Colletotrichum
20.2K views | +4 today
Follow
 
Scooped by Serenella A Sukno
onto Colletotrichum
Scoop.it!

Gene/QTL discovery for Anthracnose in common bean (Phaseolus vulgaris L.) from North-western Himalayas

Gene/QTL discovery for Anthracnose in common bean (Phaseolus vulgaris L.) from North-western Himalayas | Colletotrichum | Scoop.it
Abstract

Common bean (Phaseolus vulgaris L.) is one of the most important grain legume crops in the world. The beans grown in north-western Himalayas possess huge diversity for seed color, shape and size but are mostly susceptible to Anthracnose disease caused by seed born fungus Colletotrichum lindemuthianum. Dozens of QTLs/genes have been already identified for this disease in common bean world-wide. However, this is the first report of gene/QTL discovery for Anthracnose using bean germplasm from north-western Himalayas of state Jammu & Kashmir, India. A core set of 96 bean lines comprising 54 indigenous local landraces from 11 hot-spots and 42 exotic lines from 10 different countries were phenotyped at two locations (SKUAST-Jammu and Bhaderwah, Jammu) for Anthracnose resistance. The core set was also genotyped with genome-wide (91) random and trait linked SSR markers. The study of marker-trait associations (MTAs) led to the identification of 10 QTLs/genes for Anthracnose resistance. Among the 10 QTLs/genes identified, two MTAs are stable (BM45 & BM211), two MTAs (PVctt1 & BM211) are major explaining more than 20% phenotypic variation for Anthracnose and one MTA (BM211) is both stable and major. Six (06) genomic regions are reported for the first time, while as four (04) genomic regions validated the already known QTL/gene regions/clusters for Anthracnose. The major, stable and validated markers reported during the present study associated with Anthracnose resistance will prove useful in common bean molecular breeding programs aimed at enhancing Anthracnose resistance of local bean landraces grown in north-western Himalayas of state Jammu and Kashmir.
more...
No comment yet.
Colletotrichum
All about the anthracnose fungus, plant pathogen, fungus pathogen, plant microbe interactions, plant disease, evolution, genomics
Your new post is loading...
Your new post is loading...
Scooped by Serenella A Sukno
Scoop.it!

The expression of the genes involved in redox metabolism and hydrogen peroxide balance is associated with the resistance of cowpea to the hemibiotrophic fungus Collet...

The expression of the genes involved in redox metabolism and hydrogen peroxide balance is associated with the resistance of cowpea to the hemibiotrophic fungus Collet... | Colletotrichum | Scoop.it

Correlations between the transcriptional responses of genes that encode superoxide dismutase (SOD), catalase (CAT), ascorbate peroxidase (APX), and peroxiredoxin (Prx) enzymes and Colletotrichum gloeosporioides development in cowpea leaves were assessed. Each of these genes is involved in the redox metabolism and hydrogen peroxide balance. Although electron microscopy revealed that conidia adhered to and germinated on the leaf cuticle, the inoculated cowpea leaves did not show any characteristic anthracnose symptoms. The adhered and germinated conidia showed irregular surfaces and did not develop further. This was apparently due to increased leaf H2O2 levels in response to inoculation with C. gloeosporioides. During the early stages post inoculation, cowpea leaves elevated the H2O2 content and modulated the defense gene expression, as well as associated pathways. During the later stages, the increased expression of the CuZnSODI and CuZnSODII genes suggested an active superoxide dismutation to further elevate H2O2 levels, which indicated that higher H2O2 content may function as a toxic agent that kills the fungus. The second increase in H2O2 production above the threshold level was correlated with the expression of the APXI, CATI, CATII, PrxIIBCD, and PrxIIE genes, which resulted in a coordinated pattern to establish an appropriate balance between H2O2 generation and scavenging. Therefore, appropriate H2O2 content in cowpea leaves inhibited C. gloeosporioides development and maintained intracellular redox homeostasis to avoid uncontrolled programmed cell death and necrosis in cowpea leaves.


more...
No comment yet.
Scooped by Serenella A Sukno
Scoop.it!

 Differences in the Characteristics and Pathogenicity of Colletotrichum camelliae and C. fructicola Isolated From the Tea Plant [Camellia sinensis (L.) O. Kuntze] 

 Differences in the Characteristics and Pathogenicity of Colletotrichum camelliae and C. fructicola Isolated From the Tea Plant [Camellia sinensis (L.) O. Kuntze]  | Colletotrichum | Scoop.it
Colletotrichum, the causative agent of anthracnose, is an important pathogen that invades the tea plant (Camellia sinensis). In this study, 38 isolates were obtained from the diseased leaves of tea plants collected in different areas of Zhejiang Province, China. A combination of multigene (ITS, ACT, GAPDH, TUB2, CAL, and GS) and morphology analyses showed that the 38 strains belonged to two different species, namely, C. camelliae (CC), and C. fructicola (CF). Pathogenicity tests revealed that CC was more invasive than CF. In vitro inoculation experiments demonstrated that CC formed acervuli at 72 hpi and developed appressoria on wound edges, but CF did not develop these structures. Under treatment with catechins and caffeine, the growth inhibition rates of CF were remarkably higher than those of CC, indicating that the nonpathogenic species CF was more vulnerable to catechins and caffeine. Growth condition testing indicated that CF grew at a wide temperature range of 15–35°C and that the optimum temperature for CC growth was 25°C. Growth of both CC and CF did not differ between acidic and weakly alkaline environments (pH 5–8), but the growth of CC was significantly reduced at pH values of 9 and 10. Furthermore, the PacC/RIM101 gene, which associated with pathogenicity, was identified from CC and CF genomes, and its expression was suppressed in the hyphae of both species under pH value of 5 and 10, and much lower expression level was detected in CC than that in CF at pH 6. These results indicated that temperature has more important effect than pH for the growth of two Colletotrichum species. In conclusion, the inhibition by secondary metabolite is an important reason why the pathogenicity by CC and CF are different to tea plant, although the environmental factors including pH and temperature effect the growth of two Colletotrichum species.

