scholarly journals Gene Duplication and Mutation in the Emergence of a Novel Aggressive Allele of the AVR-Pik Effector in the Rice Blast Fungus

2019 ◽  
Vol 32 (6) ◽  
pp. 740-749 ◽  
Author(s):  
Apinya Longya ◽  
Chaivarakun Chaipanya ◽  
Marina Franceschetti ◽  
Josephine H. R. Maidment ◽  
Mark J. Banfield ◽  
...  
Keyword(s):  
Rice Blast ◽  
Blast Disease ◽  
Yield Potential ◽  
Crop Breeding ◽  
Breeding Programs ◽  
Blast Fungus ◽  
Resistant Varieties ◽  
Novel Variant ◽  
Avr Gene

Higher yield potential and greater yield stability are common targets for crop breeding programs, including those in rice. Despite these efforts, biotic and abiotic stresses continue to impact rice production. Rice blast disease, caused by Magnaporthe oryzae, is the most devastating disease affecting rice worldwide. In the field, resistant varieties are unstable and can become susceptible to disease within a few years of release due to the adaptive potential of the blast fungus, specifically in the effector (avirulence [AVR]) gene pool. Here, we analyzed genetic variation of the effector gene AVR-Pik in 58 rice blast isolates from Thailand and examined the interaction between AVR-Pik and the cognate rice resistance gene Pik. Our results reveal that Thai rice blast isolates are very diverse. We observe four AVR-Pik variants in the population, including three previously identified variants, AVR-PikA, AVR-PikD, and AVR-PikE, and one novel variant, which we named AVR-PikF. Interestingly, 28 of the isolates contained two copies of AVR-Pik, always in the combination of AVR-PikD and AVR-PikF. Blast isolates expressing only AVR-PikF show high virulence to rice cultivars encoding allelic Pik resistance genes, and the AVR-PikF protein does not interact with the integrated heavy metal–associated domain of the Pik resistance protein in vitro, suggesting a mechanism for immune evasion.

scholarly journals Long Non-coding RNAs Responsive to Blast Fungus Infection in Rice

Rice ◽  
2020 ◽  
Vol 13 (1) ◽  
Author(s):  
Lan-Lan Wang ◽  
Jing-Jing Jin ◽  
Li-Hua Li ◽  
Shao-Hong Qu
Keyword(s):  
Rice Blast ◽  
Blast Resistance ◽  
Enrichment Analysis ◽  
Defense Responses ◽  
Pathogen Resistance ◽  
Blast Disease ◽  
Fungus Infection ◽  
Blast Fungus ◽  
Gene Transcription Level ◽  
Non Coding Rnas

Abstract Background Long non-coding RNAs (LncRNAs) have emerged as important regulators in many physiological processes in plant. By high-throughput RNA-sequencing, many pathogen-associated LncRNAs were mapped in various plants, and some of them were proved to be involved in plant defense responses. The rice blast disease caused by Magnaporthe oryzae (M. oryzae) is one of the most destructive diseases in rice. However, M. oryzae-induced LncRNAs in rice is yet to be studied. Findings We investigated rice LncRNAs that were associated with the rice blast fungus. Totally 83 LncRNAs were up-regulated after blast fungus infection and 78 were down-regulated. Of them, the natural antisense transcripts (NATs) were the most abundant. The expression of some LncRNAs has similar pattern with their host genes or neighboring genes, suggesting a cis function of them in regulating gene transcription level. The deferentially expressed (DE) LncRNAs and genes co-expression analysis revealed some LncRNAs were associated with genes known to be involved in pathogen resistance, and these genes were enriched in terpenoid biosynthesis and defense response by Gene Ontology (GO) enrichment analysis. Interestingly, one of up-regulated DE-intronic RNA was derived from a jasmonate (JA) biosynthetic gene, lipoxygenase RLL (LOX-RLL). Levels of JAs were significantly increased after blast fungus infection. Given that JA is known to regulate blast resistance in rice, we suggested that LncRNA may be involved in JA-mediated rice resistance to blast fungus. Conclusions This study identified blast fungus-responsive LncRNAs in rice, which provides another layer of candidates that regulate rice and blast fungus interactions.

