scholarly journals Exclusión de linajes como estrategia para la obtención de resistencia durable en el arroz a Pyricularia grisea Sacc. en Colombia

2003 ◽  
Vol 4 (1) ◽  
pp. 15
Author(s):  
Aníbal L. Tapiero ◽  
Diego Aristizábal ◽  
Morris Levy
Keyword(s):  
Rice Blast ◽  
Population Studies ◽  
Durable Resistance ◽  
Breeding Strategy ◽  
Pyricularia Grisea ◽  
R Genes ◽  
Resistance Breakdown ◽  
Major Resistance Genes ◽  
Colombian Isolate ◽  
Virulence Spectrum

<p>La durabilidad de la resistencia genética del arroz a <em>Pyricularia grisea </em>Sacc. había estado comprometida en Colombia, por una rápida adaptación aparente del patógeno a los genes dispuestos para contrarrestar su incidencia. Las variedades mejoradas se veían afectadas por la enfermedad en el curso de pocos años y, en ocasiones, a sólo meses de haber sido liberadas. La exclusión de linajes es una estrategia de mejoramiento que propone la identificación y posterior ‘piramidación’ de genes con habilidad para reconocer de manera complementaria las avirulencias de las familias genéticas (linajes) del patógeno. Poblaciones ecológicamente distintitas, caracterizadas molecularmente mediante la sonda MGR-586, exhiben una estructura clonal en la que cada aislamiento del linaje comparte históricamente el mismo espectro de virulencia. La resistencia obtenida con la piramidación de genes complementarios funciona como factor de exclusión hacia la totalidad de la virulencia en la población del patógeno en un ecosistema determinado. Así, en Colombia, los genes <em>Pi-1 (t) </em>y <em>Pi-2 (t) </em>son diferencial y complementariamente excluyentes de la virulencia de las poblaciones de <em>P. grisea</em>. Fueron obtenidas líneas con estos genes piramidados mediante el cruzamiento de dos líneas isogénicas; la presencia y condición homocigota de los genes de resistencia en las nuevas líneas fue establecida a través de marcadores moleculares. El comportamiento de las pirámides fue evaluado en el laboratorio, en cámaras de crecimiento con aislamientos representativos de los linajes colombianos y, en el campo, en una región dedicada tradicionalmente a la producción de arroz donde las epidemias de piricularia son frecuentes.Tanto en las inoculaciones artificiales, como en las áreas de cultivo, las pirámides conservaron la resistencia. La estructura de virulencia entre la población del patógeno en el campo permaneció estable durante tres años, aunque estacional y transitoriamente se identificaron algunos aislamientos virulentos a las pirámides en la estación experimental.</p><p> </p><p><strong><em>Abstract</em></strong></p><p><strong>Lineaje-exclusion, a strategy for breeding rice with durable resistance to </strong><strong><em>Pyricularia grisea </em></strong><strong>Sacc. in Colombia</strong></p><p>Rice blast has challenged plant breeders when they were searching for durable resistance in Colombia. Rapid resistance breakdowns were commonly observed in newly bred cultivars and they are attributed to frequent appearance of new pathotypes. Recent population studies of the rice blast pathosystem have shown that <em>Pyricularia grisea </em>in a given region, typically expresses a phylogenetic organization of distinct lineages (‘genetic families’ as defined by MGR-DNA  fingerprinting). Each lineage exhibits a definable virulence  spectrum, and the potential for developing new pathotypes appears to be constrained by lineage-specific avirulences. Lineageexclusion is a breeding strategy aimed to enlighten the choosing of genes to obtain more durable resistance in the field. Combining genes that complementary exclude fragments of virulence, will provide complete resistance to known lineages. The resistance of pyramids bearing the major resistance genes <em>Pi-1 (t) </em>and <em>Pi-2 (t) </em>was determined at three sites in a primary rice growing region in Colombia, from 1996 to 1998.The chosen R-genes are individually defeated by common lineages in Colombia, but combined, provide resistance to the complementary spectra of virulence. The pyramids were selected by screening the progeny of a cross of nearisogenic lines with the representative.The presence and homozygosity of both genes were confirmed through molecular markers. Neither single Colombian isolate, nor mixture of isolates infected the pyramids. The pyramids proved to be highly resistant in the field, and no major changes in lineage composition or virulence spectrum were observed. However, some moderately compatible isolates of lineage SRL-6 were transiently observed in the area of Santa Rosa. Resistance breakdown (vulnerability) may depend on within lineage rather than between lineage distributions of virulence.</p>

