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Results for “quantitative trait locus”

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PubMed2002

Interacting QTLs for cholesterol gallstones and gallbladder mucin in AKR and SWR strains of mice.

We employed quantitative trait locus (QTL) mapping in a backcross between gallstone-susceptible SWR/J and gallstone-resistant AKR/J inbred mice to identify additional susceptibility loci for cholesterol gallstone formation. After 12 wk of feeding the mice a lithogenic diet, we phenotyped 330 backcross progeny for gallstones, gallbladder mucin accumulation, liver weight, and body weight. Marker-based regression analysis revealed significant single QTLs associated with gallstone formation on chromosome 9 and the liver weight/body weight ratio on chromosomes 5 and X. A search for gene pairs detected significant gene-gene interactions for mucin accumulation between loci on chromosomes 5 and 11 and suggestive gene-gene interactions linked to gallstone formation between the QTL on chromosome 9 and loci on chromosomes 6 and 15. These findings uncover new QTLs for cholesterol gallstones, reveal independent loci for mucin accumulation, and demonstrate the importance of considering gene-gene interactions in cholesterol cholelithiasis. According to standard nomenclature, the gallstone QTL on chromosome 9 is named Lith5.

Animals↗
PubMed2005

A model selection-based interval-mapping method for autopolyploids.

While extensive progress has been made in quantitative trait locus (QTL) mapping for diploid species, similar progress in QTL mapping for polyploids has been limited due to the complex genetic architecture of polyploids. To date, QTL mapping in polyploids has focused mainly on tetraploids with dominant and/or codominant markers. Here, we extend this view to include any even ploidy level under a dominant marker system. Our approach first selects the most likely chromosomal marker configurations using a Bayesian selection criterion and then fits an interval-mapping model to each candidate. Profiles of the likelihood-ratio test statistic and the maximum-likelihood estimates (MLEs) of parameters including QTL effects are obtained via the EM algorithm. Putative QTL are then detected using a resampling-based significance threshold, and the corresponding parental configuration is identified to be the underlying parental configuration from which the data are observed. Although presented via pseudo-doubled backcross experiments, this approach can be readily extended to other breeding systems. Our method is applied to single-dose restriction fragment autotetraploid alfalfa data, and the performance is investigated through simulation studies.

Algorithms↗
PubMed2005

Quantitative trait loci and interaction effects responsible for variation in female postmating mortality in Drosophila simulans and D. sechellia introgression lines.

Mating appears to inflict a cost to Drosophila females, resulting in a reduction of their lifespan shortly after mating. Males from different chromosome extracted lines differ significantly in their detrimental effects on postmating female survival, and seminal fluid proteins produced in the male accessory glands are at least partially responsible for the effect. This suggests that there is a genetic basis underlying the male inflicted effect on female's postmating mortality. However, the genes responsible for this effect remain elusive. Using males from introgression lines between D. simulans and D. sechellia genomes and a quantitative trait locus (QTL) mapping approach, we identified chromosomal regions that affect postmating mortality of females. We found a second chromosome QTL with an effect on average female lifespan after mating and a third chromosome QTL with an effect on postmating female mortality rate. Under the general observation of a faster divergence of sex-related genes among closely related species, it is predicted that genes for reproductive traits other than hybrid sterility will show evidence of epistatic effects when brought into a heterospecific background. We detected a significant epistatic genetic effect on postmating female mortality rate that supports this prediction.

Animals↗
PubMed1997

MCMC segregation and linkage analysis.

Our objective was to infer the genetic model for the quantitative traits using a variety of methods developed in our group. Only a single data set was analyzed in any one analysis, although some comparison between data sets was made. In addition, the simulated model was not known during the course of the analysis. Basic modeling and segregation analyses for the five quantitative traits was followed by several simple genome scans to indicate areas of interest. A Markov chain Monte Carlo (MCMC) multipoint quantitative trait locus (QTL) mapping approach was then used to estimate the posterior probabilities of linkage of QTL to each chromosome simultaneously with trait model parameters, and to further localize the genes. Comparisons between the nuclear family and pedigree data sets indicated a greater power for QTL detection and mapping with the pedigree data sets. Even with the pedigree data, however, precise localization of the QTL did not appear to be possible using single replicate data sets. Two of the three genes with effects on trait Q1 were detected by the MCMC method.

Chromosome Mapping↗
PubMed2005

Extensive chromosomal repatterning and the evolution of sterility barriers in hybrid sunflower species.

