Microsatellite marker analysis of an anther-derived potato family: skewed segregation and gene–centromere mapping

Genome ◽  
2002 ◽  
Vol 45 (2) ◽  
pp. 236-242 ◽  
Author(s):  
Eduard Chani ◽  
Varda Ashkenazi ◽  
Jossi Hillel ◽  
Richard E Veilleux

Segregation patterns of polymorphic simple sequence repeat (SSR) primer pairs were investigated in monoploid potato families derived from anther culture. A total of 14 primers developed from the sequences in the database, as well as from a genomic library of potato, was used. Distorted segregation was observed for seven (50%) polymorphic loci among monoploids derived from an interspecific hybrid. Similar distortion was observed for only one of five loci that could be contrasted between the two monoploid families. Segregation distortion was less common in the sexually derived backcross population between the interspecific hybrid and either of its parents. One locus could be putatively linked to a lethal allele because it showed distorted segregation in both monoploid families, a group of 70 heterozygous diploids derived from unreduced gametes through anther culture, and a backcross population. These diploids were used to map the polymorphic SSR markers with respect to the centromeres using half-tetrad analysis. The majority of the SSR loci mapped more than 33 cM from the centromere, suggesting the occurrence of a single crossover per chromosome arm.Key words: androgenesis, segregation distortion, simple sequence repeats (SSRs), Solanum phureja, unreduced gametes.

Genetics ◽  
1998 ◽  
Vol 149 (1) ◽  
pp. 319-327 ◽  
Author(s):  
J D Faris ◽  
B Laddomada ◽  
B S Gill

Abstract Distorted segregation ratios of genetic markers are often observed in progeny of inter- and intraspecific hybrids and may result from competition among gametes or from abortion of the gamete or zygote. In this study, 194 markers mapped in an Aegilops tauschii F2 population were surveyed for distorted segregation ratios. Region(s) with skewed segregation ratios were detected on chromosomes 1D, 3D, 4D, and 7D. These distorter loci are designated as QSd.ksu-1D, QSd.ksu-3D, QSd.ksu-4D, and QSd.ksu-7D. Three regions of segregation distortion identified on chromosome 5D were analyzed in two sets of reciprocal backcross populations to analyze the effect of sex and cytoplasm on segregation distortion. Extreme distortion of marker segregation ratios was observed in populations in which the F1 was used as the male parent, and ratios were skewed in favor of TA1691 alleles. There was some evidence of differential transmission caused by nucleo-cytoplasmic interactions. Our results agree with other studies stating that loci affecting gametophyte competition in male gametes are located on 5DL. The distorter loci on 5DL are designated as QSd.ksu-5D.1, QSd.ksu-5D.2, and QSd.ksu-5D.3.


1994 ◽  
Author(s):  
Richard E. Veilleux ◽  
Jossi Hillel ◽  
A. Raymond Miller ◽  
David Levy

More than 15,000 anthers of an interspecific hybrid (CP2) between two diploid (2n=2x=24) potato species, Solanum chacoense (weedy) and S. phureja (cultivated), were cultured to generate a family of monoploid (haploid, 2n-1x=12) plants. Of 260 regenerated plants, 34 were monoploid, 210 diploid and 16 tetraploid. SSR analysis revealed that six monoploids were genetically identical and 14 diploids were homozygous, thus limiting the population to 42 (28 monoploids and 14 homozygous diploids). New microsatellite loci were developed for potato from database sequences (15), a conventional genomic library (6), an enriched library (18) and tomato (11). Of these, 13 were polymorphic in the CP2 family and 11 were used to study genetic segregatin. Four of 11 exhibited skewed segregation in the monoploid family. Seven of 18 microsatellite markers were polymorphic and informative on a set of 12 tetraploid potato cultivars. Acetylleptinidine (ALD) is the aglycone of leptines, a natural defense against insects, especially the highly destructuve Colorado potato beetle. ALD is absend in S. phureja but highly expressed in the S. chacoense parent of CP2. A backcross population between CP2 and tis S. phureja parent was used to examine segregation for ALD. Bulks of 10 backcross individuals that expressed ALD and 10 that did not were used to identify putative RAPD markers associatd with the trait. Of 80 primers tested, one putative marker amplified by OPQ02 was present in eight of ten individuals comprising the high bulk and absent in all 10 individuals comprising the low bulk. This is a putative marker for ALD expression in potato.