more...
No comment yet.
Scooped by Serenella A Sukno
Scoop.it!

 Diversity of Colletotrichum Species Associated with Olive Anthracnose and New Perspectives on Controlling the Disease in Portugal

 Diversity of Colletotrichum Species Associated with Olive Anthracnose and New Perspectives on Controlling the Disease in Portugal | Colletotrichum | Scoop.it
Abstract
Olive anthracnose is a very common and severe disease caused by diverse species of fungi belonging to Colletotrichumacutatum and Colletotrichumgloeosporioides complexes. To understand aspects of the Colletotrichum colonization and primary infection in olives, Colletotrichum spp. were isolated from the interior of 2-year stems, flower buds, and immature fruits of three important olive cultivars, Galega vulgar, Cobrançosa, and Azeiteira, from different sites within Alentejo, a major olive-producing region in Portugal. A total of 270 trees was sampled, and 68 Colletotrichum spp. isolates were obtained from 46 olive trees. DNA extraction and amplification of β-tubulinand GADPH genes through PCR revealed that the vast majority of the isolates showed high similarity to Colletotrichum nymphaeae, and only three isolates showed high similarity to Colletotrichumgodetiae. The highest number of Colletotrichum spp. isolates was detected in olive trees from Galega vulgar and in immature fruits. No significant differences in the number of Colletotrichum spp. isolates were found in trees from different sites. The highest percentages of infected immature fruits were obtained in trees that also presented a high percentage of 2-year stem infections, which may indicate that 2-year stems serve as important sources of inoculum, and the fungus may travel from the stems to other parts of the plant. Another indication of such possibility is that one isolate of C.nymphaeae (C.nymphaeae 2), characterized by a unique nucleotide mutation within the beta tubulin gene, was present in different organs of the same tree, both in 2-year stems and in recently formed vegetative organs as flower buds and immature fruits, which seem to suggest that it may be the same isolate, which has moved systemically inside the plant. The results presented here can play an important role in working out strategies for the effective and timely management of the disease and in reducing the number of unnecessary fungicide applications.
more...
No comment yet.
Scooped by Serenella A Sukno
Scoop.it!

Widespread Resistance to QoI Fungicides of Colletotrichum acutatum from Strawberry Nurseries and Production Fields

Strawberry anthracnose, caused mainly by the Colletotrichum acutatum species complex, is a major disease in strawberry nurseries and production fields. The use of fungicides, such as the quinone outside inhibitors (QoIs), has been extensively deployed for the control of C. acutatum for the past 20 years. C. acutatum resistance to the QoIs was first reported in 2013 in Florida strawberry production fields. In 2015, anthracnose outbreaks were reported in strawberry nurseries and production fields across the United States. To elucidate the significance and geographical extension of C. acutatum resistance, fungicide use surveys were conducted, and isolates were collected in the affected areas. QoI-resistant isolates were collected from strawberry production fields and nurseries in six states in the United States. Fungicide use surveys indicated that, in some locations, the number of QoI applications exceeded the recommendation for this fungicide group. Thus, the current situation warrants immediate changes in anthracnose management strategies that integrate other chemical as well as nonchemical strategies to limit resistant population selection and prevent future anthracnose outbreaks.

more...
No comment yet.
Scooped by Serenella A Sukno
Scoop.it!

Colletotrichum acutatum and C. gloeosporioides Species Complexes Associated with Apple in Brazil

Glomerella leaf spot (GLS) is an apple disease that concerns growers due to the increases in severity over the years and the difficulties in control. Species within the Colletotrichum acutatum and C. gloeosporioides species complexes cause GLS, but the proportion of species within each complex in Brazilian apple orchards is not known. The objectives of this study were to identify isolates of Colletotrichum causing GLS on apple orchards in the main Brazilian producing regions to the species level. Two hundred and seven isolates were obtained in orchards in São Paulo (SP), Parana (PR), Santa Catarina (SC), and Rio Grande do Sul (RS) states. Genomic DNA was extracted, and the ITS, GAPDH, CHS-1, and TUB2 genes were amplified and sequenced. The phylogenetic trees were generated using a concatenated alignment. One hundred and fourteen isolates were identified as belonging to the C. acutatum species complex (Cac) and 93 to the C. gloeosporioides species complex (Cgc). Five phylogenetic species were identified: C. melonis (1.9%), C. nymphaeae (47.4%), C. paranaense (2.4%), C. limetticola (3.4%), and C. fructicola (44.9%). In SC, Cgc predominates, but in the states of SP, PR, and RS, Cac was predominant. This is the first report of C. limetticola from apple.

more...
No comment yet.
Scooped by Serenella A Sukno
Scoop.it!

