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1.
Stein J Quarin CL Martínez EJ Pessino SC Ortiz JP 《TAG. Theoretical and applied genetics. Theoretische und angewandte Genetik》2004,109(1):186-191
The objective of this work was to determine the type of inheritance (disomic/polysomic) in tetraploid (2n=4x=40) Paspalum notatum and investigate the transmission pattern of the chromosome region associated with apospory. An F1 family segregating for the reproductive mode (aposporous vs non-aposporous) was generated by crossing a tetraploid sexual plant as female parent with an apomictic individual as pollen donor. Pollen mother cells from both parental plants were examined to ascertain chromosome-pairing behavior at meiosis. The high rate of quadrivalent chromosome associations indicated an autotetraploid origin of the species, although bivalent pairing and occasional univalents were detected. The observation of a lagging bivalent, a bridge of chromatin, or two aligned laggards in the aposporous parent suggested a chromosome inversion in this strain. Segregation ratios of AFLP markers and the proportion of linkages in repulsion versus coupling phase denoted tetrasomic inheritance, but markers displaying disomic ratios were also observed. Preferential chromosome pairing (disomic inheritance) in the chromosome segment related to apospory was detected. The possible relationship between a chromosome rearrangement and the inheritance of apospory is discussed.Communicated by H.C. Becker 相似文献
2.
In their recent article, Albertin et al. (2009) suggest an autotetraploid origin of 10 tetraploid strains of baker’s yeast (Saccharomyces cerevisiae), supported by the frequent observation of double reduction meiospores. However, the presented inheritance results were puzzling and seemed to contradict the authors’ interpretation that segregation ratios support a tetrasomic model of inheritance. Here, we provide an overview of the expected segregation ratios at the tetrad and meiospore level given scenarios of strict disomic and tetrasomic inheritance, for cases with and without recombination between locus and centromere. We also use a power analysis to derive adequate sample sizes to distinguish alternative models. Closer inspection of the Albertin et al. data reveals that strict disomy can be rejected in most cases. However, disomic inheritance with strong but imperfect preferential pairing could not be excluded with the sample sizes used. The possibility of tetrad analysis in tetraploid yeast offers a valuable opportunity to improve our understanding of meiosis and inheritance of tetraploids. 相似文献
3.
E. J. Lewis 《TAG. Theoretical and applied genetics. Theoretische und angewandte Genetik》1981,59(3):139-143
Summary Segregation at one of the loci controlling tiller-base pigmentation was studied to determine the mode of inheritance in tetraploid hybrids between Lolium perenne and L. multiflorum. The results could be explained by tetrasomic inheritance and thus did not support previous reports of a degree of preferential chromosome pairing in this material. However, double reduction and aneuploidy may to some extent have masked any tendency to disomic segregation brought about by preferential pairing. Moreover, there was significant heterogeneity between families in the segregation ratios which may indicate genetically controlled differences in pairing behaviour. The results are related to previous cytological and genetic studies. 相似文献
4.
Tetraploid inheritance has two extremes: disomic in allotetraploids and tetrasomic in autotetraploids. The possibility of mixed, or intermediate, inheritance models has generally been neglected. These could well apply to newly formed hybrids or to diploidizing (auto)tetraploids. We present a simple likelihood-based approach that is able to incorporate disomic, tetrasomic, and intermediate inheritance models and estimates the double-reduction rate. Our model shows that inheritance of microsatellite markers in natural tetraploids of Rorippa amphibia and R. sylvestris is tetrasomic, confirming their autotetraploid origin. However, in F(1) hybrids inheritance was intermediate to disomic and tetrasomic inheritance. Apparently, in meiosis, chromosomes paired preferentially with the homolog from the same parental species, but not strictly so. Detected double-reduction rates were low. We tested the general applicability of our model, using published segregation data. In two cases, an intermediate inheritance model gave a better fit to the data than the tetrasomic model advocated by the authors. The existence of inheritance intermediate to disomic and tetrasomic has important implications for linkage mapping and population genetics and hence breeding programs of tetraploids. Methods that have been developed for either disomic or tetrasomic tetraploids may not be generally applicable, particularly in systems where hybridization is common. 相似文献
5.
