Quantitative Trait Loci for Susceptibility to Tapeworm Infection in the Red Flour Beetle

Abstract Parasites have profound effects on host ecology and evolution, and the effects of parasites on host ecology are often influenced by the magnitude of host susceptibility to parasites. Many parasites have complex life cycles that require intermediate hosts for their transmission, but little is known about the genetic basis of the intermediate host's susceptibility to these parasites. This study examined the genetic basis of susceptibility to a tapeworm (Hymenolepis diminuta) in the red flour beetle (Tribolium castaneum) that serves as an intermediate host in its transmission. Quantitative trait loci (QTL) mapping experiments were conducted with two independent segregating populations using amplified fragment length polymorphism (AFLP) markers and randomly amplified polymorphic DNA (RAPD) markers. A total of five QTL that significantly affected beetle susceptibility were identified in the two reciprocal crosses. Two common QTL on linkage groups 3 and 6 were identified in both crosses with similar effects on the phenotype, and three QTL were unique to each cross. In one cross, the three main QTL accounted for 29% of the total phenotypic variance and digenic epistasis explained 39% of the variance. In the second cross, the four main QTL explained 62% of the variance and digenic epistasis accounted for only 5% of the variance. The actions of these QTL were either overdominance or underdominance. Our results suggest that the polygenic nature of beetle susceptibility to the parasites and epistasis are important genetic mechanisms for the maintenance of variation within or among beetle strains in susceptibility to tapeworm infection.

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Overdominance and Epistasis Are Important for the Genetic Basis of Heterosis in Brassica rapa

HortScience ◽

10.21273/hortsci.42.5.1207 ◽

2007 ◽

Vol 42 (5) ◽

pp. 1207-1211 ◽

Cited By ~ 9

Author(s):

De-Kun Dong ◽

Jia-Shu Cao ◽

Kai Shi ◽

Le-Cheng Liu

Keyword(s):

Quantitative Trait Loci ◽

Brassica Rapa ◽

Quantitative Trait ◽

Genetic Basis ◽

Phenotypic Variance ◽

Epistasis Analysis ◽

Main Effect ◽

Trait Loci ◽

Component Traits ◽

The Cross

To investigate the genetic basis of heterosis in Brassica rapa, an F2 population was produced from the cross of B. rapa L. subsp. chinensis (L.) Hanelt and B. rapa L. subsp. rapifera Metzg. Trait performances of the F1 hybrid showed evident mid parent heterosis, which varied from 18.55% to 101.62% for the 11 traits investigated. A total of 23 main effect quantitative trait loci (QTLs) were detected for biomass and its component traits, which could explain 4.38% to 47.80% of the phenotypic variance, respectively. Sixty-five percent of these QTLs showed obvious overdominance. Epistasis analysis detected 444 two-locus interactions for the 11 traits at the threshold of P < 0.005. Some of them remained significant when more stringent threshold were set. These results suggested that overdominance and epistasis might play an important role as the genetic basis of heterosis in B. rapa.

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Identifying Quantitative Trait Loci for Resistance to Sclerotinia Head Rot in Two USDA Sunflower Germplasms

Phytopathology ◽

10.1094/phyto-98-8-0926 ◽

2008 ◽

Vol 98 (8) ◽

pp. 926-931 ◽

Cited By ~ 33

Author(s):

B. Yue ◽

S. A. Radi ◽

B. A. Vick ◽

X. Cai ◽

S. Tang ◽

...

Keyword(s):

Quantitative Trait Loci ◽

Quantitative Trait ◽

Genetic Basis ◽

Field Experiments ◽

Disease Incidence ◽

Block Design ◽

Phenotypic Variance ◽

Target Region ◽

Trait Loci ◽

Head Rot

Sclerotinia head rot is a major disease of sunflower in the world, and quantitative trait loci (QTL) mapping could facilitate understanding of the genetic basis of head rot resistance and breeding in sunflower. One hundred twenty-three F2:3 and F2:4 families from a cross between HA 441 and RHA 439 were studied. The mapping population was evaluated for disease resistance in three field experiments in a randomized complete block design with two replicates. Disease incidence (DI) and disease severity (DS) were assessed. A genetic map with 180 target region amplification polymorphism, 32 simple sequence repeats, 11 insertion-deletion, and 2 morphological markers was constructed. Nine DI and seven DS QTL were identified with each QTL explaining 8.4 to 34.5% of phenotypic variance, suggesting the polygenic basis of the resistance to head rot. Five of these QTL were identified in more than one experiment, and each QTL explained more than 12.9% of phenotypic variance. These QTL could be useful in sunflower breeding. Although a positive correlation existed between the two disease indices, most of the respective QTL were located in different chromosomal regions, suggesting a different genetic basis for the two indices.

