scholarly journals Expression of Magnaporthe grisea Avirulence Gene ACE1 Is Connected to the Initiation of Appressorium-Mediated Penetration

2007 ◽  
Vol 6 (3) ◽  
pp. 546-554 ◽  
Author(s):  
Isabelle Fudal ◽  
Jérôme Collemare ◽  
Heidi U. Böhnert ◽  
Delphine Melayah ◽  
Marc-Henri Lebrun
Keyword(s):  
Host Plant ◽  
Magnaporthe Grisea ◽  
Plant Cell Wall ◽  
Current Control ◽  
Camp Signaling ◽  
Avirulence Gene ◽  
Rice Cultivars ◽  
Avirulence Genes ◽  
Specific Expression ◽  
Melanin Biosynthesis

ABSTRACT Magnaporthe grisea is responsible for a devastating fungal disease of rice called blast. Current control of this disease relies on resistant rice cultivars that recognize M. grisea signals corresponding to specific secreted proteins encoded by avirulence genes. The M. grisea ACE1 avirulence gene differs from others, since it controls the biosynthesis of a secondary metabolite likely recognized by rice cultivars carrying the Pi33 resistance gene. Using a transcriptional fusion between ACE1 promoter and eGFP, we showed that ACE1 is only expressed in appressoria during fungal penetration into rice and barley leaves, onion skin, and cellophane membranes. ACE1 is almost not expressed in appressoria differentiated on Teflon and Mylar artificial membranes. ACE1 expression is not induced by cellophane and plant cell wall components, demonstrating that it does not require typical host plant compounds. Cyclic AMP (cAMP) signaling mutants ΔcpkA and Δmac1 sum1-99 and tetraspanin mutant Δpls1::hph differentiate melanized appressoria with normal turgor but are unable to penetrate host plant leaves. ACE1 is normally expressed in these mutants, suggesting that it does not require cAMP signaling or a successful penetration event. ACE1 is not expressed in appressoria of the buf1::hph mutant defective for melanin biosynthesis and appressorial turgor. The addition of hyperosmotic solutes to buf1::hph appressoria restores appressorial development and ACE1 expression. Treatments of young wild-type appressoria with actin and tubulin inhibitors reduce both fungal penetration and ACE1 expression. These experiments suggest that ACE1 appressorium-specific expression does not depend on host plant signals but is connected to the onset of appressorium-mediated penetration.

scholarly journals Identification of an Avirulence Gene in the Fungus Magnaporthe grisea Corresponding to a Resistance Gene at the Pik Locus

2005 ◽  
Vol 95 (7) ◽  
pp. 768-772 ◽  
Author(s):  
N. Yasuda ◽  
M. T. Noguchi ◽  
Y. Fujita
Keyword(s):  
Resistance Gene ◽  
Genetic Basis ◽  
Magnaporthe Grisea ◽  
Fragment Length Polymorphism ◽  
Random Amplified Polymorphic Dna ◽  
Genetic Maps ◽  
Avirulence Gene ◽  
Chinese Isolate ◽  
Rice Cultivars ◽  
Almost All

A rice isolate of Magnaporthe grisea collected from China was avirulent on rice cvs. Hattan 3 and 13 other Japanese rice cultivars. The rice cv. Hattan 3 is susceptible to almost all Japanese blast fungus isolates from rice. The genetic basis of avirulence in the Chinese isolate on Japanese rice cultivars was studied using a cross between the Chinese isolate and a laboratory isolate. The segregation of avirulence or virulence was studied in 185 progeny from the cross, and monogenic control was demonstrated for avirulence to the 14 rice cultivars. The resistance gene that corresponds to the avirulence gene (Avr-Hattan 3) is thought to be located at the Pik locus. Resistance and susceptibility in response to the Chinese isolate in F3 lines of a cross of resistant and susceptible rice cultivars were very similar to the Pik tester isolate, Ken54-20. Random amplified polymorphic DNA markers and restriction fragment length polymorphism markers from genetic maps of the fungus were used to construct a partial genetic map of Avr-Hattan 3. We obtained several flanking markers and one co-segregated marker of Avr-Hattan 3 in the 144 mapping population.

scholarly journals Magnaporthe grisea genes for pathogenicity and virulence identified through a series of backcrosses.

