scholarly journals First Report of Aspergillus flavus Causing Fruit Rot on Kiwifruit in China

Plant Disease ◽  
2021 ◽  
Author(s):  
Guiyang Zhu ◽  
Xin Wang ◽  
Tangmin Chen ◽  
Suyan Wang ◽  
Xin Chen ◽  
...  
Keyword(s):  
Rna Polymerase Ii ◽  
Rhizopus Oryzae ◽  
Elongation Factor ◽  
Soft Rot ◽  
Fruit Rot ◽  
Local Market ◽  
Single Spore ◽  
Safety Hazards ◽  
First Report ◽  
Molecular Phylogenetic

In October 2020, fruit rot symptoms were detected on kiwifruit (Actinidia chinensis var. deliciosa ‘Xuxiang’) in southwestern Shaanxi (Hanzhong municipality; 107.27° E, 33.23° N) in China. Mature kiwifruit, during the harvest period, exhibited soft rot and brown lesions. The symptoms were similar than those reported for Alternaria alternata, Colletotrichum spp., Fusarium avenaceum and Rhizopus oryzae causing fruit rot on kiwifruit (Feng et al. 2019; Li et al. 2017; Kim et al. 2018; Zhao et al. 2020). The symptoms were observed in approximately 15% of the fruit in 6 kiwifruit orchards (31 ha in total). Ten samples of symptomatic tissue, approximately 1 cm2 in size, were sterilized in 2% NaOCl for 30 seconds and washed twice with sterilized water. The pathogen was isolated from all collected samples via culturing on PDA medium, containing 50 µg/mL chloramphenicol, at 28 ºC. Green powdery-like colonies were detected after 5 days (Figure 1). A total of 12 isolates were obtained via single spore isolation. Internal transcribed spacer (ITS), elongation factor 1-α (EF1-α) and RNA polymerase II subunit (RPB2) genes were amplified using ITS5/ITS4, A_EF1_F/A_EF1_R and RPB2-5F/RPB2-7cR (NJC03), or RPB2-7cF/RPB2-11aR (NJC04), primers, respectively. Eleven isolates shared the same sequences (NJC03), MZ801787 (ITS), MZ701709 (EF1-α) and MZ701707 (RPB2), while one of the isolates provided different sequences (NJC04), OK618459 (ITS), OK634020 (EF1-α) and OL331017 (RPB2). The obtained ITS sequences shared >99% homology to the ITS gene from A. flavus KU20018.4 (MT487825), the EF1-α sequences shared 100% homology to the EF1-α gene from A. flavus clinical2342 (KP054370) and the RPB2 sequences shared >99% homology to the RPB2 genes from A. flavus PW3170 (LC000581) and A. flavus NRRL3357 (XM_041293948). Molecular phylogenetic tree was constructed using MEGA7 with reference Aspergillus strains (Figure 2). Microscope observations of all isolates showed the presence of septate mycelium, circular unicellular conidia (2-4 µm diameter) and conidiophores, and agree with the morphology of A. flavus (Horn 2005). The pathogenicity of all isolates was screened using intact and wounded ‘Xuxiang’ kiwifruits (ten kiwifruits were used for each combination with 3 replicates), which were purchased from a local market. A 1 × 106 spores/mL (10 µL) solution of the isolates was used for the inoculation. Sterilized water was used in the control experiment. Inoculated kiwifruits were storage at 26 °C and 60% relative humidity for 10 days. Rot lesions in the wounded kiwifruits were totally covered by green mycelia, while the lesions on the intact kiwifruits were similar to the symptoms observed in the field. The pathogen was recovered and its identity was confirmed by sequence analysis of ITS, EF1-α and RPB2, fulfilling Koch’s postulates. A. flavus is known to be an important fungal pathogen of corn, cotton and peanuts (Zhang et al. 2020). During recent years, A. flavus was reported to cause fruit rot on grapes (Ghuffar et al. 2020), and was identified on almond, fig, organic spelt and pistachio (Krulj et al. 2017; Ortega-Beltran et al. 2019). The presence of A. flavus in food products is an issue of global concern due to A. flavus is able to produce carcinogenic aflatoxin (Maxwell et al. 2021). As far as we know, this is the first report of A. flavus causing fruit rot on kiwifruit. This report will help to understand the distribution of A. flavus in crops and the food safety hazards that are present in China.

scholarly journals First Report of Fusarium proliferatum Causing Fruit Rot on Muskmelon (Cucumis melo L.) in China