2006 ◽  
Vol 131 (3) ◽  
pp. 380-387 ◽  
Author(s):  
L.H. Zhang ◽  
D.H. Byrne ◽  
R.E. Ballard ◽  
S. Rajapakse

Microsatellite or simple sequence repeat (SSR) markers were developed from Rosa wichurana Crépin to combine two previously constructed tetraploid rose (Rosa hybrida L.) genetic maps. To isolate SSR-containing sequences from rose a small-insert genomic library was constructed from diploid Rosa wichurana and screened with several SSR probes. Specific primers were designed for 43 unique SSR regions, of which 30 primer pairs gave rise to clear PCR products. Seventeen SSR primer pairs (57%) produced polymorphism in the tetraploid rose 90-69 mapping family. These markers were incorporated into existing maps of the parents 86-7 and 82-1134, which were constructed primarily with AFLP markers. The current map of the male parent, amphidiploid 86-7, consists of 286 markers assigned to 14 linkage groups and covering 770 cm. The map of the female tetraploid parent, 82-1134, consists of 256 markers assigned to 20 linkage groups and covering 920 cm. Nineteen rose SSR loci were mapped on the 86-7 map and 11 on the 82-1134 map. Several homeologous linkage groups within maps were identified based on SSR markers. In addition, some of the SSR markers provided anchoring points between the two parental maps. SSR markers were also useful for joining small linkage groups. Based on shared SSR markers, consensus orders for four rose linkage groups between parental maps were generated. Microsatellite markers developed in this study will provide valuable tools for many aspects of rose research including future consolidation of diploid and tetraploid rose genetic linkage maps, genetic, phylogenetic and population analyses, cultivar identification, and marker-assisted selection.


2009 ◽  
Vol 134 (6) ◽  
pp. 610-617 ◽  
Author(s):  
Eiichi Inoue ◽  
Lin Ning ◽  
Hiromichi Hara ◽  
Shuan Ruan ◽  
Hiroyuki Anzai

To develop and characterize valid simple sequence repeat (SSR) markers in chestnut (Castanea spp.), we used a selective hybridization method to perform SSR sequence enrichment in the genomic library of chinese chestnut (Castanea mollissima). From 47 sequences of the enriched library, we designed 24 primer pairs for SSR polymerase chain reaction (PCR). SSR PCR was performed for 23 chinese chestnut cultivars. Among the 24 primers, 22 primers amplified their respective SSR loci; 21 primer pairs yielded polymorphic fragments across the cultivars. Among these 21 primer pairs, 17 primer pairs amplified single SSR loci with polymorphisms. Multilocus amplification patterns were observed in the other four primers. For the corresponding 17 SSR loci, the number of alleles per locus was two to 13, and the average number of alleles was 7.19. The observed heterozygosity (number of genotypes of the heterozygote/total number of genotypes scored at that locus) ranged from 0.00 to 0.87 (average = 0.68), and the expected heterozygosity ranged from 0.00 to 0.87 (average = 0.68). One of the SSR loci—ICMA014—was a unique locus, because the primer pair for this locus did not amplify any fragment in any of the cultivars, except in Qianchi, which was used to construct the SSR-enriched genomic library. Cross-species amplifications using the 17 primer pairs were also successful in the other species of genus Castanea. A dendrogram depicting the relationships among the genotypes on the basis of genetic distances was generated using the unweighted pair group method with arithmetic mean cluster analysis. The genotypes were clearly separated into three large groups, which reflected the three cultivated species, namely, C. mollissima, C. crenata, and C. sativa.