J. V. Raelson P. C. Lemaître K. M. Starkie W. F. Grant 《TAG. Theoretical and applied genetics. Theoretische und angewandte Genetik》1989,77(3):360-368
Summary Segregation of the cytosolic Pgi2 locus was studied among progeny of the synthetic allotetraploid (L. japonicus × L. alpinus)2, the synthetic autotetraploid (L. alpinus)2, and the cultivated tetraploid species L. corniculatus L. Evidence of an original diploid duplication found within the interspecific hybrid L. japonicus × L. alpinus was also found within the synthetic allotetraploid (quadruplication of loci). Evidence suggesting quadruplication of loci was also found in the tetraploid L. corniculatus, but not in the synthetic autotetraploid (L. alpinus)2. It is suggested that the original duplication resulted from unequal crossing-over between homoeologues and that it provides evidence that L. corniculatus is a segmental allotetraploid. Quadruplication of loci in L. corniculatus could explain previously reported distorted tetrasomic ratios for segregation of qualitative characters in this species. 相似文献
6.
Lashermes P Paczek V Trouslot P Combes MC Couturon E Charrier A 《The Journal of heredity》2000,91(1):81-85
Molecular cytogenetic analysis has indicated that Coffea arabica is an amphidiploid formed from the hybridization between two closely related diploid progenitor species, C. canephora and C. eugenioides. Our aim was to determine the mode of inheritance in C. arabica and in a tetraploid interspecific hybrid (called arabusta) between C. arabica and C. canephora as revealed by segregation analyses of restriction fragment length polymorphism (RFLP) loci markers. The observed RFLP allele segregations in an F(2) progeny of C. arabica conform to disomic inheritance as expected, with regular bivalent pairing of homologous chromosomes in the F1 hybrid. In contrast, RFLP loci followed tetrasomic inheritance in the arabusta interspecific hybrid, although bivalents have been reported to predominate greatly at meiosis in its hybrid. These results suggest that homologous chromosomes do not pair in C. arabica, not as a consequence of structural differentiation, but because of the functioning of pairing regulating factors. Moreover, the arabusta hybrid seems to offer the possibility of gene exchange between the homologous genomes. 相似文献
7.
Barone A Li J Sebastiano A Cardi T Frusciante L 《TAG. Theoretical and applied genetics. Theoretische und angewandte Genetik》2002,104(4):539-546
In order to assess the potential for interspecific recombination between the cultivated Solanum tuberosum (tbr) and the sexually isolated wild species Solanum commersonii (cmm), genetic analysis of a F2 progeny obtained by selfing one tetraploid cmm (+) tbr somatic hybrid was performed through molecular markers. For this purpose,
the extent of disomic and/or tetrasomic inheritance of species-specific RAPD and AFLP markers was determined by following
their segregation in a 90-genotype progeny, and testing all the possible segregation ratios in a selfed tetraploid progeny.
The RAPD analysis performed using 16 primers revealed that the cmm-specific RAPDs were mainly (93.7%) duplex markers and were
equally distributed between loci with a disomic (46.7%) and tetrasomic (53.3%) inheritance. The AFLP analysis led to the identification
of 272 (58%) informative AFLPs, which were either cmm- or tbr-specific markers. About 63% of cmm-specific AFLPs were duplex
loci, most of which (92.6%) were inherited as tetrasomic loci. As regards the tbr-specific AFLPs, the percentage of simplex
loci (52.9%) was higher than that of duplex loci (32.6%), and among the latter most (88.5%) were inherited as tetrasomic loci.