Investigating the biology of rice blast disease and prospects for durable resistance

2021 ◽  
pp. 643-680
Author(s):  
Vincent M. Were ◽  
◽  
Nicholas J. Talbot ◽  
Keyword(s):  
Cell Biology ◽  
Rice Blast ◽  
Plant Pathogens ◽  
Blast Resistance ◽  
Durable Resistance ◽  
Rice Blast Disease ◽  
Blast Disease ◽  
Global Food Security ◽  
Major Resistance Genes ◽  
Effector Secretion

There are important biological process involved in rice blast disease that are now well-studied during the early events in plant infection which include: the cell biology of appressorium formation, the biology of invasive growth and effector secretion, the two distinct mechanisms of effector secretion, the nature of the plant-pathogen interface, PAMP-triggered immunity modulation by secreted effectors and effector-triggered immunity and blast resistance. The devastating losses caused by the blast fungus have been documented in most grasses, but this chapter discusses the use of major resistance genes to rice blast and wheat blast disease as an emerging threat to global food security. This chapter also highlights an emerging approach to breed for durable resistance to plant pathogens using gene editing technologies with an example: CRISPR-Cas9 mutagenesis of dominant S-genes for disease control.

scholarly journals Avirulence (AVR) Gene-Based Diagnosis Complements Existing Pathogen Surveillance Tools for Effective Deployment of Resistance (R) Genes Against Rice Blast Disease

2017 ◽  
Vol 107 (6) ◽  
pp. 711-720 ◽  
Author(s):  
S. M. Selisana ◽  
M. J. Yanoria ◽  
B. Quime ◽  
C. Chaipanya ◽  
G. Lu ◽  
...  
Keyword(s):  
Rice Blast ◽  
Polymerase Chain Reaction Amplification ◽  
Rice Blast Disease ◽  
Blast Disease ◽  
R Gene ◽  
R Genes ◽  
Pathogen Population ◽  
Avr Gene ◽  
Avr Genes ◽  
Virulence Spectrum

Avirulence (AVR) genes in Magnaporthe oryzae, the fungal pathogen that causes the devastating rice blast disease, have been documented to be major targets subject to mutations to avoid recognition by resistance (R) genes. In this study, an AVR-gene-based diagnosis tool for determining the virulence spectrum of a rice blast pathogen population was developed and validated. A set of 77 single-spore field isolates was subjected to pathotype analysis using differential lines, each containing a single R gene, and classified into 20 virulent pathotypes, except for 4 isolates that lost pathogenicity. In all, 10 differential lines showed low frequency (<24%) of resistance whereas 8 lines showed a high frequency (>95%), inferring the effectiveness of R genes present in the respective differential lines. In addition, the haplotypes of seven AVR genes were determined by polymerase chain reaction amplification and sequencing, if applicable. The calculated frequency of different AVR genes displayed significant variations in the population. AVRPiz-t and AVR-Pii were detected in 100 and 84.9% of the isolates, respectively. Five AVR genes such as AVR-Pik-D (20.5%) and AVR-Pik-E (1.4%), AVRPiz-t (2.7%), AVR-Pita (0%), AVR-Pia (0%), and AVR1-CO39 (0%) displayed low or even zero frequency. The frequency of AVR genes correlated almost perfectly with the resistance frequency of the cognate R genes in differential lines, except for International Rice Research Institute-bred blast-resistant lines IRBLzt-T, IRBLta-K1, and IRBLkp-K60. Both genetic analysis and molecular marker validation revealed an additional R gene, most likely Pi19 or its allele, in these three differential lines. This can explain the spuriously higher resistance frequency of each target R gene based on conventional pathotyping. This study demonstrates that AVR-gene-based diagnosis provides a precise, R-gene-specific, and differential line-free assessment method that can be used for determining the virulence spectrum of a rice blast pathogen population and for predicting the effectiveness of target R genes in rice varieties.

scholarly journals Multiyear Evaluation of the Durability of the Resistance Conferred by Ma and RMia Genes to Meloidogyne incognita in Prunus Under Controlled Conditions

