A Gene-for-Gene Relationship Underlying the Species-Specific Parasitism of Avena/Triticum Isolates of Magnaporthe grisea on Wheat Cultivars

To elucidate genetic mechanisms of the species-specific parasitism of Magnaporthe grisea, a Triticum isolate (pathogenic on wheat) was crossed with an Avena isolate (pathogenic on oat), and resulting F1 progeny were subjected to segregation analyses on wheat cvs. Norin 4 and Chinese Spring. We found two fungal loci, Pwt3 and Pwt4, which are involved in the specific parasitism on wheat. Pwt3 operated on both cultivars while Pwt4 operated only on ‘Norin 4’. Using the cultivar specificity of Pwt4, its corresponding resistance gene was successfully identified in ‘Norin 4’ and designated as Rmg1 (Rwt4). The presence of the corresponding resistance gene indicated that Pwt4 is an avirulence locus. Pwt3 was assumed to be an avirulence locus because of its temperature sensitivity. We suggest that gene-for-gene interactions underlie the species-specific parasitism of M. grisea.

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Gene-for-gene interactions between the rye mildew fungus and wheat cultivars

Genome ◽

10.1139/g94-108 ◽

1994 ◽

Vol 37 (5) ◽

pp. 758-762 ◽

Cited By ~ 9

Author(s):

Y. Tosa

Keyword(s):

Triticum Aestivum ◽

Powdery Mildew ◽

Chinese Spring ◽

Single Gene ◽

Erysiphe Graminis ◽

Gene Interactions ◽

Wheat Cultivars ◽

Genetic Mechanisms ◽

Host Parasite ◽

Gene For Gene

Genetic mechanisms of the incompatibility between Erysiphe graminis f.sp. secalis and wheat cultivars were analyzed using F1 hybrids between E. graminis f.sp. secalis, Sk-1, and f.sp. tritici, Tk-1. The avirulence of Sk-1 on Triticum aestivum 'Norin 4', 'Chinese Spring', and 'Kokeshi-komugi' was controlled by a single gene. The resistance of the three cultivars to Sk-1 was also controlled by a single gene, Pm15, a gene for resistance to E. graminis f.sp. agropyri. Implications of these results were discussed in terms of host–parasite coevolution.Key words: powdery mildew, Erysiphe graminis, resistance, wheat.

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Analysis of Host Species Specificity of Magnaporthe grisea Toward Foxtail Millet Using a Genetic Cross Between Isolates from Wheat and Foxtail Millet

Phytopathology ◽

10.1094/phyto.2003.93.1.42 ◽

2003 ◽

Vol 93 (1) ◽

pp. 42-45 ◽

Cited By ~ 30

Author(s):

J. Murakami ◽

R. Tomita ◽

T. Kataoka ◽

H. Nakayashiki ◽

Y. Tosa ◽

...

Keyword(s):

Host Species ◽

Magnaporthe Grisea ◽

Foxtail Millet ◽

Species Specificity ◽

The Other ◽

Single Locus ◽

Gene Interactions ◽

Genetic Cross ◽

Genetic Mechanisms ◽

Cultivar Specificity

Host species specificity of Magnaporthe grisea toward foxtail millet was analyzed using F1 cultures derived from a cross between a Triticum isolate (pathogenic on wheat) and a Setaria isolate (pathogenic on foxtail millet). On foxtail millet cvs. Beni-awa and Oke-awa, avirulent and virulent cultures segregated in a 1:1 ratio, suggesting that a single locus is involved in the specificity. This locus was designated as Pfm1. On cv. Ki-awa, two loci were involved and one of them was Pfm1. The other locus was designated as Pfm2. Interestingly, Pfm1 was not involved in the pathogenic specificity on cv. Kariwano-zairai. These results suggest that there is no “master gene” that determines the pathogenic specificity on all foxtail millet cultivars and that the species specificity of M. grisea toward foxtail millet is governed by cultivar-dependent genetic mechanisms that are similar to gene-for-gene interactions controlling race-cultivar specificity.

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Characterization of an Avena isolate of Magnaporthe grisea and identification of a locus conditioning its specificity on oat

Canadian Journal of Botany ◽

10.1139/b02-101 ◽

2002 ◽

Vol 80 (10) ◽

pp. 1088-1095 ◽

Cited By ~ 23

Author(s):

H S Oh ◽

Y Tosa ◽

N Takabayashi ◽

S Nakagawa ◽

R Tomita ◽

...

