scholarly journals Ecological Differentiation and Incipient Speciation in the Fungal Pathogen Causing Rice Blast

2020 ◽  
Author(s):  
Maud Thierry ◽  
Joëlle Milazzo ◽  
Henri Adreit ◽  
Sébastien Ravel ◽  
Sonia Borron ◽  
...  
Keyword(s):  
Rice Blast ◽  
Plant Pathogens ◽  
Female Sterility ◽  
Niche Separation ◽  
Incipient Speciation ◽  
Crop Species ◽  
Heterogeneous Habitats ◽  
Differential Adaptation ◽  
Pathogenicity Tests ◽  
World Distribution

ABSTRACTNatural variation in plant pathogens has an impact on food security and ecosystem health. The rice blast fungus Pyricularia oryzae, which limits rice production in all rice-growing areas, is structured into multiple lineages. Diversification and the maintenance of multiple rice blast lineages have been proposed to be due to separation in different areas and differential adaptation to rice subspecies. However, the precise world distribution of rice blast populations, and the factors controlling their presence and maintenance in the same geographic areas, remain largely unknown. We used genotyping data for 886 isolates from more than 185 locations in 51 countries to show that P. oryzae is structured into one recombining and three clonal lineages, each with broad geographic distributions. No evidence was found for admixture in clonal lineages, and crossing experiments revealed that female sterility and early postmating genetic incompatibilities acted as strong barriers to gene flow between these lineages. An analysis of climatic and geographic data indicated that the four lineages of P. oryzae were found in areas differing in terms of the prevailing environmental conditions and types of rice grown. Pathogenicity tests with representatives of the five main rice subspecies revealed differences in host range between pathogenic lineages, highlighting a contribution of specialization to niche separation between lineages, despite co-existence on the same host species. Our results demonstrate that the spread of a pathogen across heterogeneous habitats and divergent populations of a crop species can lead to niche separation and incipient speciation in the pathogen.

Investigating the biology of rice blast disease and prospects for durable resistance

2021 ◽  
pp. 643-680
Author(s):  
Vincent M. Were ◽  
◽  
Nicholas J. Talbot ◽  
Keyword(s):  
Cell Biology ◽  
Rice Blast ◽  
Plant Pathogens ◽  
Blast Resistance ◽  
Durable Resistance ◽  
Rice Blast Disease ◽  
Blast Disease ◽  
Global Food Security ◽  
Major Resistance Genes ◽  
Effector Secretion

There are important biological process involved in rice blast disease that are now well-studied during the early events in plant infection which include: the cell biology of appressorium formation, the biology of invasive growth and effector secretion, the two distinct mechanisms of effector secretion, the nature of the plant-pathogen interface, PAMP-triggered immunity modulation by secreted effectors and effector-triggered immunity and blast resistance. The devastating losses caused by the blast fungus have been documented in most grasses, but this chapter discusses the use of major resistance genes to rice blast and wheat blast disease as an emerging threat to global food security. This chapter also highlights an emerging approach to breed for durable resistance to plant pathogens using gene editing technologies with an example: CRISPR-Cas9 mutagenesis of dominant S-genes for disease control.

scholarly journals Colletotrichum species associated with anthracnose of Pyrus spp. in China

2019 ◽  
Vol 42 (1) ◽  
pp. 1-35 ◽  
Author(s):  
M. Fu ◽  
P.W. Crous ◽  
Q. Bai ◽  
P.F. Zhang ◽  
J. Xiang ◽  
...  
Keyword(s):  
Plant Pathogens ◽  
Novel Species ◽  
Phylogenetic Analyses ◽  
Koch’S Postulates ◽  
Colletotrichum Species ◽  
Organ Specific ◽  
Pathogenicity Tests ◽  
Koch's Postulates

