Genetics of Brassica rapa (syn. campestris). 2. Multiple disease resistance to three fungal pathogens: Peronospora parasitica, Albugo Candida and Leptosphaeria maculans

Mitchell-Olds, Thomas; James, R. V.; Palmer, M.; Williams, Paul H.

doi:10.1038/hdy.1995.147

Cited by 47 publications

(17 citation statements)

References 28 publications

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“…The phenomenon of multiple disease resistance (MDR) has been inferred based on the detection of QTL clusters affecting different diseases [2,19,20,85], genetic correlations in populations [86], non-specific defense mechanisms (eg. SAR [87-89]), and genes (eg.…”

Section: Discussionmentioning

confidence: 99%

Resistance loci affecting distinct stages of fungal pathogenesis: use of introgression lines for QTL mapping and characterization in the maize - Setosphaeria turcicapathosystem

et al. 2010

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BackgroundStudies on host-pathogen interactions in a range of pathosystems have revealed an array of mechanisms by which plants reduce the efficiency of pathogenesis. While R-gene mediated resistance confers highly effective defense responses against pathogen invasion, quantitative resistance is associated with intermediate levels of resistance that reduces disease progress. To test the hypothesis that specific loci affect distinct stages of fungal pathogenesis, a set of maize introgression lines was used for mapping and characterization of quantitative trait loci (QTL) conditioning resistance to Setosphaeria turcica, the causal agent of northern leaf blight (NLB). To better understand the nature of quantitative resistance, the identified QTL were further tested for three secondary hypotheses: (1) that disease QTL differ by host developmental stage; (2) that their performance changes across environments; and (3) that they condition broad-spectrum resistance.ResultsAmong a set of 82 introgression lines, seven lines were confirmed as more resistant or susceptible than B73. Two NLB QTL were validated in BC4F2 segregating populations and advanced introgression lines. These loci, designated qNLB1.02 and qNLB1.06, were investigated in detail by comparing the introgression lines with B73 for a series of macroscopic and microscopic disease components targeting different stages of NLB development. Repeated greenhouse and field trials revealed that qNLB1.06Tx303 (the Tx303 allele at bin 1.06) reduces the efficiency of fungal penetration, while qNLB1.02B73 (the B73 allele at bin 1.02) enhances the accumulation of callose and phenolics surrounding infection sites, reduces hyphal growth into the vascular bundle and impairs the subsequent necrotrophic colonization in the leaves. The QTL were equally effective in both juvenile and adult plants; qNLB1.06Tx303 showed greater effectiveness in the field than in the greenhouse. In addition to NLB resistance, qNLB1.02B73 was associated with resistance to Stewart's wilt and common rust, while qNLB1.06Tx303 conferred resistance to Stewart's wilt. The non-specific resistance may be attributed to pleiotropy or linkage.ConclusionsOur research has led to successful identification of two reliably-expressed QTL that can potentially be utilized to protect maize from S. turcica in different environments. This approach to identifying and dissecting quantitative resistance in plants will facilitate the application of quantitative resistance in crop protection.

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Section: Discussionmentioning

confidence: 99%

Resistance loci affecting distinct stages of fungal pathogenesis: use of introgression lines for QTL mapping and characterization in the maize - Setosphaeria turcicapathosystem

et al. 2010

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“…), Brassica rapa (Mitchell‐Olds et al. ), and Medicago sativa (Hill and Leath ) for the correlated resistance to multiple fungal pathogens from different genera, at least in some of the pairwise comparisons. In Microbotryum, the results suggest that resistance mechanisms that have evolved in response to either pathogen species may often provide protection against the other con‐generic pathogen.…”

Section: Discussionmentioning

confidence: 99%

Variation in resistance to multiple pathogen species: anther smuts of Silene uniflora

Chung

Petit

Antonovics

et al. 2012

Ecology and Evolution

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The occurrence of multiple pathogen species on a shared host species is unexpected when they exploit the same micro-niche within the host individual. One explanation for such observations is the presence of pathogen-specific resistances segregating within the host population into sites that are differentially occupied by the competing pathogens. This study used experimental inoculations to test whether specific resistances may contribute to the maintenance of two species of anther-smut fungi, Microbotryum silenes-inflatae and Microbotryum lagerheimii, in natural populations of Silene uniflora in England and Wales. Overall, resistance to the two pathogens was strongly positively correlated among host populations and to a lesser degree among host families within populations. A few instances of specific resistance were also observed and confirmed by replicated inoculations. The results suggest that selection for resistance to one pathogen may protect the host from the emergence via host shifts of related pathogen species, and conversely that co-occurrence of two species of pathogens may be dependent on the presence of host genotypes susceptible to both.

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“…Because many of these traits are continuous in their response, small changes in resistance are often difficult to detect (Burdon, ; Burdon, Barrett, Rebetzke, & Thrall, ). Furthermore, changes in resistance in response to pathogen attack may be correlated across multiple pathogen species (Mitchell‐Olds, James, Palmer, & Williams, ).…”

Section: Evolution In Traits Under Biotic Selection Pressurementioning

confidence: 99%

In situ conservation—harnessing natural and human‐derived evolutionary forces to ensure future crop adaptation

Bellon

Dulloo

Sardos³

et al. 2017

Evolutionary Applications

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Ensuring the availability of the broadest possible germplasm base for agriculture in the face of increasingly uncertain and variable patterns of biotic and abiotic change is fundamental for the world's future food supply. While ex situ conservation plays a major role in the conservation and availability of crop germplasm, it may be insufficient to ensure this. In situ conservation aims to maintain target species and the collective genotypes they represent under evolution. A major rationale for this view is based on the likelihood that continued exposure to changing selective forces will generate and favor new genetic variation and an increased likelihood that rare alleles that may be of value to future agriculture are maintained. However, the evidence that underpins this key rationale remains fragmented and has not been examined systematically, thereby decreasing the perceived value and support for in situ conservation for agriculture and food systems and limiting the conservation options available. This study reviews evidence regarding the likelihood and rate of evolutionary change in both biotic and abiotic traits for crops and their wild relatives, placing these processes in a realistic context in which smallholder farming operates and crop wild relatives continue to exist. It identifies areas of research that would contribute to a deeper understanding of these processes as the basis for making them more useful for future crop adaptation.

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Genetics of Brassica rapa (syn. campestris). 2. Multiple disease resistance to three fungal pathogens: Peronospora parasitica, Albugo Candida and Leptosphaeria maculans

Cited by 47 publications

References 28 publications

Resistance loci affecting distinct stages of fungal pathogenesis: use of introgression lines for QTL mapping and characterization in the maize - Setosphaeria turcicapathosystem

Resistance loci affecting distinct stages of fungal pathogenesis: use of introgression lines for QTL mapping and characterization in the maize - Setosphaeria turcicapathosystem

Variation in resistance to multiple pathogen species: anther smuts of Silene uniflora

In situ conservation—harnessing natural and human‐derived evolutionary forces to ensure future crop adaptation

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