New species may arise via hybridization and without a change in ploidy. This process, termed homoploid hybrid speciation, is theoretically difficult because it requires the development of reproductive barriers in sympatry or parapatry. Theory suggests that isolation may arise through rapid karyotypic evolution and/or ecological divergence of hybrid neospecies. Here, we investigate the role of karyotypic change in homoploid hybrid speciation by generating detailed genetic linkage maps for three hybrid sunflower species, Helianthus anomalus, H. deserticola, and H. paradoxus, and comparing these maps to those previously generated for the parental species, H. annuus and H. petiolaris. We also conduct a quantitative trait locus (QTL) analysis of pollen fertility in a BC2 population between the parental species and assess levels of pollen and seed fertility in all cross-combinations of the hybrid and parental species. The three hybrid species are massively divergent from their parental species in karyotype; gene order differences were observed for between 9 and 11 linkage groups (of 17 total), depending on the comparison. About one-third of the karyoypic differences arose through the sorting of chromosomal rearrangements that differentiate the parental species, but the remainder appear to have arisen de novo (six breakages/six fusions in H. anomalus, four breakages/three fusions in H. deserticola, and five breakages/five fusions in H. paradoxus). QTL analyses indicate that the karyotypic differences contribute to reproductive isolation. Nine of 11 pollen viability QTL occur on rearranged chromosomes and all but one map close to a rearrangement breakpoint. Finally, pollen and seed fertility estimates for F1's between the hybrid and parental species fall below 11%, which is sufficient for evolutionary independence of the hybrid neospecies.

Chromosome Mapping↗
PubMed2006

A sodium transporter (HKT7) is a candidate for Nax1, a gene for salt tolerance in durum wheat.

Durum wheat (Triticum turgidum subsp. durum) is more salt sensitive than bread wheat (Triticum aestivum). A novel source of Na(+) exclusion conferring salt tolerance to durum wheat is present in the durum wheat Line 149 derived from Triticum monococcum C68-101, and a quantitative trait locus contributing to low Na(+) concentration in leaf blades, Nax1, mapped to chromosome 2AL. In this study, we used the rice (Oryza sativa) genome sequence and data from the wheat expressed sequence tag deletion bin mapping project to identify markers and construct a high-resolution map of the Nax1 region. Genes on wheat chromosome 2AL and rice chromosome 4L had good overall colinearity, but there was an inversion of a chromosomal segment that includes the Nax1 locus. Two putative sodium transporter genes (TmHKT7) related to OsHKT7 were mapped to chromosome 2AL. One TmHKT7 member (TmHKT7-A1) was polymorphic between the salt-tolerant and -sensitive lines, and cosegregated with Nax1 in the high-resolution mapping family. The other TmHKT7 member (TmHKT7-A2) was located within the same bacterial artificial chromosome contig of approximately 145 kb as TmHKT7-A1. TmHKT7-A1 and -A2 showed 83% amino acid identity. TmHKT7-A2, but not TmHKT7-A1, was expressed in roots and leaf sheaths of the salt-tolerant durum wheat Line 149. The expression pattern of TmHKT7-A2 was consistent with the physiological role of Nax1 in reducing Na(+) concentration in leaf blades by retaining Na(+) in the sheaths. TmHKT7-A2 could control Na(+) unloading from xylem in roots and sheaths.

Amino Acid Sequence↗
PubMed2004

Genetic variation and responses to vaccines.