Plant Disease ◽  
2021 ◽  
Author(s):  
Xiaoyan Yu ◽  
Jing Zhang ◽  
Lifeng Guo ◽  
Aoran Yu ◽  
Xiangjing Wang ◽  
...  
Keyword(s):  
Rna Polymerase Ii ◽  
Phylogenetic Trees ◽  
Salvia Miltiorrhiza ◽  
Disease Incidence ◽  
Morphological Characteristics ◽  
Fusarium Proliferatum ◽  
Fruit Rot ◽  
Single Spore ◽  
Effective Prevention ◽  
First Report

Muskmelon is an economically important crop in the world, especially in China, the largest producer of muskmelon with an annual output up to 12.7 million tonnes (Gómez-García et al. 2020). Since 2018, fruit rot was observed on muskmelon in Malianzhuang Base, the main muskmelon producing area in Shandong Province, whose disease incidence was about 25-30%. Water-soaked dark brown spots were initially appeared on the side of the fruit near the ground, then gradually expanded and covered with white mold with time. To isolate the pathogens, ten muskmelon fruits with typical symptoms were collected from different greenhouses in the base. Small tissues taken from the edge of the diseased and healthy tissues were immersed in 1% NaClO for 2 min, then soaked in 75% ethanol for 30 s, and rinsed 3 times with sterile distilled water (SDW). The sterilized tissues were naturally dried and placed on potato dextrose agar (PDA) amended with streptomycin sulfate (50 mg/L) for 7 days at 28℃. The emerging fungal mycelia were transferred to fresh PDA using the hyphal tip technology. Ten colonies were purified by single spore method and cultured on PDA for 7 days at 28℃ in the dark for morphological and molecular analyses. All colonies were flocculent with abundant white to light purple aerial hyphae, and the undersides of the colonies were observed to be from white to purple over time. Microconidia produced on PDA were hyaline, fusiform, ovoid, single cell without septum, and 4.5 to 12.7 × 2.0 to 3.6 μm in size (n=50). Macroconidia produced on carboxymethylcellulose agar (CMC) were slightly curved at both ends with three to five septa, and 17.6 to 35.7 × 2.8 to 4.0 μm in size (n=30). According to the morphological characteristics, these isolates were preliminarily identified as Fusarium sp. (Leslie and Summerell 2006). To further identify these isolates, genomic DNA of five isolates was extracted by CTAB method (Wu et al. 2001). The internal transcribed spacer (ITS) region of ribosomal DNA, translation elongation factor 1-α (TEF1) region, and the RNA polymerase II second largest subunit (RPB2) were amplified by PCR amplification with primers ITS1/ITS4, EF-1/EF-2, and RPB2-5F2/fRPB2-7cR, respectively (White et al. 1990; O’Donnell et al. 2008; Liu et al. 1999). Sequences of the five isolates were identical. The ITS, EF1-α, and RPB2 gene sequences of isolate NEAU-Mf-10-2 were submitted to NCBI GenBank with accession numbers of MZ950914, MZ960928, and MZ960929, respectively, having 100% similarity to those of Fusarium proliferatum (MK372368, MK952799 and MN245721). Phylogenetic trees were constructed based on the concatenated sequences of EF1-α and RPB2 genes using neighbour-joining and maximum-likelihood algorithms with MEGA 7.0. Two similar tree topologies both showed isolate NEAU-Mf-10-2 clustered with F. proliferatum NRRL 43665. Therefore, isolate NEAU-Mf-10-2 was identified as F. proliferatum based on morphological characteristics and phylogenetic analysis. To fulfill Koch’s postulates, ten muskmelon fruits (var. Tianbao) were soaked in 2% NaClO for 2 min, and then washed three times with SDW. Muskmelon fruits were inoculated by injecting conidia suspension (200 μL, 1×106 spores/mL) with a sterile injector. Ten other surface sterilized muskmelon fruits inoculated with sterile water were used as control. The fruits were placed in a light incubator at 28℃ with 12h light cycles for 7 days. All inoculated fruits showed symptoms highly similar to those of infected muskmelon fruits observed in the field. No symptoms were observed on fruits used as control. The Fusarium isolates were successfully re-isolated from the symptomatic fruits, and identified based on above morphological and molecular biological methods. Previous studies have reported that F. proliferatum can infect Polygonatum cyrtonema, Salvia miltiorrhiza, Allium cepa, A. sativum, and so on. To our knowledge, this is the first report of F. proliferatum causing fruit rot on muskmelon in China, which will provide basic information for designing effective prevention and control strategies on this disease.