Species diversity of Colletotrichum infecting Annona spp. in Brazil

Anthracnose disease caused by Colletotrichum species is a limiting factor in the production and commercialization of annonaceous crops in different regions of the world. In this study, 96 Colletotrichum isolates were collected from soursop and sugar apple leaves showing anthracnose symptoms in commercial plantations of the state of Alagoas, northeastern region of Brazil. To assess initially the species diversity, the isolates were identified by phylogeny based on the sequences of the glyceraldehyde-3-phosphate dehydrogenase (GAPDH) gene. Representative strains were selected for further identification based on multigene phylogeny analysis using sequences of the internal transcribed spacer region (ITS), actin (ACT), chitin synthase (CHS-1), β-tubulin (TUB2), calmodulin (CAL), histone3 (HIS3), glutamine synthetase (GS) and (GAPDH) genes. Morpho-cultural characterization and pathogenicity tests were also performed. These analyses allowed the identification of nine species: Colletotrichum brevisporum, C. cliviae, C. fructicola, C. gigasporum, C. gloeosporioides, C. karstii, C. siamense, C. theobromicola and C. tropicale. Until now, only C. fructicola, C. gloeosporioides and C. theobromicola had been associated with anthracnose of soursop and sugar apple in Brazil. C. brevisporum, C. cliviae and C. gigasporum species are also described for the first time on annonaceous species worldwide.
more...
No comment yet.
Scooped by Serenella A Sukno
Scoop.it!

Capsicum-Colletotrichum interaction: Identification of resistance sources and quantification of secondary metabolites in unripe and ripe fruits in response to anthracnose infection 

Capsicum-Colletotrichum interaction: Identification of resistance sources and quantification of secondary metabolites in unripe and ripe fruits in response to anthracnose infection  | Colletotrichum | Scoop.it
Abstract
Anthracnose, caused by Colletotrichum species complex, is one of the main fungal diseases in pepper (Capsicum spp.) crops, resulting in extensive fruit losses during pre- and post-harvesting. Plants have structural and biochemical defense mechanisms produced before and/or after the pathogen attack. Biochemical defense involve the production of compounds that accumulate at the site of infection and are toxic to the pathogen. However, the accumulation and biosynthesis of these compounds during Capsicum-Colletotrichum interaction, especially during fruit development stages remain poorly understood. In order to identify potential resistant genotypes and to improve our knowledge about the metabolites produced by pepper fruits against fungus infection, we inoculated unripe and ripe fruits of 59 accessions of Capsicum spp. with C. gloeosporioides and analyzed the disease severity during 8 days after inoculation. In this study, we observed a wide variability of fungus resistance response in unripe and ripe fruits of Capsicum spp. accessions, and ripe fruits presented greater resistance to anthracnose than unripe. Six accessions (GBUEL06, GBUEL28, GBUEL73, GBUEL87, GBUEL104 and GBUEL106) were considered as resistant for both fruits development stages and have potential to be used in future breeding programs. In addition, we selected two C. annuum accessions GBUEL103 (susceptible) and GBUEL104 (resistant), to describe the histological aspects of C. gloeosporioides infection in pepper fruits, followed by the quantification of secondary metabolites produced during this plant-pathogen interaction, using light microscopy and ultra-high performance liquid chromatography (UHPLC), respectively. The quantification of secondary metabolites produced in pepper fruits during fungus infection showed different values according genotype characteristic (susceptible or resistant), fruit development stages (unripe and ripe) and time (1st and 8th day post-inoculation). Interestingly, high concentrations of caffeic and chlorogenic acid were quantified in unripe and ripe fruits characterized as resistant genotype, showing that these biochemical compounds are putatively involved in fruit defense mechanism in response to anthracnose disease.
more...
No comment yet.
Scooped by Serenella A Sukno
Scoop.it!

A High-Quality Draft Genome Sequence of Colletotrichum gloeosporioides sensu stricto SMCG1#C, a Causal Agent of Anthracnose on Cunninghamia lanceolata in China

A High-Quality Draft Genome Sequence of Colletotrichum gloeosporioides sensu stricto SMCG1#C, a Causal Agent of Anthracnose on Cunninghamia lanceolata in China

Lin Huang,1 Ki-Tae Kim,2 Ji-Yun Yang,1 Hyeunjeong Song,3 Gobong Choi,3 Jongbum Jeon,3 Kyeongchae Cheong,3 Jaeho Ko,2 Haibin Xu,4,† and Yong-Hwan Lee2,3,5,†
1Co-Innovation Center for Sustainable Forestry in Southern China, College of Forestry, Nanjing Forestry University, Nanjing, Jiangsu 210037, China;
more...
No comment yet.
Scooped by Serenella A Sukno
Scoop.it!

Dealing with anthracnose

Dealing with anthracnose | Colletotrichum | Scoop.it
This fungal disease can wipe out a dry bean crop. Here’s how to prevent, and treat, this problem.
more...
No comment yet.
Scooped by Serenella A Sukno
Scoop.it!

