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 Differential loss of effector genes in three recently expanded pandemic clonal lineages of the rice blast fungus

BMC Biology ◽  
2020 ◽  
Vol 18 (1) ◽  
Author(s):  
Sergio M. Latorre ◽  
C. Sarai Reyes-Avila ◽  
Angus Malmgren ◽  
Joe Win ◽  
Sophien Kamoun ◽  
...  
Keyword(s):  
Rice Blast ◽  
Rice Blast Fungus ◽  
Effector Genes ◽  
Blast Fungus

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.

scholarly journals Effects of Rice Blast Fungus (Pyricularia grisea) on Phenolics, Flavonoids, Antioxidant Capacity in Rice (Oryza sativa L.)

2017 ◽  
Vol 61 ◽  
pp. 1-7
Author(s):  
Nguyen Phu Toan ◽  
Pham Thi Thu Ha ◽  
Tran Dang Xuan
Keyword(s):  
Antioxidant Capacity ◽  
Cinnamic Acid ◽  
Rice Blast ◽  
Rice Blast Fungus ◽  
Blast Disease ◽  
Pyricularia Grisea ◽  
Rice Cultivars ◽  
Blast Fungus ◽  
Phenolic Components ◽  
Dpph Scavenging

Rice blast fungus (Pyricularia grisea) is one of the most problematic pathogen to significantly reduce rice production worldwide. In this study, after being inoculated withP. grisea, changes in phenolic components and antioxidant capacity and correlation with the resistant level against rice blast fungus were investigated. Among screened rice cultivars, AV-3 was the strongest resistant, whereas BII-3 was the most susceptible. It was found that although total contents of phenolics and flavonoids, and antioxidant capacities varied among studied varieties, no significant coefficient with the resistance againstP. griseawas observed. After rice was affected by rice blast fungus, total phenolics and flavonoids were markedly reduced, but in contrast, the DPPH scavenging activities of only the susceptible rice cultivars was reduced. Among the 11 phenolic acids detected, catechol was found only in the tolerant cultivar AV-3, whereas the amount of cinnamic acid was increased after infection. Quantity of vanillin was also promoted, except in the susceptible cultivar BII-3 that was significantly reduced. Findings of this study showed that the resistant level againstP. griseawas proportionally correlated to the antioxidant capacity. Catechol, cinnamic acid, and vanillin may play a role but it needs further elaboration. Observations of this study suggested that the infection of blast disease by reducing amount of phenolics and flavonoids that may weaken the resistance of rice against this detrimental fungus.

Diversity of ACE1 Genotypes of the Rice Blast Fungus (Magnaporthe oryzae B.C. Couch) in the Philippines

2015 ◽  
Vol 16 (1) ◽  
Author(s):  
Ana Liza C. Lopez ◽  
Christian Joseph R. Cumagun ◽  
Didier Tharreau
Keyword(s):  
Rice Blast ◽  
Plant Pathogens ◽  
Indica Rice ◽  
Geographic Location ◽  
Rice Blast Fungus ◽  
The Philippines ◽  
Contingency Analysis ◽  
Rice Varieties ◽  
Blast Fungus ◽  
Rainfed Lowland

Knowledge of the avirulence (Avr) genes present in plant pathogens facilitates the identification of the required resistance (R) gene to be incorporated in host plants to overcome pathogen infection. The plus/minus Polymerase Chain Reaction (PCR) assay was conducted to determine the presence of the virulent and avirulent ACE1 genotypes of the rice blast fungus in Philippine rice fields. Results indicated that the avirulent genotype Guy11 was present only in 13% of the test isolates, whereas the virulent genotypes, PH14 and CM28, appeared in 83% of the total number of test isolates. With contingency analysis on the type of agroecosystem and presence of ACE1 genotype, it was known that Guy11 is significantly associated with the upland agroecosystem. Whereas, PH14 was present in both the irrigated and rainfed lowland and CM28 was ubiquitously associated with any type of agroecosystems. No significant association, however, was noted between a specific ACE1 genotype and geographic location. The isolates having virulent ACE1 genotype can overcome the resistance Pi33 which is commonly introgressed into popular semi-dwarf indica rice varieties. Keywords - Biodiversity, ACE1 genotypes, rice blast fungus, experimental design, Philippines

scholarly journals OsNAC111, a Blast Disease–Responsive Transcription Factor in Rice, Positively Regulates the Expression of Defense-Related Genes

