Transformation of fungal isolates with avirulence genes provides tools for identification of corresponding resistance genes in the host plant

2014 ◽  
Vol 140 (4) ◽  
pp. 875-882 ◽  
Author(s):  
Angela P. Van de Wouw ◽  
Candace E. Elliott ◽  
Barbara J. Howlett
Keyword(s):  
Host Plant ◽  
Resistance Genes ◽  
Avirulence Genes ◽  
Fungal Isolates

Molecular aspects of avirulence genes of the tomato pathogen Cladosporium fulvum

1995 ◽  
Vol 73 (S1) ◽  
pp. 490-494 ◽  
Author(s):  
Pierre J. G. M. de Wit ◽  
Matthieu H. A. J. Joosten ◽  
Guy Honée ◽  
Paul J. M. J. Vossen ◽  
Ton J. Cozijnsen ◽  
...  
Keyword(s):  
Host Plant ◽  
Resistance Genes ◽  
Hypersensitive Response ◽  
Fungal Pathogens ◽  
Direct Interaction ◽  
Defense Responses ◽  
Cladosporium Fulvum ◽  
Avirulence Genes ◽  
Host Genotype ◽  
Gene For Gene

Host genotype specificity in interactions between biotrophic fungal pathogens and plants in most cases complies with the gene-for-gene model. Success or failure of infection is determined by the absence or presence of complementary genes, avirulence and resistance genes, in the pathogen and the host plant, respectively. Resistance, expressed by the induction of a hypersensitive response followed by other defence responses in the host, is envisaged to be based on recognition of the pathogen, mediated through direct interaction between products of avirulence genes of the pathogen (the so-called race-specific elicitors) and receptors in the host plant, the putative products of resistance genes. The interaction between the biotrophic fungus Cladosporium fulvum and its only host, tomato, is a model system to study fungus–plant gene-for-gene relationships. Here we review research on isolation, characterization, and biological function of two race-specific elicitors AVR4 and AVR9 of C. fulvum and cloning and regulation of their encoding genes. Key words: avirulence genes, race-specific elicitors, resistance genes, hypersensitive response, host defense responses.

scholarly journals Multiple Evolutionary Trajectories Have Led to the Emergence of Races in Fusarium oxysporum f. sp. lycopersici

2016 ◽  
Vol 83 (4) ◽  
Author(s):  
V. Chellappan Biju ◽  
Like Fokkens ◽  
Petra M. Houterman ◽  
Martijn Rep ◽  
Ben J. C. Cornelissen
Keyword(s):  
Transposable Elements ◽  
Fusarium Oxysporum ◽  
Resistance Genes ◽  
Pcr Analysis ◽  
Genomic Fragment ◽  
Avirulence Genes ◽  
Content Type ◽  
Race 1 ◽  
Tomato Cultivars ◽  
Race 2

ABSTRACT Race 1 isolates of Fusarium oxysporum f. sp. lycopersici (FOL) are characterized by the presence of AVR1 in their genomes. The product of this gene, Avr1, triggers resistance in tomato cultivars carrying resistance gene I. In FOL race 2 and race 3 isolates, AVR1 is absent, and hence they are virulent on tomato cultivars carrying I. In this study, we analyzed an approximately 100-kb genomic fragment containing the AVR1 locus of FOL race 1 isolate 004 (FOL004) and compared it to the sequenced genome of FOL race 2 isolate 4287 (FOL4287). A genomic fragment of 31 kb containing AVR1 was found to be missing in FOL4287. Further analysis suggests that race 2 evolved from race 1 by deletion of this 31-kb fragment due to a recombination event between two transposable elements bordering the fragment. A worldwide collection of 71 FOL isolates representing races 1, 2, and 3, all known vegetative compatibility groups (VCGs), and five continents was subjected to PCR analysis of the AVR1 locus, including the two bordering transposable elements. Based on phylogenetic analysis using the EF1-α gene, five evolutionary lineages for FOL that correlate well with VCGs were identified. More importantly, we show that FOL races evolved in a stepwise manner within each VCG by the loss of function of avirulence genes in a number of alternative ways. IMPORTANCE Plant-pathogenic microorganisms frequently mutate to overcome disease resistance genes that have been introduced in crops. For the fungus Fusarium oxysporum f. sp. lycopersici, the causal agent of Fusarium wilt in tomato, we have identified the nature of the mutations that have led to the overcoming of the I and I-2 resistance genes in all five known clonal lineages, which include a newly discovered lineage. Five different deletion events, at least several of which are caused by recombination between transposable elements, have led to loss of AVR1 and overcoming of I. Two new events affecting AVR2 that led to overcoming of I-2 have been identified. We propose a reconstruction of the evolution of races in FOL, in which the same mutations in AVR2 and AVR3 have occurred in different lineages and the FOL pathogenicity chromosome has been transferred to new lineages several times.