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The Genetic Basis of the Interspecific Differences in Wing Size in Nasonia (Hymenoptera; Pteromalidae): Major Quantitative Trait Loci and Epistasis

Genetics ◽

10.1093/genetics/161.2.673 ◽

2002 ◽

Vol 161 (2) ◽

pp. 673-684

Author(s):

J Gadau ◽

R E Page ◽

J H Werren

Keyword(s):

Quantitative Trait Loci ◽

Qtl Analysis ◽

Quantitative Trait ◽

Wing Length ◽

Size Difference ◽

Phenotypic Variance ◽

Wing Size ◽

Epistatic Interactions ◽

Trait Loci ◽

Wing Width

Abstract There is a 2.5-fold difference in male wing size between two haplodiploid insect species, Nasonia vitripennis and N. giraulti. The haploidy of males facilitated a full genomic screen for quantitative trait loci (QTL) affecting wing size and the detection of epistatic interactions. A QTL analysis of the interspecific wing-size difference revealed QTL with major effects and epistatic interactions among loci affecting the trait. We analyzed 178 hybrid males and initially found two major QTL for wing length, one for wing width, three for a normalized wing-size variable, and five for wing seta density. One QTL for wing width explains 38.1% of the phenotypic variance, and the same QTL explains 22% of the phenotypic variance in normalized wing size. This corresponds to a region previously introgressed from N. giraulti into N. vitripennis that accounts for 44% of the normalized wing-size difference between the species. Significant epistatic interactions were also found that affect wing size and density of setae on the wing. Screening for pairwise epistatic interactions between loci on different linkage groups revealed four additional loci for wing length and four loci for normalized wing size that were not detected in the original QTL analysis. We propose that the evolution of smaller wings in N. vitripennis males is primarily the result of major mutations at few genomic regions and involves epistatic interactions among some loci.

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Quantitative Trait Loci Affecting Differences in Floral Morphology Between Two Species of Monkeyflower (Mimulus)

Genetics ◽

10.1093/genetics/149.1.367 ◽

1998 ◽

Vol 149 (1) ◽

pp. 367-382 ◽

Cited By ~ 11

Author(s):

H D Bradshaw ◽

Kevin G Otto ◽

Barbara E Frewen ◽

John K McKay ◽

Douglas W Schemske

Keyword(s):

Quantitative Trait Loci ◽

Reproductive Isolation ◽

Quantitative Trait ◽

Floral Morphology ◽

Cumulative Effect ◽

Sympatric Species ◽

Accurate Estimate ◽

Phenotypic Variance ◽

Trait Loci ◽

Morphological Differences

Abstract Conspicuous differences in floral morphology are partly responsible for reproductive isolation between two sympatric species of monkeyflower because of their effect on visitation of the flowers by different pollinators. Mimulus lewisii flowers are visited primarily by bumblebees, whereas M. cardinalis flowers are visited mostly by hummingbirds. The genetic control of 12 morphological differences between the flowers of M. lewisii and M. cardinalis was explored in a large linkage mapping population of F2 plants (n = 465) to provide an accurate estimate of the number and magnitude of effect of quantitative trait loci (QTLs) governing each character. Between one and six QTLs were identified for each trait. Most (9/12) traits appear to be controlled in part by at least one major QTL explaining ≥25% of the total phenotypic variance. This implies that either single genes of individually large effect or linked clusters of genes with a large cumulative effect can play a role in the evolution of reproductive isolation and speciation.

