Plant Diseases Caused by Fungi

Agrios, George N.

doi:10.1016/b978-0-08-047378-9.50017-8

Cited by 139 publications

(27 citation statements)

References 240 publications

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“…Exserohilum turcicum (sexual stage Setosphaeria turcica) is the causal agent of northern leaf blight (NLB), a destructive foliar disease of maize, sorghum, and related grass species (Agrios, 2005). In maize, four major resistance (R-) genes have been characterized, which convey resistance to E.…”

Section: Introductionmentioning

confidence: 99%

Time-Course RNAseq Reveals Exserohilum turcicum Effectors and Pathogenicity Determinants

2020

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Exserohilum turcicum (sexual stage Setosphaeria turcica) is the hemibiotrophic causal agent of northern leaf blight of maize and sorghum. This study aimed to identify the genes involved in host colonization during the biotrophic and necrotrophic phases of infection. It also aimed to identify race-specific differences in gene expression. RNAseq of maize seedlings inoculated with a race 13N or 23N E. turcicum isolate was conducted before inoculation and at 2, 5, 7, and 13 days post-inoculation (dpi). Biological replicates were pooled per time point for each race and sequenced. A bioinformatics pipeline was used to identify candidate effectors, and expression was validated for selected candidates. Fungal biomass was positively correlated with the percentages of E. turcicum reads mapped, which were low at early time points (2-7 dpi) with a significant increase at 13 dpi, indicating a lifestyle switch from biotrophy to necrotrophy between 7 and 13 dpi. AVRHt1 is the putative E. turcicum effector recognized by the maize resistance gene Ht1. Consistent with this, AVRHt1 was expressed in planta by race 23N, but transcripts were absent in race 13N. In addition, specific transposable elements were expressed in 23N only. Genes encoding the virulence-associated peptidases leupeptin-inhibiting protein 1 and fungalysin were expressed in planta. Transcriptional profiles of genes involved in secondary metabolite synthesis or cell wall degradation revealed the importance of these genes during late stages of infection (13 dpi). A total of 346 expressed candidate effectors were identified, including Ecp6 and proteins similar to the secreted in xylem (SIX) effectors common to formae speciales of Fusarium oxysporum, SIX13 and SIX5. Expression profiling of Ecp6 and SIX13-like indicated a peak in expression at 5 and 7 dpi compared to 2 and 13 dpi. Sequencing of SIX13-like from diverse isolates of E. turcicum revealed host-specific polymorphisms that were mostly non-synonymous, resulting in two groups of SIX13-like proteins that corresponded to the maize or sorghum origin of each isolate. This study suggests putative mechanisms whereby E. turcicum causes disease. Identification of the candidate effector SIX13-like is consistent with the infection mode of E. turcicum through the xylem of susceptible hosts.

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Section: Introductionmentioning

confidence: 99%

Time-Course RNAseq Reveals Exserohilum turcicum Effectors and Pathogenicity Determinants

2020

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“…Additionally, there is some inconsistency in terminology of aecial morphology, which could lead to misinterpretations. According to many textbooks and other literature [ 14 , 36 , 37 ], a single cup in an aecial cluster of P. graminis represents an aecium. However in some studies, the whole aecial cluster (with several aecial cups) is denoted as an aecium [ 38 , 39 ].…”

Section: Discussionmentioning

confidence: 99%

Multiple genotypes within aecial clusters in Puccinia graminis and Puccinia coronata: improved understanding of the biology of cereal rust fungi

Berlin

Samils

Andersson

2017

Fungal Biol Biotechnol

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BackgroundCereal rust fungi (Puccinia spp.) are among the most economically important plant pathogens. These fungi have a complex life cycle, including five spore stages and two hosts. They infect one grass host on which they reproduce clonally and cause the cereal rust diseases, while the alternate host is required for sexual reproduction. Although previous studies clearly demonstrate the importance of the alternate host in creating genetic diversity in cereal rust fungi, little is known about the amount of novel genotypes created in each successful completion of a sexual reproduction event.ResultsIn this study, single sequence repeat markers were used to study the genotypic diversity within aecial clusters by genotyping individual aecial cups. Two common cereal rusts, Puccinia graminis causing stem rust and Puccinia coronata the causal agent of crown rust were investigated. We showed that under natural conditions, a single aecial cluster usually include several genotypes, either because a single pycnial cluster is fertilized by several different pycniospores, or because aecia within the cluster are derived from more than one fertilized adjoining pycnial cluster, or a combination of both.ConclusionOur results imply that although sexual events in cereal rust fungi in most regions of the world are relatively rare, the events that occur may still significantly contribute to the genetic variation within the pathogen populations.Electronic supplementary materialThe online version of this article (doi:10.1186/s40694-017-0032-3) contains supplementary material, which is available to authorized users.

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“…This outcome was unexpected since Alternaria , Phoma , and Phomopsis species are well recognized as aggressive plant pathogens, causing lesions and rots in a variety of crops (Agrios, 2005). Subsequently, we asked whether these fungal isolates play supplementary role in Pokkah Boeng pathogenesis, perhaps enhancing the aggressiveness of F. verticillioides during colonization and rot.…”

Section: Discussionmentioning

confidence: 99%

Identification and Characterization of Pathogenic and Endophytic Fungal Species Associated with Pokkah Boeng Disease of Sugarcane

Hilton

Zhang

Shim

2017

The Plant Pathology Journal

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Pokkah Boeng is a serious disease of sugarcane, which can lead to devastating yield losses in crop-producing regions, including southern China. However, there is still uncertainty about the causal agent of the disease. Our aim was to isolate and characterize the pathogen through morphological, physiological, and molecular analyses. We isolated sugarcane-colonizing fungi in Fujian, China. Isolated fungi were first assessed for their cell wall degrading enzyme capabilities, and five isolates were identified for further analysis. Internal transcribed spacer sequencing revealed that these five strains are Fusarium, Alternaria, Phoma, Phomopsis, and Epicoccum. The Fusarium isolate was further identified as F. verticillioides after Calmodulin and EF-1α gene sequencing and microscopic morphology study. Pathogenicity assay confirmed that F. verticillioides was directly responsible for disease on sugarcane. Co-inoculation of F. verticillioides with other isolated fungi did not lead to a significant difference in disease severity, refuting the idea that other cellulolytic fungi can increase disease severity as an endophyte. This is the first report characterizing pathogenic F. verticillioides on sugarcane in southern China.

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Plant Diseases Caused by Fungi

Cited by 139 publications

References 240 publications

Time-Course RNAseq Reveals Exserohilum turcicum Effectors and Pathogenicity Determinants

Time-Course RNAseq Reveals Exserohilum turcicum Effectors and Pathogenicity Determinants

Multiple genotypes within aecial clusters in Puccinia graminis and Puccinia coronata: improved understanding of the biology of cereal rust fungi

Identification and Characterization of Pathogenic and Endophytic Fungal Species Associated with Pokkah Boeng Disease of Sugarcane

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