Rapid mapping of two genes for resistance to downy mildew from Lactuca serriola to existing clusters of resistance genes

Maisonneuve, Brigitte; Bellec, Yannick; Anderson, Peter; Michelmore, Richard W.

doi:10.1007/bf00226989

Cited by 61 publications

(36 citation statements)

References 21 publications

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“…Cultivars carrying Dm6 and Dm7 may exhibit partial resistance associated with macroscopically visible hypersensitive necrosis . Additionally, gene dosage affects the resistance phenotype of some Dm genes, for example Dm17 under high pathogen pressure (Maisonneuve et al 1994). Some lettuce cultivars such as Iceberg and Grand Rapids exhibit resistance at the adult plant stage in the field that cannot be attributed to Dm genes (Milbrath 1923;Verhoeff 1960;Crute and Norwood 1981).…”

Section: Genetics Of Resistance and Nomenclature Of Resistance Genesmentioning

confidence: 99%

Rationalization of genes for resistance to Bremia lactucae in lettuce

Parra¹,

Maisonneuve²,

Lebeda³

et al. 2016

Euphytica

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Lettuce downy mildew caused by Bremia lactucae is the most important disease of lettuce worldwide. Breeding for resistance to this disease is a major priority for most lettuce breeding programs. Many genes and factors for resistance to B. lactucae have been reported by multiple researchers over the past *50 years. Their nomenclature has not been coordinated, resulting in duplications and gaps in nominations. We have reviewed the available information and rationalized it into 51 resistance genes and factors and 15 quantitative trait loci along with supporting documentation as well as genetic and molecular information. This involved multiple rounds of consultation with many of the original authors. This paper provides the foundation for naming additional genes for resistance to B. lactucae in the future as well as for deploying genes to provide more durable resistance. Keywords

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Section: Genetics Of Resistance and Nomenclature Of Resistance Genesmentioning

confidence: 99%

Rationalization of genes for resistance to Bremia lactucae in lettuce

Parra¹,

Maisonneuve²,

Lebeda³

et al. 2016

Euphytica

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“…Each gene spans 15 to 25 kb, and the estimated number of RGC2 genes in the lettuce genome varies from 14 to 40 copies depending on the genotype Kuang et al, 2004). One member of the RGC2 gene family, Dm3, confers resistance to downy mildew (Bremia lactucae; Meyers et al, 1998;Shen et al, 2002), while other family members are responsible for up to eight different Dm specificities and root aphid resistance (Crute and Dunn, 1980;Hulbert and Michelmore, 1985;Farrara et al, 1987;Maisonneuve et al, 1994). All of the individual specificities confer resistance to downy mildew in a gene-for-gene manner; however, only single specificities are usually identified in individual genotypes.…”

Section: Evidence Of Recombination In the Rpp4 Locusmentioning

confidence: 99%

Identification and Analyses of Candidate Genes for Rpp4-Mediated Resistance to Asian Soybean Rust in Soybean

et al. 2009

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Asian soybean rust is a formidable threat to soybean (Glycine max) production in many areas of the world, including the United States. Only five sources of resistance have been identified (Resistance to Phakopsora pachyrhizi1 [Rpp1], Rpp2, Rpp3, Rpp4, and Rpp5). Rpp4 was previously identified in the resistant genotype PI459025B and mapped within 2 centimorgans of Satt288 on soybean chromosome 18 (linkage group G). Using simple sequence repeat markers, we developed a bacterial artificial chromosome contig for the Rpp4 locus in the susceptible cv Williams82 (Wm82). Sequencing within this region identified three Rpp4 candidate disease resistance genes (Rpp4C1–Rpp4C3 [Wm82]) with greatest similarity to the lettuce (Lactuca sativa) RGC2 family of coiled coil-nucleotide binding site-leucine rich repeat disease resistance genes. Constructs containing regions of the Wm82 Rpp4 candidate genes were used for virus-induced gene silencing experiments to silence resistance in PI459025B, confirming that orthologous genes confer resistance. Using primers developed from conserved sequences in the Wm82 Rpp4 candidate genes, we identified five Rpp4 candidate genes (Rpp4C1–Rpp4C5 [PI459025B]) from the resistant genotype. Additional markers developed from the Wm82 Rpp4 bacterial artificial chromosome contig further defined the region containing Rpp4 and eliminated Rpp4C1 (PI459025B) and Rpp4C3 (PI459025B) as candidate genes. Sequencing of reverse transcription-polymerase chain reaction products revealed that Rpp4C4 (PI459025B) was highly expressed in the resistant genotype, while expression of the other candidate genes was nearly undetectable. These data support Rpp4C4 (PI459025B) as the single candidate gene for Rpp4-mediated resistance to Asian soybean rust.