Colletotrichum species are plant pathogens, saprobes, and endophytes on a range of economically important hosts. However, the species occurring on pear remain largely unresolved. To determine the morphology, phylogeny and biology of Colletotrichum species associated with Pyrus plants, a total of 295 samples were collected from cultivated pear species (including P. pyrifolia, P. bretschneideri, and P. communis) from seven major pear-cultivation provinces in China. The pear leaves and fruits affected by anthracnose were sampled and subjected to fungus isolation, resulting in a total of 488 Colletotrichum isolates. Phylogenetic analyses based on six loci (ACT, TUB2, CAL, CHS-1, GAPDH, and ITS) coupled with morphology of 90 representative isolates revealed that they belong to 10 known Colletotrichum species, including C. aenigma, C. citricola, C. conoides, C. fioriniae, C. fructicola, C. gloeosporioides, C. karstii, C. plurivorum, C. siamense, C. wuxiense, and two novel species, described here as C. jinshuiense and C. pyrifoliae. Of these, C. fructicola was the most dominant, occurring on P. pyrifolia and P. bretschneideri in all surveyed provinces except in Shandong, where C. siamense was dominant. In contrast, only C. siamense and C. fioriniae were isolated from P. communis, with the former being dominant. In order to prove Koch's postulates, pathogenicity tests on pear leaves and fruits revealed a broad diversity in pathogenicity and aggressiveness among the species and isolates, of which C. citricola, C. jinshuiense, C. pyrifoliae, and C. conoides appeared to be organ-specific on either leaves or fruits. This study also represents the first reports of C. citricola, C. conoides, C. karstii, C. plurivorum, C. siamense, and C. wuxiense causing anthracnose on pear.

scholarly journals The rice blast pathosystem as a case study for the development of new tools and raw materials for genome analysis of fungal plant pathogens

2003 ◽  
Vol 159 (1) ◽  
pp. 53-61 ◽  
Author(s):  
Thomas K. Mitchell ◽  
Michael R. Thon ◽  
Jun-Seop Jeong ◽  
Doug Brown ◽  
Jixin Deng ◽  
...  
Keyword(s):  
Genome Analysis ◽  
Rice Blast ◽  
Plant Pathogens ◽  
Raw Materials ◽  
Fungal Plant Pathogens

scholarly journals Structural basis of pathogen recognition by an integrated HMA domain in a plant NLR immune receptor

eLife ◽  
2015 ◽  
Vol 4 ◽  
Author(s):  
A Maqbool ◽  
H Saitoh ◽  
M Franceschetti ◽  
CEM Stevenson ◽  
A Uemura ◽  
...  
Keyword(s):  
Nicotiana Benthamiana ◽  
Rice Blast ◽  
Plant Pathogens ◽  
Rice Cultivar ◽  
Blast Disease ◽  
Structural Basis ◽  
Immune Receptor ◽  
Immune Receptors ◽  
Direct Recognition

Plants have evolved intracellular immune receptors to detect pathogen proteins known as effectors. How these immune receptors detect effectors remains poorly understood. Here we describe the structural basis for direct recognition of AVR-Pik, an effector from the rice blast pathogen, by the rice intracellular NLR immune receptor Pik. AVR-PikD binds a dimer of the Pikp-1 HMA integrated domain with nanomolar affinity. The crystal structure of the Pikp-HMA/AVR-PikD complex enabled design of mutations to alter protein interaction in yeast and in vitro, and perturb effector-mediated response both in a rice cultivar containing Pikp and upon expression of AVR-PikD and Pikp in the model plant Nicotiana benthamiana. These data reveal the molecular details of a recognition event, mediated by a novel integrated domain in an NLR, which initiates a plant immune response and resistance to rice blast disease. Such studies underpin novel opportunities for engineering disease resistance to plant pathogens in staple food crops.

