plantation in Southern China

2021 ◽  
Vol 7 (2) ◽  
pp. 73
Author(s):  
WenXia Wu ◽  
ShuaiFei Chen
Keyword(s):  
Species Diversity ◽  
Southern China ◽  
Elongation Factor ◽  
Morphological Characteristics ◽  
Reproductive Mode ◽  
Mating Strategy ◽  
Leaf Blight ◽  
Eucalyptus Plantation ◽  
Type Assignment ◽  
Epidemiological Characteristics

Many Calonectria species are causal agents of diseases on several forestry, agricultural and horticultural crops. Calonectria leaf blight is one of the most important diseases associated with Eucalyptus plantations and nurseries in Asia and South America. Recently, symptoms of leaf rot and leaf blight caused by Calonectria species were observed in a one-year-old Eucalyptus experimental plantation in GuangXi Province, southern China. To better understand the species diversity, mating strategy and pathogenicity of Calonectria species isolated from diseased tissues and soils, diseased leaves and soils under the trees from ten Eucalyptus urophylla hybrid genotypes were collected. Three hundred and sixty-eight Calonectria isolates were obtained from diseased Eucalyptus leaves and soils under these trees, and 245 representative isolates were selected based on the sampling substrates and Eucalyptus genotypes and identified by DNA sequence analyses based on the translation elongation factor 1-alpha (tef1), β-tubulin (tub2), calmodulin (cmdA) and histone H3 (his3) gene regions, as well as a combination of morphological characteristics. These isolates were identified as Calonectria hongkongensis (50.2%), C. pseudoreteaudii (47.4%), C. aconidialis (1.6%), C. reteaudii (0.4%) and C. auriculiformis (0.4%). This is the first report of C. reteaudii and C. auriculiformis occurrence in China. Calonectria pseudoreteaudii was isolated from both Eucalyptus diseased leaves and soils; the other four species were only obtained from soils. MAT1-1-1 and MAT1-2-1 gene amplification and mating type assignment results showed that C. pseudoreteaudii is heterothallic and an asexual cycle represents the primary reproductive mode, C. reteaudii and C. auriculiformis are likely to be heterothallic and C. hongkongensis and C. aconidialis are homothallic. Based on the genetic diversity comparisons for C. pseudoreteaudii isolates from diseased leaves and soils, we hypothesize that C. pseudoreteaudii in soils was spread from diseased leaves. Both the mycelia plug and conidia suspension inoculations indicated that all five Calonectria species were pathogenic to the two Eucalyptus genotypes tested and the tolerance of the two genotypes differed. It is necessary to understand the ecological niche and epidemiological characteristics of these Calonectria species and to select disease resistant Eucalyptus genotypes in southern China in the future.

scholarly journals Calonectria pentaseptata Causes Severe Leaf Disease of Cultivated Eucalyptus on the Leizhou Peninsula of Southern China

Plant Disease ◽  
2020 ◽  
Vol 104 (2) ◽  
pp. 493-509
Author(s):  
QuanChao Wang ◽  
ShuaiFei Chen
Keyword(s):  
Southern China ◽  
Eucalyptus Grandis ◽  
Elongation Factor ◽  
Morphological Characteristics ◽  
Single Species ◽  
Leaf Blight ◽  
Eucalyptus Species ◽  
Leizhou Peninsula ◽  
Susceptibility To Infection ◽  
Shoot Blight