2014 ◽  
Vol 27 (10) ◽  
pp. 1027-1034 ◽  
Author(s):  
Naoki Yokotani ◽  
Tomoko Tsuchida-Mayama ◽  
Hiroaki Ichikawa ◽  
Nobutaka Mitsuda ◽  
Masaru Ohme-Takagi ◽  
...  
Keyword(s):  
Transcription Factor ◽  
Transgenic Rice ◽  
Transcriptional Activation ◽  
Rice Blast ◽  
Rice Blast Fungus ◽  
Blast Disease ◽  
Pr Genes ◽  
Rice Plants ◽  
Blast Fungus ◽  
Transgenic Rice Plants

Plants respond to pathogen attack by transcriptionally regulating defense-related genes via various types of transcription factors. We identified a transcription factor in rice, OsNAC111, belonging to the TERN subgroup of the NAC family that was transcriptionally upregulated after rice blast fungus (Magnaporthe oryzae) inoculation. OsNAC111 was localized in the nucleus of rice cells and had transcriptional activation activity in yeast and rice cells. Transgenic rice plants overexpressing OsNAC111 showed increased resistance to the rice blast fungus. In OsNAC111-overexpressing plants, the expression of several defense-related genes, including pathogenesis-related (PR) genes, was constitutively high compared with the control. These genes all showed blast disease-responsive expression in leaves. Among them, two chitinase genes and one β-1,3-glucanase gene showed reduced expression in transgenic rice plants in which OsNAC111 function was suppressed by a chimeric repressor (OsNAC111-SRDX). OsNAC111 activated transcription from the promoters of the chitinase and β-1,3-glucanase genes in rice cells. In addition, brown pigmentation at the infection sites, a defense response of rice cells to the blast fungus, was lowered in OsNAC111-SRDX plants at the early infection stage. These results indicate that OsNAC111 positively regulates the expression of a specific set of PR genes in the disease response and contributes to disease resistance.

scholarly journals Genetic Variation Bias toward Noncoding Regions and Secreted Proteins in the Rice Blast Fungus Magnaporthe oryzae

mSystems ◽  
2020 ◽  
Vol 5 (3) ◽  
Author(s):  
Zhenhui Zhong ◽  
Meilian Chen ◽  
Lianyu Lin ◽  
Ruiqi Chen ◽  
Dan Liu ◽  
...  
Keyword(s):  
Genetic Variation ◽  
Magnaporthe Oryzae ◽  
Experimental Evolution ◽  
Rice Blast ◽  
Plant Pathogens ◽  
Rice Blast Fungus ◽  
Content Type ◽  
Noncoding Regions ◽  
Blast Fungus ◽  
Pathogen Populations

ABSTRACT The genomes of plant pathogens are highly variable and plastic. Pathogen gene repertoires change quickly with the plant environment, which results in a rapid loss of plant resistance shortly after the pathogen emerges in the field. Extensive studies have evaluated natural pathogen populations to understand their evolutionary effects; however, the number of studies that have examined the dynamic processes of the mutation and adaptation of plant pathogens to host plants remains limited. Here, we applied experimental evolution and high-throughput pool sequencing to Magnaporthe oryzae, a fungal pathogen that causes massive losses in rice production, to observe the evolution of genome variation. We found that mutations, including single-nucleotide variants (SNVs), insertions and deletions (indels), and transposable element (TE) insertions, accumulated very rapidly throughout the genome of M. oryzae during sequential plant inoculation and preferentially in noncoding regions, while such mutations were not frequently found in coding regions. However, we also observed that new TE insertions accumulated with time and preferentially accumulated at the proximal region of secreted protein (SP) coding genes in M. oryzae populations. Taken together, these results revealed a bias in genetic variation toward noncoding regions and SP genes in M. oryzae and may contribute to the rapid adaptive evolution of the blast fungal effectors under host selection. IMPORTANCE Plants “lose” resistance toward pathogens shortly after their widespread emergence in the field because plant pathogens mutate and adapt rapidly under resistance selection. Thus, the rapid evolution of pathogens is a serious threat to plant health. Extensive studies have evaluated natural pathogen populations to understand their evolutionary effects; however, the study of the dynamic processes of the mutation and adaptation of plant pathogens to host plants remains limited. Here, by performing an experimental evolution study, we found a bias in genetic variation toward noncoding regions and SPs in the rice blast fungus Magnaporthe oryzae, which explains the ability of the rice blast fungus to maintain high virulence variation to overcome rice resistance in the field.

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