Genetics ◽  
1991 ◽  
Vol 127 (1) ◽  
pp. 87-101 ◽  
Author(s):  
B Valent ◽  
L Farrall ◽  
F G Chumley
Keyword(s):  
Dna Sequences ◽  
Magnaporthe Grisea ◽  
Pathogenic Fungus ◽  
Field Isolate ◽  
Recurrent Parent ◽  
High Fertility ◽  
Rice Cultivars ◽  
Avirulence Genes ◽  
Chromosomal Dna ◽  
Fertile Female

Abstract We have identified genes for pathogenicity toward rice (Oryza sativa) and genes for virulence toward specific rice cultivars in the plant pathogenic fungus Magnaporthe grisea. A genetic cross was conducted between the weeping lovegrass (Eragrostis curvula) pathogen 4091-5-8, a highly fertile, hermaphroditic laboratory strain, and the rice pathogen O-135, a poorly fertile, female-sterile field isolate that infects weeping lovegrass as well as rice. A six-generation backcrossing scheme was then undertaken with the rice pathogen as the recurrent parent. One goal of these crosses was to generate rice pathogenic progeny with the high fertility characteristic of strain 4091-5-8, which would permit rigorous genetic analysis of rice pathogens. Therefore, progeny strains to be used as parents for backcross generations were chosen only on the basis of fertility. The ratios of pathogenic to nonpathogenic (and virulent to avirulent) progeny through the backcross generations suggested that the starting parent strains differ in two types of genes that control the ability to infect rice. First, they differ by polygenic factors that determine the extent of lesion development achieved by those progeny that infect rice. These genes do not appear to play a role in infection of weeping lovegrass because both parents and all progeny infect weeping lovegrass. Second, the parents differ by simple Mendelian determinants, "avirulence genes," that govern virulence toward specific rice cultivars in all-or-none fashion. Several crosses confirm the segregation of three unlinked avirulence genes, Avr 1-CO39, Avr 1-M201 and Avr1-YAMO, alleles of which determine avirulence on rice cultivars CO39, M201, and Yashiro-mochi, respectively. Interestingly, avirulence alleles of Avr1-CO39, Avr1-M201 and Avr1-YAMO were inherited from the parent strain 4091-5-8, which is a nonpathogen of rice. Middle repetitive DNA sequences ("MGR sequences"), present in approximately 40-50 copies in the genome of the rice pathogen parent, and in very low copy number in the genome of the nonpathogen of rice, were used as physical markers to monitor restoration of the rice pathogen genetic background during introgression of fertility. The introgression of highest levels of fertility into the most successful rice pathogen progeny was incomplete by the sixth generation, perhaps a consequence of genetic linkage between genes for fertility and genes for rice pathogenicity. One chromosomal DNA segment with MGR sequence homology appeared to be linked to the gene Avr1-CO39. Finally, many of the crosses described in this paper exhibited a characteristic common to many crosses involving M. grisea rice pathogen field isolates.(ABSTRACT TRUNCATED AT 400 WORDS)

scholarly journals Induced Rice Resistance to Blast Varies as a Function of Magnaporthe grisea Avirulence Genes

Plant Disease ◽  
2008 ◽  
Vol 92 (8) ◽  
pp. 1144-1149 ◽  
Author(s):  
N. Yasuda ◽  
M. T. Noguchi ◽  
Y. Fujita
Keyword(s):  
Genetic Analysis ◽  
Resistance Genes ◽  
Magnaporthe Grisea ◽  
Specific Resistance ◽  
Blast Disease ◽  
Avirulence Gene ◽  
Avirulence Genes ◽  
Leaf Blast ◽  
Incompatibility Reactions ◽  
Avirulent Isolate