Eucalyptus (Myrtaceae, Myrtales) trees are widely cultivated for commercial purposes worldwide. Calonectria leaf blight is one of the most prominent diseases associated with Eucalyptus trees grown in plantations in Asia and South America. Recently, symptoms of leaf blight, shoot blight, tree death, and seedling rot caused by Calonectria species have been observed in commercial Eucalyptus plantations and nurseries in Leizhou Peninsula, which is one of the most densely Eucalyptus-planted areas in southern China. Disease samples were collected from 10 Eucalyptus species and a number of Eucalyptus grandis, E. tereticornis, and E. urophylla hybrid genotypes that were planted on plantations at 13 sites and one experimental nursery. A total of 773 isolates of Calonectria were obtained from 683 plantation trees and nursery seedlings. Fifty-five representative isolates from all the surveyed sites and Eucalyptus species/genotypes were selected for molecular identification. These 55 isolates were identified by DNA sequence analyses based on the calmodulin (cmdA), histone H3 (his3), translation elongation factor 1-alpha (tef1), and β-tubulin (tub2) gene regions, as well as a combination of morphological characteristics. The results indicated that these 55 isolates present one single species, Calonectria pentaseptata. Determined by sequences of cmdA, his3, tef1, and tub2 gene regions, only two genotypes were identified among the 55 representative isolates; 54 of these isolates share the same genotype, suggesting that the genetic diversity of Ca. pentaseptata collected during this study was relatively low. A growth study indicated that Ca. pentaseptata is a high-temperature species. The mating test results suggested that Ca. pentaseptata is heterothallic or lacks the ability to recombine to produce fertile progeny. Inoculation results showed that Ca. pentaseptata causes leaf blight and stem rot, resulting in tree death of the two widely planted Eucalyptus genotypes in southern China, and that the two genotypes differ significantly in their susceptibility to infection by Ca. pentaseptata. A selection program to develop Eucalyptus planting stocks with high levels of resistance to Calonectria leaf blight in China during the long-term should be urgently initiated. [Formula: see text] Copyright © 2020 The Author(s). This is an open access article distributed under the CC BY-NC-ND 4.0 International license .

scholarly journals Leaf blight on Photinia × fraseri caused by Pestalotiopsis trachicarpicola in China

Plant Disease ◽  
2021 ◽  
Author(s):  
Xiulan Xu ◽  
Si-yi Liu ◽  
Yicong Lv ◽  
Qian Zeng ◽  
Yinggao Liu ◽  
...  
Keyword(s):  
Yellow River ◽  
Large Subunit ◽  
Elongation Factor ◽  
Morphological Characteristics ◽  
Its Region ◽  
Yellow River Basin ◽  
Green Plant ◽  
Leaf Blight ◽  
Leaf Margin ◽  
Basal Cells

Photinia × fraseri is a well-known green plant mainly distributed in the Yangtze River and Yellow River Basin, east and southwest of China (Guan et al. 2013). In October 2020, typical leaf blight symptoms on roughly 10% leaves in a Photinia × fraseri shrub were observed in the campus of Sichuan Agricultural University (30°42′19″ N, 103°51′29″ E). Initially, chlorotic lesions with brown margins occurred on the leaf margin, then the large patches formed to cause leaves necrotic, finally lesions to dry and acervulus bred in 2–4 months later. Five single conidium isolates were carried out (Chomnunti et al. 2014) cultured on potato dextrose agar (PDA) at 25 ℃. All isolates shared similarly morphological characteristics, which was white and thin, and the reverse were yellowish. Mycelium was hyaline, sparsely septate, measuring 1–4 μm in diam. Conidiogenesis formed after 7 days. Conidiogenous cells were discrete, lageniform, smooth, thin-walled, colorless. Conidia were fusiform, straight to slightly curved, 4-septate, 21–30 × 5–7 μm (x ̅= 27 × 6.0 μm, n=30); basal cells were obconic with truncate base, hyaline, thin- and smooth-walled, 4–7 μm long (x ̅= 5.5 μm, n=30); three median cells were doliiform with thick walls, concolorous, olivaceous, constricted at the septa, and septa and periclinal walls were darker than the rest of the cell, 14–20 μm long (x ̅= 17 μm, n=30); apical cells were hyaline, conic to cylindrical, 3.0–6.5 μm long (x ̅= 4.5 μm, n=30), with 2–4 (mostly 3) tubular apical appendages arising from the upper portion, rarely branched, 7.5–18 μm long (x ̅= 12 μm, n=50); basal appendage was single, unbranched, 3–10 μm long (x ̅= 6.5 μm, n=30). DNA was extracted from the representative strain (SICAUCC 21-0012), and the internal transcribed spacer (ITS) region, the large subunit of the nrDNA (LSU), translation elongation factor 1-alpha (tef1-α), and partial sequences of β-tubulin (tub2) were amplified by polymerase chain reaction and sequenced with primers ITS5/ITS4, LR0R/LR5, 728F/1567R, and Bt2a/Bt2b, respectively (Zhang et al. 2012, Ariyawansa & Hyde 2018). The sequences were deposited in GenBank, viz. MZ453106, MZ453108, MZ467300, MZ467301, respectively. The nucleotide blast showed 99% (ITS, 0 gaps), 100% (tub2, 0 gaps), 100% (tef1-α, 0 gaps) identities with the ex-type Pestalotiopsis trachicarpicola Yan M. Zhang & K. D. Hyde (IFRDCC 2440). The fungus was identified as P. trachicarpicola combined with phylogeny and morphology (Maharachchikumbura et al. 2012, Zhang et al. 2012). To conduct Koch’s postulates, five healthy 6-year-old P. × fraseri were inoculated with 10 µl spore suspension (106 conidia/ml) onto the wounded sites (five leaves per plant, ~1 to 2 years old) via sterile pin, and five healthy plants treated with sterile dH2O as controls (Yang et al. 2021). The plants were placed in a greenhouse at 25°C with relative humidity >80%. After 2 months, leaf blight symptoms gradually emerged on inoculated leaves, and the controls were symptomless. Fungal isolates from symptomatic plants showed similar morphological characteristics as SICAUCC 21-0012, and the pathogen was not isolated from asymptomatic plants. To our knowledge, this is the first report of leaf blight caused by P. trachicarpicola on Photinia × fraseri in China. Disease management should be adopted properly to restore and improve its ornamental value.