2013 ◽  
Vol 103 (8) ◽  
pp. 833-840 ◽  
Author(s):  
Samira Khallouk ◽  
Roger Voisin ◽  
Ulysse Portier ◽  
Joël Polidori ◽  
Cyril Van Ghelder ◽  
...  
Keyword(s):  
Meloidogyne Incognita ◽  
Economic Losses ◽  
R Gene ◽  
R Genes ◽  
Tomato Plants ◽  
Controlled Conditions ◽  
Meloidogyne Spp ◽  
Resistance Breakdown ◽  
Susceptible Tomato ◽  
Prunus Spp

Root-knot nematodes (RKNs) (Meloidogyne spp.) are highly polyphagous pests that parasitize Prunus crops in Mediterranean climates. Breeding for RKN-resistant Prunus cultivars, as an alternative to the now-banned use of nematicides, is a real challenge, because the perennial nature of these trees increases the risk of resistance breakdown. The Ma plum resistance (R) gene, with a complete spectrum, and the RMia peach R gene, with a more restricted spectrum, both provide total control of Meloidogyne incognita, the model parthenogenetic species of the genus and the most important RKN in terms of economic losses. We investigated the durability of the resistance to this nematode conferred by these genes, comparing the results obtained with those for the tomato Mi-1 reference gene. In multiyear experiments, we applied a high and continuous nematode inoculum pressure by cultivating nematode-infested susceptible tomato plants with either Prunus accessions carrying Ma or RMia R genes, or with resistant tomato plants carrying the Mi-1 gene. Suitable conditions for Prunus development were achieved by carrying out the studies in a glasshouse, in controlled conditions allowing a short winter leaf fall and dormancy. We first assessed the plum accession ‘P.2175’, which is heterozygous for the Ma gene, in two successive 2-year evaluations, for resistance to two M. incognita isolates. Whatever the isolate used, no nematodes reproducing on P.2175 were detected, whereas galls and nematodes reproducing on tomato plants carrying Mi-1 were observed. In a second experiment with the most aggressive isolate, interspecific full-sib material (P.2175 × [‘Garfi’ almond × ‘Nemared’ peach]), carrying either Ma or RMia (from Nemared) or both (in the heterozygous state) or neither of these genes, was evaluated for 4 years. No virulent nematodes developed on Prunus spp. carrying R genes, whereas galling and virulent individuals were observed on Mi-1-resistant tomato plants. Thus, the resistance to M. incognita conferred by Ma in Prunus material in both a pure-plum and an interspecific genetic background, or by RMia in an interspecific background, appears to be durable, highlighting the value of these two genes for the creation of Prunus rootstock material.

scholarly journals Resistance spectra of six elite breeding lines of upland rice to Pyricularia grisea

2003 ◽  
Vol 38 (2) ◽  
pp. 203-210 ◽  
Author(s):  
Anne Sitarama Prabhu ◽  
Emílio da Maia de Castro ◽  
Leila Garcês de Araújo ◽  
Rodrigo Fascin Berni
Keyword(s):  
Resistance Genes ◽  
Rice Blast ◽  
Grain Quality ◽  
Upland Rice ◽  
Pyricularia Grisea ◽  
Rice Cultivars ◽  
Breeding Lines ◽  
Differential Reaction ◽  
Progress Curve ◽  
Elite Breeding Lines

The objective of this work was to evaluate the resistance spectra of six elite breeding lines of rice, developed for improved yield and grain quality, in inoculation tests in the greenhouse and in the field. Forty-six isolates of Pyricularia grisea collected from the cultivar Primavera, 31 from the cultivar Maravilha and 19 from six elite breeding lines, totaling 96 were utilized for inoculations. Out of 11 international and 15 Brazilian pathotypes, IC-1, IB-9, and BD-16, respectively, were identified as most frequent isolates collected from the cultivar Primavera. The isolates retrieved from Maravilha belong to four international and 11 Brazilian pathotypes, the predominant ones being IB-9 and IB-49 and BB-1 and BB-21, respectively. Lines CNAs 8711 and CNAs 8983 showed resistant reaction to all test isolates from Maravilha, while CNAs 8983 was susceptible to three isolates of Primavera pertaining to the pathotype IC-1. A majority of isolates exhibiting compatible reaction to Primavera were incompatible to Maravilha and vice-versa.Field assessment of rice blast utilizing the area under disease progress curve as a criterion for measuring disease severity showed significant differences among the six breeding lines. The isolates of P. grisea exhibiting differential reaction on breeding lines can be utilized in pyramiding resistance genes in new upland rice cultivars.