scholarly journals First Report of Fruit Blotch on Plum caused by Fusarium fujikuroi in China

Plant Disease ◽  
2021 ◽  
Author(s):  
Haijiang Long ◽  
Xianhui Yin ◽  
Zhibo Zhao ◽  
Youhua Long ◽  
Juan Fan ◽  
...  
Keyword(s):  
Rna Polymerase Ii ◽  
Sequence Data ◽  
Apical Cell ◽  
Pcr Amplification ◽  
Fruit Rot ◽  
Guizhou Province ◽  
Universal Primers ◽  
Fusarium Fujikuroi ◽  
Single Spore ◽  
First Report

Plum is commercially cultivated worldwide for the rich nutrient in its fruit. In May 2019, plum with symptoms of fruit rot were collected from fields located in Liuma town, Guizhou Province, China. The incidence of the disease varied from 10 to 20%, which was observed in 15 plum orchards (18 hectares) surveyed. Estimated yield loss was~5 to 10% for each field. Diseased fruits showed deformity, wilting and sunken lesions, and subsequenly became melanized and rotted. Diseased tissues were surface disinfected with 70% ethanol for 45 s and rinsed with sterile distilled water three times. Four morphologically similar colonies with white fluffy aerial mycelium and a reddish pigment were obtained after 3 days incubation on potato dextrose agar (PDA) at 25°C. Four single-spore isolates produced conidia with 1 to 2 septa that were sickle-shaped, thin-walled with a tapering and curved apical cell, measuring 15.6 to 29.6 × 4.8 to 8.7 μm (average 19.5×5.9 μm, n=50). Based on the cultural and conidial morphology, the isolates were identified as Fusarium (Mun et al. 2012; Leslie and Summerell 2006). DNA of two isolates was extracted using the Ezup Column Fungal Genomic DNA Extraction Kit (Sangon Bioengineering Shanghai, LTD.). To confirm the morphological diagnosis, DNA sequence data from three loci were obtained. PCR amplification was carried out with universal primers ITS1/ITS4 (White et al. 1990), translation elongation factor (EF-1α), EF1-H (5′-ATGGGTAAGGAAGACAAGAC-3′) and EF2-T (5′-GGAAGTACCAGTGATCATGTT-3′) (O’Donnell et al. 1998) and the second largest subunit of RNA polymerase II (RPB2), 5F2(5′-GGGGWGAYCAGAAGAAGGC-3′) and 7cR (5′-CCCATRGCTTGYTTRCCCAT-3′) (O’Donnell et al. 2007). Primers ITS1 and ITS4 produced a 559-bp amplicon (GenBank accession. MW085028). BLAST analysis showed 100% sequence identity to sequences of several species, deposited in GenBank, including F. fujikuroi. The EF-1α sequence (MW086868) was 100% identical to that of Fusarium fujikuroi (MN193860.1). The RPB2 primers amplified a fragment (MW086869) that was 99.9% identical to that of F. fujikuroi (MN193888.1). The BLASTn results based on the partial EF-1α and RPB2 sequences suggest isolate HJGF1 is F. fujikuroi. A pathogenicity assay was conducted using an agar disk inoculation method on plum. Fruits were stab inoculated with HJGF1 by piercing 1-mm at 3 points using a sterile needle, and fruits were mock inoculated with sterile PDA, each fruit was inoculated with three disks. (Fig. 1). The treated fruit were maintained in a growth chamber with 90% relative humidity at 25°C, and a daily 12-h photoperiod. After 5 days, the artificially inoculated fruit showed blotches with sunken lesions similar to those observed in the orchards, whereas no symptoms were observed on the control fruit. The experiment was repeated twice with similar results. F. fujikuroi was reisolated from infected tissues and confirmed by sequence analysis. To our knowledge, this is the first report of F. fujikuroi causing fruit blotch of plum in China. Considering the economic importance of plum in China and throughout the world, F. fujikuroi may be an emerging problem for plum cultivation. Thus, further study of fruit blotch of plum is warranted.

scholarly journals Phylogeny and Mycotoxin Profile of Pathogenic Fusarium Species Isolated from Sudden Decline Syndrome and Leaf Wilt Symptoms on Date Palms (Phoenix dactylifera) in Tunisia

