colletotrichum spp
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2023 ◽  
Vol 83 ◽  
Author(s):  
L. L. Casas ◽  
J. L. Azevedo ◽  
L. N. Almeida ◽  
P. Q. Costa-Neto ◽  
R. A. Bianco ◽  
...  

Abstract Colletotrichum is one of the most economically important fungal genera, which affects a wide range of hosts, specifically tropical and subtropical crops. Thus far, there have been several records of mycovirus infection in Colletotrichum spp., primarily by viruses of the Partitiviridae family. There have also been records of infections by mycoviruses of the Chrysoviridae family. Mycoviruses are (+)ssRNA and dsRNA genome viruses, which may or may not be enveloped. To date, no mycovirus with a DNA genome has been isolated from Colletotrichum spp. Typically, mycoviruses cause latent infections, although hypo- and hypervirulence have also been reported in Colletotrichum spp. In addition to its effects on pathogenic behavior, mycovirus infection can lead to important physiological changes, such as altered morphological characteristics, reduced vegetative growth, and suppressed conidia production. Therefore, research on mycoviruses infecting phytopathogenic fungi can help develop alternative methods to chemical control, which can cause irreversible damage to humans and the environment. From an agricultural perspective, mycoviruses can contribute to sustainable agriculture as biological control agents via changes in fungal physiology, ultimately resulting in the total loss of or reduction in the virulence of these pathogens.


Author(s):  
Julian David Restrepo Leal ◽  
Deimys Friset Rada González ◽  
Alberto Rafael Páez Redondo

Epidemiological analyzes of foliar diseases associated with Colletotrichum spp. in Enterolobium cyclocarpum and Platymiscium pinnatum  were performed under field  conditions and without any type of intervention. At the  Universidad del Magdalena (Santa Marta, Colombia), four trees for each species and four equidistant monitoring sites per tree were established. The incidence and severity were recorded for 33 weeks (March to November 2016), including two follow-up periods: dry and rainy season. Disease development curves were elaborated. Moreover, the  development rate (r) and the area under the disease  progress curve (AUDPC) were calculated for each follow-up period. The effect of the meteorological variables was  statistically analyzed by correlation and multiple regression. In E. cyclocarpum, the highest incidence and severity were recorded  between September and  November with 100 and 19.6%, respectively, showing a positive correlation with  relative humidity and negative with average temperature, solar radiation and wind speed. In P. pinnatum, the maximum values of incidence and severity were observed  between March and April with 68.9 and 1.3%, respectively. However, correlation analyzes did not support their relationship with the environmental factors. The r values during the dry months were 0.136 and 0.107 units week-1 and the AUDPCs were calculated at 51 and 4 units week-1 for E. cyclocarpum and P. pinnatum, respectively. In the rainy months, the r values were 0.187 and 0.016 units week-1 and the AUDPCs were 186 and 2 units week-1,  respectively. In conclusion, the development of the disease  varies according to the forest species, time of year and some meteorological variables.


2021 ◽  
Vol 27 (4) ◽  
pp. 164-171
Author(s):  
Hyeon-Yeong Ju ◽  
Mi-Ra Son ◽  
Jin-Won Kim

In August 2020, 377 anthracnose strains were isolated from anthracnose-infected peppers collected from 25 farms in Sunchang-gun, Jeollabuk-do. Inhibition rate of mycelial growth of 11 pepper anthracnose fungicides registered in Korea was investigated for 62 strains selected by region and the degree of susceptibility to each fungicide was investigated. As a result of the fungicide susceptibility test of anthracnose to the fungicide, no resistant strains were observed in fluazinam, prochloraz manganese, and benomyl, but resistant strains appeared in at least three areas for other fungicides, and all strains in all regions were resistant to dithianon. Through this, it was confirmed that the fungicide resistance was expressed in the strain group due to the continuous treatment of the fungicide in some areas. By region, resistant strains to seven pesticides appeared in Sunchang-eup and Paldeok-myeon, and resistant strains to six pesticides appeared in Geumgwa-myeon, Bokheung-myeon, Ssangchi-myeon, Yudeung-myeon, and Pungsan-myeon. There was no significant correlation between fungicide registration time and emergence of resistant strains.