Novel insights on colonization routes and evolutionary potential of Colletotrichum kahawae, a severe pathogen of Coffea arabica 

Summary
Pathogenic fungi are emerging at an increasing rate on a wide range of host plants, leading to tremendous threats to the global economy and food safety. Several plant pathogens have been considered to be invasive species, rendering large‐scale population genomic analyses crucial to better understand their demographic history and evolutionary potential. Colletotrichum kahawae (Ck) is a highly aggressive and specialized pathogen, causing coffee berry disease in Arabica coffee in Africa. This pathogen leads to severe production losses and its dissemination out of Africa is greatly feared. To address this issue, a population genomic approach using thousands of single nucleotide polymorphisms (SNPs) spaced throughout the genome was used to unveil its demographic history and evolutionary potential. The current study confirms that Ck is a true clonal pathogen, perfectly adapted to green coffee berries, with three completely differentiated populations (Angolan, Cameroonian and East African). Two independent clonal lineages were found within the Angolan population as opposed to the remaining single clonal populations. The most probable colonization scenario suggests that this pathogen emerged in Angola and immediately dispersed to East Africa, where these two populations began to differentiate, followed by the introduction in Cameroon from an Angolan population. However, the differentiation between the two Angolan clonal lineages masks the mechanism for the emergence of the Cameroonian population. Our results suggest that Ck is completely differentiated from the ancestral lineage, has a low evolutionary potential and a low dispersion ability, with human transport the most likely scenario for its potential dispersion, which makes the fulfilment of the quarantine measures and management practices implemented crucial.

more...
No comment yet.
Scooped by Serenella A Sukno
Scoop.it!

The histidine kinase slnCl1 of Colletotrichum lindemuthianum as a pathogenicity factor against Phaseolus vulgaris L

The histidine kinase slnCl1 of Colletotrichum lindemuthianum as a pathogenicity factor against Phaseolus vulgaris L | Colletotrichum | Scoop.it
Abstract
Colletotrichum lindemuthianum, the causal agent of anthracnose, is responsible for significant damage in the common bean (Phaseolus vulgaris L.). Unraveling the genetic mechanisms involved in the plant/pathogen interaction is a powerful approach for devising efficient methods to control this disease. In the present study, we employed the Restriction Enzyme-Mediated Integration (REMI) methodology to identify the gene slnCl1, encoding a histidine kinase protein, as involved in pathogenicity. The mutant strain, MutCl1, generated by REMI, showed an insertion in the slnCl1 gene, deficiency of the production and melanization of appressoria, as well as the absence of pathogenicity on bean leaves when compared with the wild-type strain. The slnCl1 gene encodes a histidine kinase class IV called SlnCl1 showing identity of 97% and 83% with histidine kinases from Colletotrichum orbiculare and Colletotrichum gloesporioides, respectively. RNA interference was used for silencing the histidine kinase gene and confirm slnCl1 as a pathogenicity factor. Furthermore, we identified four major genes involved in the RNA interference-mediated gene silencing in Colletotrichum spp. and demonstrated the functionality of this process in C. lindemuthianum. Silencing of the EGFP reporter gene and slnCl1 were demonstrated using qPCR. This work reports for the first time the isolation and characterization of a HK in C. lindemuthianum and the occurrence of gene silencing mediated by RNA interference in this organism, demonstrating its potential use in the functional characterization of pathogenicity genes.
more...
No comment yet.
Scooped by Serenella A Sukno
Scoop.it!

Inhibition on anthracnose and induction of defense response by nitric oxide in pitaya fruit 

Inhibition on anthracnose and induction of defense response by nitric oxide in pitaya fruit  | Colletotrichum | Scoop.it
Highlights

Nitric oxide (NO) inhibited anthracnose, Colletotrichum gloeosporioides, in pitaya fruit.


NO enhanced defense responses and delayed senescence in pitaya fruit.


NO treatment could be a promising approach to control anthracnose in pitaya fruit.


Abstract
The effect of nitric oxide (NO) on resistance of pitaya fruit against anthracnose caused by Colletotrichum gloeosporioides and its related mechanisms were investigated in this study. ‘Baiyulong’ pitaya fruit were immersed in 0.1 mM sodium nitroprusside (a NO donor) for 8 min, inoculated with spore suspension of C. gloeosporioides after 24 h of NO treatment, and then stored at 25 °C for up to 8 days. NO treatment markedly inhibited the lesion expansion on pathogen-inoculated pitaya fruit during storage. NO treatment also reduced the natural disease incidence and index of pitaya fruit stored at 25 °C. Furthermore, NO treatment increased the activities of defense-related enzymes including phenylalanine ammonia-lyase (PAL), CoA ligase (4CL), peroxidase (POD), polyphenol oxidase (PPO), chitinase (CHI) and β-1,3-glucanase (GLU), as well as elevated the contents of antifungal compounds including total phenolics, flavonoids and lignin. In addition, NO treatment reduced respiration rate and weight loss, while delayed the declines of firmness and soluble solids content (SSC). These results indicate that NO could effectively enhance the resistance of pitaya fruit to anthracnose, which might be ascribed to activation of defense responses and retardation of senescence.

more...
No comment yet.
Scooped by Serenella A Sukno
Scoop.it!