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Quantitative Trait Loci Affecting Survival and Fertility-Related Traits in Caenorhabditis elegans Show Genotype-Environment Interactions, Pleiotropy and Epistasis

Genetics ◽

10.1093/genetics/153.3.1233 ◽

1999 ◽

Vol 153 (3) ◽

pp. 1233-1243 ◽

Cited By ~ 6

Author(s):

David R Shook ◽

Thomas E Johnson

Keyword(s):

Caenorhabditis Elegans ◽

Quantitative Trait Loci ◽

Population Growth ◽

Quantitative Trait ◽

Age Of Onset ◽

Inbred Strains ◽

Interval Mapping ◽

Phenotypic Variance ◽

Epistatic Interactions ◽

Trait Loci

Abstract We have identified, using composite interval mapping, quantitative trait loci (QTL) affecting a variety of life history traits (LHTs) in the nematode Caenorhabditis elegans. Using recombinant inbred strains assayed on the surface of agar plates, we found QTL for survival, early fertility, age of onset of sexual maturity, and population growth rate. There was no overall correlation between survival on solid media and previous measures of survival in liquid media. Of the four survival QTL found in these two environments, two have genotype-environment interactions (GEIs). Epistatic interactions between markers were detected for four traits. A multiple regression approach was used to determine which single markers and epistatic interactions best explained the phenotypic variance for each trait. The amount of phenotypic variance accounted for by genetic effects ranged from 13% (for internal hatching) to 46% (for population growth). Epistatic effects accounted for 9–11% of the phenotypic variance for three traits. Two regions containing QTL that affected more than one fertility-related trait were found. This study serves as an example of the power of QTL mapping for dissecting the genetic architecture of a suite of LHTs and indicates the potential importance of environment and GEIs in the evolution of this architecture.

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Meta-Analysis of Quantitative Trait Loci Associated with Seedling-Stage Salt Tolerance in Rice (Oryza sativa L.)

Plants ◽

10.3390/plants8020033 ◽

2019 ◽

Vol 8 (2) ◽

pp. 33 ◽

Cited By ~ 6

Author(s):

Md. Islam ◽

John Ontoy ◽

Prasanta Subudhi

Keyword(s):

Quantitative Trait Loci ◽

Salt Tolerance ◽

Candidate Genes ◽

Quantitative Trait ◽

Oryza Sativa L ◽

Meta Analysis ◽

Seedling Stage ◽

Phenotypic Variance ◽

A Genome ◽

Trait Loci

Soil and water salinity is one of the major abiotic stresses that reduce growth and productivity in major food crops including rice. The lack of congruence of salt tolerance quantitative trait loci (QTLs) in multiple genetic backgrounds and multiple environments is a major hindrance for undertaking marker-assisted selection (MAS). A genome-wide meta-analysis of QTLs controlling seedling-stage salt tolerance was conducted in rice using QTL information from 12 studies. Using a consensus map, 11 meta-QTLs for three traits with smaller confidence intervals were localized on chromosomes 1 and 2. The phenotypic variance of 3 meta-QTLs was ≥20%. Based on phenotyping of 56 diverse genotypes and breeding lines, six salt-tolerant genotypes (Bharathy, I Kung Ban 4-2 Mutant, Langmanbi, Fatehpur 3, CT-329, and IARI 5823) were identified. The perusal of the meta-QTL regions revealed several candidate genes associated with salt-tolerance attributes. The lack of association between meta-QTL linked markers and the level of salt tolerance could be due to the low resolution of meta-QTL regions and the genetic complexity of salt tolerance. The meta-QTLs identified in this study will be useful not only for MAS and pyramiding, but will also accelerate the fine mapping and cloning of candidate genes associated with salt-tolerance mechanisms in rice.