Agrociencia ◽  
2021 ◽  
Vol 55 (8) ◽  
pp. 695-709
Author(s):  
Ulises Enrique Campos Ferreira ◽  
Juan Manuel González Camacho

México es el productor principal de aguacate (Persea americana Mill.) en el mundo; sin embargo, este fruto en postcosecha es susceptible a hongos fitopatógenos que reducen su calidad. Por ello, la identificación oportuna de estos organismos con base en herramientas no invasivas, como los análisis por medio de inteligencia artificial resulta de interés para reducir pérdidas económicas. El objetivo de este estudio fue implementar un modelo de aprendizaje automático con una base de datos de imágenes digitales de frutos colectados en campo, a través de crear un clasificador de red neuronal convolucional (CNN), entrenarlo y validarlo para identificar frutos sanos de aguacate cv. Fuerte y frutos infectados con roña (Sphaceloma perseae Jenkins) o antracnosis (Colletotrichum spp.) de la zona productora en el Estado de Morelos, México. Frutos de aguacate sanos se recolectaron en campo, y también frutos con roña y antracnosis de huertos diferentes para generar un conjunto de 569 imágenes digitales. Las transformaciones de éstas aumentaron el conjunto de datos a 3983 imágenes. El modelo CNN se entrenó con una partición aleatoria de 80% de las imágenes y se validó para predicción con el 20% restante. La CNN alcanzó una precisión global de clasificación correcta de 80% con el conjunto de validación. Además, el clasificador se evaluó con un conjunto de prueba de 100 imágenes no incluidas en el conjunto original y obtuvo una precisión global de clasificación correcta de 87%. El clasificador de aprendizaje profundo por CNN implementado en este estudio representa el uso factible de la inteligencia artificial para su aplicación en la identificación de enfermedades en aguacate a partir de imágenes digitales en la etapa de postcosecha.


Plant Disease ◽  
2021 ◽  
Author(s):  
Aichang Chen ◽  
Saba Najeeb ◽  
Yanxia Wang ◽  
Raja Asad Ali Khan ◽  
Xingxing Ping ◽  
...  