Toxins ◽  
2021 ◽  
Vol 13 (7) ◽  
pp. 463
Author(s):  
Amal Rabaaoui ◽  
Chiara Dall’Asta ◽  
Laura Righetti ◽  
Antonia Susca ◽  
Antonio Logrieco ◽  
...  
Keyword(s):  
Rna Polymerase Ii ◽  
Fusarium Solani ◽  
Fusarium Species ◽  
Elongation Factor ◽  
Phoenix Dactylifera ◽  
Fusarium Proliferatum ◽  
Fruit Rot ◽  
Morphological Identification ◽  
Single Strain ◽  
Date Palms

In 2017–2018, extensive symptoms of sudden decline and fruit rot were observed on date palms in southern Tunisia. Samples of diseased plants were randomly collected in six localities. Based on morphological identification, Fusarium was the most frequent fungal genus detected. A sequencing of translation elongation factor, calmodulin, and second largest subunit of RNA polymerase II genes was used to identify 63 representative Fusarium strains at species level and investigate their phylogenetic relationships. The main species detected was Fusarium proliferatum, and at a much lesser extent, Fusarium brachygibbosum, Fusarium caatingaense, Fusarium clavum, Fusarium incarnatum, and Fusarium solani. Pathogenicity on the Deglet Nour variety plantlets and the capability to produce mycotoxins were also assessed. All Fusarium species were pathogenic complying Koch’s postulates. Fusarium proliferatum strains produced mainly fumonisins (FBs), beauvericin (BEA), and, to a lesser extent, enniatins (ENNs) and moniliformin (MON). All F. brachygibbosum strains produced low levels of BEA, diacetoxyscirpenol, and neosolaniol; two strains produced also T-2 toxin, and a single strain produced HT-2 toxin. Fusarium caatingaense, F. clavum, F. incarnatum produced only BEA. Fusarium solani strains produced MON, BEA, and ENNs. This work reports for the first time a comprehensive multidisciplinary study of Fusarium species on date palms, concerning both phytopathological and food safety issues.

scholarly journals First Report of a Fruit Rot of Pumpkin Caused by Acidivorax avenae subsp. citrulli in Georgia

Plant Disease ◽  
1999 ◽  
Vol 83 (2) ◽  
pp. 199-199 ◽  
Author(s):  
D. B. Langston ◽  
R. D. Walcott ◽  
R. D. Gitaitis ◽  
F. H. Sanders
Keyword(s):  
Polyclonal Antibodies ◽  
Pcr Amplification ◽  
Tween 80 ◽  
Soft Rot ◽  
Fruit Rot ◽  
Identification System ◽  
Banding Patterns ◽  
First Report ◽  
Microbial Identification ◽  
Necrotic Spots

In September 1998, a fruit rot was reported affecting pumpkin (Cucurbita pepo) in a commercial field in Terrell Co., Georgia. Symptoms on the surface of fruit occurred as round, necrotic spots or cracks a few millimeters in diameter. With age, the tissue surrounding these lesions became soft and wrinkled. A soft rot expanded into the flesh of the pumpkin, originating from the lesions observed on the surface. In time, infected pumpkins totally collapsed. V-shaped, necrotic lesions occurred at the margin of the leaf and extended inward toward the mid-rib. Samples were collected from the field and bacteria were isolated from fruit and leaf lesions onto King's medium B (1). The bacterium isolated was rod shaped, gram negative, nonflourescent, oxidase positive, Tween 80 positive, carboxymethyl cellulose positive, β-OH butyrate positive, and malonate negative. The bacterium reacted positively with polyclonal antibodies specific for the watermelon fruit blotch pathogen Acidivorax avenae subsp. citrulli and was identified as A. avenae subsp. citrulli by MIDI (Microbial Identification System, Newark, DE) according to statistical analysis of fatty acid data. Results from polymerase chain reaction (PCR) amplification of the bacterium isolated from pumpkin yielded 360-bp fragments that, when digested with the restriction enzyme HaeIII, had DNA banding patterns identical to those of stock A. avenae subsp. citrulli DNA. Koch's postulates were completed successfully with 2-week-old watermelon seedlings. This is the first report of A. avenae subsp. citrulli causing fruit rot of pumpkin in Georgia. Reference: (1) E. O. King et al. J. Lab. Clin. Med. 44:301, 1954.

scholarly journals First Report of Fruit Rot of Melon Caused by Fusarium asiaticum in China

Plant Disease ◽  
2020 ◽  
Author(s):  
Fangmin Hao ◽  
Quanyu Zang ◽  
Weihong Ding ◽  
Erlei Ma ◽  
Yunping Huang ◽  
...  
Keyword(s):  
Disease Incidence ◽  
Elongation Factor ◽  
Morphological Characteristics ◽  
Its Region ◽  
Fruit Rot ◽  
Post Inoculation ◽  
Basal Cells ◽  
First Report ◽  
Fusarium Asiaticum ◽  
Sterile Needle