Overall, 130 duplex markers were found, of which 53.1% were cmm-specific and 46.9% were tbr-specific. Out of 130 markers,
18 (13.8%) were inherited as disomic, and 112 (86.2%) as tetrasomic, loci. This implies that the majority of duplex markers
were located on chromosomes which at meiosis tend to randomly pair as bivalents or to form tetravalents. The total number
of simplex loci was 119, and most of them (82.3%) were tbr-specific loci. In some cases the observed segregation ratios even
allowed us to clearly determine whether a random chromosome or chromatid segregation was detected. This was the case of three
cmm-specific RAPDs, 19 cmm- and 25 tbr-specific AFLPs, which fit a 20.8:1 or 2.5:1 ratio, both cases for which a clear random
chromatid segregation can be assumed, since they represent the limit of segregation expected when the distance between the
locus and the centromere always leads to a cross-over event. The percentage of ascertained crossing-over events was around
37% out of the tetrasomically inherited loci clearly identified (128 loci), a value indicating that the flow of genes from
the sexually isolated S. commersonii to the cultivated potato is possible, for at least a large proportion of genes.
Received: 23 July 2001 / Accepted: 9 August 2001 相似文献
8.
MIGUEL ANGEL GONZÁLEZ‐PÉREZ M. DOLORES LLEDÓ CHRISTIAN LEXER MICHAEL FAY MANUEL MARRERO ANGEL BAÑARES‐BAUDET EDUARDO CARQUÉ PEDRO A. SOSA 《Botanical journal of the Linnean Society. Linnean Society of London》2009,160(4):429-441
Variation at five polymorphic microsatellite loci was used to investigate genetic diversity and differentiation of two tetraploid Canarian endemics, Bencomia exstipulata and B. caudata. Data were analysed and are discussed in terms of tetrasomic (autotetraploid) and disomic (allotetraploid) inheritance. In both cases, genetic diversity values were similar to those described in other tetraploid plant species. High genetic differentiation between the only two described natural populations of B. exstipulata was detected (FST = 0.411). Bayesian cluster analysis revealed a geographical structure with distinct genetic groups from each island. High genetic differentiation and low genetic diversity of the B. exstipulata population from Tenerife suggest a recent population bottleneck, perhaps caused by the most recent major volcanic eruption, for this natural locality. This may be heightened by possible inbreeding depression and the monoecy of these species. Polymorphic microsatellite loci were also tested across all species in the Bencomia alliance. These reliably amplified the target sequence, suggesting a high degree of conservation of the sequences flanking the microsatellites. © 2009 The Linnean Society of London, Botanical Journal of the Linnean Society, 2009, 160 , 429–441. 相似文献
9.
P. Gauthier R. Lumaret A. Bedecarrats 《TAG. Theoretical and applied genetics. Theoretische und angewandte Genetik》1997,95(4):629-636
To resolve the maternal parentage of the tetraploid Lotus corniculatus, restriction-site variation of chloroplast DNA (cpDNA) was studied in several accessions of that species, in the four putative
parental diploid species, L. tenuis, L. alpinus, L. japonicus and L. uliginosus, and in four phylogenetically more distant diploid species, L. hispidus, L. edulis, L. ornithopodoides and Tetragonolobus maritimus var. siliquosus. Evidence of cpDNA maternal inheritance was obtained by using reciprocal controlled crosses between plants of L. corniculatus and natural tetraploid individuals of L. alpinus showing very distinct restriction patterns. Interspecific cpDNA variation in the eight Lotus species and T. siliquosus was analysed by comparing cpDNA fragment patterns produced by five restriction endonucleases and totalling 304 distinct fragments.
Genetic differentiation in cpDNA was very high between the L. corniculatus group and L. hispidus on the one hand, and the three other species on the other hand. Sixteen restriction-site mutations and eight length polymorphisms
were identified among the five species of the L. corniculatus group and L. hispidus, Lotus uliginosus, L. alpinus and L. japonicus showed at least six DNA changes with regard to the molecule of L. corniculatus. Accordingly, these species should be excluded as maternal progenitors of L. corniculatus. Conversely, the cpDNA of L. tenuis differed from that of L. corniculatus by only two small-length mutations. As also suggested previously from an analysis of several nuclear markers, the results
reported here show decisively that L. tenuis may be considered as the most probable maternal ancestor of L. corniculatus.