Disease is a major source of economic loss to the livestock industry. Understanding the role of genetic factors in immune responsiveness and disease resistance should provide new approaches to the control of disease through development of safe synthetic subunit vaccines and breeding for disease resistance. The major histocompatibility complex (MHC) has been an important candidate locus for immune responsiveness studies. However, it is clear that other loci play an important role. Identifying these and quantifying the relative importance of MHC and non-MHC genes should result in new insights into host-pathogen interactions, and information that can be exploited by vaccine designers. The rapidly increasing information available about the bovine genome and the identification of polymorphisms in immune-related genes will offer potential candidates that control immune responses to vaccines. The bovine MHC, BoLA, encodes two distinct isotypes of class II molecules, DR and DQ, and in about half the common haplotypes the DQ genes are duplicated and expressed. DQ molecules are composed of two polymorphic chains whereas DR consists of one polymorphic and one non-polymorphic chain. Although, it is clear that MHC polymorphism is related to immune responsiveness, it is less clear how different allelic and locus products influence the outcome of an immune response in terms of generating protective immunity in outbred animals. A peptide derived from foot-and-mouth disease virus (FMDV) was used as a probe for BoLA class II function. Both DR and DQ are involved in antigen presentation. In an analysis of T-cell clones specific for the peptide, distinct biases to particular restriction elements were observed. In addition inter-haplotype pairings of DQA and DQB molecules produced functional molecules, which greatly increases the numbers of possible restriction elements, compared with the number of genes, particularly in cattle with duplicated DQ genes. In a vaccine trial with several peptides derived from FMDV, BoLA class II DRB3 polymorphisms were correlated with both protection and non-protection. Although variation in immune responsiveness to the FMDV peptide between different individuals is partly explainable by BoLA class II alleles, other genetic factors play an important role. In a quantitative trait locus project, employing a second-generation cross between Charolais and Holstein cattle, significant sire and breed effects were also observed in T-cell, cytokine and antibody responses to the FMDV peptide. These results suggest that both MHC and non-MHC genes play a role in regulating bovine immune traits of relevance to vaccine design. Identifying these genes and quantifying their relative contributions is the subject of further studies.

Animals↗
PubMed2000

Mapping quantitative trait loci that regulate sensitivity and tolerance to quinpirole, a dopamine mimetic selective for D(2)/D(3) receptors.

Acute sensitivity and tolerance to quinpirole (a dopamine mimetic with selectivity for D(2)/D(3) dopamine receptors) were evaluated in the C57BL/6J and DBA/2J inbred strains of mice, 24 of their BXD recombinant inbred strains, and 233 F(2) mice. Baseline locomotor activity, locomotor activity following 0.03 mg/kg quinpirole (and 0. 01 mg/kg in BXD mice), body temperature following 1 mg/kg quinpirole, and hypothermic tolerance following 2 or 3 days of quinpirole administration were evaluated. Quantitative trait locus (QTL) analysis was employed to identify genetic determinants of baseline locomotor activity and five behavioral responses to quinpirole. We examined correlated allelic variation in genetic markers of known chromosomal location with variation in each of these phenotypes. We definitively mapped a QTL on Chromosome (Chr) 9 linked to the D(2) dopamine receptor gene, Drd2, for hypothermic sensitivity to quinpirole, and identify a suggestive QTL in the same chromosomal region for tolerance to quinpirole after repeated treatments. Suggestive QTLs were also identified on Chr 19 for sensitivity and tolerance to quinpirole-induced hypothermia and for baseline locomotor activity; on Chr 15 for locomotor sensitivity to quinpirole; and on Chr 13 and 5 for baseline locomotor activity. Our results indicate that genetic differences in quinpirole sensitivity and tolerance are associated with QTLs near Drd2, and that baseline locomotor activity is associated with a suggestive QTL in proximity to the dopamine transporter gene Dat1. These data suggest that the genes influencing locomotor activity, dopamine mimetic sensitivity, and tolerance do not overlap completely.

Animals↗
PubMed2026

Selection of GhTT2-A07 promoter enhances fiber quality in improved cotton varieties.

Modern cultivated cotton fibers are predominantly white with enhanced quality compared to their wild ancestors. However, the molecular mechanisms and evolutionary drivers linking fiber color to quality remain least focused. In this study, we identified FQC1 (Fiber Quality and Color 1), a major quantitative trait locus (QTL) on chromosome A07 that concurrently regulates both fiber quality and pigmentation. Through map-based cloning, we revealed that Gossypium hirsutum TRANSPARENT TESTA2-A07 (GhTT2-A07), an R2R3-MYB transcription factor, resides within this locus. GhTT2-A07 modulates fiber development by directly activating genes in the general phenylpropanoid pathway, thereby promoting the metabolic flux toward downstream secondary metabolites. Variations in the GhTT2-A07 promoter led to its reduced expression in modern white cotton cultivars. This down-regulation suppresses the accumulation of S/G/H-type lignin monomers and proanthocyanidins, resulting in altered secondary cell wall composition and ultimately enhancing the quality of mature white fibers. Population genetic analyses further indicate that the white-fiber allele GhTT2-A07W has been fixed in modern breeding genotypes, underscoring the impact of artificial selection during cotton domestication. Overall, our study elucidates the biochemical and molecular mechanisms underlying fiber quality and pigmentation in cotton, clarifies the selection criteria for high-quality white fibers in modern cultivars, and provides a theoretical basis for future targeted genetic improvement of cotton fibers.