Melon (Cucumis melo L.) is a member of the Cucurbitaceae family, an important economical and horticultural crop, which is widely grown in China. In May 2020, fruit rot disease with water-soaked lesions and pink molds on cantaloupe melons was observed in several greenhouses with 50% disease incidence in Ningbo, Zhejiang Province in China. In order to know the causal agent, diseased fruits were cut into pieces, surface sterilized for 1 min with 1% sodium hypochlorite (NaClO), 2 min with 75% ethyl alcohol, rinsed in sterile distilled water three times (Zhou et al. 2018), and then placed on potato dextrose agar (PDA) medium amended with streptomycin sulfate (100 μg/ml) plates at 25°C for 4 days. The growing hyphae were transferred to new PDA plates using the hyphal tip method, putative Fusarium colonies were purified by single-sporing. Twenty-five fungal isolates were obtained and formed red colonies with white aerial mycelia at 25°C for 7 days, which were identified as Fusarium isolates based on the morphological characteristics and microscopic examination. The average radial mycelial growth rate of Fusarium isolate Fa-25 was 11.44 mm/day at 25°C in the dark on PDA. Macroconidia were stout with curved apical and basal cells, usually with 4 to 6 septa, and 29.5 to 44.2 × 3.7 to 5.2 μm on Spezieller Nährstoffarmer agar (SNA) medium at 25°C for 10 days (Leslie and Summerell 2006). To identify the species, the internal transcribed spacer (ITS) region and translational elongation factor 1-alpha (TEF1-α) gene of the isolates were amplified and cloned. ITS and TEF1-α was amplified using primers ITS1/ITS4 and EF1/EF2 (O’Donnell et al. 1998), respectively. Sequences of ITS (545 bp, GenBank Accession No. MT811812) and TEF1-α (707 bp, GenBank Acc. No. MT856659) for isolate Fa-25 were 100% and 99.72% identical to those of F. asiaticum strains MSBL-4 (ITS, GenBank Acc. MT322117.1) and Daya350-3 (TEF1-α, GenBank Acc. KT380124.1) in GenBank, respectively. A phylogenetic tree was established based on the TEF1-α sequences of Fa-25 and other Fusarium spp., and Fa-25 was clustered with F. asiaticum. Thus, both morphological and molecular characterizations supported the isolate as F. asiaticum. To confirm the pathogenicity, mycelium agar plugs (6 mm in diameter) removed from the colony margin of a 2-day-old culture of strain Fa-25 were used to inoculate melon fruits. Before inoculation, healthy melon fruits were selected, soaked in 2% NaClO solution for 2 min, and washed in sterile water. After wounding the melon fruits with a sterile needle, the fruits were inoculated by placing mycelium agar plugs on the wounds, and mock inoculation with mycelium-free PDA plugs was used as control. Five fruits were used in each treatment. The inoculated and mock-inoculated fruits were incubated at 25°C with high relative humidity. Symptoms were observed on all inoculated melon fruits 10 days post inoculation, which were similar to those naturally infected fruits, whereas the mock-inoculated fruits remained symptomless. The fungus re-isolated from the diseased fruits resembled colony morphology of the original isolate. The experiment was conducted three times and produced the same results. To our knowledge, this is the first report of fruit rot of melon caused by F. asiaticum in China.

scholarly journals First Report of Rhizopus oryzae Causing Potato Soft Rot in the Hebei Province of China

Plant Disease ◽  
2019 ◽  
Vol 103 (4) ◽  
pp. 773 ◽  
Author(s):  
W. G. Cui ◽  
H. L. Zheng ◽  
F. B. Zhang ◽  
B. Swingle ◽  
H. T. Zhu ◽  
...  
Keyword(s):  
Rhizopus Oryzae ◽  
Soft Rot ◽  
Hebei Province ◽  
First Report

scholarly journals Multi-gene phylogeny and taxonomy of Amauroderma s. lat. (Ganodermataceae)

2020 ◽  
Vol 44 (1) ◽  
pp. 206-239 ◽  
Author(s):  
Y.-F. Sun ◽  
D.H. Costa-Rezende ◽  
J.-H. Xing ◽  
J.-L. Zhou ◽  
B. Zhang ◽  
...  
Keyword(s):  
Rna Polymerase ◽  
Rna Polymerase Ii ◽  
Phylogenetic Analyses ◽  
Large Subunit ◽  
Elongation Factor ◽  
Morphological Examination ◽  
Translation Elongation ◽  
Multiple Loci ◽  
Phylogenetic Studies ◽  
Molecular Phylogenetic