Keyword(s):

Magnaporthe Grisea ◽

Single Gene ◽

Severe Disease ◽

Hypersensitive Reaction ◽

Temperature Sensitive ◽

Rdna Its ◽

Genetic Mechanisms ◽

Pathogenicity Tests ◽

Wheat Leaves ◽

Species Specific

An isolate of Magnaporthe grisea was collected from a blast lesion on oat in Brazil. Sequence analysis of the rDNA-ITS-2 region and DNA fingerprinting with repetitive elements revealed that the Avena isolate belongs to the "crop isolate group" and is similar to Triticum isolates. At high temperature (28°C), the Avena isolate caused severe disease symptoms on primary leaves of oat and wheat. When the temperature was decreased to 20°C, wheat leaves expressed resistance to the Avena isolate. Cytologically, this temperature-dependent resistance was associated with an increase in the incidences of papilla formation and a hypersensitive reaction. Pathogenicity tests with various plant species at 20°C revealed that the Avena isolate is exclusively parasitic on oat. To elucidate genetic mechanisms of this species-specific parasitism, the Avena isolate was crossed with a Triticum isolate and resulting F1 progenies were subjected to pathogenicity tests on oat seedlings. In the F1 population, avirulent and virulent cultures segregated in a 1:1 ratio, suggesting that the specific parasitism on oat is controlled by a single gene. This locus was designated as Pat1.Key words: Magnaporthe grisea, species-specific parasitism, oat, temperature sensitive.

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Genetic analysis and molecular mapping of the avirulence gene PRE1, a gene for host-species specificity in the blast fungus Magnaporthe grisea

Genome ◽

10.1139/g06-043 ◽

2006 ◽

Vol 49 (8) ◽

pp. 873-881 ◽

Cited By ~ 12

Author(s):

Q H Chen ◽

Y C Wang ◽

X B Zheng

Keyword(s):

Genetic Analysis ◽

Ssr Markers ◽

Host Species ◽

Magnaporthe Grisea ◽

Species Specificity ◽

Avirulence Gene ◽

Chromosome 3 ◽

Genetic Linkage Analysis ◽

Genetic Mechanisms ◽

Species Specific

We analyzed host-species specificity of Magnaporthe grisea on rice using 110 F1 progeny derived from a cross between the Oryza isolate CH87 (pathogenic to rice) and the Digitaria isolate 6023 (pathogenic to crabgrass). To elucidate the genetic mechanisms controlling species specificity in M. grisea, we performed a genetic analysis of species-specific avirulence on this rice population. Avirulent and virulent progeny segregated in a 1:1 ratio on the 2 rice cultivars 'Lijiangxintuanheigu' (LTH) and 'Shin2', suggesting that a single locus, designated PRE1, was involved in the specificity. In a combination between 'Kusabue' and 'Tsuyuake', the segregation of the 4 possible phenotypes of F1 progeny was significantly different from the expected 3:1:3:1 and instead fit a ratio of 2:0:1:1. This indicated that 2 loci, PRE1 and AVR2, were involved in specific parasitism on rice. These results suggest that the species specificity of M. grisea on rice is governed by species-dependent genetic mechanisms that are similar to the gene-for-gene interactions controlling cultivar specificity. Pathogenicity tests with various plant species revealed that the Digitaria isolate 6023 was exclusively parasitic on crabgrass. Genetic linkage analysis showed that PRE1 was mapped on chromosome 3 with respect to RAPD and SSR markers. RAPD marker S361 was linked to the avirulence gene at a distance of ~6.4 cM. Two SSR markers, m677678 and m7778, were linked to the PRE1 gene on M. grisea chromosome 3 at distances of 5.9 and 7.1 cM, respectively. Our results will facilitate positional cloning and functional studies of this gene.Key words: genetic analysis, graminaceous plants, Magnaporthe grisea, species-specific avirulence gene.

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DISTRIBUTION OF NONSTRUCTURAL VARIATION ALONG THREE CHROMOSOME ARMS BETWEEN WHEAT CULTIVARS CHINESE SPRING AND CHEYENNE

Genetics ◽

10.1093/genetics/106.2.309 ◽

1984 ◽

Vol 106 (2) ◽

pp. 309-324

Author(s):

Anne Crossway ◽

Jan Dvořák

Keyword(s):