Alleles↗
PubMed1998

An MboI two-allele polymorphism may implicate the human renin gene in primary hypertension.

As a key enzyme of the renin-angiotensin-aldosterone system, the renin gene (REN) is a good candidate quantitative trait locus that may be implicated in the molecular etiology of essential hypertension. Among mixed reports on the subject, a REN MboI restriction fragment length polymorphism has been shown to be significantly associated with a family history of hypertension in a Japanese population. We show here that the REN MboI dimorphic site is located in the ninth intron of the gene, and we describe a polymerase chain reaction-based assay for detection of this site. We investigated MboI genotype distributions in 331 hypertensive and 279 normotensive subjects from the United Arab Emirates (UAE), a genetically homogeneous ethnic population with no history of smoking or alcohol consumption. A statistically significant association was found between alleles on which the MboI site is present and clinical diagnosis of essential hypertension, indicating that 1) the presence of the MboI site is a marker for susceptibility to hypertension in the UAE (the associated odds ratio is 3.16); and 2) variations of the REN (or of a nearby) gene that may be in linkage disequilibrium with this marker play a role in the development of essential hypertension in the UAE.

Aging↗
PubMed2006

QTL with pleiotropic effects on serum levels of bone-specific alkaline phosphatase and osteocalcin maps to the baboon ortholog of human chromosome 6p23-21.3.

UNLABELLED: Bone ALP and OC are under partial genetic control. This study of 591 pedigreed baboons shows a QTL corresponding to human 6p23-21.3 that accounts for 25% (bone ALP) and 20% (OC) of the genetic variance. A gene affecting osteoblast activity, number, or recruitment likely resides in this area. INTRODUCTION: Serum levels of bone alkaline phosphatase (ALP) and osteocalcin (OC) reflect osteoblast activity. Both of these measures are under partial genetic control. Genetic effects on bone ALP have not been previously localized to chromosomal regions in primates, nor has the degree to which genetic effects are shared (pleiotropic) between bone ALP and OC been studied. MATERIALS AND METHODS: We applied variance components methods to a sample of 591 adult pedigreed baboons to detect and quantify effects of genes that influence bone ALP and that have pleiotropic effects on bone ALP and OC. A univariate linkage analysis was conducted for bone ALP. Bivariate linkage analyses were conducted in areas for which the bone ALP results presented here and a previous univariate OC linkage analysis showed evidence for linkage on the same chromosome for both bone ALP and OC. RESULTS: A quantitative trait locus (QTL) for serum levels of bone ALP is evident on the baboon ortholog of human chromosomal region 6p (LOD 2.93). Thirty-seven percent (genetic correlation [rho(G)] = 0.61) of the genetic variance in bone ALP and OC is caused by pleiotropic effects of the same gene(s). Bivariate linkage analysis revealed a QTL in the region corresponding to human chromosome 6p23-21.3, with the strongest evidence for bivariate linkage near D6S422 (LOD = 2.97 at 22 cM from our pter-most marker). D6S422 maps to 20.4 Mb in the human genome. The QTL-specific heritability (h2) is 0.25 and 0.20 for bone ALP and OC, respectively. CONCLUSIONS: This first formal test for shared genetic effects on two serum markers of osteoblast activity indicates that a significant pleiotropic effect on bone ALP and OC levels, and thus on bone formation, is detectible. The fact that this region corresponds to one on mouse chromosome 13 that has repeatedly yielded QTLs for BMD should encourage more intensive study of the effect of genes in this region on bone maintenance and turnover.

Alkaline Phosphatase↗
PubMed2002

Microtubule-associated protein 1A is a modifier of tubby hearing (moth1).

Once a mutation in the gene tub was identified as the cause of obesity, retinal degeneration and hearing loss in tubby mice, it became increasingly evident that the members of the tub gene family (tulps) influence maintenance and function of the neuronal cell lineage. Suggested molecular functions of tubby-like proteins include roles in vesicular trafficking, mediation of insulin signaling and gene transcription. The mechanisms through which tub functions in neurons, however, have yet to be elucidated. Here we report the positional cloning of an auditory quantitative trait locus (QTL), the modifier of tubby hearing 1 gene (moth1), whose wildtype alleles from strains AKR/J, CAST/Ei and 129P2/OlaHsd protect tubby mice from hearing loss. Through a transgenic rescue experiment, we verified that sequence polymorphisms in the neuron-specific microtubule-associated protein 1a gene (Mtap1a) observed in the susceptible strain C57BL/6J (B6) are crucial for the hearing-loss phenotype. We also show that these polymorphisms change the binding efficiency of MTAP1A to postsynaptic density molecule 95 (PSD95), a core component in the cytoarchitecture of synapses. This indicates that at least some of the observed polymorphisms are functionally important and that the hearing loss in C57BL/6J-tub/tub (B6-tub/tub) mice may be caused by impaired protein interactions involving MTAP1A. We therefore propose that tub may be associated with synaptic function in neuronal cells.