Amauroderma s.lat. has been defined mainly by the morphological features of non-truncate and double-walled basidiospores with a distinctly ornamented endospore wall. In this work, taxonomic and phylogenetic studies on species of Amauroderma s.lat. are carried out by morphological examination together with ultrastructural observations, and molecular phylogenetic analyses of multiple loci including the internal transcribed spacer regions (ITS), the large subunit of nuclear ribosomal RNA gene (nLSU), the largest subunit of RNA polymerase II (RPB1) and the second largest subunit of RNA polymerase II (RPB2), the translation elongation factor 1-α gene (TEF) and the β-tubulin gene (TUB). The results demonstrate that species of Ganodermataceae formed ten clades. Species previously placed in Amauroderma s.lat. are divided into four clades: Amauroderma s.str., Foraminispora, Furtadoa and a new genus Sanguinoderma. The classification of Amauroderma s. lat. is thus revised, six new species are described and illustrated, and eight new combinations are proposed. SEM micrographs of basidiospores of Foraminispora and Sanguinoderma are provided, and the importance of SEM in delimitation of taxa in this study is briefly discussed. Keys to species of Amauroderma s.str., Foraminispora, Furtadoa, and Sanguinoderma are also provided.

scholarly journals First Report of Fruit Rot Disease on Pomelo Caused by Lasiodiplodia theobromae in China

Plant Disease ◽  
2011 ◽  
Vol 95 (9) ◽  
pp. 1190-1190 ◽  
Author(s):  
M. Luo ◽  
Z. Y. Dong ◽  
S. Y. Bin ◽  
J. T. Lin
Keyword(s):  
Its Region ◽  
Fruit Rot ◽  
Economic Losses ◽  
Single Spore ◽  
Lasiodiplodia Theobromae ◽  
First Report ◽  
Potted Plants ◽  
Diseased Fruit ◽  
Long Time ◽  
Water Plants

Pomelo (Citrus grandis) is widely cultivated in MeiZhou Guangdong Province of China. In 2008, a disease on pomelo fruit caused significant economic losses by affecting fruit quality. Diseased fruit was collected in December 2008 from MeiZhou Guangdong, surface sterilized in 75% ethanol for 1 min and internal necrotic tissue was transferred to potato dextrose agar (PDA) and incubated at 28°C for 5 days. Three single-spore isolates were obtained from different fruit and identified as Lasiodiplodia theobromae (Pat.) Griffon & Maubl. (synonyms Diplodia natalensis Pole-Evans and Botryodiplodia theobromae Pat.; teleomorph Botryosphaeria rhodina (Cooke) Arx) on the basis of morphological and physiological features. The fungus produced dark brown colonies (initially grayish) on PDA. Young hyphae were hyaline and aseptate, whereas mature hyphae were septate with irregular branches. Cultures of L. theobromae produced globular or irregular pycnidia abundantly on PDA (pH 3.5) at 28°C after 1 month. Mature conidia of L. theobromae were 20 to 26 × 12 to 15.5 μm, subovoid to ellipsoid-ovoid, initially hyaline and nonseptate, remaining hyaline for a long time, and finally becoming dark brown and one septate with melanin deposits on the inner surface of the wall arranged longitudinally giving a striate appearance to the conidia. The internal transcribed spacer (ITS) region of the rDNA was amplified from gDNA using primers ITS1 (5′-TCCGATGGTGAACCTGCGG-3′) and ITS4 (5′-TCCTCCGCTTATTGATATGC-3′) (1). Amplicons were 542 bp long (GenBank Accession No. JF693024) and had 100% nucleotide identity with the corresponding sequence (GenBank Accession No. EU860391) of L. theobromae isolated from a Pinus sp. (2). To satisfy Koch's postulates, six asymptomatic fruit on potted plants were sprayed until runoff with a spore suspension (1 × 106 spores/ml) prepared from 30-day-old cultures of one isolate. Control fruit received water. Plants were covered with sterile wet gauze to maintain high humidity. Fruit spot symptoms similar to those on diseased field fruit appeared after 15 days on all inoculated fruits. L. theobromae was reisolated from all inoculated test fruit. No symptoms were observed on the fruit of control plants. To our knowledge, this is the first report of L. theobromae causing disease on pomelo fruit in China. This pathogen has also been previously reported to be economically important on a number of other hosts by mostly affecting the leaves. References: (1) J. C. Batzer et al. Mycologia 97:1268, 2005. (2) C. A. Pérez et al. Fungal Divers. 41:53,2010.

