The relationship between genetic and cytogenetic maps of pea. II. Physical maps of linkage mapping populations

Genome ◽  
1997 ◽  
Vol 40 (5) ◽  
pp. 755-769 ◽  
Author(s):  
K. J. Hall ◽  
J. S. Parker ◽  
T. H. N. Ellis ◽  
L. Turner ◽  
M. R. Knox ◽  
...  

A cytogenetic analysis of inbred lines that have been used to generate genetic maps of pea is presented. Mitotic karyotyping of the inbred lines and meiotic studies of their F1 hybrids have been used to test the prediction that structural differences exist between the parental lines. The results are not compatible with the previously published molecular data. A reordered and updated linkage map of pea is presented that is consistent with the cytogenetic data.Key words: Pisum, linkage map, recombination, synaptonemal complex, chiasmata.


Genetics ◽  
1996 ◽  
Vol 142 (2) ◽  
pp. 537-548 ◽  
Author(s):  
Michael W Nachman ◽  
Gary A Churchill

Abstract If loci are randomly distributed on a physical map, the density of markers on a genetic map will be inversely proportional to recombination rate. First proposed by MARY LYON, we have used this idea to estimate recombination rates from the Drosophila melanogaster linkage map. These results were compared with results of two other studies that estimated regional recombination rates in D. melanogaster using both physical and genetic maps. The three methods were largely concordant in identifying large-scale genomic patterns of recombination. The marker density method was then applied to the Mus musculus microsatellite linkage map. The distribution of microsatellites provided evidence for heterogeneity in recombination rates. Centromeric regions for several mouse chromosomes had significantly greater numbers of markers than expected, suggesting that recombination rates were lower in these regions. In contrast, most telomeric regions contained significantly fewer markers than expected. This indicates that recombination rates are elevated at the telomeres of many mouse chromosomes and is consistent with a comparison of the genetic and cytogenetic maps in these regions. The density of markers on a genetic map may provide a generally useful way to estimate regional recombination rates in species for which genetic, but not physical, maps are available.



Genes ◽  
2021 ◽  
Vol 12 (4) ◽  
pp. 604
Author(s):  
Paolo Vitale ◽  
Fabio Fania ◽  
Salvatore Esposito ◽  
Ivano Pecorella ◽  
Nicola Pecchioni ◽  
...  

Traits such as plant height (PH), juvenile growth habit (GH), heading date (HD), and tiller number are important for both increasing yield potential and improving crop adaptation to climate change. In the present study, these traits were investigated by using the same bi-parental population at early (F2 and F2-derived F3 families) and late (F6 and F7, recombinant inbred lines, RILs) generations to detect quantitative trait loci (QTLs) and search for candidate genes. A total of 176 and 178 lines were genotyped by the wheat Illumina 25K Infinium SNP array. The two genetic maps spanned 2486.97 cM and 3732.84 cM in length, for the F2 and RILs, respectively. QTLs explaining the highest phenotypic variation were found on chromosomes 2B, 2D, 5A, and 7D for HD and GH, whereas those for PH were found on chromosomes 4B and 4D. Several QTL detected in the early generations (i.e., PH and tiller number) were not detected in the late generations as they were due to dominance effects. Some of the identified QTLs co-mapped to well-known adaptive genes (i.e., Ppd-1, Vrn-1, and Rht-1). Other putative candidate genes were identified for each trait, of which PINE1 and PIF4 may be considered new for GH and TTN in wheat. The use of a large F2 mapping population combined with NGS-based genotyping techniques could improve map resolution and allow closer QTL tagging.



Genome ◽  
2002 ◽  
Vol 45 (2) ◽  
pp. 282-295 ◽  
Author(s):  
Elizabeth S Jones ◽  
Natalia L Mahoney ◽  
Michael D Hayward ◽  
Ian P Armstead ◽  
J Gilbert Jones ◽  
...  