scholarly journals Shoot Blight on Chinese Fir (Cunninghamia lanceolata) is Caused by Bipolaris oryzae

Plant Disease ◽  
2018 ◽  
Vol 102 (3) ◽  
pp. 500-506 ◽  
Author(s):  
Lin Huang ◽  
Ya-Nan Zhu ◽  
Ji-Yun Yang ◽  
De-Wei Li ◽  
Yong Li ◽  
...  
Keyword(s):  
Southern China ◽  
Phylogenetic Analyses ◽  
Large Subunit ◽  
Elongation Factor ◽  
Morphological Characteristics ◽  
Chinese Fir ◽  
Cunninghamia Lanceolata ◽  
Timber Species ◽  
Bipolaris Oryzae ◽  
Shoot Blight

Chinese fir (Cunninghamia lanceolata) is a significant timber species that has been broadly cultivated in southern China. A shoot blight disease on Chinese fir seedlings was discovered in Fujian, China and a fungus was then consistently associated with the symptoms. This fungus was determined to be causing this disease, among others by fulfilling Koch’s postulates. Based on morphological characteristics and multilocus phylogenetic analyses with the sequences of the internal transcribed spacer, partial glyceraldehyde-3-phosphate dehydrogenase gene, partial translation elongation factor 1-α gene, and partial 28S large subunit ribosomal RNA gene, the fungus was identified as Bipolaris oryzae. These characteristics and phylogenetic analyses clearly support that this pathogen is different from B. sacchari, which was, until now, considered to be the causal agent of a similar blight on Chinese fir in Guangdong, China. The fungus was also shown to be strongly pathogenic to rice, one of the most susceptible hosts to B. oryzae. Crop rotation involving rice is often carried out with Chinese fir in southern China, a practice that most likely increases the risk of shoot blight on C. lanceolata. To our knowledge, shoot blight caused by B. oryzae is reported for the first time in a gymnosperm species.

scholarly journals Phylogeny and Pathogenicity of Celoporthe Species from Plantation Eucalyptus in Southern China