In September 2018, severe symptoms and high incidence (about 60%) of an onion anthracnose disease attributable to infection by Colletotrichum spp. was observed in production fields of Dingxi city, Gansu Province, China. The mature onion plants near to harvest (Allium fistulosum L. var. giganteum Makino) expressing necrotic symptoms had oval lesions with dark spots that were made up of stromatic masses that had formed beneath the cuticle of the plant base. Twenty symptomatic plants were sampled. Symptomatic tissues were surface sterilized with sodium hypochlorite, transferred aseptically to 20 mL potato dextrose agar in a petri plate and incubated at 30 ± 2 °C. After seven days, cultures produced acervuli and setae, a characteristic sign of Colletotrichum spp. Acervuli were observed with a black, bulbous base and acicular setae while conidia were elliptical (14-25 x 3-6 µm), unicellular hyaline and slightly falcate (Figure 1). DNA was extracted from a 7-day old culture and the ITS region was amplified using primers D1 (5’-GCATATCAATAAGCGGAGGAAAAG-3’) and D2 (5’-GGTCCGTGTTTCAAGACGG-3’) (Kurtzman and Robnett, 1997). The resulting sequence (548 bp) was deposited with NCBI GeneBank under accession number MW127281. The fungus was confirmed as Colletotrichum circinans after conducting a BLAST search with the ITS sequence that reported a highest homology (99% similarity) with MH81329.1 (C. circinans). The speciation was further confirmed by amplifying regions of the TUB2, GAPDH, and ACT genes using primers given in Table S1 and sequences were also submitted to NCBI GeneBank under accession numbers MZ456033, MZ456032 and MZ456031, respectively. The subsequent BLAST results for these three additional gene regions were consistent with the results of the ITS region and fungus was identified as C. circinans. The isolated pathogen was tested for its pathogenicity on onion plants (Allium fistulosum L. var. giganteum Makino). A conidial suspension 30 ml (5 × 105 conidia/ml) was mixed with 1 kg sterilized potted soil in 15 cm diameter plastic pots. Un-inoculated, sterilized soil was used as control. Three green onion plants per pot were planted (Figure S2). The experiment was repeated three times with 15 replications in each experiment. Plants were maintained for 120 days under greenhouse conditions and were monitored for the development of anthracnose symptoms. Symptoms recorded previously on onion plants in field (i.e. necrosis, sunken oval lesions and dark spots) were observed after 30 days on plants grown in inoculated soil while control plants remained asymptomatic (Figure S1). Three samples from symptomatic tissues of each plant were used for re-isolation of the pathogen on PDA, as described above. Cultures grown on PDA were confirmed both on a morphological and molecular basis as Colletotrichum circinans.These morphological, molecular, and pathogenicity tests of the isolated fungus confirm that the anthracnose symptoms observed on onion in Gansu Province, Beijing, China was caused by Colletotrichum circinans. Six different Colletotrichum spp. have been reported to cause diseases on onion worldwide (Rodriguez et al. 2012). C. circinans, which causes smudge, is an occasional onion pathogen was previously recorded as C. dematium (Pers.) Grove f. circinans Arx, which is specific to Allium spp. (von Arx 1970; von Arx 1981). However, Sutton (1992) described C. circinans as a distinct species from C. dematium. The fungus causes smudge or leaf spot of Allium spp. (Farr et al. 1989) and has been reported from Korea, Japan, Argentina, India, the UK and most other regions of the world (Cho & Shin 2004; Kiehr et al. 2012). Smudge may be a disease of concern post-harvest as fungal growth compromises the onion scales and bulb (Walker 1921). In China, this is the first report of C. circinans causing anthracnose in Allium fistulosum L. var. giganteum Makino in Gansu Province.


Forests ◽  
2021 ◽  
Vol 12 (12) ◽  
pp. 1712
Author(s):  
Xinggang Chen ◽  
Lingyu Jiang ◽  
Anhua Bao ◽  
Changlin Liu ◽  
Junang Liu ◽  
...  

Camellia yuhsienensis Hu, a species of tea oil tree with resistance to anthracnose, is widely used to breed disease-resistant Camellia varieties. In 2019, anthracnose symptoms were observed on Ca. yuhsienensis for the first time. However, the species and biological characteristics of Colletotrichum spp. isolated from Ca. yuhsienensis (YX-Colletotrichum spp.) have not been elucidated. In this study, five isolates (YX2-5-2, 2YX-3-1, 2YX-5-1, 2YX-8-1-1 and 2YX-8-1-2), which were consistent with the morphological characteristics of Colletotrichum spp., were obtained from Ca. yuhsienensis. A phylogenetic analysis demonstrated that YX2-5-2, 2YX-3-1 and 2YX-8-1-2 belonged to first clade along with Colletotrichum fructicola. 2YX-8-1-1 belonged to the second clade along with Colletotrichum siamense. 2YX-5-1 belonged to the third clade with Colletotrichum camelliae. Pathogenicity tests revealed that the pathogenicity of YX-Colletotrichum spp. was stronger than that of Colletotrichum spp. isolated from Camellia oleifera (GD-Colletotrichum spp.). Biological characteristics illustrated that the mycelial growth of YX-Co. camelliae (2YX-5-1) was slower than that of GD-Co. camelliae when the temperature exceeded 20 °C. In addition, in the presence of ions, the mycelial growth of YX-Co. fructicola (YX2-5-2) and YX-Co. siamense (2YX-8-1-1) was also slower than that of GD-Co. fructicola and GD-Co. siamense. Furthermore, the ability of YX-Colletotrichum spp. to utilize lactose and mannitol was weaker than that of GD-Colletotrichum spp., while the ability to utilize NH4+ was generally stronger than that of GD-Colletotrichum spp. This is the first report of anthracnose of Ca. yuhsienensis induced by Co. fructicola, Co. siamense and Co. camelliae in China. These results will provide theoretical guidance for the study of the pathogenesis and control of anthracnose on Ca. yuhsienensis.