Pyricularia Grisea the Correct Name for the Rice Blast Disease Fungus

Mycologia ◽  
1990 ◽  
Vol 82 (4) ◽  
pp. 509-512 ◽  
Author(s):  
Amy Y. Rossman ◽  
Richard J. Howard ◽  
Barbara Valent
Keyword(s):  
Rice Blast ◽  
Rice Blast Disease ◽  
Blast Disease ◽  
Pyricularia Grisea

Durable resistance to rice blast

Science ◽  
2017 ◽  
Vol 355 (6328) ◽  
pp. 906-907 ◽  
Author(s):  
Guo-Liang Wang ◽  
Barbara Valent
Keyword(s):  
Rice Blast ◽  
Durable Resistance

scholarly journals The Ambivalence of the Barley Mlo Locus: Mutations Conferring Resistance Against Powdery Mildew (Blumeria graminis f. sp. hordei) Enhance Susceptibility to the Rice Blast Fungus Magnaporthe grisea

1999 ◽  
Vol 12 (6) ◽  
pp. 508-514 ◽  
Author(s):  
Birgit Jarosch ◽  
Karl-Heinz Kogel ◽  
Ulrich Schaffrath
Keyword(s):  
Powdery Mildew ◽  
Rice Blast ◽  
Magnaporthe Grisea ◽  
Durable Resistance ◽  
Rice Blast Fungus ◽  
Blumeria Graminis ◽  
Negative Regulator ◽  
Powdery Mildew Fungus ◽  
Mesophyll Cells ◽  
Blast Fungus

Recessive alleles of the barley Mlo locus confer non-race-specific resistance against the powdery mildew fungus Blumeria graminis f. sp. hordei (Bgh). Recently the Mlo gene has been isolated and it was suggested that the Mlo product is a negative regulator of cell death. Thus, loss of function can precondition cells to a higher responsiveness for the onset of multiple defense functions. Here, we document an enhanced susceptibility of barley mlo mutants to the rice blast fungus Magnaporthe grisea. The disease phenotype is independent of the barley cultivar in which the mlo allele has been introgressed and occurs in equal amounts in barley backcross lines of cv. Ingrid carrying the mlo-1, mlo-3, or mlo-5 allele. Ror genes, which are required for the full expression of mlo resistance in barley against Bgh, do not affect the specific mlo-mediated phenotype observed after M. grisea infection. Formation of an effective papilla restricts blast development in epidermal cells of Mlo plants. In contrast, papillae are mostly penetrated in mlo mutants and, as a consequence, the fungus spreads into adjacent mesophyll cells. Both wild-type plants and mlo mutants did not differ in perception of a purified elicitor derived from M. grisea. Thus, we hypothesize that a functional Mlo protein is a prerequisite for penetration resistance of barley to fungal pathogens like M. grisea. The benefit of mlo alleles for durable resistance in barley and a proposed role of mlo-type-mutations in rice are discussed.

scholarly journals Occurrence, Distribution, Epidemiology, Cultivar Reaction, and Management of Rice Blast Disease in California

Plant Disease ◽  
2001 ◽  
Vol 85 (10) ◽  
pp. 1096-1102 ◽  
Author(s):  
C. A. Greer ◽  
R. K. Webster
Keyword(s):  
Rice Blast ◽  
Large Scale ◽  
Rice Fields ◽  
Blast Disease ◽  
Weather Data ◽  
Disease Surveys ◽  
Spore Trapping ◽  
Small Plot ◽  
Epidemic Development ◽  
Major Resistance Genes

Rice blast, caused by Pyricularia grisea, was first found in California in 1996. Disease surveys have shown the blast disease is spreading at a moderate rate in California rice fields. Although no effective major resistance genes are known to occur in widely grown commercial California cultivars, there appear to be differences among the cultivars with respect to field susceptibility to the pathogen. P. grisea was recovered from rice crop residue and commercial seedlots which are suggested as possible sources of initial P. grisea inoculum in California rice fields. Examination of weather data indicates that environmental conditions in California rice-producing areas are permissive for rice blast but generally not optimal for epidemic development. Spore trapping determined that the majority of P. grisea conidia are generally not released until approximately 6:00 A.M. and would not have sufficient time for infection before leaf wetness periods end. Azoxystrobin showed positive results with respect to reduction of neck blast incidence and yield increases in small-plot and large-scale fungicide trials.