Plant Disease ◽  
2018 ◽  
Vol 102 (10) ◽  
pp. 1915-1927 ◽  
Author(s):  
Wen Wang ◽  
QianLi Liu ◽  
GuoQing Li ◽  
FeiFei Liu ◽  
ShuaiFei Chen
Keyword(s):  
Dna Sequence ◽  
Southern China ◽  
Eucalyptus Grandis ◽  
Morphological Characteristics ◽  
Stem Canker ◽  
Undescribed Species ◽  
Sequence Comparisons ◽  
Translation Elongation ◽  
Eucalyptus Plantation ◽  
Hybrid Clones

The family of Cryphonectriaceae (Diaporthales) includes many important tree pathogens, such as those that cause severe cankers on Eucalyptus trees. Recently, stem canker and cracked bark were observed on 8-year-old Eucalyptus grandis × E. urophylla trees in a plantation in southern China. Fruiting structures typical of Cryphonectriaceae fungi were observed on the surface of the diseased tissues. In this study, the isolated fungi were identified based on DNA sequence analyses and morphological characteristics, and their pathogenicity was tested on three Eucalyptus clones. DNA sequence comparisons of the internal transcribed spacer (ITS) regions (including the intervening 5.8S nrRNA gene), two regions of β-tubulin (BT2/BT1), and partial translation elongation factor1-α (TEF-1α), indicated that these isolates represent Celoporthe syzygii and one previously undescribed species. The undescribed species was also morphologically distinct from the other species of Celoporthe. The new species was described and named C. cerciana sp. nov. The results of this study based on the ITS, BT2/BT1, and TEF-1α sequences indicated that more than one haplotype was isolated from the same Eucalyptus tree. The findings of a previous study, whereby C. eucalypti was isolated from the same plantation as that of this study, revealed the high species diversity of Celoporthe within a single plantation, which is associated with a single Eucalyptus sp. in southern China. The results further suggested that hybridization may occur between C. syzygii and C. eucalypti. In addition to the Eucalyptus trees, C. syzygii was also isolated from native Melastoma candidum in the same Eucalyptus plantation. The inoculation results showed that these fungi isolated from E. grandis × E. urophylla and M. candidum are pathogenic to all three tested E. grandis hybrid clones. Significant differences in tolerance were observed between the tested Eucalyptus clones, suggesting that disease-tolerant Eucalyptus genotypes can be selected for disease management.

scholarly journals Morphology, Phylogeny and Pathogenicity of Pestalotioid Species on Camellia oleifera in China

2021 ◽  
Vol 7 (12) ◽  
pp. 1080
Author(s):  
Lingling Li ◽  
Qin Yang ◽  
He Li
Keyword(s):  
Woody Plant ◽  
Sequence Data ◽  
Southern China ◽  
Elongation Factor ◽  
Morphological Characteristics ◽  
Camellia Oleifera ◽  
Translation Elongation Factor ◽  
Translation Elongation ◽  
Elongation Factor 1 Alpha ◽  
Elongation Factor 1

Tea-oil tree (Camellia oleifera) is an important edible oil woody plant with a planting area of over 3,800,000 hectares in southern China. Pestalotioid fungi are associated with a wide variety of plants worldwide along with endophytes, pathogens, and saprobes. In this study, symptomatic leaves of C. oleifera were collected from Guangdong, Guangxi, Hainan, Hunan, and Jiangsu Provinces and pestalotioid fungi are characterized based on combined sequence data analyses of internal transcribed spacer (ITS), beta tubulin (tub2), and translation elongation factor 1-alpha (tef-1α) coupled with morphological characteristics. As a result, seven species were confirmed, of which five species are described as new viz. N. camelliae-oleiferae, P. camelliae-oleiferae, P. hunanensis, P. nanjingensis, P. nanningensis, while the other two are reported as known species, viz., N. cubana and N. iberica. Pathogenicity assays showed that all species except for P. nanjingensis developed brown lesions on healthy leaves and P. camelliae-oleiferae showed stronger virulence.

scholarly journals First Report of Diaporthe longicolla Causing Leaf Spot on Kalanchoe pinnata in China

