Transgressive segregation for very low and high levels of basal resistance to powdery mildew in barley

Hybridization in animals is a much more common phenomenon as previously thought and may have profound implications for speciation research. The cichlid genus Steatocranus (Teleostei: Cichlidae), a close relative to members of the East African cichlid radiations, radiated under riverine conditions in the lower Congo rapids and produced a small species flock. Previous phylogenetic analyses suggested that hybridization occurred and contributed to speciation in this genus. A re‐analysis of an already published 2000 loci‐AFLP data set explicitly testing for patterns of ancient gene flow provided strong evidence for a highly reticulate phylogenetic history of the genus. We provide, to our knowledge, the first example of a complex reticulate network in vertebrates, including multiple closely related species connected through ancient as well as recent gene flow. In this context, the limited validity of strictly bifurcating tree hypotheses as a phylogenetic basis for hypothesis testing in evolutionary biology is discussed.

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“…, 2009; Larsen et al. , 2010; Aghnoum & Niks, 2011). The lower Congo rapids were colonized in at least two waves (Fig.…”

Section: Discussionmentioning

confidence: 99%

“…Speciation within genomic networks 145 & Seehausen, 2009a;Stelkens et al, 2009;Larsen et al, 2010;Aghnoum & Niks, 2011). The lower Congo rapids were colonized in at least two waves ( Fig.…”

Section: Potential Sources and Interpretation Of Conflict Signalmentioning

confidence: 99%

Speciation within genomic networks: a case study based onSteatocranuscichlids of the lower Congo rapids

Schwarzer

Misof

Schliewen

2011

J of Evolutionary Biology

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“…Quantitative resistance of barley to Bgh is mediated by many QTLs with small to moderate effect [7,9,46,47]. This implies at least as many (non) host genes to be relevant for the trait.…”

Section: Discussionmentioning

confidence: 99%

Discovery of genes affecting resistance of barley to adapted and non-adapted powdery mildew fungi

Douchkov

Lück

Johrde³

et al. 2014

Genome Biol

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Background: Non-host resistance, NHR, to non-adapted pathogens and quantitative host resistance, QR, confer durable protection to plants and are important for securing yield in a longer perspective. However, a more targeted exploitation of the trait usually possessing a complex mode of inheritance by many quantitative trait loci, QTLs, will require a better understanding of the most important genes and alleles.

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“…Transgressive segregation also has been observed in other pathogen-cotton systems, such as for Verticillium wilt resistance in an F 2 (resistant Pima S-7 x susceptible Acala 44) [10] and in an F 2:3 family ( G. barbadense H7124 x G. hirsutum XLZ1) [11], for Fusarium wilt resistance in the F 2 or F 3 populations (resistant Pima S-7 x susceptible Acala NemX or Acala SJ-2) [12], and for bacterial blight resistance in the BC 4 F 4 generation within an intraspecific cross of cotton [13]. Transgressive segregation for resistance also has been reported in other plant-pathogen systems, such as soybean - soybean cyst nematodes [14], soybean - Rhizoctonia root and hypocotyl rot [15], Arabidopsis – Leptosphaeria maculans , blackleg disease [16], wheat – stripe rust [17]–[20], barley – Pyrenophora teres [21] and barley - powdery mildew [22].…”

Section: Introductionmentioning

confidence: 88%

QTL Analysis for Transgressive Resistance to Root-Knot Nematode in Interspecific Cotton (Gossypium spp.) Progeny Derived from Susceptible Parents

et al. 2012

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The southern root-knot nematode (RKN, Meloidogyne incognita) is a major soil-inhabiting plant parasite that causes significant yield losses in cotton (Gossypium spp.). Progeny from crosses between cotton genotypes susceptible to RKN produced segregants in subsequent populations which were highly resistant to this parasite. A recombinant inbred line (RIL) population of 138 lines developed from a cross between Upland cotton TM-1 (G. hirsutum L.) and Pima 3–79 (G. barbadense L.), both susceptible to RKN, was used to identify quantitative trait loci (QTLs) determining responses to RKN in greenhouse infection assays with simple sequence repeat (SSR) markers. Compared to both parents, 53.6% and 52.1% of RILs showed less (P<0.05) root-galling index (GI) and had lower (P<0.05) nematode egg production (eggs per gram root, EGR). Highly resistant lines (transgressive segregants) were identified in this RIL population for GI and/or EGR in two greenhouse experiments. QTLs were identified using the single-marker analysis nonparametric mapping Kruskal-Wallis test. Four major QTLs located on chromosomes 3, 4, 11, and 17 were identified to account for 8.0 to 12.3% of the phenotypic variance (R2) in root-galling. Two major QTLs accounting for 9.7% and 10.6% of EGR variance were identified on chromosomes 14 and 23 (P<0.005), respectively. In addition, 19 putative QTLs (P<0.05) accounted for 4.5–7.7% of phenotypic variance (R2) in GI, and 15 QTLs accounted for 4.2–7.3% of phenotypic variance in EGR. In lines with alleles positive for resistance contributed by both parents in combinations of two to four QTLs, dramatic reductions of >50% in both GI and EGR were observed. The transgressive segregants with epistatic effects derived from susceptible parents indicate that high levels of nematode resistance in cotton may be attained by pyramiding positive alleles using a QTL mapping approach.

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Transgressive segregation for very low and high levels of basal resistance to powdery mildew in barley

Cited by 16 publications

References 34 publications

Speciation within genomic networks: a case study based onSteatocranuscichlids of the lower Congo rapids

Speciation within genomic networks: a case study based onSteatocranuscichlids of the lower Congo rapids

Discovery of genes affecting resistance of barley to adapted and non-adapted powdery mildew fungi

QTL Analysis for Transgressive Resistance to Root-Knot Nematode in Interspecific Cotton (Gossypium spp.) Progeny Derived from Susceptible Parents

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