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“…Most of them had been used previously in genetic studies of resistance to lettuce downy mildew and contain diverse resistance loci introgressed from wild species (Farrara et al, 1987;Ilott et al, 1987;Maisonneuve et al, 1994). Tomato (Solanum lycopersicum) cultivars and genetic stocks were similarly selected to ensure high diversity in resistance to various pathogens and were obtained from the Tomato Genetic Resource Center (http://tgrc.ucdavis.edu).…”

Section: Plant Materials and Growth Conditionsmentioning

confidence: 99%

Comparative Large-Scale Analysis of Interactions between Several Crop Species and the Effector Repertoires from Multiple Pathovars of Pseudomonas and Ralstonia

et al. 2009

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Bacterial plant pathogens manipulate their hosts by injection of numerous effector proteins into host cells via type III secretion systems. Recognition of these effectors by the host plant leads to the induction of a defense reaction that often culminates in a hypersensitive response manifested as cell death. Genes encoding effector proteins can be exchanged between different strains of bacteria via horizontal transfer, and often individual strains are capable of infecting multiple hosts. Host plant species express diverse repertoires of resistance proteins that mediate direct or indirect recognition of bacterial effectors. As a result, plants and their bacterial pathogens should be considered as two extensive coevolving groups rather than as individual host species coevolving with single pathovars. To dissect the complexity of this coevolution, we cloned 171 effector-encoding genes from several pathovars of Pseudomonas and Ralstonia. We used Agrobacterium tumefaciens-mediated transient assays to test the ability of each effector to induce a necrotic phenotype on 59 plant genotypes belonging to four plant families, including numerous diverse accessions of lettuce (Lactuca sativa) and tomato (Solanum lycopersicum). Known defense-inducing effectors (avirulence factors) and their homologs commonly induced extensive necrosis in many different plant species. Nonhost species reacted to multiple effector proteins from an individual pathovar more frequently and more intensely than host species. Both homologous and sequence-unrelated effectors could elicit necrosis in a similar spectrum of plants, suggesting common effector targets or targeting of the same pathways in the plant cell.Plants and potential pathogens are locked in continual antagonism involving alternating cycles of selection to increase resistance and virulence, respectively. There are many biochemical exchanges between plants and pathogens, and selection can act at multiple points in the host-pathogen interaction. Several overlapping mechanisms of resistance in plants and strategies of pathogens to interdict these resistance responses are being elucidated (Jones and Dangl, 2006). The combined abilities of a pathogen to overcome host resistance mechanisms are major determinants of its host range and success as a pathogen.

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Rapid mapping of two genes for resistance to downy mildew from Lactuca serriola to existing clusters of resistance genes

Cited by 61 publications

References 21 publications

Rationalization of genes for resistance to Bremia lactucae in lettuce

Rationalization of genes for resistance to Bremia lactucae in lettuce

Identification and Analyses of Candidate Genes for Rpp4-Mediated Resistance to Asian Soybean Rust in Soybean

Comparative Large-Scale Analysis of Interactions between Several Crop Species and the Effector Repertoires from Multiple Pathovars of Pseudomonas and Ralstonia

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