A molecular-marker linkage map has been constructed for perennial ryegrass (Lolium perenne L.) using a one-way pseudo-testcross population based on the mating of a multiple heterozygous individual with a doubled haploid genotype. RFLP, AFLP, isoenzyme, and EST data from four collaborating laboratories within the International Lolium Genome Initiative were combined to produce an integrated genetic map containing 240 loci covering 811 cM on seven linkage groups. The map contained 124 codominant markers, of which 109 were heterologous anchor RFLP probes from wheat, barley, oat, and rice, allowing comparative relationships between perennial ryegrass and other Poaceae species to be inferred. The genetic maps of perennial ryegrass and the Triticeae cereals are highly conserved in terms of synteny and colinearity. This observation was supported by the general agreement of the syntenic relationships between perennial ryegrass, oat, and rice and those between the Triticeae and these species. A lower level of synteny and colinearity was observed between perennial ryegrass and oat compared with the Triticeae, despite the closer taxonomic affinity between these species. It is proposed that the linkage groups of perennial ryegrass be numbered in accordance with these syntenic relationships, to correspond to the homoeologous groups of the Triticeae cereals.Key words: Lolium perenne, genetic linkage map, RFLP, AFLP, conserved synteny.



1995 ◽  
Vol 66 (2) ◽  
pp. 109-126 ◽  
Author(s):  
Jinrui Shi ◽  
David G. Heckel ◽  
Marian R. Goldsmith

SummaryWe present data for the initial construction of a molecular linkage map for the domesticated silkworm, Bombyx mori, based on 52 progeny from an F2 cross from a pair mating of inbred strains p50 and C108, using restriction fragment length polymorphisms (RFLPs). The map contains 15 characterized single copy sequences, 36 anonymous sequences derived from a follicular cDNA library, and 10 loci corresponding to a low copy number retrotransposon, mag. The 15 linkage groups and 8 ungrouped loci account for 23 of the 28 chromosomes and span a total recombination length of 413 cM; 10 linkage groups were correlated with established classic genetic maps. Scoring data from Southern blots were analysed using two Pascal programs written specifically to analyse linkage data in Lepidoptera, where females are the heterogametic sex and have achiasmatic meiosis (no crossing-over). These first examine evidence for linkage by calculating the maximum lod score under the hypothesis that the two loci are linked over the likelihood under the hypothesis that the two loci assort independently, and then determine multilocus linkage maps for groups of putatively syntenic loci by calculating the maximum likelihood estimate of the recombination fractions and the log likelihood using the EM algorithm for a specified order of loci along the chromosome. In addition, the possibility of spurious linkage was exhaustively tested by searching for genotypes forbidden by the absence of crossing-over in one sex.



1989 ◽  
Vol 69 (3) ◽  
pp. 749-761 ◽  
Author(s):  
ULRICH HERTER ◽  
JOSEPH S. BURRIS

Mechanical drying has frequently caused injury in corn seed. Changes in seed moisture, temperature, and quality were determined for inbred lines A632, B73 and Mo17 to define the relationship between these variables. Ears harvested at ca. 48 and 38% seed moisture could be dried at 50 °C for 4–15 h and 18–24 h, respectively, before germination started to decline linearly with prolonged 50 °C drying. Drying time at 50 °C, seed moisture, or embryo moisture after 50 °C drying could be used equally well for prediction of seed quality. Seedling dry weights often declined even when seed was dried for only a few hours at 50 °C. Temperature measurements within seeds indicated that evaporation cooled the seed no more than 5 °C. Drying susceptibility of seed parents varied greatly between years.Key words: Moisture, temperature changes, seed corn, drying



Zootaxa ◽  
2021 ◽  
Vol 4926 (3) ◽  
pp. 401-416
Author(s):  
MOHAMMAD HUSSAIN FALAHZADAH ◽  
EBRAHIM SHOKOOHI ◽  
GHOLAM HOSSEIN MORAVEJ ◽  
PHATU WILLIAM MASHELA ◽  
ABDUL KHALID MADADI ◽  
...  

Several soil samples from different habitats in Badakhshan province of Afghanistan were collected to isolate and characterize bacteria feeding nematodes. The Galleria mellonella-baiting method was used for the isolation of the Afghan insect-associated nematodes. The nematodes were studied using morphological and morphometric data. The Oscheius specimen was characterized by a longer body (630–820 µm) and shorter pharynx (125–145 µm), whereas other morphological characters were not unusual. The Diploscapter specimen had an annulated cuticle, with lip region width 1.5 times shorter than the stoma, and had separated pharyngeal corpus from the isthmus and vulva located in the middle of the body. The molecular data were derived using three loci; 18S, 28S (D2/D3 segment), and ITS rRNA region, which were utilized to measure the genetic distance. The phylogenetic analysis was conducted to reconstruct the relationship tree. Both morphological and molecular approaches confirmed the identity of nematode isolates as Oscheius tipulae and Diploscapter coronatus. This is the first report of insect-associated nematodes from the soil of Afghanistan. Both species were capable of infecting and killing G. mellonella larvae in less than 96 h. 