Plant Disease ◽  
2021 ◽  
Author(s):  
Xiaodong Sun ◽  
Xinglai Cai ◽  
Qiangqiang Pang ◽  
Man Zhou ◽  
Wen Zhang ◽  
...  
Keyword(s):  
Leaf Spot ◽  
Southern China ◽  
Elongation Factor ◽  
Morphological Characteristics ◽  
Negative Control ◽  
Hainan Province ◽  
Conidial Suspension ◽  
Single Spore ◽  
First Report ◽  
Kalanchoe Pinnata

Kalanchoe pinnata (Lam.) Pers. [syn.: Bryophyllum pinnatum (Lam.) Oken] is an important medicinal agent in southern China. The succulent leaves of this plant are used in the treatment of cholera, bruises, uri­nary diseases and whitlow. In Oct. 2019, leaf spots were detected on K. pinnata plants in Chengmai County, Hainan Province, China. Lesions with brown to black margins were irregularly shaped and associated with leaf margins. Spots coalesced to form larger lesions (Fig. S1-A), with black pycnidia present in more mature lesions. Symptomatic K. pinnata were found with 10-20% incidence during the humid winters of Hainan Province. Leaf tissues of 10 symptomatic plants were collected and surface sterilized in 70% ETOH for 30s, 0.1% HgCl2 for 30 s, rinsed 3x with sterile distilled water for 30s, placed on potato dextrose agar (PDA) amended with 30mg/L of kanamycin sulfate, and incubated at 25°C in the dark for 3-5 days. Four fungal isolates were obtained using a single-spore isolation method. The colonies were floccose, dense, and white with forming on older colonies grown on PDA (Fig. S1-B-1&2). Alpha conidia exuded from ostiole, rostrate, long-beaked pycnidia in creamy-to-yellowish drops. Alpha conidia were hyaline, ellipsoidal, separated and averaged 6.3μm (SD ± 1.13) long × 1.9μm (SD ± 0.33) wide (n=50). Beta conidia were not seen. The morphological characteristics matched the previous description of Diaporthe longicolla (syn. Phomopsis longicolla) (Hobbs et al. 1985). Mycelial genomic DNA of the representative isolate LDSG3-2 was extracted as template. The internal transcribed spacer (ITS) , translation elongation factor 1α gene (TEF) and β-tubulin (TUB2) regions were amplified. These loci were amplified using primer pairs ITS4/ITS5 (White, et al. 1990), EF1-728F/EF1-986R (Carbone and Kohn 1999) and Bt2a/Bt2b (Glass and Donaldson 1995), respectively. A BLAST search of GenBank showed ITS (MN960195), TEF (MN974483) and TUB2 (MN974482) sequences of the isolate were 99%, 100%, and 99% homologous with D. longicolla strains DL11 (MF125048, 557/563 bp), D55 (MN584792, 347/347 bp) and DPC-HOH-32 (MK161506, 502/504 bp). Maximum likelihood trees based on concatenated nucleotide sequences of the three genes were constructed using MEGA 7.0, and bootstrap values indicated the isolate was D. longicolla (Fig. S1-D). Pathogenicity testing was performed using isolate LDSG3-2 by depositing 5µl droplets of a conidial suspension (1 × 106 ml-1) into 5 artificially wounded leaves (using a sterile needle) of 10 healthy 3-month-old K. pinnata plants. An equal number of artificially wounded control leaves were inoculated with sterile water to serve as a negative control. The test was conducted three times. Plants were kept at 25°C in 80% relative humidity and observed for symptoms. Two weeks after inoculation, no symptoms were observed on control plants (Fig. S1-C-1) and all inoculated plants showed symptoms (Fig. S1-C-2) similar to those observed in the field. The fungus was re-isolated from the infected tissues and showed the same cultural and morphological characteristics of the strain inoculated and could not be isolated from the controls fulfilling Koch’s postulates. To our knowledge, this is the first report of leaf spot on K. pinnata caused by D. longicolla in China. This disease is of concern since Phomopsis diseases are common in K. pinnata fields and can cause significant reduction in yield. References: White, T. J., et al. 1990. Page 315 in: PCR Protocols: A Guide to Methods and Applications. Academic Press, San Diego, CA. DOI: 10.1016/0167-7799(90)90215-J Carbone, I., and Kohn, L. M. 1999. Mycologia. 91:553. DOI: 10.2307/3761358 Glass, N. L., and Donaldson, G. C. 1995. Appl. Environ. Microbiol. 61:1323. DOI: 10.1002/bit.260460112 Hobbs, T. W. et al. 1985. Mycologia. 77: 535. DOI: 10.2307/3793352

scholarly journals Identification of Lasiodiplodia pseudotheobromae Causing Fruit Rot of Citrus in China