scholarly journals Genotyping-by-Sequencing-Based Genetic Analysis of African Rice Cultivars and Association Mapping of Blast Resistance Genes Against Magnaporthe oryzae Populations in Africa

2017 ◽  
Vol 107 (9) ◽  
pp. 1039-1046 ◽  
Author(s):  
Emmanuel M. Mgonja ◽  
Chan Ho Park ◽  
Houxiang Kang ◽  
Elias G. Balimponya ◽  
Stephen Opiyo ◽  
...  
Keyword(s):  
Genetic Diversity ◽  
Association Mapping ◽  
Magnaporthe Oryzae ◽  
Rice Blast ◽  
Blast Resistance ◽  
Genotyping By Sequencing ◽  
Rice Breeding ◽  
Rice Cultivars ◽  
R Genes ◽  
African Rice

Understanding the genetic diversity of rice germplasm is important for the sustainable use of genetic materials in rice breeding and production. Africa is rich in rice genetic resources that can be utilized to boost rice productivity on the continent. A major constraint to rice production in Africa is rice blast, caused by the hemibiotrophic fungal pathogen Magnaporthe oryzae. In this report, we present the results of a genotyping-by-sequencing (GBS)-based diversity analysis of 190 African rice cultivars and an association mapping of blast resistance (R) genes and quantitative trait loci (QTLs). The 190 African cultivars were clustered into three groups based on the 184K single nucleotide polymorphisms generated by GBS. We inoculated the rice cultivars with six African M. oryzae isolates. Association mapping identified 25 genomic regions associated with blast resistance (RABRs) in the rice genome. Moreover, PCR analysis indicated that RABR_23 is associated with the Pi-ta gene on chromosome 12. Our study demonstrates that the combination of GBS-based genetic diversity population analysis and association mapping is effective in identifying rice blast R genes/QTLs that contribute to resistance against African populations of M. oryzae. The identified markers linked to the RABRs and 14 highly resistant cultivars in this study will be useful for rice breeding in Africa.

scholarly journals A Comprehensive Review of the Major Genes Conditioning Resistance to Anthracnose in Common Bean

HortScience ◽  
2004 ◽  
Vol 39 (6) ◽  
pp. 1196-1207 ◽  
Author(s):  
James D. Kelly ◽  
Veronica A. Vallejo
Keyword(s):  
Common Bean ◽  
Resistance Genes ◽  
Durable Resistance ◽  
Gene Pyramiding ◽  
Resistance Breeding ◽  
Gene Clusters ◽  
Allelic Series ◽  
Multiple Alleles ◽  
Differential Cultivars ◽  
Major Resistance Genes

Resistance to anthracnose in common bean is conditioned primarily by nine major independent genes, Co-1 to Co-10 as the Co-3/Co-9 genes are allelic. With the exception of the recessive co-8 gene, all other nine are dominant genes and multiple alleles exist at the Co-1, Co-3 and Co-4 loci. A reverse of dominance at the Co-1 locus suggests that an order of dominance exists among individual alleles at this locus. The nine resistance genes Co-2 to Co-10 are Middle American in origin and Co-1 is the only locus from the Andean gene pool. Seven resistance loci have been mapped to the integrated bean linkage map and Co-1 resides on linkage group B1; Co-2 on B11, Co-3 on B4; Co-4 on B8; Co-6 on B7; and Co-9 and Co-10 are located on B4 but do not appear to be linked. Three Co-genes map to linkage groups B1, B4 and B11 where clusters with genes for rust resistance are located. In addition, there is co-localization with major resistance genes and QTL that condition partial resistance to anthracnose. Other QTL for resistance may provide putative map locations for the major resistance loci still to be mapped. Molecular markers linked to the majority of major Co-genes have been reported and these provide the opportunity to enhance disease resistance through marker-assisted selection and gene pyramiding. The 10 Co-genes are represented in the anthracnose differential cultivars, but are present as part of a multi-allelic series or in combination with other Co-genes, making the characterization of more complex races difficult. Although the Co-genes behave as major Mendelian factors, they most likely exist as resistance gene clusters as has been demonstrated on the molecular level at the Co-2 locus. Since the genes differ in their effectiveness in controlling the highly variable races of the anthracnose pathogen, the authors discuss the value of individual genes and alleles in resistance breeding and suggest the most effective gene pyramids to ensure long-term durable resistance to anthracnose in common bean.

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