DNA Research ◽  
2016 ◽  
Vol 23 (5) ◽  
pp. 487-494 ◽  
Author(s):  
Niraj Shah ◽  
Hideki Hirakawa ◽  
Shohei Kusakabe ◽  
Niels Sandal ◽  
Jens Stougaard ◽  
...  


Agronomy ◽  
2022 ◽  
Vol 12 (1) ◽  
pp. 203
Author(s):  
Sylwester Sobkowiak ◽  
Marta Janiszewska ◽  
Emil Stefańczyk ◽  
Iwona Wasilewicz-Flis ◽  
Jadwiga Śliwka

Tuber dry rot is an important disease of potato caused by soil and seed-borne pathogens of the Fusarium genus leading to losses that may reach 60% of the yield. The goal of this work was to study the inheritance of the dry rot resistance in two diploid potato hybrid populations (11-36 and 12-3) with complex pedigrees, including several wild Solanum spp. We used an aggressive isolate of F. sambucinum for phenotyping both progenies, parents, and standard potato cultivars in laboratory tuber tests, in three subsequent years. The QTL for dry rot resistance were mapped by interval mapping on existing genetic maps of both mapping populations. The most important and reproducible QTL for this trait was mapped on chromosome I and additional year- and population-specific QTL were mapped on chromosomes II, VII, IX, XI, and XII, confirming polygenic control of this resistance. This is the first study mapping the loci affecting tuber dry rot resistance in potato genome that can contribute to better understanding of potato-F. sambucinum interaction and to more efficient breeding of resistant potato cultivars.



Genome ◽  
1994 ◽  
Vol 37 (1) ◽  
pp. 61-71 ◽  
Author(s):  
C. S. Echt ◽  
K. K. Kidwell ◽  
S. J. Knapp ◽  
T. C. Osborn ◽  
T. J. McCoy

A genome map of cultivated alfalfa was constructed using segregating restriction fragment length polymorphisms (RFLPs) and random amplified polymorphic DNAs (RAPDs) in a diploid backcross population generated from noninbred parents. Among the 153 loci scored in 87 progeny, four segregation ratios were observed for codominant and dominant markers: 1:1, 1:2:1, 1:1:1:1, and 3:1. Deviations from expected Mendelian ratios (p < 0.05) were observed for 34% of the loci studied. A genome map was assembled from two separate linkage maps, each constructed from a subset of the segregation data. One linkage map was constructed from 46 RFLP and 40 RAPD markers segregating 1:1 from the F1 parent of the backcross and the other linkage map was constructed from 33 RFLP and 28 RAPD markers segregating 1:1 from the recurrent parent. Sixteen loci with alleles segregating 1:1 from both parents were used as locus bridges to align individual linkage groups between the two maps. The combined use of RFLPs and RAPDs was an effective method for developing an alfalfa genome map.Key words: genome mapping, RAPD, RFLP, locus bridges.



Genome ◽  
1997 ◽  
Vol 40 (5) ◽  
pp. 744-754 ◽  
Author(s):  
K. J. Hall ◽  
J. S. Parker ◽  
T. H. N. Ellis

A detailed cytogenetical study of inbred lines of pea and their F1 hybrids has been undertaken to study the relationship between the cytogenetic map and the molecular linkage map. The mitotic karyotypes of a standard pea line, JI15, a translocation line, JI61, and line JI281, a line used in the production of a mapping population, are given. A chromosome rearrangement detected by cytogenetic analysis of mitotic chromosomes has been further defined by synaptonemal complex (SC) analysis and the study of metaphase I chromosome behaviour. This meiotic analysis has allowed a comparison of SC physical lengths, observed chiasma frequencies, and recombination frequencies, as estimated from the genetic map, as a means of comparing physical and genetic distances.Key words: Pisum, linkage map, cytogenetics, chromosome rearrangement, synaptonemal complex.



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