Incompatibility reactions between rice and the blast fungus Magnaporthe grisea produce various degrees of lesions, from large brown flecks to small, nearly invisible lesions. We previously identified four avirulence genes (AvrPia, AvrPii, AvrPit, and Avr-Hattan3) in M. grisea isolates by genetic analysis of progeny from crosses between isolates with differing pathogenicity. Using progeny known to contain a specific avirulence gene, we demonstrated that the type of resistance lesion produced in rice by an avirulent isolate and the degree of leaf blast suppression by preinoculation with that isolate were determined by the combination of avirulence and resistance genes in the isolate and the cultivar. The degree of leaf blast suppression by preinoculation with an avirulent isolate increased with larger resistance lesions. When two genes were involved in an isolate's avirulence, lesions appeared that resembled those expected for the gene that produced the smaller lesion. The degree of leaf blast suppression by the isolate with two avirulence genes was comparable with that induced by the isolate with the avirulence gene that produced the smaller effect. The ability of specific resistance gene combinations that effectively suppress blast disease is discussed for each avirulence gene.

scholarly journals Mapping of Avirulence Genes in the Rice Blast Fungus, Magnaporthe grisea, with RFLP and RAPD Markers

2000 ◽  
Vol 13 (2) ◽  
pp. 217-227 ◽  
Author(s):  
Waly Dioh ◽  
Didier Tharreau ◽  
Jean Loup Notteghem ◽  
Marc Orbach ◽  
Marc-Henri Lebrun
Keyword(s):  
Genetic Map ◽  
Rice Blast ◽  
Rapd Markers ◽  
Magnaporthe Grisea ◽  
Rice Blast Fungus ◽  
Single Copy ◽  
Avirulence Gene ◽  
Rflp Markers ◽  
Avirulence Genes ◽  
Blast Fungus

Three genetically independent avirulence genes, AVR1-Irat7, AVR1-MedNoï, and AVR1-Ku86, were identified in a cross involving isolates Guy11 and 2/0/3 of the rice blast fungus, Magnaporthe grisea. Using 76 random progeny, we constructed a partial genetic map with restriction fragment length polymorphism (RFLP) markers revealed by probes such as the repeated sequences MGL/MGR583 and Pot3/MGR586, cosmids from the M. grisea genetic map, and a telomere sequence oligonucleotide. Avirulence genes AVR1-MedNoï and AVR1-Ku86 were closely linked to te-lomere RFLPs such as marker TelG (6 cM from AVR1-MedNoï) and TelF (4.5 cM from AVR1-Ku86). Avirulence gene AVR1-Irat7 was linked to a cosmid RFLP located on chromosome 1 and mapped at 20 cM from the avirulence gene AVR1-CO39. Using bulked segregant analysis, we identified 11 random amplified polymorphic DNA (RAPD) markers closely linked (0 to 10 cM) to the avirulence genes segregating in this cross. Most of these RAPD markers corresponded to junction fragments between known or new transposons and a single-copy sequence. Such junctions or the whole sequences of single-copy RAPD markers were frequently absent in one parental isolate. Single-copy sequences from RAPD markers tightly linked to avirulence genes will be used for positional cloning.

scholarly journals Genetic Analysis of Avirulence/Virulence of an Isolate of Magnaporthe grisea from a Rice Field in Texas

1997 ◽  
Vol 87 (1) ◽  
pp. 71-76 ◽  
Author(s):  
C. T. Chao ◽  
A. H. Ellingboe
Keyword(s):  
Genetic Analysis ◽  
Magnaporthe Grisea ◽  
Rice Field ◽  
Laboratory Strain ◽  
Avirulence Gene ◽  
Avirulence Genes ◽  
Three Generations ◽  
Segregation Ratios