Chinese Spring ◽

Continuous Distribution ◽

Inbred Lines ◽

Wheat Cultivars ◽

Chromosome Variation ◽

Homologous Chromosomes ◽

Ring Bivalents ◽

Chromosome Arm ◽

Parental Inbred ◽

The Mean

ABSTRACT Metaphase I (MI) pairing of wheat homologous chromosomes is usually reduced in hybrids between cultivars relative to the parental inbred lines. Previous work suggested that this phenomenon is caused by polymorphism in nucleotide sequences (nonstructural chromosome variation) among wheat cultivars. The present work investigated the distribution of this variation along three selected chromosome arms between cultivars Chinese Spring and Cheyenne. Chinese Spring ditelosomics 3Aq, 6Ap and 6Bp were crossed with disomic substitutions of Cheyenne chromosomes 3A, 6A and 6B in Chinese Spring, respectively. The resulting F1 plants, called substituted monotelodisomics, were crossed with the respective Chinese Spring monosomics, producing potentially "recombinant" substituted monosomics. When these "recombinant" chromosomes were combined with the parental Chinese Spring telosomes, marked reductions in mean telosome-pairing frequency were found compared with the corresponding Chinese Spring monotelodisomics. The mean pairing frequencies of the "recombinant" chromosomes showed a continuous distribution between those of the substituted and Chinese Spring monotelodisomics. The results suggest that the nonstructural variation that reduces MI pairing between chromosomes of different wheat cultivars is not localized in a specific site but distributed along each chromosome arm. Little variation was found among monotelodisomics for either the number of ring bivalents per cell or the number of univalents other than those constituting the heteromorphic pair. This implies that the reductions in MI pairing between the Cheyenne and Chinese Spring chromosomes are caused by something residing within these specific chromosomes that does not affect the pairing of the remaining Chinese Spring chromosomes in the same cell. Furthermore, the absence of parental types among the "recombinant"-substituted monotelodisomics suggests that the sequences involved in the variation studied here are capable of converting heterohomologous chromosomes to something intermediate in nature in the span of only a single generation.

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Host Species-Specific Protoplast Damaging Activity of Spore Germination Fluids of Blast Pathogen Magnaporthe grisea

Journal of Phytopathology ◽

10.1046/j.1439-0434.2002.00808.x ◽

2002 ◽

Vol 150 (10) ◽

pp. 576-578 ◽

Cited By ~ 3

Author(s):

R. Rathour ◽

B. M. Singh ◽

P. Plaha

Keyword(s):

Spore Germination ◽

Host Species ◽

Magnaporthe Grisea ◽

Species Specific

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Identification and fine mapping of Pi33, the rice resistance gene corresponding to the Magnaporthe grisea avirulence gene ACE1

Theoretical and Applied Genetics ◽

10.1007/s00122-003-1349-2 ◽

2003 ◽

Vol 107 (6) ◽

pp. 1139-1147 ◽

Cited By ~ 88

Author(s):

R. Berruyer ◽

H. Adreit ◽

J. Milazzo ◽

S. Gaillard ◽

A. Berger ◽

...

Keyword(s):

Resistance Gene ◽

Fine Mapping ◽

Magnaporthe Grisea ◽

Avirulence Gene

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The risk of wheat blast in rice-wheat-co-planting regions in China: MoO strains of Pyricularia oryzae cause typical symptom and host reaction on both wheat leaves and spikes

Phytopathology ◽

10.1094/phyto-10-20-0470-r ◽

2021 ◽

Author(s):

Shizhen Wang ◽

Jiaoyu Wang ◽

Zhen Zhang ◽

Zhongna Hao ◽

Xueming Zhu ◽

...

Keyword(s):

Global Warming ◽

Pyricularia Oryzae ◽

Wheat Cultivars ◽

Host Reaction ◽

Typical Symptom ◽

Wheat Blast ◽

Resistant Genes ◽

Wheat Leaves ◽

Cultivar Specificity ◽

Heading Stage

Triticum pathotype (MoT) of Magnaporthe oryzae (syn. Pyricularia oryzae) causes wheat blast, which has recently spread to Asia. To assess the potential risk of wheat blast in rice-wheat growing regions, we investigated the pathogenicity of 14 isolates of P. oryzae on 32 wheat cultivars, among which MoO isolates were completely avirulent on the wheat cultivars at 22℃, but caused various infection degrees at 25℃. These reactions at 25℃ were isolate- and cultivar- dependent like race-cultivar specificity which was also recognized at the heading stage and caused typical blast symptoms on spikes. Microscopic analyses indicated that a compatible MoO isolates produced appressoria and infection hyphae on wheat as on rice. By comparing transcriptomes in wheat-MoO interactions, a bulk of pathogen-related genes was up-/down- regulated in compatible and incompatible patterns, but that changes of gene transcription were more significant in compatible pattern. These results indicate that the temperature could influence the infection ratio of wheat with MoO, and some MoO strains could be potential pathogens that increase the risk for the outbreak of wheat blast in wheat-rice growing regions with global warming. In addition, certain wheat cultivars exhibited resistance and are assumed to carry promoting resistant genes to the MoO strains.

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