Biosynthetic pathway and optimal conditions for the production of indole-3-acetic acid by an endophytic fungus, Colletotrichum fructicola CMU-A109

Biosynthetic pathway and optimal conditions for the production of indole-3-acetic acid by an endophytic fungus, Colletotrichum fructicola CMU-A109 | Colletotrichum | Scoop.it
Abstract

Endophytic fungi are known to produce indole-3-acetic acid (IAA), which can stimulate plant growth. Twenty-seven isolates of endophytic fungi were isolated from Coffea arabica in northern Thailand. Only one isolate (CMU-A109) produced IAA in vitro. This isolate was identified as Colletotrichum fructicola based on morphological characteristics and molecular phylogenetic analysis of a combined five loci (internal transcribed spacer of ribosomal DNA, actin, β-tubulin 2, chitin synthase and glyceraldehyde-3-phosphate dehydrogenase genes). Identification of a fungal IAA production obtained from indole 3-acetamide (IAM) and tryptophan 2-monooxygenase activity is suggestive of IAM routed IAA biosynthesis. The highest IAA yield (1205.58±151.89 μg/mL) was obtained after 26 days of cultivation in liquid medium supplemented with 8 mg/mL L-tryptophan at 30°C. Moreover, the crude fungal IAA could stimulate coleoptile elongation of maize, rice and rye. This is the first report of IAA production by C. fructicola and its ability to produce IAA was highest when compared with previous reports on IAA produced by fungi.

Figures
more...
No comment yet.
Scooped by Serenella A Sukno
Scoop.it!

 Genomic characterization provides new insights into the biosynthesis of the secondary metabolite Huperzine A in the endophyte Colletotrichum gloeosporioides Cg01 

A reliable source of Huperzine A (HupA) meets an urgent need due to its wide use in Alzheimer’s disease treatment. In this study, we sequenced and characterized the whole genomes of two HupA-producing endophytes, Penicillium polonicum hy4 and Colletotrichum gloeosporioides Cg01, to clarify the mechanism of HupA biosynthesis. The whole genomes of hy4 and Cg01 were 33.92 Mb and 55.77 Mb, respectively. We compared the differentially expressed genes (DEGs) between the induced group (with added extracts of Huperzia serrata) and a control group. We focused on DEGs with similar expression patterns in hy4 and Cg01. The DEGs identified in GO (Gene ontology) and KEGG (Kyoto Encyclopedia of Genes and Genomes) pathways were primarily located in carbon and nitrogen metabolism and nucleolus, ribosome, and rRNA processing. Furthermore, we analyzed the gene expression for HupA biosynthesis genes proposed in plants, which include lysine decarboxylase (LDC), copper amine oxidase (CAO), polyketides synthases (PKS), etc. Two LDCs, one CAO, and three PKSs in Cg01 were selected as prime candidates for further validation. We found that single candidate biosynthesis-gene knock-out did not influence the HupA production, while both LDC gene knock-out led to increased HupA production. These results reveal that HupA biosynthesis in endophytes might differ from that proposed in plants, and imply that the HupA-biosynthesis genes in endophytic fungi might co-evolve with the plant machinery rather than being acquired through horizontal gene transfer (HGT). Moreover, we analyzed the function of the differentially expressed epigenetic modification genes. HupA production of the histone acetyltransferase (HAT) deletion mutant △CgSAS-2 was not changed, while that of the histone methyltransferase (HMT) and histone deacetylase (HDAC) deletion mutants △CgClr4, △CgClr3, and △CgSir2-6 was reduced. Recovery of HupA-biosynthetic ability can be achieved by retro-complementation, demonstrating that HMT and HDACs associated with histone modification are involved in the regulation of HupA biosynthesis in endophytic fungi. This is the first report on epigenetic modification in high value secondary metabolite- producing endophytes. These findings shed new light on HupA biosynthesis and regulation in HupA-producing endophytes and are crucial for industrial production of HupA from fungi.

more...
No comment yet.
Scooped by Serenella A Sukno
Scoop.it!

Acetyl‐coenzyme A synthetase gene ChAcs1 is essential for lipid metabolism, carbon utilization and virulence of the hemibiotrophic fungus Colletotrichum higginsianum 

Acetyl‐coenzyme A (acetyl‐CoA) is a key molecule that participates in many biochemical reactions in amino acid, protein, carbohydrate and lipid metabolism. Here, we genetically dissected the distinct roles of two acetyl‐CoA synthetase genes, ChAcs1 and ChAcs2, in the regulation of fermentation, lipid metabolism and virulence of the hemibiotrophic fungus Colletotrichum higginsianum. ChAcs1 and ChAcs2 are both highly expressed during appressorial development and the formation of primary hyphae, and are constitutively expressed in the cytoplasm throughout development. We found that C. higginsianum strains without ChAcs1 were non‐viable in the presence of most non‐fermentable carbon sources, including acetate, ethanol and acetaldehyde. Deletion of ChAcs1 also led to a decrease in lipid content of mycelia and delayed lipid mobilization in conidia to developing appressoria, which suggested that ChAcs1 contributes to lipid metabolism in C. higginsianum. Furthermore, a ChAcs1 deletion mutant was defective in the switch to invasive growth, which may have been directly responsible for its reduced virulence. Transcriptomic analysis and quantitative reverse transcription‐polymerase chain reaction (qRT‐PCR) revealed that ChAcs1 can affect the expression of genes involved in virulence and carbon metabolism, and that plant defence genes are up‐regulated, all demonstrated during infection by a ChAcs1 deletion mutant. In contrast, deletion of ChAcs2 only conferred a slight delay in lipid mobilization, although it was highly expressed in infection stages. Our studies provide evidence for ChAcs1 as a key regulator governing lipid metabolism, carbon source utilization and virulence of this hemibiotrophic fungus.
more...
No comment yet.
Scooped by Serenella A Sukno
Scoop.it!