scholarly journals Genetic control of Pyrenophora teres virulence to three barley accessions

2017 ◽  
Vol 38 (SI 2 - 6th Conf EFPP 2002) ◽  
pp. 612-614
Author(s):  
N. Mironenko ◽  
O. Filatova ◽  
O. Afanasenko
Keyword(s):  
Genetic Control ◽  
Resistance Genes ◽  
Pyrenophora Teres ◽  
Avirulence Genes ◽  
Monogenic Inheritance ◽  
Barley Resistance ◽  
Barley Genotypes

Ascospore progeny of cross of Pyrenophora teres f. teres isolates was evaluated on virulence to three barley genotypes. Monogenic inheritance of virulence (26 a:17 v and 31 a:18 v) was shown to cultivar Harbin and accession c 21272 and supported by results of two fungal backcrosses. The existence of three unlinked avirulence genes to CI 4922 is suggested (37 a:7 v). The model of interaction between barley resistance genes and avirulence genes with postulated fungal genotypes is proposed.

Molecular Markers Linked to Phytophthora fragariae Resistance Genes in Strawberry

HortScience ◽  
1998 ◽  
Vol 33 (3) ◽  
pp. 500a-500 ◽  
Author(s):  
K.M. Haymes ◽  
S.C. Hokanson ◽  
K. Salazar ◽  
J. Maas
Keyword(s):  
Molecular Markers ◽  
Resistance Genes ◽  
Bulked Segregant Analysis ◽  
Aflp Markers ◽  
Avirulence Genes ◽  
Phytophthora Fragariae ◽  
Red Stele ◽  
Strawberry Breeding ◽  
Direct Applicability ◽  
Selection Of

The commercial strawberry (Fragaria × ananassa Duch.) is susceptible to red stele root rot caused by the fungus Phytophthora fragariae Hickman var. fragariae. Characteristics of the disease are the reddened steles and “rat tail” appearance of the roots. Infected plants are dwarfed, exhibit wilting, and eventually die. Red stele resistance in strawberries and virulence of P. fragariae behave according to the gene-for-gene system. Resistance genes and their corresponding avirulence genes have been identified by screening plant roots for infection. The goal of this international research project with CPRO-DLO, The Netherlands, is to develop highly specific molecular markers for various Rpf resistance genes (Rpf1, Rpf2, Rpf3, and Rpf6) that confer resistance against P. fragariae. Bulked Segregant Analysis was used to identify RAPD and AFLP markers putatively linked to P. fragariae resistance genes. The bulked DNAs representing subsets of three F1 populations that segregated monogenically for either resistance or susceptibility to P. fragariae. The map of these Rpf loci was generated using JoinMap®. The RAPD markers linked to the resistance genes are being converted into SCAR markers, while the AFLP markers will be used as probes for the detection of P. fragariae. The application of the molecular markers linked to resistance genes will have direct applicability to strawberry breeding programs. Marker-facilitated selection of these resistance genes would allow an efficient means in the screening and selection of plant material containing these genes and help in the pyramiding for resistance to P. fragariae. Genetic improvement of the strawberry by the ability to pyramid resistance genes will contribute to the productivity of the strawberry industry worldwide.

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.

Flax rust from Linum marginale: pathogenicity reactions on the Linum usitatissimum set of differential varieties

1989 ◽  
Vol 67 (11) ◽  
pp. 3187-3191 ◽  
Author(s):  
G. J. Lawrence
Keyword(s):  
Resistance Gene ◽  
Resistance Genes ◽  
Linum Usitatissimum ◽  
Virulence Genes ◽  
Avirulence Genes ◽  
Reaction Type ◽  
Melampsora Lini ◽  
Two Factors ◽  
Standard Set ◽  
Differential Varieties

Flax rust, Melampsora lini (Ehrenb.) Lév., occurs on Linum marginale Cunn., the only Linum species indigenous to Australia. Evidence suggests that the rust is native to L. marginale and is not a recent introduction. Forty-five isolates from this rust population, collected from 21 locations, were tested for reaction type on the standard set of 28 flax (L. usitatissimum) differential lines. All isolates were avirulent on the majority of differentials and only three clearly different virulence phenotypes were distinguished. This finding contrasts with the results of a companion study in which the same isolates displayed many different virulence phenotypes when tested on a set of L. marginale lines. Two factors apparently contribute to the failure of the L. usitatissimum differentials to detect most of the variation for virulence present in this rust population. First, 10 of the differentials have been reported to possess resistance gene L9 in addition to their designated gene. Since all isolates recognize the L9 gene, these differentials could make no contribution to differentiating between the isolates. Second, many of the L. usitatissimum resistance genes apparently do not occur in L. marginale and with no selection on the rust to conserve or evolve the corresponding virulence genes, the corresponding avirulence genes appear to have become, or remained, fixed in the rust population.

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