scholarly journals High resolution genetic dissection of the major QTL for tipburn resistance in lettuce, Lactuca sativa

2021 ◽  
Author(s):  
Miguel Macias-González ◽  
Maria Jose Truco ◽  
Rongkui Han ◽  
Sylvie Jenni ◽  
Richard W Michelmore
Keyword(s):  
Quantitative Trait Locus ◽  
Lactuca Sativa ◽  
Quantitative Trait ◽  
Calcium Deficiency ◽  
Phenotypic Variance ◽  
Physiological Disorder ◽  
Phenotypic Data ◽  
Resistant Parent ◽  
Trait Locus ◽  
Calcium Transporter

Abstract Tipburn is an important physiological disorder of lettuce, Lactuca sativa L., related to calcium deficiency that can result in leaf necrosis and unmarketable crops. The major quantitative trait locus, qTPB5.2, can account for up to 70% of the phenotypic variance for tipburn incidence in the field. This quantitative trait locus was genetically dissected to identify candidate genes for tipburn by creating lines with recombination events within the quantitative trait locus and assessing their resistance to tipburn. By comparing lines with contrasting haplotypes, the genetic region was narrowed down to ∼877 Kb that was associated with a reduction of tipburn by ∼60%. Analysis of the lettuce reference genome sequence revealed 12 genes in this region, one of which is a calcium transporter with a single nucleotide polymorphism in an exon between haplotypes with contrasting phenotypes. RNA-seq analysis of recombinants revealed two genes that were differentially expressed between contrasting haplotypes consistent with the tipburn phenotype. One encodes a Teosinte branched1/Cycloidea/Proliferating Cell factor transcription factor; however, differential expression of the calcium transporter was not detected. The phenotypic data indicated that there is a second region outside of the ∼877 Kb region but within the quantitative trait locus, at which a haplotype from the susceptible parent decreased tipburn by 10 to 20%. A recombinant line was identified with beneficial haplotypes in each region from both parents that showed greater tipburn resistance than the resistant parent; this line could be used as the foundation for breeding cultivars with more resistance than is currently available.

scholarly journals A Major Quantitative Trait Locus for Resistance to Potato leafroll virus Is Located in a Resistance Hotspot on Potato Chromosome XI and Is Tightly Linked to N-Gene-Like Markers

2001 ◽  
Vol 14 (12) ◽  
pp. 1420-1425 ◽  
Author(s):  
Waldemar Marczewski ◽  
Bogdan Flis ◽  
Jerzy Syller ◽  
Ralf Schäfer-Pregl ◽  
Christiane Gebhardt
Keyword(s):  
Quantitative Trait Locus ◽  
Quantitative Trait ◽  
Quantitative Resistance ◽  
Sequence Similarity ◽  
Potato Leafroll Virus ◽  
N Gene ◽  
Phenotypic Variance ◽  
Potato Chromosome ◽  
Trait Locus ◽  
Leafroll Virus

Potato leafroll virus (PLRV) causes one of the most widespread and important virus diseases in potato. Resistance to PLRV is controlled by genetic factors that limit plant infection by viruliferous aphids or virus multiplication and accumulation. Quantitative trait locus (QTL) analysis of resistance to virus accumulation revealed one major and two minor QTL. The major QTL, PLRV.1, mapped to potato chromosome XI in a resistance hotspot containing several genes for qualitative and quantitative resistance to viruses and other potato pathogens. This QTL explained between 50 and 60% of the phenotypic variance. The two minor QTL mapped to chromosomes V and VI. Genes with sequence similarity to the tobacco N gene for resistance to Tobacco mosaic virus were tightly linked to PLRV.1. The cDNA sequence of an N-like gene was used to develop the sequence characterized amplified region (SCAR) marker N1271164 that can assist in the selection of potatoes with resistance to PLRV.

Genetic Analysis of Traits Distinguishing Outcrossing and Self-Pollinating Forms of Currant Tomato, Lycopersicon pimpinellifolium (Jusl.) Mill.

Genetics ◽  
2002 ◽  
Vol 161 (1) ◽  
pp. 333-344 ◽  
Author(s):  
Michael S Georgiady ◽  
Richard W Whitkus ◽  
Elizabeth M Lord
Keyword(s):  
Quantitative Trait Locus ◽  
Quantitative Trait ◽  
Natural Populations ◽  
Rflp Markers ◽  
Phenotypic Variance ◽  
Style Length ◽  
Lycopersicon Pimpinellifolium ◽  
Anther Length ◽  
Trait Locus ◽  
Locus Mapping