Genome ◽  
1997 ◽  
Vol 40 (4) ◽  
pp. 433-441 ◽  
Author(s):  
R. L. Jarret ◽  
L. C. Merrick ◽  
T. Holms ◽  
J. Evans ◽  
M. K. Aradhya

Simple sequence repeat length polymorphisms were utilized to examine genetic relatedness among accessions of watermelon (Citrullus lanatus (Thunb.) Matsum. &Nakai). A size-fractionated TaqI genomic library was screened for the occurrence of dimer and trimer simple sequence repeats (SSRs). A total of 96 (0.53%) SSR-bearing clones were identified and the inserts from 50 of these were sequenced. The dinucleotide repeats (CT)n and (GA)n accounted for 82% of the SSRs sequenced. PCR primer pairs flanking seven SSR loci were used to amplify SSRs from 32 morphologically variable watermelon genotypes from Africa, Europe, Asia, and Mexico and a single accession of Citrullus colocynthis from Chad. Cluster analysis of SSR length polymorphisms delineated 4 groups at the 25% level of genetic similarity. The largest group contained C. lanatus var. lanatus accessions. The second largest group contained only wild and cultivated "citron"-type or C. lanatus var. citroides accessions. The third group contained an accession tentatively identified as C. lanatus var. lanatus but which perhaps is a hybrid between C. lanatus var. lanatus and C. lanatus var. citroides. The fourth group consisted of a single accession identified as C. colocynthis. "Egusi"-type watermelons from Nigeria grouped with C. lanatus var. lanatus. The use of SSRs for watermelon germplasm characterization and genetic diversity studies is discussed.Key words: Citrullus, watermelon, simple sequence repeats, genetic diversity.


Genome ◽  
1999 ◽  
Vol 42 (4) ◽  
pp. 676-680 ◽  
Author(s):  
J D Krenz ◽  
R D Semlitsch ◽  
H C Gerhardt ◽  
P A Mahoney

A gray tree frog (Hyla chrysoscelis) genomic library was constructed and characterized with regard to the incidence and complexity of simple sequence repeat (SSR) loci. The partial genomic library, containing approximately 10 000 clones with an average-sized insert of 350 bp, was screened with six SSR repeat oligonucleotides (AC, AG, ACG, AGC, AAC, and AAG). Screening identified 31 unique positive clones containing 41 SSR loci. Sequences of tandemly arrayed dinucleotide repeats were more common (36 of 41) than trinucleotide repeats. Twenty-six loci were identified using the AC dinucleotide probe, while 7 loci were identified using the AG dinucleotide probe. An additional 3 AT dinucleotide loci were serendipitously identified. The AT repeats generally comprised the longest dinucleotide repeat loci. The SSR repeat loci reported here should provide potent markers for identity, parentage, and short-lineage determinations in large-scale experiments using gray tree frogs.Key words: Hyla chrysoscelis, simple sequence repeat, SSR, gray tree frog, microsatellite.


Genome ◽  
1999 ◽  
Vol 42 (6) ◽  
pp. 1057-1065 ◽  
Author(s):  
K Damodar Reddy ◽  
E G Abraham ◽  
J Nagaraju

We have isolated and characterized microsatellites (simple sequence repeat (SSR) loci) from the silkworm genome. The screening of a partial genomic library by the conventional hybridization method led to the isolation of 28 microsatellites harbouring clones. The abundance of (CA)n repeats in the silkworm genome was akin to those reported in the other organisms such as honey bee, pig, and human, but the (CT)n repeat motif is less common compared to bumble bee and honey bee genomes. Detailed analysis of 13 diverse silkworm strains with a representative of 15 microsatellite loci revealed a number of alleles ranging from 3 to 17 with heterozygosity values of 0.66-0.90. Along with strain-specific microsatellite markers, diapause and non-diapause strain-specific alleles were also identified. The repeat length did not show any relationship with the degree of polymorphism in the present study. The co-dominant inheritance of microsatellite markers was demonstrated in F1 offspring. A list of primer sequences that tag each locus is provided. The availability of microsatellite markers can be expected to enhance the power and resolution of genome analysis in silkworm.Key words: microsatellites, simple sequence repeats, polymorphisms, silkworm strains, Bombyx mori.