Received: 23 February 1997/Accepted: 28 February 1997 相似文献
10.
Chakraborty N Bae J Warnke S Chang T Jung G 《TAG. Theoretical and applied genetics. Theoretische und angewandte Genetik》2005,111(4):795-803
Creeping bentgrass (Agrostis stolonifera L.) is one of the most adapted bentgrass species for use on golf course fairways and putting greens because of its high tolerance to low mowing height. It is a highly outcrossing allotetraploid species (2n=4x=28, A2 and A3 subgenomes). The first linkage map in this species is reported herein, and it was constructed based on a population derived from a cross between two heterozygous clones using 169 RAPD, 180 AFLP, and 39 heterologous cereal and 36 homologous bentgrass cDNA RFLP markers. The linkage map consists of 424 mapped loci covering 1,110 cM in 14 linkage groups, of which seven pairs of homoeologous chromosomes were identified based on duplicated loci. The numbering of all seven linkage groups in the bentgrass map was assigned according to common markers mapped on syntenous chromosomes of ryegrass and wheat. The number of markers linked in coupling and repulsion phase was in a 1:1 ratio, indicating disomic inheritance. This supports a strict allotetraploid inheritance in creeping bentgrass, as suggested by previous work based on chromosomal pairing and isozymes. This linkage map will assist in the tagging and eventually in marker-assisted breeding of economically important quantitative traits like disease resistance to dollar spot (Sclerotinia homoeocarpa F.T. Bennett) and brown patch (Rhizoctonia solani Kuhn). 相似文献
11.
Kamiri M Stift M Srairi I Costantino G El Moussadik A Hmyene A Bakry F Ollitrault P Froelicher Y 《Plant cell reports》2011,30(8):1415-1425
Artificial tetraploid somatic hybrids have been developed for sterile triploid citrus breeding by sexual hybridization between
diploid and tetraploid somatic hybrids. The genetic structure of diploid gametes produced by tetraploid genotypes depends
on the mode of chromosome association at meiosis. In order to evaluate tetraploid inheritance in a tetraploid interspecific
somatic hybrid between mandarin and lemon, we performed segregation studies using cytogenetic and single sequence repeat molecular
markers. Cytogenetic analysis of meiosis in the somatic hybrid revealed 11% tetravalents and 76% bivalents. Inheritance of
the tetraploid hybrid was analyzed by genotyping the triploid progeny derived from a cross between a diploid pummelo and the
tetraploid somatic hybrid, in order to derive genotypes of the meiospores produced by the tetraploid. A likelihood-based approach
was used to distinguish between disomic, tetrasomic, and intermediate inheritance models and to estimate the double reduction
rate. In agreement with expectations based the cytogenetic data, marker segregation was largely compatible with tetrasomic
and inheritance intermediate between disomic and tetrasomic, with some evidence for preferential pairing of homoeologous chromosomes.
This has important implications for the design of breeding programs that involve tetraploid hybrids, and underscores the need
to consider inheritance models that are intermediate between disomic and tetrasomic. 相似文献
12.
C. Taylor K. W. Shepherd P. Langridge 《TAG. Theoretical and applied genetics. Theoretische und angewandte Genetik》1998,97(5-6):1000-1012
A genetic map of the long arm of chromosome 6R of rye was constructed using eight homoeologous group-6 RFLP clones and five
PCR markers derived from the rye-specific dispersed repetitive DNA family, R173. The map was developed using a novel test-cross
F1 (TC-F1) population segregating for resistance to the cereal cyst nematode. Comparisons were made between the map generated with
other rye and wheat group-6 chromosome maps by the inclusion of RFLP clones previously mapped in those species. Co-linearity
was observed for common loci. This comparison confirmed a dramatic reduction in recombination for chromosome 6R in the TC-F1 population. The CreR locus was included in the linkage map via progeny testing of informative TC-F1 individuals. CreR mapped 3.7 cM distal from the RFLP locus, XksuF37. Comparative mapping should allow the identification of additional RFLP markers more closely linked to the CreR locus.