Adaptor Proteins, Signal Transducing↗
PubMed1998

Localization of genes mediating acute and sensitized locomotor responses to cocaine in BXD/Ty recombinant inbred mice.

Sensitization to the psychostimulant effects of cocaine has received widespread attention because concomitant changes occur in neurochemical pathways that are part of the brain reward pathway. The current study was undertaken with the purpose of mapping genes determining sensitivity to the acute stimulant and sensitizing effects of cocaine. Sensitivity and sensitization to cocaine (5, 10, and 40 mg/kg) were measured in 25 BXD/Ty recombinant inbred (BXD RI) strains and the progenitor C57BL/6J (B6) and DBA/2J (D2) strains. Quantitative trait locus (QTL) mapping provisionally localized cocaine sensitivity genes to regions on all chromosomes except 6, 11, 17, and X; sensitization QTLs were localized to chromosomes 1-10, 13, 15, 18, 19, and X. Provisional QTLs for locomotion after saline injection in a novel setting were mapped to chromosomes 1, 3-6, 9, 12, 13, 18, and 19 and in a familiar setting to chromosomes 4-7, 9, 13, and 19. There were both common and unique QTL regions across the phenotypes. Evidence for a genetic association between magnitude of acute cocaine response and sensitization was obtained for only the 10 mg/kg dose. Some common QTL regions for cocaine, ethanol, and methamphetamine responses suggest the possibility that these drugs induce stimulant effects or sensitization through some common mechanisms. However, independent mechanisms were also indicated. Many candidate genes reside near the provisional QTLs mapped for cocaine responses, including genes coding a variety of neurotransmitter and hormone receptors. These data, once confirmed, should prove useful for directing investigations of acute and chronic cocaine effects down already suspected and novel avenues.

Animals↗
PubMed2006

Genetic and structural analysis of the basolateral amygdala complex in BXD recombinant inbred mice.

The amygdala integrates and coordinates emotional and autonomic responses. The genetics that underlie variation in amygdala structure may be coupled to variation in levels of aggression, fear, anxiety, and affiliated behaviors. We systematically quantified the volume and cell populations of the basolateral amygdala complex (BLAc) across 35 BXD recombinant inbred (RI) lines, the parental strains--C57BL/6J (B6) and DBA/2J (D2)--and F1 hybrids (n cases=199, bilateral analysis). Neuron number and volume vary 1.7- to 2-fold among strains (e.g., neuron number ranged from 88,000 to 170,000). Glial and endothelial populations ranged more widely (5- to 8-fold), in part because of higher technical error. A quantitative trait locus (QTL) for the BLAc size is located on chromosome (Chr) 8 near the Large gene. This locus may also influence volume of other regions including hippocampus and cerebellum. Cell populations in the BLAc appear to be modulated more weakly by loci on Chrs 11 and 13. Candidate genes were selected on the basis of correlation with BLAc traits, chromosomal location, single nucleotide polymorphism (SNP) density, and expression patterns in the Allen Brain Atlas. Neurod2, a gene shown to be significant for the formation of the BLAc by knockout studies, is among the candidates genes. Other candidates include Large, and Thra. Responses to drugs of abuse and locomotor activity were the most notable behavioral correlates of the BLAc traits.

Amygdala↗
PubMed2005

An EM algorithm for mapping quantitative resistance loci.

Many disease resistance traits in plants have a polygenic background and the disease phenotypes are modified by environmental factors. As a consequence, the phenotypic values usually show a quantitative variation. The phenotypes of such disease traits, however, are often measured in discrete but ordered categories. These traits are called ordinal traits. In terms of disease resistance, they are called quantitative resistance traits, as opposed to qualitative resistance traits, and are controlled by the quantitative resistance loci (QRL). Classical quantitative trait locus mapping methods are not optimal for ordinal trait analysis because the assumption of normal distribution is violated. Methods for mapping binary trait loci are not suitable either because there are more than two categories in ordinal traits. We developed a maximum likelihood method to map these QRL. The method is implemented via a multicycle expectation-conditional-maximization (ECM) algorithm under the threshold model, where we can estimate both the QRL effects and the thresholds that link the disease liability and the categorical phenotype. The method is verified in simulated data under various combinations of the parameters. An SAS program is available to implement the multicycle ECM algorithm. The program can be downloaded from our website at www.statgen.ucr.edu.