 Adaptation of a Fungal Pathogen to Host Quantitative Resistance 

 Adaptation of a Fungal Pathogen to Host Quantitative Resistance  | Colletotrichum | Scoop.it
Impact of host quantitative resistance on pathogen evolution is still poorly documented. In our study, we characterized the adaptation of the pathogenic fungus Colletotrichum gloeosporioides, to the quantitative resistance of its host, the water yam (Dioscorea alata). Genetic and pathogenic diversities of C. gloeosporioides populations were specified at the field scale. We used nuclear markers to describe fungal population structuring within and between six fields of three cultivars differently susceptible to the fungus. Strain aggressiveness was then quantified in the laboratory through cross-inoculation tests. The high level of genetic diversity and significant linkage disequilibrium revealed a significant influence of clonal reproduction in the C. gloeosporioides evolution. The recorded fungal migration between fields was weak (evidence for a dispersion mode via tubers rather than splashing dispersal), which provides the first molecular evidence for limited C. gloeosporioides migration via yam tuber exchanges. C. gloeosporioides’s populations are adapted to their host resistance. The aggressiveness of the fungal clones seems to have evolved toward an accumulation of components specific to each host cultivar. Despite the remaining marks of adaptation to the former widely cultivated host, adaptation to current cultivars was clearly depicted.
more...
No comment yet.
Scooped by Serenella A Sukno
Scoop.it!

The homeobox transcription factor CoHox1 is required for the morphogenesis of infection hyphae in host plants and pathogenicity in Colletotrichum orbiculare 

The homeobox transcription factor CoHox1 is required for the morphogenesis of infection hyphae in host plants and pathogenicity in Colletotrichum orbiculare  | Colletotrichum | Scoop.it
Abstract
The hemibiotrophic fungus Colletotrichum orbiculare is the causal agent of anthracnose of cucumber. During host plant infection, appressoria penetrate into the host cells, and biotrophic infection hyphae elongate inside the host cells, then switch to necrotrophic phase. We found that the homeobox transcription factor CoHox1 is a novel type of pathogenesis-related gene. CoHox1 disruption mutants of C. orbiculare were non-pathogenic on host cucumber cotyledons and formed no lesions at wound sites on leaves. On artificial surfaces (glass and cellulose membrane), CoHox1 disruption mutants formed normal appressoria and infection hyphae similar to a wild-type strain. On the other hand, microscope observation showed that CoHox1 disruption mutants has a decreased rate of penetration of host leaves, and the infection hyphae of CoHox1 disruption mutants did not extend from the penetrated host cell into neighboring cells. On heat-shocked host leaves, CoHox1 disruption mutants also formed no lesions. These results showed that homeobox transcription factor CoHox1 may be required for pathogenicity, especially the morphogenesis of infection hyphae in host cells by C. orbiculare.
more...
No comment yet.
Scooped by Serenella A Sukno
Scoop.it!

Possible contribution of impact injury at harvest to anthracnose expression in ripening avocado: A review 

Abstract
In spite of burgeoning global demand for avocados, meeting consumer expectations for fruit quality is an ongoing challenge. Flesh bruising and body rots (principally anthracnose) are the main postharvest quality defects of avocado fruit. Mechanical damage causes bruising more so in ripening fruit than in hard unripe fruit. As a result, current emphasis is on careful handling of avocado fruit during later supply chain stages. However, emerging evidence suggests mechanical injury to unripe avocado fruit may trigger body rot development. Fruit responses to impact injury and their possible relevance to the pathogenicity of fungi which cause anthracnose in avocado (i.e. various Colletotrichum species) are presented here. Research on impact-induced physiological and biochemical changes that occur in avocado fruit appears to be limited and contradictory. The pathogenicity of Colletotrichum spp. in avocado is influenced by tissue pH, lipoxygenase activity, and concentrations of reactive oxygen species, antifungal compounds, epicatechin and mineral nutrients. Understanding how these parameters change in response to impact is important for predicting disease development and providing appropriate postharvest handling advice to industry.
more...
No comment yet.
Scooped by Serenella A Sukno
Scoop.it!