In vitro evaluation of bio-agents against Pyricularia oryzae (Cav.) causing rice blast disease

2017 ◽  
Vol 37 (03) ◽  
Author(s):  
Akhilesh Kumar Kulmitra ◽  
Neha Sahu ◽  
V.B. Sanath Kumar ◽  
Thejesha A. G. ◽  
Amlan Ghosh ◽  
...  
Keyword(s):  
Bacillus Subtilis ◽  
Pseudomonas Fluorescens ◽  
Rice Blast ◽  
Mycelial Growth ◽  
Trichoderma Viride ◽  
Culture Technique ◽  
Pyricularia Oryzae ◽  
Blast Disease ◽  
Dual Culture

The five different bio-agents viz., Trichoderma viride, T. harzianum, T. virens, Pseudomonas fluorescens and Bacillus subtilis were evaluated against Pyricularia oryzae at four and eight days after incubation through dual culture technique. Among the five different bio-agents, highest per cent inhibition of mycelial growth of fungus was recorded in T. virens i.e. 67 per cent and 70 percent after four and eight days after incubation respectively with mean of 68.5 per cent followed by Trichoderma viride with the inhibition of 61 and 63 per cent respectively with mean of 62 per cent. The Pseudomonas fluorescens did not show any inhibition of mycelial growth of P. oryzae as the pathogen over grew the bio-agents.

scholarly journals A Novel Role for Catalase B in the Maintenance of Fungal Cell-Wall Integrity During Host Invasion in the Rice Blast Fungus Magnaporthe grisea

2007 ◽  
Vol 20 (5) ◽  
pp. 568-580 ◽  
Author(s):  
Pari Skamnioti ◽  
Catherine Henderson ◽  
Ziguo Zhang ◽  
Zena Robinson ◽  
Sarah Jane Gurr
Keyword(s):  
Rice Blast ◽  
Magnaporthe Grisea ◽  
Large Subunit ◽  
Rice Blast Fungus ◽  
Gene Replacement ◽  
Fungal Cell ◽  
Antioxidant Genes ◽  
Blast Fungus

Asexual spores of the rice blast fungus germinate to produce a specialized and melanized infection structure, the appressorium, which is pivotal to successful plant penetration. To investigate whether Magnaporthe grisea counteracts the toxic burst of H2O2 localized beneath the site of attempted invasion, we examined the temporal expression of five candidate antioxidant genes. Of these, the putatively secreted large subunit catalase CATB gene was 600-fold up-regulated in vivo, coincident with penetration, and moderately up-regulated in vitro, in response to exogenous H2O2. Targeted gene replacement of CATB led to compromised pathogen fitness; the catB mutant displayed paler pigmentation and accelerated hyphal growth but lower biomass, poorer sporulation, fragile conidia and appressoria, and impaired melanization. The catB mutant was severely less pathogenic than Guy 11 on barley and rice, and its infectivity was further reduced on exposure to H2O2. The wild-type phenotype was restored by the reintroduction of CATB into the catB mutant. We found no evidence to support a role for CATB in detoxification of the host-derived H2O2 at the site of penetration. Instead, we demonstrated that CATB plays a part in strengthening the fungal wall, a role of particular importance during forceful entry into the host.

scholarly journals PEA (Pisum sativum L.) BREEDING: ADVANCES OF THE BREEDING PROGRAM AT UNIVERSIDAD NACIONAL DE ROSARIO

2021 ◽  
Vol 32 (Issue 2) ◽  
pp. 14-22
Author(s):  
I. Gatti ◽  
F. Cazzola ◽  
C.J. Bermejo ◽  
M.F. Guindón ◽  
M.A. Espósito ◽  
...  
Keyword(s):  
Local Development ◽  
Doubled Haploids ◽  
Breeding Program ◽  
Yield Potential ◽  
High Yield ◽  
Breeding Programs ◽  
Commercial Line ◽  
National University ◽  
Reducing Costs

A pea breeding program to increase production in quantity and quality was started in 2005 in the College of Agrarian Sciences (FCA), National University of Rosario (UNR). The first steps were to gather an active collection of germplasm from around the world and to analyze genetic variability through morpho-agronomic and molecular traits in order to set objectives. In 2014, the National Institute of Agropecuarian Technology (INTA) and the FCA-UNR, joined forces to unite inter-institutional efforts for promoting the local development of pea genotypes adapted to the region. This program, using conventional methodologies, has so far obtained a new commercial line (Primogénita FCA-INTA) of green cotyledons, semi-leafless, with high adaptation to local agro ecological conditions and high yield potential. Breeding, nevertheless, is a slow process. Developing new pea varieties usually takes a decade or more when using traditional methodologies; thus, different alternatives were proposed for the reduction of this period. Doubled haploids and in vitro culture have been some of the methodologies developed; in pulses, however, they have not been efficiently implemented in breeding programs. In this context, Speed Breeding emerges as a technology that allows increasing the efficiency of the programs, while reducing costs and the required labor. Key words: peas, conventional methodologies, Speed Breeding, doubled haploids.