Abstract The evolution of inbreeding is common throughout the angiosperms, although little is known about the developmental and genetic processes involved. Lycopersicon pimpinellifolium (currant tomato) is a self-compatible species with variation in outcrossing rate correlated with floral morphology. Mature flowers from inbreeding and outcrossing populations differ greatly in characters affecting mating behavior (petal, anther, and style lengths); other flower parts (sepals, ovaries) show minimal differences. Analysis of genetic behavior, including quantitative trait locus (QTL) mapping, was performed on representative selfing and outcrossing plants derived from two contrasting natural populations. Six morphological traits were analyzed: flowers per inflorescence; petal, anther, and style lengths; and lengths of the fertile and sterile portions of anthers. All traits were smaller in the selfing parent and had continuous patterns of segregation in the F2. Phenotypic correlations among traits were all positive, but varied in strength. Quantitative trait locus mapping was done using 48 RFLP markers. Five QTL total were found involving four of the six traits: total anther length, anther sterile length, style length, and flowers per inflorescence. Each of these four traits had a QTL of major (>25%) effect on phenotypic variance.

Differential inspiratory timing is genetically linked to mouse chromosome 3

1998 ◽  
Vol 85 (1) ◽  
pp. 360-365 ◽  
Author(s):  
C. G. Tankersley ◽  
D. A. DiSilvestre ◽  
A. E. Jedlicka ◽  
H. M. Wilkins ◽  
L. Zhang
Keyword(s):  
Quantitative Trait Locus ◽  
Mouse Chromosome ◽  
Dna Markers ◽  
Quantitative Trait ◽  
Chromosome 3 ◽  
Phenotypic Variance ◽  
Putative Quantitative Trait Locus ◽  
Strain Distribution Pattern ◽  
Log Likelihood ◽  
Trait Locus

Genetic control of differential inspiratory timing (Ti) at baseline has been previously demonstrated among inbred mouse strains. The inheritance pattern for Ti between C3H/HeJ (C3; 188 ± 3 ms) and C57BL/6J (B6; 111 ± 2 ms) progenitors was consistent with a two-gene model. By using the strain distribution pattern for recombinant inbred strains derived from C3 and B6 progenitors, 100% concordance was established between Ti phenotypes and DNA markers on mouse chromosome 3. This genotype-phenotype hypothesis was tested by typing 52 B6C3F2(F2) progeny by using simple sequence repeat DNA markers ( n = 21) polymorphic between C3 and B6 strains on mouse chromosome 3. Linkage analysis compared marker genotypes to baseline ventilatory phenotypes by computing log-likelihood values. A putative quantitative trait locus located in proximity to D3Mit119 was significantly associated with baseline Ti phenotypes. At the peak (log-likelihood = 3.3), the putative quantitative trait locus determined 25% of the phenotypic variance in Ti among F2 progeny. In conclusion, this genetic model of ventilatory characteristics demonstrated an important linkage between differential baseline Ti and a candidate genomic region on mouse chromosome 3.

scholarly journals Mapping a Quantitative Trait Locus Involved in Melanotic Encapsulation of Foreign Bodies in the Malaria Vector, Anopheles gambiae

Genetics ◽  
1997 ◽  
Vol 146 (3) ◽  
pp. 965-971 ◽  
Author(s):  
Maureen J Goman ◽  
David W Severson ◽  
Anton J Cornel ◽  
Frank H Collins ◽  
Susan M Paskewitz
Keyword(s):  
Quantitative Trait Locus ◽  
Anopheles Gambiae ◽  
Quantitative Trait ◽  
Interval Mapping ◽  
Phenotypic Variance ◽  
Method Of Maximum Likelihood ◽  
Significant Difference ◽  
Trait Locus ◽  
F2 Progeny ◽  
Melanotic Encapsulation

A Plasmodium-refractory strain of Anopheles gambiae melanotically encapsulates many species of Plasmodium, whereas wild-type mosquitoes are usually susceptible. This encapsulation trait can also be observed by studying the response of refractory and susceptible straintos intrathoracically injected CM-Sephadex beads. We report the results of broad-scale quantitative trait locus (QTL) mapping of the encapsulation trait using the bead model system. Interval mapping using the method of maximum likelihood identified one major QTL, Pen1. The 13.7-cM interval containing Pen1 was defined by marker AGH157 at 8E and AGH46 at 7A on 2R. Pen1 was associated with a maximum LOD score of 9.0 and accounted for 44% of the phenotypic variance in the distribution of phenotypes in the backcross. To test if this QTL is important for encapsulation of Plasmodium berghei, F2 progeny were infected with P. berghei and evaluated for degree of parasite encapsulation. For each of the two markers that define the interval containing Pen1, a significant difference of encapsulation was seen in progeny with at least one refractory allele in contrast with homozygous susceptible progeny. These results suggest that Pen1 is important for melanotic encapsulation of Plasmodium as well as beads.

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