scholarly journals Chaetomium Application in Agriculture

2021 ◽  
Author(s):  
Kasem Soytong ◽  
Somdej Kahonokmedhakul ◽  
Jiaojiao Song ◽  
Rujira Tongon
Keyword(s):  
Disease Control ◽  
Rice Blast ◽  
Plant Disease ◽  
Plant Pathogens ◽  
Control Plant ◽  
Phytophthora Palmivora ◽  
Human Pathogens ◽  
Plant Disease Control ◽  
Different Strains ◽  
New Compounds

Chaetomium species for plant disease control are reported to be antagonize many plant pathogens. It is a new broad spectrum biological fungicide from Chaetomium species which firstly discovered and patented No. 6266, International Code: AO 1 N 25/12, and registered as Ketomium® mycofungicide for plant disease control in Thailand, Laos, Vietnam, Cambodia and China. Chaetoimum biofungicide and biostimulants are applied to implement integrated plant disease control. It showed protective and curative effects in controlling plant disease and promoting plant growth. It has been successfully applied to the infested soils with integrated cultural control for the long-term protection against rice blast (Magnaporte oryzae), durian and black Pepper rot (Piper nigram L.) (Phytophthora palmivora), citrus rot (Phytophthora parasitica) and strawberry rot (Fragaria spp.) caused by Phytophthora cactorum, wilt of tomato (Fusarium oxysporum f. sp. lycopersici), basal rot of corn (Sclerotium rolfsii) and anthracnose (Colletotrichum spp.) etc. Further research is reported on the other bioactive compounds from active strains of Chaetomium spp. We have discovered various new compounds from Ch. globosum, Ch. cupreum, Ch. elatum, Ch. cochliodes, Ch. brasiliense, Ch. lucknowense, Ch. longirostre and Ch. siamense. These new compounds are not only inhibiting human pathogens (anti-malaria, anti-tuberculosis, anti-cancer cell lines and anti-C. albicans etc) but also plant pathogens as well. These active natural products from different strains of Chaetomium spp. are further developed to be biodegradable nanoparticles from active metabolites as a new discovery of scientific investigation which used to induce plant immunity, namely microbial degradable nano-elicitors for inducing immunity through phytoalexin production in plants e.g. inducing tomato to produce alpha-tomaline against Fusarium wilt of tomato, capsidiol against chili anthracnose, sakuranitin and oryzalexin B against rice blast, scopletin and anthrocyaidin against Phytophthora or Pythium rot Durian and scoparone against Phytophthora or Pythium rot of citrus. Chaetomium biofungicide can be applied instead of toxic chemical fungicides to control plant diseases.

scholarly journals Recently expanded clonal lineages of the rice blast fungus display distinct patterns of presence/absence of effector genes

2020 ◽  
Author(s):  
Sergio M. Latorre ◽  
C. Sarai Reyes-Avila ◽  
Angus Malmgren ◽  
Joe Win ◽  
Sophien Kamoun ◽  
...  
Keyword(s):  
Rice Blast ◽  
Plant Pathogens ◽  
Rice Blast Fungus ◽  
Population History ◽  
Blast Disease ◽  
Diverse Group ◽  
Genetic History ◽  
Effector Genes ◽  
Blast Fungus ◽  
History Of

AbstractBackgroundUnderstanding the mechanisms and timescales of plant pathogen outbreaks requires a detailed genome-scale analysis of their population history. The fungus Magnaporthe (Syn. Pyricularia) oryzae —the causal agent of blast disease of cereals— is among the most destructive plant pathogens to world agriculture and a major threat to the production of rice, wheat and other cereals. Although M. oryzae is a multihost pathogen that infects more than 50 species of cereals and grasses, all rice-infecting isolates belong to a single genetically defined lineage. Here, we combined multiple genomics datasets to reconstruct the genetic history of the rice-infecting lineage of M. oryzae based on 131 isolates from 21 countries.ResultsThe global population of the rice blast fungus consists of a diverse set of individuals and three well-defined genetic groups. Multiple population genetic tests revealed that the rice-infecting lineage of the blast fungus probably originated from a recombining diverse group in South East Asia followed by three independent clonal expansions that took place over the last ∼200 years. Patterns of allele sharing identified a subpopulation from the recombining diverse group that introgressed with one of the clonal lineages before its global expansion. Remarkably, the four genetic lineages of the rice blast fungus vary in the number and patterns of presence/absence of candidate effector genes. In particular, clonal lineages carry a reduced repertoire of effector genes compared with the diverse group, and specific combinations of effector presence/absence define each of the pandemic clonal lineages.ConclusionsOur analyses reconstruct the genetic history of the rice-infecting lineage of M. oryzae revealing three clonal lineages associated with rice blast pandemics. Each of these lineages displays a specific pattern of presence/absence of effector genes that may have shaped their adaptation to the rice host and their evolutionary history.