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 The mitotic spindle mediates nuclear migration through an extremely narrow infection structure of the rice blast fungus Magnaporthe oryzae

2021 ◽  
Author(s):  
Mariel A. Pfeifer ◽  
Chang Hyun Khang
Keyword(s):  
Magnaporthe Oryzae ◽  
Mitotic Spindle ◽  
Rice Blast ◽  
Mechanistic Model ◽  
Nuclear Migration ◽  
Blast Disease ◽  
Cellular Structures ◽  
Blast Fungus ◽  
Single Nucleus ◽  
Migration Event

The blast fungus, Magnaporthe oryzae, causes severe destruction to rice and other crops worldwide. As the fungus infects rice, it develops unique cellular structures, such as an appressorium and a narrow penetration peg, to permit successful invasion of host rice cells. Fundamental knowledge about these cellular structures and how organelles, such as the nucleus, are positioned within them is still emerging. Previous studies show that a single nucleus becomes highly stretched during movement through the narrow penetration peg in an extreme nuclear migration event. Yet, the mechanism permitting this nuclear migration event remains elusive. Here, we investigate the role of the mitotic spindle in mediating nuclear migration through the penetration peg. We find that disruption of spindle function during nuclear migration through the penetration peg prevents development of invasive hyphae and virulence on rice. Furthermore, regulated expression of conserved kinesin motor proteins, MoKin5 and MoKin14, is essential to form and maintain the spindle, as well as, properly nucleate the primary hypha. Overexpression of MoKin5 leads to formation of aberrant microtubule protrusions, which contributes to formation of nuclear fragments within the appressorium and primary hypha. Conversely, overexpression of MoKin14 causes the spindle to collapse leading to the formation of monopolar spindles. These results establish a mechanistic model towards understanding the intricate subcellular dynamics of extreme nuclear migration through the penetration peg, a critical step in the development of rice blast disease.

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 Morphological Characterization and Genetic Diversity of Rice Blast Fungus, Pyricularia oryzae, from Thailand Using ISSR and SRAP Markers

2020 ◽  
Vol 6 (1) ◽  
pp. 38 ◽  
Author(s):  
Apinya Longya ◽  
Sucheela Talumphai ◽  
Chatchawan Jantasuriyarat
Keyword(s):  
Genetic Diversity ◽  
Genetic Variation ◽  
Rice Blast ◽  
Rice Blast Fungus ◽  
Pyricularia Oryzae ◽  
Blast Disease ◽  
Host Recognition ◽  
Srap Markers ◽  
Blast Fungus ◽  
Polymorphic Bands

Rice blast disease is caused by the ascomycete fungus Pyricularia oryzae and is one of the most destructive rice diseases in the world. The objectives of this study were investigating various fungal morphological characteristics and performing a phylogenetic analysis. Inter-simple sequence repeat (ISSR) and sequence-related amplified polymorphism (SRAP) markers were used to examine the genetic variation of 59 rice blast fungus strains, including 57 strains collected from different fields in Thailand and two reference strains, 70-15 and Guy11. All isolates used in this study were determined to be P. oryzae by internal transcribed spacer (ITS) sequence confirmation. A total of 14 ISSR primers and 17 pairs of SRAP primers, which produced clear and polymorphic bands, were selected for assessing genetic diversity. A total of 123 polymorphic bands were generated. The similarity index value for the strains ranged from 0.25 to 0.95. The results showed that the blast fungus population in Thailand has both morphological and genetic variations. A high level of genetic variation, or genome adaptation, is one of the fungal mechanisms that could overcome host resistance to avoid host recognition. Results from this research study could bring substantial benefits and ultimately help to understand the blast fungal pathogen genome and the population structure in Thai blast fungus.

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