Author(s):  
Júlia Halász ◽  
Noémi Makovics-Zsohár ◽  
Ferenc Szőke ◽  
Sezai Ercisli ◽  
Attila Hegedűs

AbstractPolyploid Prunus spinosa (2n = 4 ×) and P. domestica subsp. insititia (2n = 6 ×) represent enormous genetic potential in Central Europe, which can be exploited in breeding programs. In Hungary, 16 cultivar candidates and a recognized cultivar ‘Zempléni’ were selected from wild-growing populations including ten P. spinosa, four P. domestica subsp. insititia and three P. spinosa × P. domestica hybrids (2n = 5 ×) were also created. Genotyping in eleven simple sequence repeat (SSR) loci and the multiallelic S-locus was used to characterize genetic variability and achieve a reliable identification of tested accessions. Nine SSR loci proved to be polymorphic and eight of those were highly informative (PIC values ˃ 0.7). A total of 129 SSR alleles were identified, which means 14.3 average allele number per locus and all accessions but two clones could be discriminated based on unique SSR fingerprints. A total of 23 S-RNase alleles were identified and the complete and partial S-genotype was determined for 10 and 7 accessions, respectively. The DNA sequence was determined for a total of 17 fragments representing 11 S-RNase alleles. ‘Zempléni’ was confirmed to be self-compatible carrying at least one non-functional S-RNase allele (SJ). Our results indicate that the S-allele pools of wild-growing P. spinosa and P. domestica subsp. insititia are overlapping in Hungary. Phylogenetic and principal component analyses confirmed the high level of diversity and genetic differentiation present within the analysed accessions and indicated putative ancestor–descendant relationships. Our data confirm that S-locus genotyping is suitable for diversity studies in polyploid Prunus species but non-related accessions sharing common S-alleles may distort phylogenetic inferences.


2008 ◽  
Vol 90 (2) ◽  
pp. 151-156 ◽  
Author(s):  
XUE-XIA MIAO ◽  
WEI-HUA LI ◽  
MU-WANG LI ◽  
YUN-PO ZHAO ◽  
XIAN-RU GUO ◽  
...  

SummaryMicrosatellites or simple sequence repeats (SSRs) are co-dominant molecular markers. When we used fluorescent SSR markers to construct a linkage map for the female heterogametic silkworm (Bombyx mori, ZW), we found that some loci did not segregate in a Mendelian ratio of 1:1 in a backcross population. These loci segregated in a 3:1 ratio of single bands compared with double bands. Further examination of band patterns indicated that three types of SSR bands were present: two homozygotes and one heterozygote. In the beginning, we considered to discard these markers. By scoring male and female F1 individuals, we confirmed that these loci were located on the Z chromosome. Using the sex-linked visible mutation sch (K05) and its wild-type (C108), we constructed an F1 male backcross (BC1M) mapping population. The combination of sch backcross and SSR data enabled us to map the SSR markers to the Z chromosome. By adjusting input parameters based on these data, we were able to use Mapmaker software to construct a linkage map. This strategy takes advantage of co-dominant markers for positional cloning of genes on the Z chromosome. We localized sch to the Z chromosome relative to six SSR markers and one PCR marker, covering a total of 76·1 cM. The sch mutation is an important sex-linked visible mutation widely used in breeding of commercial silkworms (e.g. male silkworm selection rearing). Localization of the sch gene may prove helpful in cloning the gene and developing strains for marker-assisted selection in silkworm breeding.


Plant Disease ◽  
2010 ◽  
Vol 94 (4) ◽  
pp. 420-424 ◽  
Author(s):  
Paola Mantovani ◽  
Marco Maccaferri ◽  
Roberto Tuberosa ◽  
James Kolmer

Twenty-four isolates of Puccinia triticina from Italy were characterized for virulence to seedlings of 22 common wheat Thatcher isolines, each with a different leaf rust resistance gene, and for molecular genotypes at 15 simple sequence repeat (SSR) loci. The isolates were compared to a set of 13 previously characterized P. triticina isolates from either durum or common wheat. Clustering based on virulence phenotypes and SSR genotypes grouped the Italian P. triticina isolates into three groups. In the first group, the isolates had virulence phenotypes and SSR genotypes that were similar to the isolates collected from durum wheat. Isolates in the second group were unique because they had virulence similar to the isolates from common wheat but were distinct for SSR genotypes compared to the isolates from durum wheat and from common wheat. Isolates in the third group had virulence phenotypes and SSR genotypes closely related to the isolates from common wheat. The isolates were grouped based on the known or assumed host of origin, virulence phenotype, and SSR genotypes. Measures of FST and RST for SSR genotypes, and ΦST for virulence phenotype were significant, which indicated differentiation among the three groups of isolates. Virulence phenotypes and molecular genotypes were highly correlated with r = 0.74.


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