Metabolic response and volatile profile induced by temperature, on Colletotrichum fragariae and Rhizopus stolonifer 

Abstract
During growth, fungi usually synthesize and emit different metabolic products. The objective of this work was to determine the metabolic activity of Colletotrichum fragariae and Rhizopus stolonifer isolated from strawberries, based on their biomass production, the synthesis of ergosterol and their respiration rate, and to identify their volatile profile, during an incubation period of up to 30 days at 10 and 20°C. For C. fragariae and R. stolonifer, the biomass production at the end of incubation was 30% and 25% higher at 10°C than at 20°C, respectively, and ergosterol production was higher at 10°C than at 20°C. Regardless of the incubation temperature, the typical respiration rate pattern was shown. Terpenes were the major chemical group identified in both fungi, accounting for 41% and 84% of the volatile composition of C. fragariae at 10 and 20°C, respectively, while in the case of R. stolonifer, they represented 59% and 45% at 10 and 20°C, respectively; α‐terpineol was detected during the growing period of C. fragariae and R. stolonifer at 10 and 20°C, whereas γ‐terpinene was emitted only by R. stolonifer at 20°C. Therefore, they might serve as specific indicators of the presence of these two fungi.
more...
No comment yet.
Scooped by Serenella A Sukno
Scoop.it!

Multiple introductions without admixture of Colletotrichum truncatum associated with soybean anthracnose in Brazil

Knowledge of the population structure, genetic diversity and reproductive mode of plant pathogens can help to implement effective disease management strategies. Anthracnose is one of the most prominent diseases in soybean and is mainly associated with the species Colletotrichum truncatum. However, the genetic structure of C. truncatum populations associated with soybean remains unknown. We collected C. truncatum isolates from 10 sites representing two Brazilian states (Mato Grosso and Goiás) and used 13 highly polymorphic microsatellite markers to investigate the population genetic structure of the pathogen. Analyses revealed high gene and haplotypic diversity within populations, as well low genetic differentiation and sharing of multilocus haplotypes among populations and regions. Bayesian and multivariate analysis revealed the presence of three distinct genetic clusters with at least two groups coexisting in all locations, and all of them coexisting in 8 locations. We found limited evidence for admixture between clusters, with only two isolates showing non-zero membership with a second cluster. Analyses of linkage disequilibrium rejected the hypothesis of random mating in all clusters, but values of the index of association were low and not consistent with long-term lack of sexual reproduction. Our findings suggest that Brazilian C. truncatum populations resulted from at least three founder events that led to three genetic clusters that spread throughout the country, raising questions with respect to the factors allowing their maintenance in syntopy without evidence of admixture between them.

Keywords: Population biology, Mycology
more...
No comment yet.
Scooped by Serenella A Sukno
Scoop.it!

Comparison of Whole Plant and Detached Leaf Screening Techniques for Identifying Anthracnose Resistance in Strawberry Plants

Anthracnose is a destructive disease of strawberry caused by several Colletotrichum species including C. acutatum, C. fragariae, and C. gloeosporioides. Identification of anthracnose resistant strawberry germplasm has commonly relied on inoculation of whole plants with isolates of these pathogens. In this study, whole plants and detached leaves from 81 germplasm lines were inoculated with a conidial suspension of isolates of C. acutatum, C. fragariae, and C. gloeosporioides, incubated in the dark at 30°C, 100% relative humidity, for 48 h, and assessed for disease severity based on symptoms on inoculated petioles and leaves. The correlation between the disease severity ratings of the whole plants rated 30 days after inoculation and detached leaves rated 5 days after inoculation was determined. Based on leaf symptoms and petiole lesions, the association between the whole plant leaf disease severity rating (DSR) and detached leaf DSR was positive (rp = 0.70), and the association between the whole plant DSR and the detached leaf DSR was also positive (rp = 0.66). Whole plant and detached leaf DSRs were used to assign each germplasm line to a resistance category, and a posthoc Tukey’s test showed that the whole plant DSR means and the detached leaf DSR means for each resistance category differed significantly at p < 0.05. This research was used to develop a strawberry detached leaf assay which can reliably and quickly determine the degree of resistance of strawberry germplasm to anthracnose.

more...
No comment yet.
Scooped by Serenella A Sukno
Scoop.it!

Colletotrichum orbiculare MTF4 is a key transcription factor downstream of MOR essential for plant signal-dependent appressorium development and pathogenesis

The cucumber anthracnose fungus, Colletotrichum orbiculare, forms a specialized infection structure, called an appressorium. Appressorium differentiation relies on fungal perception of physical and biochemical signals at the plant surface. Our previous report showed that the morphogenesis-related NDR (nuclear Dbf2-related) kinase pathway (MOR) is crucial for translating plant-derived signals for appressorium development. Here, we focused on identifying transcriptional regulators downstream of MOR that are involved in plant signal sensing and transduction for appressorium development. Based on whole-genome transcript profiling, we identified a Zn(II)2Cys6 transcription factor, CoMTF4, as a potential downstream factor of MOR. CoMTF4 was expressed in planta rather than in vitro under the control of the NDR kinase CoCbk1. Phenotypes of comtf4 mutants, strains with constitutively active CoCbk1 and strains with constitutive overexpression of CoMTF4 suggested that CoMtf4 acts downstream of MOR. Furthermore, nuclear localization of CoMtf4 was dependent on the MOR and responsive to plant-derived signals that lead to appressorium morphogenesis. Thus, we conclude that CoMtf4 is a transcription factor downstream of MOR that is essential for appressorium morphogenesis and pathogenesis and is regulated in response to plant-derived signals. This study provides insights into fungal sensing of plant signals and subsequent responses critical for appressorium formation.
more...
No comment yet.
Scooped by Serenella A Sukno
Scoop.it!