Algorithms↗
PubMed2003

Localization of a blood pressure QTL to a 2.4-cM interval on rat chromosome 9 using congenic strains.

A blood pressure (BP) quantitative trait locus (QTL) was previously found on rat chromosome 9 using Dahl salt-sensitive (S) and Dahl salt-resistant (R) rats. A congenic strain, S.R(chr9), constructed by introgressing an R chromosomal segment into the S background, previously proved the existence of a BP QTL in a large 34.2-cM segment of chromosome 9. In the current work congenic substrains were constructed from the progenitor congenic strain, S.R(chr9). BP and heart weight comparisons between these congenic substrains and their S control localized the BP QTL to a 4.6-cM interval. Two solute carrier (Na(+)/H(+) exchanger) genes, Nhe2 and Nhe4, were excluded as candidates based on their map locations. A second iteration of congenic substrains was used to localize the QTL further to a 2.4-cM interval. Another solute carrier (Cl(-)/HCO3- exchanger) gene, Ae3, is in this reduced interval and was sequenced for both S and R strains, but no coding sequence variations were found. Ae3 mRNA was not differentially expressed in the kidney of congenic compared to S rats. Although the identity of the QTL remains unknown its map location has been reduced from an interval of 34.2 to 2.4 cM.

Animals↗
PubMed2026

Genetic diversity of Collaborative Cross mice implicates FFAR3 as a target for ILC2 anti-inflammatory reprogramming.

Pulmonary group 2 innate lymphoid cells (ILC2s) are key drivers of Type 2 inflammation in diseases like asthma, yet the molecular mechanisms regulating their function are incompletely understood. Using the genetically diverse Collaborative Cross (CC) mouse panel, we mapped a quantitative trait locus (QTL) that governs ILC2 prevalence in the lung after aeroallergen exposure. This QTL induces a large population of ILC2s in the lung that are resistant to activation and have diminished Type 2 effector function. We identified free-fatty acid receptor 3 (Ffar3) as a gene responsible for this effect and demonstrated that FFAR3 signaling reprograms ILC2s to an anti-inflammatory state by promoting their survival, reducing Type 2 cytokine production, and enhancing IL-10 expression. This anti-inflammatory state is dependent on IL-2 signaling, is characterized by decreased ST2 expression, and is distinct from previously described IL-10-producing ILC2 phenotypes. FFAR3-dependent reprogramming is mediated by epidermal growth factor receptor (EGFR) upregulation, and FFAR3's anti-inflammatory effect is partially conserved in human ILC2s.

Animals↗
PubMed2004

Effect of pubescence tip on soybean resistance to lepidopteran insects.

DNA marker analysis has mapped a quantitative trait locus for soybean, Glycine max (L.) Merr., resistance to the corn earworm, Helicoverpa zea (Boddie) (Lepidoptera: Noctuidae), on the USDA soybean genetic linkage map near the classical gene Pb, which conditions pubescence tip. This study was initiated to determine the effect of pubescence tip on resistance to H. zea larvae and to examine the effect on beet armyworm, Spodoptera exigua (Hübner) (Lepidoptera: Noctuidae), and soybean looper, Pseudoplusia includens (Walker) (Lepidoptera: Noctuidae), larvae. The effect of blunt (pb) and sharp (Pb) pubescence tip was tested in antixenosis and antibiosis bioassays on H. zea, S. exigua, and P. includens larvae with near-isolines and insect-resistant and -susceptible genotypes differing in pubescence tip morphology. Sharp pubescence tip significantly reduced defoliation (antixenosis) from H. zea, S. exigua, and P. includens and weight gain (antibiosis) of H. zea. The weight gain of P. includens was unaffected, and S. exigua weight gain was significant for one pair of near-isolines differing in pubescence tip but not the other. The results indicate that sharp pubescence tip would be beneficial to introgress into elite soybean germplasm due to its association with resistance to H. zea, S. exigua, and P. includens.

Animals↗