2021 ◽  
Vol 4 (4) ◽  
pp. 6012-6020
Author(s):  
Manuel Ángel Gómez Cruz ◽  
Laura Gómez Tovar ◽  
Luis Enrique Ortíz-Martínez ◽  
Alejandro Hernández-Carlos

México es el cuarto productor de cítricos a nivel mundial (FAOSTAT, 2019) y el estado de Veracruz aporta el 53 % de la producción nacional (SIAP, 2019). El problema de la abscisión de frutos de naranja cobró importancia en 2017, pero ya existía este problema desde hace 15 años, lo cual ocasiona pérdidas en la producción del 20% en la zona Norte de Veracruz (Gómez et al., 2020). El ataque de patógenos: Colletotrichum spp, Botryodiplodia spp, Fusarium spp, Citrus tristeza virus (VTC), Candidatus Liberibacter asiaticus (CLas), Citrus exocortis viroid (CEVd) y Hop stunt viroid (HSVd); pueden influir, entre otros factores, en la caída de naranja. El experimento se llevó a cabo en la huerta `Grupo Los Gómez’ en el ejido de San Pablo, Papantla, Veracruz, México; en naranja ‘Valencia’ portainjerto ‘Agrio’ y en suelo tipo aluvión. El objetivo central de la investigación fue evaluar 15 insumos agroecológicos para disminuir la abscisión de naranja, 7 de estos insumos con micorrizas y el resto sin su aplicación. Los tratamientos con mejores resultados fueron: Agua de vidrio (1.25 %) + Micorriza; Optifer amino (0.5 %) + Micorriza; y EM (5 %) + Micorriza con menor porcentaje de caída de naranja con 4.97%, 5.79%, 6.10% respectivamente. 


Pathogens ◽  
2021 ◽  
Vol 10 (11) ◽  
pp. 1520
Author(s):  
Thaís R. Boufleur ◽  
Nelson S. Massola Júnior ◽  
Ísis Tikami ◽  
Serenella A. Sukno ◽  
Michael R. Thon ◽  
...  

Colletotrichum is one of the most important plant pathogenic genus of fungi due to its scientific and economic impact. A wide range of hosts can be infected by Colletotrichum spp., which causes losses in crops of major importance worldwide, such as soybean. Soybean anthracnose is mainly caused by C. truncatum, but other species have been identified at an increasing rate during the last decade, becoming one of the most important limiting factors to soybean production in several regions. To gain a better understanding of the evolutionary origin of soybean anthracnose, we compared the repertoire of effector candidates of four Colletotrichum species pathogenic to soybean and eight species not pathogenic. Our results show that the four species infecting soybean belong to two lineages and do not share any effector candidates. These results strongly suggest that two Colletotrichum lineages have acquired the capability to infect soybean independently. This study also provides, for each lineage, a set of candidate effectors encoding genes that may have important roles in pathogenicity towards soybean offering a new resource useful for further research on soybean anthracnose management.


2021 ◽  
Vol 22 (22) ◽  
pp. 12454
Author(s):  
Thomas Svoboda ◽  
Michael R. Thon ◽  
Joseph Strauss

Colletotrichum is a plant pathogenic fungus which is able to infect virtually every economically important plant species. Up to now no common infection mechanism has been identified comparing different plant and Colletotrichum species. Plant hormones play a crucial role in plant-pathogen interactions regardless whether they are symbiotic or pathogenic. In this review we analyze the role of ethylene, abscisic acid, jasmonic acid, auxin and salicylic acid during Colletotrichum infections. Different Colletotrichum strains are capable of auxin production and this might contribute to virulence. In this review the role of different plant hormones in plant—Colletotrichum interactions will be discussed and thereby auxin biosynthetic pathways in Colletotrichum spp. will be proposed.


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