scholarly journals Longevity of Plant Pathogens in Dry Agricultural Seeds During 30 Years of Storage

2021 ◽  
Vol 9 (10) ◽  
pp. 2175
Author(s):  
Guro Brodal ◽  
Åsmund Asdal
Keyword(s):  
Plant Pathogens ◽  
Seed Storage ◽  
Plant Diseases ◽  
Alternaria Brassicicola ◽  
Seed Infection ◽  
Meadow Fescue ◽  
Crop Species ◽  
Seed Health ◽  
Phoma Betae ◽  
Drechslera Dictyoides

Plant diseases may survive and be spread by infected seeds. In this study we monitored the longevity of 14 seed-borne pathogens in 9 crop species commonly grown in the Nordic countries, in addition to a sample of sclerotia of Sclerotinia sclerotiorum. The data from the first 30 years of a 100-year seed storage experiment located in a natural −3.5 °C environment (permafrost) in Svalbard, Norway, are presented. To date, the pathogens, tested by traditional seed health testing methods (freezing blotter, agar plates, growing on tests), have survived. Linear regression analyses showed that the seed infection percentages of Drechslera dictyoides in meadow fescue, Drechslera phlei in timothy, and Septoria nodorum in wheat were significantly reduced compared to the percentages at the start of the experiment (from 63% to 34%, from 70% to 65%, and from 15% to 1%, respectively), and that Phoma betae in beet had increased significantly (from 43% to 56%). No trends in the infection percentage were observed over the years in Drechslera spp. in barley (fluctuating between 30% and 64%) or in Alternaria brassicicola in cabbage (fluctuating between 82% and 99%), nor in pathogens with low seed infection percentages at the start of the experiment. A major part of the stored sclerotia was viable after 30 years. To avoid the spread of seed-borne diseases, it is recommended that gene banks implement routines that avoid the use of infected seeds.

scholarly journals Secondary Metabolites of the Rice Blast Fungus Pyricularia oryzae: Biosynthesis and Biological Function

2020 ◽  
Vol 21 (22) ◽  
pp. 8698
Author(s):  
Takayuki Motoyama
Keyword(s):  
Secondary Metabolites ◽  
Secondary Metabolism ◽  
Rice Blast ◽  
Plant Pathogens ◽  
Pathogenic Fungus ◽  
Pathogenic Fungi ◽  
Pyricularia Oryzae ◽  
Blast Disease ◽  
Plant Pathogenic Fungi ◽  
Biosynthetic Genes

Plant pathogenic fungi produce a wide variety of secondary metabolites with unique and complex structures. However, most fungal secondary metabolism genes are poorly expressed under laboratory conditions. Moreover, the relationship between pathogenicity and secondary metabolites remains unclear. To activate silent gene clusters in fungi, successful approaches such as epigenetic control, promoter exchange, and heterologous expression have been reported. Pyricularia oryzae, a well-characterized plant pathogenic fungus, is the causal pathogen of rice blast disease. P. oryzae is also rich in secondary metabolism genes. However, biosynthetic genes for only four groups of secondary metabolites have been well characterized in this fungus. Biosynthetic genes for two of the four groups of secondary metabolites have been identified by activating secondary metabolism. This review focuses on the biosynthesis and roles of the four groups of secondary metabolites produced by P. oryzae. These secondary metabolites include melanin, a polyketide compound required for rice infection; pyriculols, phytotoxic polyketide compounds; nectriapyrones, antibacterial polyketide compounds produced mainly by symbiotic fungi including endophytes and plant pathogens; and tenuazonic acid, a well-known mycotoxin produced by various plant pathogenic fungi and biosynthesized by a unique NRPS-PKS enzyme.