scholarly journals First report of Trichoderma afroharzianum causing seed rot on maize in Italy

Plant Disease ◽  
2022 ◽  
Author(s):  
Martina Sanna ◽  
Massimo Pugliese ◽  
Maria Lodovica GULLINO ◽  
Monica Mezzalama
Keyword(s):  
Rna Polymerase Ii ◽  
Elongation Factor ◽  
Aerial Mycelium ◽  
Light Cycle ◽  
Conidial Suspension ◽  
Ear Rot ◽  
Trichoderma Spp ◽  
Trichoderma Species ◽  
First Report ◽  
Pathogenicity Tests

Maize (Zea mays L.) is a cereal crop of great economic importance in Italy; production is currently of 60,602,320 t, covering 588,597 ha (ISTAT 2021). Trichoderma species are widespread filamentous fungi in soil, well known and studied as biological control agents (Vinale et al., 2008). Seeds of a yellow grain hybrid (class FAO 700, 132 days) were collected in September 2020 from an experimental field located in Carmagnola (TO, Italy: GPS: 44°53'11.0"N 7°40'60.0"E) and tested with blotter test (Warham et al., 1996) to assess their phytosanitary condition. Over the 400 seeds tested, more than 50% showed rotting and development of green mycelium typical of the genus Trichoderma. Due to the high and unexpected percentage of decaying kernels, ten colonies were identified by morphological and molecular methods. Single conidia colonies of one Trichoderma (T5.1) strain were cultured on Potato Dextrose Agar (PDA) for pathogenicity tests, and on PDA and Synthetic Nutrient-Poor Agar (SNA) for morphological and molecular identification. The colonies grown on PDA and SNA showed green, abundant, cottony, and radiating aerial mycelium, and yellow pigmentation on the reverse. Colony radius after 72 h at 30°C was of 60-65 mm on PDA and of 50-55 mm on SNA. The isolates produced one cell conidia 2.8 - 3.8 µm long and 2.1 - 3.6 µm wide (n=50) on SNA. Conidiophores and phialides were lageniform to ampulliform and measured 4.5 – 9.7 µm long and 1.6 – 3.6 µm wide (n=50); the base measure 1.5 – 2.9 µm wide and the supporting cell 1.4 – 2.8 µm wide (n=50). The identity of one single-conidia strain was confirmed by sequence comparison of the internal transcribed spacer (ITS), the translation elongation factor-1α (tef-1α), and RNA polymerase II subunit (rpb2) gene fragments (Oskiera et al., 2015). BLASTn searches of GenBank using ITS (OL691534) the partial tef-1α (OL743117) and rpb2 (OL743116) sequences of the representative isolate T5.1, revealed 100% identity for rpb2 to T. afroharzianum TRS835 (KP009149) and 100% identity for tef-1α to T. afroharzianum Z19 (KR911897). Pathogenicity tests were carried out by suspending conidia from a 14-days old culture on PDA in sterile H2O to 1×106 CFU/ml. Twenty-five seeds were sown in pots filled with a steamed mix of white peat and perlite, 80:20 v/v, and maintained at 23°C under a seasonal day/night light cycle. Twenty primary ears were inoculated, by injection into the silk channel, with 1 ml of a conidial suspension of strain T5.1 seven days after silk channel emergence (BBCH 65) (Pfordt et al., 2020). Ears were removed four weeks after inoculation and disease severity, reaching up to 75% of the kernels of the twenty cobs, was assessed visually according to the EPPO guidelines (EPPO, 2015). Five control cobs, inoculated with 1 ml of sterile distilled water were healthy. T. afroharzianum was reisolated from kernels showing a green mold developing on their surface and identified by resequencing of tef-1α gene. T. afroharzianum has been already reported on maize in Germany and France as causal agent of ear rot of maize (Pfordt et al. 2020). Although several species of Trichoderma are known to be beneficial microorganisms, our results support other findings that report Trichoderma spp. causing ear rot on maize in tropical and subtropical areas of the world (Munkvold and White, 2016). The potential production of mycotoxins and the losses that can be caused by the pathogen during post-harvest need to be explored. To our knowledge this is the first report of T. afroharzianum as a pathogen of maize in Italy.

scholarly journals First Report of Calonectria hongkongensis Causing Fruit Rot of Rambutan (Nephelium lappaceum)