An isolate of Magnaporthe grisea, Tm4, from a rice field in Texas was crossed with a fertile laboratory strain, 70-6. The progenies showed segregation of avirulence/virulence on rice cvs. Newbonnet, Lemont, Lebonnet, Leah, and Katy. The avirulent/virulent segregation ratios were 29:6 on Newbonnet, Lemont, and Lebonnet; 28:7 on Leah; and 33:2 on Katy. There was cosegregation on the first three cultivars. Several avirulent progenies were backcrossed to virulent parent 70-6. Three generations of backcrossing avirulent progenies to 70-6 led to segregation ratios that suggested certain strains had only one avirulence gene. Strains avirulent only on cv. Katy or only on cvs. Newbonnet, Lemont, and Lebonnet were test crossed with virulent siblings. Strains that gave progeny ratios approximating 1 avirulent:1 virulent when crossed with virulent siblings were selected for further test crossing. Intercrosses between strains with possible single avirulence genes were made to determine whether these strains had the same or different avirulence genes. Many lines still segregated two genes for avirulence after three generations of backcrossing. This is based on the recovery of virulent progenies from crossing two avirulent siblings.

scholarly journals Gain of Virulence Caused by Insertion of a Pot3 Transposon in a Magnaporthe grisea Avirulence Gene

2001 ◽  
Vol 14 (5) ◽  
pp. 671-674 ◽  
Author(s):  
Seogchan Kang ◽  
Marc Henri Lebrun ◽  
Leonard Farrall ◽  
Barbara Valent
Keyword(s):  
Disease Resistance ◽  
Resistance Gene ◽  
Magnaporthe Grisea ◽  
Rice Cultivar ◽  
Avirulence Gene ◽  
Disease Resistance Gene ◽  
Rice Cultivars

The avirulence gene AVR-Pita in Magnaporthe grisea prevents the fungus from infecting rice cultivars carrying the disease resistance gene Pi-ta. Insertion of Pot3 transposon into the promoter of AVR-Pita caused the gain of virulence toward Yashiro-mochi, a rice cultivar containing Pi-ta, which demonstrated the ability of Pot3 to move within the M. grisea genome. The appearance of Pot3 in M. grisea seems to predate the diversification of various host-specific forms of the fungus.

scholarly journals The draft genome of the specialist flea beetle Altica viridicyanea (Coleoptera: Chrysomelidae)

BMC Genomics ◽  
2021 ◽  
Vol 22 (1) ◽  
Author(s):  
Huai-Jun Xue ◽  
Yi-Wei Niu ◽  
Kari A. Segraves ◽  
Rui-E Nie ◽  
Ya-Jing Hao ◽  
...  
Keyword(s):  
Host Plant ◽  
Plant Cell Wall ◽  
Flea Beetle ◽  
Repetitive Sequences ◽  
Draft Genome ◽  
Gene Families ◽  
Ecological Speciation ◽  
Secondary Chemistry ◽  
Host Plant Specialization ◽  
Insight Into

Abstract Background Altica (Coleoptera: Chrysomelidae) is a highly diverse and taxonomically challenging flea beetle genus that has been used to address questions related to host plant specialization, reproductive isolation, and ecological speciation. To further evolutionary studies in this interesting group, here we present a draft genome of a representative specialist, Altica viridicyanea, the first Alticinae genome reported thus far. Results The genome is 864.8 Mb and consists of 4490 scaffolds with a N50 size of 557 kb, which covered 98.6% complete and 0.4% partial insect Benchmarking Universal Single-Copy Orthologs. Repetitive sequences accounted for 62.9% of the assembly, and a total of 17,730 protein-coding gene models and 2462 non-coding RNA models were predicted. To provide insight into host plant specialization of this monophagous species, we examined the key gene families involved in chemosensation, detoxification of plant secondary chemistry, and plant cell wall-degradation. Conclusions The genome assembled in this work provides an important resource for further studies on host plant adaptation and functionally affiliated genes. Moreover, this work also opens the way for comparative genomics studies among closely related Altica species, which may provide insight into the molecular evolutionary processes that occur during ecological speciation.

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