Plants ◽  
2021 ◽  
Vol 10 (2) ◽  
pp. 202
Author(s):  
Jianghua Chen ◽  
Zihang Zhu ◽  
Yanping Fu ◽  
Jiasen Cheng ◽  
Jiatao Xie ◽  
...  
Keyword(s):  
Phylogenetic Analyses ◽  
Elongation Factor ◽  
Morphological Characteristics ◽  
Citrus Fruit ◽  
Economic Loss ◽  
Fruit Rot ◽  
Post Inoculation ◽  
Citrus Reticulata ◽  
Postharvest Diseases ◽  
Citrus Reticulata Blanco

Considering the huge economic loss caused by postharvest diseases, the identification and prevention of citrus postharvest diseases is vital to the citrus industry. In 2018, 16 decayed citrus fruit from four citrus varieties—Satsuma mandarin (Citrus unshiu), Ponkan (Citrus reticulata Blanco cv. Ponkan), Nanfeng mandarin (Citrus reticulata cv. nanfengmiju), and Sugar orange (Citrus reticulata Blanco)—showing soft rot and sogginess on their surfaces and covered with white mycelia were collected from storage rooms in seven provinces. The pathogens were isolated and the pathogenicity of the isolates was tested. The fungal strains were identified as Lasiodiplodia pseudotheobromae based on their morphological characteristics and phylogenetic analyses using the internal transcribed spacer regions (ITS), translation elongation factor 1-α gene (TEF), and beta-tubulin (TUB) gene sequences. The strains could infect wounded citrus fruit and cause decay within two days post inoculation, but could not infect unwounded fruit. To our knowledge, this is the first report of citrus fruit decay caused by L. pseudotheobromae in China.

A molecular analysis reveals hidden species diversity within the current concept of Russula maculata (Russulaceae, Basidiomycota)

Phytotaxa ◽  
2016 ◽  
Vol 270 (2) ◽  
pp. 71 ◽  
Author(s):  
SLAVOMÍR ADAMČÍK ◽  
MIROSLAV CABOŇ ◽  
URSULA EBERHARDT ◽  
MALKA SABA ◽  
FELIX HAMPE ◽  
...  
Keyword(s):  
Species Diversity ◽  
Molecular Analysis ◽  
Morphological Characteristics ◽  
Its Region ◽  
The Other ◽  
Deciduous Forests ◽  
European Species ◽  
Spore Ornamentation ◽  
Sister Clade ◽  
Broad Concept

The current generally accepted concept of Russula maculata defines the species by yellow-brownish spots on the basidiomata, an acrid taste, a yellow spore print and a red pileus. This concept was tested using collections originating from various geographical areas mainly in Europe. Analyses of the ITS region suggested that there were three species within this broad concept. One of them, R. maculata, was identified based on the sequence from the epitype. Two other species, R. nympharum and R. sp., are described here as newly identified species. The European species R. maculata and R. nympharum grow in deciduous forests, are similar in their field aspect and are distinctly different in micro-morphological characteristics of spores, pleurocystidia and pileipellis. An Asian species, R. sp., is associated with pine and has smaller basidiomata and spores. These three species form the R. maculata complex and represent the sister clade to the R. globispora complex. This clade consists of species also characterized by a yellow-brownish context discolouration but with a different type of spore ornamentation. All of the other tested species had an acrid taste and yellow spore print but did not have a conspicuous yellow-brownish context discolouration and were placed in various unrelated clades.

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