Plant Disease ◽  
2013 ◽  
Vol 97 (8) ◽  
pp. 1117-1117 ◽  
Author(s):  
L. M. Serrato-Diaz ◽  
E. I. Latoni-Brailowsky ◽  
L. I. Rivera-Vargas ◽  
R. Goenaga ◽  
P. W. Crous ◽  
...  
Keyword(s):  
Mycelial Growth ◽  
Elongation Factor ◽  
Type Specimen ◽  
Fruit Rot ◽  
Fluorescent Light ◽  
Mycelium Growth ◽  
Tropical Fruit ◽  
First Report ◽  
Nephelium Lappaceum ◽  
Pure Cultures

Fruit rot of rambutan is a pre- and post-harvest disease problem of rambutan orchards. In 2011, fruit rot was observed at USDA-ARS orchards in Mayaguez, Puerto Rico. Infected fruit were collected and 1 mm2 tissue sections were surface disinfested with 70% ethanol followed by 0.5% sodium hypochlorite. Infected fruit were rinsed with sterile, deionized, double-distilled water and transferred to acidified potato dextrose agar (APDA). Plates were incubated at 25 ± 1°C for 6 days. Three isolates of Calonectria hongkongensis (Cah), CBS134083, CBS134084, and CBS134085, were identified morphologically using taxonomic keys (2,3). In APDA, colonies of Cah produced raw sienna to rust-colored aerial mycelial growth. Conidiophores of Cah had a penicillate arrangement of primary to quaternary branches of 2 to 6 phialides. Conidia (n = 50) were cylindrical, hyaline, 1-septate, rounded at both ends, and 44 to 52 μm × 3.5 to 4.5 μm. Conidiophores produced terminal and lateral stipe extensions with terminal sphaeropedunculate vesicles that were 8 to 12 μm wide. Subglobose to ovoid perithecia, 300 to 500 μm × 200 to 350 μm and orange to red-brown, were produced in groups of 3. Asci were clavate and contained 8 ascospores aggregated at the top of the ascus. Ascospores (n = 50) were hyaline, guttulate, fusoid with rounded ends, straight to curved, 1-septate with constriction at the septum, and 28 to 36 μm × 4 to 7 μm. For molecular identification, the ITS rDNA, fragments of β-tubulin (BT), histone H3 (HIS3), and elongation factor (EF1-α) genes were amplified by PCR, sequenced, and compared using BLASTn with Calonectria spp. submitted to the NCBI GenBank. The sequences of Cah submitted to GenBank include accessions KC342208, KC342206, and KC342207 for ITS; KC342217, KC342215, and KC342216 for BT; KC342211, KC342209, and KC342210 for HIS3; and KC342214, KC342212, and KC342213 for EF1α. The sequences were >99% or identical with the ex-type specimen of Cah CBS 114828 for all genes used. Pathogenicity tests were conducted on 5 healthy superficially sterilized fruits per isolate. Both scalpel-wounded and unwounded fruit tissues were inoculated with 5-mm mycelial disks from 8-day-old pure cultures grown in APDA. Untreated controls were inoculated with APDA disks only. Fruits were kept in a humid chamber for 8 days at 25°C under 12 h of fluorescent light. The test was repeated once. Three days after inoculation (DAI), white mycelial growth was observed on the fruit. Five DAI, the fruit changed color from red to brown and yellowish mycelia colonized 50 to 62% of the fruit surface. Eight DAI, all the fruit turned brown, the mycelium growth covered the entire fruit, and conidiophores were produced on spinterns (hairlike appendages). Fruit rot of spinterns, exocarp (skin), endocarp (aril), and light brown discoloration were observed inside the fruit. Untreated controls showed no symptoms of fruit rot and no fungi were reisolated from tissue. Cah was reisolated from diseased tissue, fulfilling Koch's postulates. Calonectria spp. (or their Cylindrocladium asexual states) have been associated with lychee decline syndrome in North Vietnam (1). Both fruits belong to the Sapindaceae family. To our knowledge, this is the first report of Cah causing fruit rot of rambutan. References: (1) L. M. Coates et al. Diseases of Longan, Lychee and Rambutan. Pages 307-325 in: Diseases of Tropical Fruit Crops. R. C. Ploetz, ed. CABI Publishing, Cambridge, MA, 2003. (2) P. W. Crous. Taxonomy and Pathology of Cylindrocladium (Calonectria) and Allied Genera. APS Press, St Paul, MN, 2002. (3) P. W. Crous, et al. Stud. Mycol. 50:415, 2004.

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