Received: 14 April 1998 / Accepted: 29 April 1998 相似文献
13.
Inheritance and genetic mapping of fruit sucrose accumulation in Lycopersicon chmielewskii 总被引:2,自引:0,他引:2
Roger T. Chetelat Ellen Klann Joseph W. DeVerna Serge Yelle Alan B. Bennett 《The Plant journal : for cell and molecular biology》1993,4(4):643-650
Fruit of the domestic tomato (Lycopersicon esculentum Mill.) accumulate soluble sugars primarily in the form of the hexoses, glucose and fructose. In contrast, the predominant sugar in fruit of the wild tomato relative, L. chmielewskii, is sucrose. In the present study, the inheritance and linkage relations of sucrose accumulation were examined in interspecific L. esculentum x L. chmielewskii populations. In backcrosses to either the wild or domestic tomato, segregation for sucrose accumulation permitted qualitative analysis of the trait and indicated monogenic recessive control, although deviations from Mendelian inheritance were observed in some populations. This major gene, designated sucr, was mapped in F2, F3, and BC1F2 populations using a set of 95 informative RFLP and isozyme markers covering the tomato genome. A map location near the centromere of chromosome 3 was established, with tight linkage to the genomic clone TG102. Association of sucrose accumulation with yellow fruit, encoded by an allele of the r gene, permitted alignment with the classical map, thereby confirming the map location of sucr. A linkage map of the region surrounding sucr was obtained by monitoring recombination between flanking markers in the back-crosses to tomato. A cDNA clone of tomato fruit acid invertase, TIV1, was mapped to TG102 and sucr, with no recombination between the two RFLP markers observed in over 1700 meiotic products. Despite the tight linkage, TG102 and TIV1 hybridize to distinct restriction fragments, hence do not represent the same gene. The genetic data strongly suggest that sucr is an allele of the invertase gene and thus support previous biochemical studies that demonstrated low invertase activity in sucrose-accumulating fruit. L. hisutum, another low-invertase, sucrose-accumulating species, was hybridized with L. chmielewskii and the resulting F1 plants accumulated sucrose, indicating that genetic control of soluble sugar composition is conserved in these two species. 相似文献
14.
JAMES W. BORRONE J. STEVEN BROWN DAVID N. KUHN JUAN C. MOTAMAYOR RAYMOND J. SCHNELL 《Molecular ecology resources》2007,7(2):236-239
Theobroma cacao L. expressed sequence tags (ESTs) were converted into useful genetic markers for fingerprinting individuals and genetic linkage mapping. Primers were designed to microsatellite‐containing ESTs. Twenty‐two T. cacao accessions, parents of various mapping populations segregating for disease resistance and crop yield characteristics, were tested. Twenty‐seven informative loci were discovered with 26 primer pairs. The number of detected alleles ranged from two to 11 and averaged 4.4 per locus. All 27 markers could be mapped into at least one of the existing F1 or F2 populations segregating for agronomically important traits. 相似文献
15.