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Detection of Quantitative Trait Loci (QTL) Associated with the Fruit Morphology of Tomato

Genes ◽

10.3390/genes11101117 ◽

2020 ◽

Vol 11 (10) ◽

pp. 1117

Author(s):

Pragya Adhikari ◽

James McNellie ◽

Dilip R. Panthee

Keyword(s):

Quantitative Trait Loci ◽

Quantitative Trait ◽

Recombinant Inbred Lines ◽

Tomato Fruit ◽

Snp Array ◽

Fruit Shape ◽

Phenotypic Variance ◽

Fruit Morphology ◽

Trait Loci ◽

Shape And Size

Tomato (Solanum lycopersicum L.) is the second most-consumed vegetable in the world. The market value and culinary purpose of tomato are often determined by fruit size and shape, which makes the genetic improvement of these traits a priority for tomato breeders. The main objective of the study was to detect quantitative trait loci (QTL) associated with the tomato fruit shape and size. The use of elite breeding materials in the genetic mapping studies will facilitate the detection of genetic loci of direct relevance to breeders. We performed QTL analysis in an intra-specific population of tomato developed from a cross between two elite breeding lines NC 30P × NC-22L-1(2008) consisting of 110 recombinant inbred lines (RIL). The precision software Tomato Analyzer (TA) was used to measure fruit morphology attributes associated with fruit shape and size traits. The RIL population was genotyped with the SolCAP 7720 SNP array. We identified novel QTL controlling elongated fruit shape on chromosome 10, explaining up to 24% of the phenotypic variance. This information will be useful in improving tomato fruit morphology traits.

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Quantitative Trait Loci Mapping for Adult-Plant Resistance to Powdery Mildew in Bread Wheat

Phytopathology ◽

10.1094/phyto-96-0784 ◽

2006 ◽

Vol 96 (7) ◽

pp. 784-789 ◽

Cited By ~ 44

Author(s):

S. S. Liang ◽

K. Suenaga ◽

Z. H. He ◽

Z. L. Wang ◽

H. Y. Liu ◽

...

Keyword(s):

Quantitative Trait Loci ◽

Powdery Mildew ◽

Plant Resistance ◽

Quantitative Trait ◽

Powdery Mildew Resistance ◽

Adult Plant Resistance ◽

Adult Plant ◽

Phenotypic Variance ◽

Mildew Resistance ◽

Trait Loci

Powdery mildew, caused by Blumeria graminis f. sp. tritici, is a major disease to wheat (Triticum aestivum) worldwide. Use of adult-plant resistance (APR) is an effective method to develop wheat cultivars with durable resistance to powdery mildew. In the present study, 432 molecular markers were used to map quantitative trait loci (QTL) for APR to powdery mildew in a doubled haploid (DH) population with 107 lines derived from the cross Fukuho-komugi × Oligoculm. Field trials were conducted in Beijing and Anyang, China during 2003-2004 and 2004-2005 cropping seasons, respectively. The DH lines were planted in a randomized complete block design with three replicates. Artificial inoculation was carried out in Beijing with highly virulent isolate E20 of B. graminis f. sp. tritici and the powdery mildew severity on penultimate leaf was evaluated four times, and the maximum disease severity (MDS) on penultimate leaf was investigated in Anyang under natural inoculation in May 2004 and 2005. The heritability of resistance to powdery mildew for MDS in 2 years and two locations ranged from 0.82 to 0.93, while the heritability for area under the disease progress curve was between 0.84 and 0.91. With the method of composite interval mapping, four QTL for APR to powdery mildew were detected on chromosomes 1AS, 2BL, 4BL, and 7DS, explaining 5.7 to 26.6% of the phenotypic variance. Three QTL on chromosomes 1AS, 2BL, and 7DS were derived from the female, Fukuho-komugi, while the one on chromosome 4BL was from the male, Oligoculm. The QTL on chromosome 1AS showed high genetic effect on powdery mildew resistance, accounting for 19.5 to 26.6% of phenotypic variance across two environments. The QTL on 7DS associated with the locus Lr34/Yr18, flanked by microsatellite Xgwm295.1 and Ltn (leaf tip necrosis). These results will benefit for improving powdery mildew resistance in wheat breeding programs.