scholarly journals Detection of Fusarium oxysporum f. sp. fragariae from Infected Strawberry Plants

Plant Disease ◽  
2019 ◽  
Vol 103 (5) ◽  
pp. 1006-1013 ◽  
Author(s):  
Alyssa Burkhardt ◽  
Peter M. Henry ◽  
Steven T. Koike ◽  
Thomas R. Gordon ◽  
Frank Martin
Keyword(s):  
Fusarium Oxysporum ◽  
Species Complex ◽  
Plant Pathogens ◽  
Genetic Locus ◽  
Quantitative Polymerase Chain Reaction ◽  
High Sensitivity ◽  
Field Samples ◽  
Pathogenicity Tests ◽  
Multiple Field ◽  
Fusarium Oxysporum Species Complex

Isolates of the Fusarium oxysporum species complex have been characterized as plant pathogens that commonly cause vascular wilt, stunting, and yellowing of the leaves in a variety of hosts. F. oxysporum species complex isolates have been grouped into formae speciales based on their ability to cause disease on a specific host. F. oxysporum f. sp. fragariae is the causal agent of Fusarium wilt of strawberry and has become a threat to production as fumigation practices have changed in California. F. oxysporum f. sp. fragariae is polyphyletic and limited genetic markers are available for its detection. In this study, next-generation sequencing and comparative genomics were used to identify a unique genetic locus that can detect all of the somatic compatibility groups of F. oxysporum f. sp. fragariae identified in California. This locus was used to develop a TaqMan quantitative polymerase chain reaction assay and an isothermal recombinase polymerase amplification (RPA) assay that have very high sensitivity and specificity for more than 180 different isolates of the pathogen tested. RPA assay results from multiple field samples were validated with pathogenicity tests of recovered isolates.

scholarly journals Agrobacterium-Mediated Plant Transformation: the Biology behind the “Gene-Jockeying” Tool

2003 ◽  
Vol 67 (1) ◽  
pp. 16-37 ◽  
Author(s):  
Stanton B. Gelvin
Keyword(s):  
Genetic Engineering ◽  
Plant Transformation ◽  
Plant Pathogens ◽  
Genetic Determinants ◽  
Genetic Engineer ◽  
Crop Species ◽  
The Past ◽  
Culture Transformation ◽  
Basic Biology ◽  
Host Genes

SUMMARY Agrobacterium tumefaciens and related Agrobacterium species have been known as plant pathogens since the beginning of the 20th century. However, only in the past two decades has the ability of Agrobacterium to transfer DNA to plant cells been harnessed for the purposes of plant genetic engineering. Since the initial reports in the early 1980s using Agrobacterium to generate transgenic plants, scientists have attempted to improve this “natural genetic engineer” for biotechnology purposes. Some of these modifications have resulted in extending the host range of the bacterium to economically important crop species. However, in most instances, major improvements involved alterations in plant tissue culture transformation and regeneration conditions rather than manipulation of bacterial or host genes. Agrobacterium-mediated plant transformation is a highly complex and evolved process involving genetic determinants of both the bacterium and the host plant cell. In this article, I review some of the basic biology concerned with Agrobacterium-mediated genetic transformation. Knowledge of fundamental biological principles embracing both the host and the pathogen have been and will continue to be key to extending the utility of Agrobacterium for genetic engineering purposes.

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