Parasexual Recombination in Magnaporthe oryzae

Noguchi, Masako Tsujimoto

doi:10.6090/jarq.45.39

Cited by 10 publications

(4 citation statements)

References 60 publications

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“…The genetic variation supports the hypothesis that the main mechanism by which P. oryzae overcomes host resistant in natural conditions might be genome adaptation to avoid host recognition. Two main mechanisms for genome adaptation in fungi are sexual mating and parasexual recombination [20], but sexual reproduction in rice blast fungus has not been observed in the field and sexual spores have been produced only in laboratory settings. Therefore, parasexual recombination could most likely be the major mechanism for the exchange of DNA fragments [21] that causes genetic variation in the rice blast population.…”

Section: Genetic Diversity Of Pyricularia Oryzae Using Srap and Issr mentioning

confidence: 99%

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

Longya

Talumphai

Jantasuriyarat

2020

JoF

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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.regions with primers targeting open reading frames (ORFs) [5]. The molecular markers differ in cost, speed, complication, labor, degree of polymorphism, and repeatability. ISSR and SRAP marker techniques are fast and low cost, they do not require sequence information, have high repeatability, and use only one-step PCR. They provide highly discriminating information with good reproducibility and are relatively abundant, while AFLP and RAPD are more labor intensive and time consuming [4,6]. We characterized blast fungal morphology, performed DNA sequence analyses of the internal transcribed spacer (ITS), and used 20 ISSR and 30 SRAP markers to assess the genetic diversity of 59 rice blast strains, including 57 strains collected from Thai rice-growing areas and two reference strains, 70-15 and Guy11. The information obtained from this study will help to understand the population structure and evolution of rice blast fungus in Thailand. Materials and Methods Rice Blast MaterialsA total of 59 rice blast strains were used, including 57 strains collected from Thai rice-growing areas representing central, northern, and north-eastern parts of Thailand. Two rice blast strains, 70-15 and Guy11, were used as reference strains (Table 1). The stock of each blast strain as in filter paper was cultured and DNA was extracted using the cetyl-trimethyl-ammonium-bromide (CTAB) method described by Longya et al. [7].

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Section: Genetic Diversity Of Pyricularia Oryzae Using Srap and Issr mentioning

confidence: 99%

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

Longya

Talumphai

Jantasuriyarat

2020

JoF

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“…To date, more than 40 AVR genes have been identified in the blast fungus and 12 of them ( PWL1, PWL2, ACE1, AVR1-CO39, AVR-Pita1, AVR-Pii, AVR-Pia, AVR-Pik, AVR-Pizt, AVR-Pi9, AVR-Pib , and AVR-Pi54 ) have been cloned (Kang et al, 1995 ; Sweigard et al, 1995 ; Farman and Leong, 1998 ; Orbach et al, 2000 ; Fudal et al, 2005 ; Ma et al, 2006 ; Li et al, 2009 ; Yoshida et al, 2009 ; Wu et al, 2015 ; Zhang et al, 2015 ; Ray et al, 2016 ). The avirulent function of AVR genes can be invalidated by different mechanisms, including mutation, genetic recombination, and sexual mating (Noguchi et al, 2006 ; Tsujimoto Noguchi, 2011 ). Mutation commonly occurs, such as insertion, point mutation, and deletion.…”

Section: Introductionmentioning

confidence: 99%

Loss and Natural Variations of Blast Fungal Avirulence Genes Breakdown Rice Resistance Genes in the Sichuan Basin of China

Huang

Lin

et al. 2022

Front. Plant Sci.

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Magnaporthe oryzae is the causative agent of rice blast, a devastating disease in rice worldwide. Based on the gene-for-gene paradigm, resistance (R) proteins can recognize their cognate avirulence (AVR) effectors to activate effector-triggered immunity. AVR genes have been demonstrated to evolve rapidly, leading to breakdown of the cognate resistance genes. Therefore, understanding the variation of AVR genes is essential to the deployment of resistant cultivars harboring the cognate R genes. In this study, we analyzed the nucleotide sequence polymorphisms of eight known AVR genes, namely, AVR-Pita1, AVR-Pii, AVR-Pia, AVR-Pik, AVR-Pizt, AVR-Pi9, AVR-Pib, and AVR-Pi54 in a total of 383 isolates from 13 prefectures in the Sichuan Basin. We detected the presence of AVR-Pik, AVR-Pi54, AVR-Pizt, AVR-Pi9, and AVR-Pib in the isolates of all the prefectures, but not AVR-Pita1, AVR-Pii, and AVR-Pia in at least seven prefectures, indicating loss of the three AVRs. We also detected insertions of Pot3, Mg-SINE, and indels in AVR-Pib, solo-LTR of Inago2 in AVR-Pizt, and gene duplications in AVR-Pik. Consistently, the isolates that did not harboring AVR-Pia were virulent to IRBLa-A, the monogenic line containing Pia, and the isolates with variants of AVR-Pib and AVR-Pizt were virulent to IRBLb-B and IRBLzt-t, the monogenic lines harboring Pib and Piz-t, respectively, indicating breakdown of resistance by the loss and variations of the avirulence genes. Therefore, the use of blast resistance genes should be alarmed by the loss and nature variations of avirulence genes in the blast fungal population in the Sichuan Basin.

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“…parasexual crosses do not exhibit heterokaryon incompatibility and are therefore viable (Crawford et al 1986). This mechanism has been suggested as a source of genetic variation in the rice blast fungus, potentially occurring under field conditions (Zeigler et al 1997; Noguchi et al 2006; Tsujimoto Noguchi 2011; Monsur and Kusaba 2018). Here, we found robust evidence that horizontal mChr transfer occurs under field conditions, a process probably parasexual in nature.…”

Section: Discussionmentioning

confidence: 99%

Multiple horizontal mini-chromosome transfers drive genome evolution of clonal blast fungus lineages

Barragan,

Latorre,

Malmgren

et al. 2024

Preprint

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Crop disease pandemics are often driven by clonal lineages of plant pathogens that reproduce asexually. How these clonal pathogens continuously adapt to their hosts despite harboring limited genetic variation, and in absence of sexual recombination remains elusive. Here, we reveal multiple instances of horizontal chromosome transfer within pandemic clonal lineages of the blast fungus Magnaporthe (Syn. Pyricularia) oryzae. We identified a horizontally transferred 1.2Mb supernumerary mini-chromosome which is remarkably conserved between M. oryzae isolates from both the rice blast fungus lineage and the lineage infecting Indian goosegrass (Eleusine indica), a wild grass that often grows in the proximity of cultivated cereal crops. Furthermore, we show that this mini-chromosome was horizontally acquired by clonal rice blast isolates through at least nine distinct transfer events over the past three centuries. These findings establish horizontal mini-chromosome transfer as a mechanism facilitating genetic exchange among different host-associated blast fungus lineages. We propose that blast fungus populations infecting wild grasses act as genetic reservoirs that drive genome evolution of pandemic clonal lineages that afflict cereal crops.

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Parasexual Recombination in Magnaporthe oryzae

Cited by 10 publications

References 60 publications

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

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

Loss and Natural Variations of Blast Fungal Avirulence Genes Breakdown Rice Resistance Genes in the Sichuan Basin of China

Multiple horizontal mini-chromosome transfers drive genome evolution of clonal blast fungus lineages

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