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Mapping Quantitative Trait Loci for Resistance to Fall Armyworm (Lepidoptera: Noctuidae) Leaf-Feeding Damage in Maize Inbred Mp705

Journal of Economic Entomology ◽

10.1093/jee/toz357 ◽

2020 ◽

Vol 113 (2) ◽

pp. 956-963 ◽

Cited By ~ 3

Author(s):

E D Womack ◽

W P Williams ◽

J S Smith ◽

M L Warburton ◽

D Bhattramakki

Keyword(s):

Molecular Markers ◽

Quantitative Trait Loci ◽

Quantitative Trait ◽

Fall Armyworm ◽

Phenotypic Variance ◽

Feeding Damage ◽

Artificial Infestation ◽

Lepidopteran Insects ◽

Trait Loci ◽

Important Pest

Abstract The fall armyworm, Spodoptera frugiperda (J. E. Smith), is an agronomically important pest that severely limits maize (Zea mays (Linnaeus) [Poales: Poaceae]) production. This migrant insect devastates maize plants in many countries threatening the livelihood of millions. Quantitative trait loci (QTL) were mapped to identify chromosomal regions that control resistance to fall armyworm leaf-feeding and to identify molecular markers linked to the target loci for use in marker-assisted selection (MAS). A bi-parental mapping population, comprising 243 F2:3 families from the cross Mp705 (resistant) × Mp719 (susceptible), was evaluated for fall armyworm leaf-feeding damage under artificial infestation over 3 yr. A linkage map comprised of 1,276 single-nucleotide polymorphism and simple sequence repeat molecular markers was constructed. Quantitative trait loci analyses identified two major QTL in bins 4.06 and 9.03 that when combined, explained 35.7% of the phenotypic variance over all environments. Mp705 was responsible for the leaf-feeding damage reducing alleles for both large effect QTL and most of the small effect QTL identified in this study. The QTL identified in bin 9.03 co-locates with a previously identified QTL that controls resistance to leaf-feeding damage in maize by fall armyworm and other lepidopteran insects. The QTL in bin 4.06 is a new source of resistance identified in this study. Beneficial alleles derived from Mp705 for the application of an integrated QTL-MAS approach could accelerate breeding efforts to minimize fall armyworm leaf-feeding in maize.

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Quantitative Trait Loci for Adult-Plant Resistance to Mycosphaerella graminicola in Two Winter Wheat Populations

Phytopathology ◽

10.1094/phyto-08-10-0203 ◽

2011 ◽

Vol 101 (10) ◽

pp. 1209-1216 ◽

Cited By ~ 31

Author(s):

P. Risser ◽

E. Ebmeyer ◽

V. Korzun ◽

L. Hartl ◽

T. Miedaner

Keyword(s):

Quantitative Trait Loci ◽

Winter Wheat ◽

Plant Height ◽

Plant Resistance ◽

Quantitative Trait ◽

Adult Plant Resistance ◽

Heading Date ◽

Adult Plant ◽

Phenotypic Variance ◽

Trait Loci

Septoria tritici blotch (STB) is one of the most important leaf spot diseases in wheat worldwide. The goal of this study was to detect chromosomal regions for adult-plant resistance in large winter wheat populations to STB. Inoculation by two isolates with virulence to Stb6 and Stb15, both present in the parents, was performed and STB severity was visually scored plotwise as percent coverage of flag leaves with pycnidia-bearing lesions. ‘Florett’/‘Biscay’ and ‘Tuareg’/‘Biscay’, each comprising a cross of a resistant and a susceptible cultivar, with population sizes of 316 and 269 F7:8 recombinant inbred lines, respectively, were phenotyped across four and five environments and mapped with amplified fragment length polymorphism, diversity array technology, and simple sequence repeat markers covering polymorphic regions of ≈1,340 centimorgans. Phenotypic data revealed significant (P < 0.01) genotypic differentiation for STB, heading date, and plant height. Entry-mean heritabilities (h2) for STB were 0.73 for ‘Florett’/‘Biscay’ and 0.38 for ‘Tuareg’/‘Biscay’. All correlations between STB and heading date as well as between STB and plant height were low (r = –0.13 to –0.20). In quantitative trait loci (QTL) analysis, nine and six QTL were found for STB ratings explaining, together, 55 and 51% of phenotypic variation in ‘Florett’/‘Biscay’ and ‘Tuareg’/‘Biscay’, respectively. Genotype–environment and QTL–environment interactions had a large impact. Two major QTL were detected consistently across environments on chromosomes 3B and 6D from ‘Florett’ and chromosomes 4B and 6B from ‘Tuareg’, each explaining 12 to 17% of normalized adjusted phenotypic variance. These results indicate that adult-plant resistance to STB in both mapping populations was of a quantitative nature.

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