Establishment of a selection marker recycling system for sequential transformation of the plant pathogenic fungus Colletotrichum orbiculare 

Summary
Genome sequencing of pathogenic fungi has revealed the presence of various effectors that help their invasion by manipulating plant immunity. Effectors are often individually dispensable, because of duplication and functional redundancy as a result of the arms race between host plants and pathogens. To study effectors that have functional redundancy, multiple gene disruption is often required. However, the number of selection markers that can be used for gene targeting has been limited. Here, we established a marker recycling system that allows to use of the same selection marker in successive transformations in the model fungal pathogen Colletotrichum orbiculare, a causal agent for anthracnose disease in Cucurbitaceae plants. We identified two C. orbiculare homologs of yeast URA3/pyrG, designated URA3A and URA3B, that can be used as a selection marker on media with no uridine. The gene can then be removed from the genome via homologous recombination when the fungus is grown in the presence of 5‐fluoroorotic acid (5‐FOA), a chemical that is converted into a toxin by the URA3 activity. The ura3a/b double mutants showed auxotrophy for uridine and insensitivity to 5‐FOA. Using the ura3a/b mutants, transformation with the URA3B marker and its removal were successfully applied to disrupt the virulence‐related gene, PKS1. The pks1 mutants showed a reduction in virulence, demonstrating that the method can be used to study virulence‐related genes in C. orbiculare. The establishment of a URA3‐based marker recycling system in plant pathogenic fungi enables genetic analysis of multiple genes that have redundant functions including effector genes.

more...
No comment yet.
Scooped by Serenella A Sukno
Scoop.it!

Interaction of Glufosinate and Colletotrichum truncatum on Ammonia Levels and Glutamine Synthetase Activity in Hemp Sesbania

ABSTRACT
The use of microbes and microbial products as bioherbicides has been studied for several decades, and combinations of bioherbicides and herbicides have been examined to discover possible synergistic interactions to improve weed control efficacy. Bioassays were conducted to assess possible interactions of the herbicide glufosinate [2-amino-4-(hydroxymethylphosphinyl) butanoic acid] and Colletotrichum truncatum (CT), a fungal bioherbicide to control hemp sesbania (Sesbania exaltata)]. Glufosinate acts as a glutamine synthetase (GS) inhibitor that causes elevated ammonia levels, but the mode of action of CT is unknown. GS has also been implicated in plant defense in certain plant-pathogen interactions. The effects of spray applications of glufosinate (1.0 mM) orbioherbicide (8.0 × 104 conidia ml-1), applied alone or in combination were monitored (88 h time-course) on seedling growth, GS activity and ammonia levels in hypocotyl tissues under controlled environmental conditions. Growth (elongation and fresh weight) and extractable GS activity were inhibited in tissues by glufosinate and glufosinate plus CT treatments as early as 16 h, but CT treatment did not cause substantial growth reduction or GS inhibition until after ~40 h. Generally, ammonia levels in hemp sesbania tissues under these various treatments were inversely correlated with GS activity. Localization of hemp sesbania GS activity on electrophoretic gels indicated a lack of activity after 30 h in glufosinate and glufosinate plus CT-treated tissue. Untreated control tissues contained much lower ammonia levels at 24, 64, and 88 h after treatment than treatments with CT, glufosinate or their combination. CT alone caused elevated ammonia levels only after 64 - 88 h. Glufosinate incorporated in agar at 0.25 mM to 2.0 mM, caused a 10% - 45% reduction of CT colony radial growth, compared to fungal growth on agar without glufosinate, and the herbicide also inhibited sporulation of CT. Although no synergistic interactions were found in the combinations of CT and glufosinate at the concentrations used, further insight on the biochemical action of CT and its interactions with this herbicide on hemp sesbania was achieved.
more...
No comment yet.
Scooped by Serenella A Sukno
Scoop.it!

Unraveling Colletotrichum species associated with Glomerella leaf spot of apple

Glomerella leaf spot (GLS), caused by Colletotrichum spp., is one of the most important diseases of apple. In this study we aimed to identify Colletotrichum species associated with GLS from different apple-producing areas in Southern Brazil and assess their differential pathogenicity towards apple. Sequencing and multilocus phylogenetic analysis using partial gene regions of ITS, GAPDH, TUB2, ACT and HIS3 allowed the identification of eighteen isolates of Colletotrichum fructicola, and only one of Colletotrichum nymphaeae. All isolates were pathogenic to apple leaves, while C. nymphaeae did not cause symptoms. Worldwide, our literature review showed nine Colletotrichum species reported associated with GLS in different countries: C. fructicola, C. nymphaeae and C. karstii in Brazil; C. fructicola and C. aenigma in China; C. fructicola, C. aenigma and C. siamense in Japan, C. fructicola, C. alienum, C. gloeosporioides, C. siamense, C. tropicale and C. fioriniae in the USA, and only C. fructicola in Uruguay. Our study confirms C. fructicola as the most frequent species causing GLS in Brazil and discusses the diversity and pathogenicity of GLS-causing species worldwide.

more...
No comment yet.