G. Bonnema D. Schipper S. van Heusden P. Lindhout P. Zabel 《Molecular & general genetics : MGG》1997,253(4):455-462
A detailed map of part of the short arm of chromosome 1 proximal to the Cf-4/Cf-9 gene cluster was generated by using an F2 population of 314 plants obtained from the cross between the remotely related species Lycopersicon esculentum and L. peruvianum. Six markers that cosegregate in an L. esculentum×L. pennellii F2 population showed high recombination frequencies in the present interspecific population, spanning an interval of approximately
13 cM. Physical distances between RFLP markers were estimated by pulsed field gel electrophoresis of high-molecular-weight
DNA and by identifying YACs that recognized more than one RFLP marker. In this region 1 cM corresponded to 55–110 kb. In comparsion
with the value of 730 kb per cM averaged over the entire genome, this reflects the remarkably high recombination frequencies
in this region in the hybrid L. esculentum×L. peruvianum progeny population. The present data underline the fact that recombination is not a process that occurs randomly over the
entire genome, but can vary dramatically in intensity between chromosomal regions and among populations.
Received: 20 May 1996 / Accepted: 10 September 1996 相似文献
16.
Jeffery D. Ray Wilfrido Morel James R. Smith Reid D. Frederick Monte R. Miles 《TAG. Theoretical and applied genetics. Theoretische und angewandte Genetik》2009,119(2):271-280
Two soybean accessions, PI 587886 and PI 587880A, previously identified as having resistance to Phakospora pachyrhizi Syd. (soybean rust, SBR) were used to create two populations (POP-1 and POP-2) segregating for SBR resistance. F2-derived F3 (F2:3) families from each population were grown in a naturally SBR-infected field in Paraguay to determine inheritance and map
resistance genes. Over 6,000 plants from 178 families in POP-1 and over 5,000 plants from 160 families in POP-2 were evaluated
at R5 for lesion type: immune reaction (IR), reddish-brown (RB), or tan (TAN) colored lesions. Based on the lesion type present,
each F2:3 family was rated as resistant, segregating or susceptible and this classification was used to infer the F2-phenotype and genotype. For both populations, the F2 segregation ratios fit a 1:2:1 (resistant:segregating:susceptible) ratio expected for a single gene (P > 0.05). The RB lesions occurred almost exclusively in the heterozygous class, indicating incomplete dominance under the
conditions of this study. Molecular markers flanking the locations of the known resistance genes were used to map the resistance
gene in both populations to the Rpp1 locus. However, evaluation of PI 587886 and PI 587880A against eight P. pachyrhizi isolates indicated that the resistance allele in these two accessions was different from Rpp1. This test also demonstrated that these accessions were resistant to at least one P. pachyrhizi isolate collected in the southern US. This is the first report of using an adult plant field-screen with natural rust pressure
to map SBR resistance. 相似文献
17.
I. Vroh Bi A. Maquet J. -P. Baudoin P. du Jardin J. M. Jacquemin G. Mergeai 《TAG. Theoretical and applied genetics. Theoretische und angewandte Genetik》1999,99(7-8):1233-1244
This work aims at breeding upland cotton [Gossypium hirsutum L., 2(AD)1 genome] with a reduced level of gossypol in the seeds for optimal food and feed uses, and a high gossypol level in the remaining
organs for resistance to pests. Two tri-species Gossypium hybrids, (G. thurberi–G. sturtianum–G. hirsutum and G. hirsutum–G. raimondii–G. sturtianum) including G. sturtianum (2C1) as a donor, G. thurberi (2D1) and G. raimondii (2D5) as a bridge species, were created. Recurrent selection initiated with these tri-species hybrids produced backcross (BC)
progenies expressing the ”low-gossypol seed and high-gossypol plant” trait at different levels. We used AFLP markers to assess
the genetic similarity among the germplasm and RFLP probes to tag the introgression of specific chomosome segments from the
parental species. Five pairs of AFLP primers generated 477 fragments, among which 417 (87.4%) were polymorphic. The genetic
similarity between the upland cotton and the wild species ranged from 29.5 to 43.2%, while similarity reached 80% between
upland cotton and BC3 plants. Introgression of species-specific AFLPs was evident from all the parental species and confirmed
the hybrid origin of the analyzed progenies. Southern-blot analysis based on 49 RFLP probes allowed us to trace the introgression
of parental DNA segments in the tri-species hybrids and in three generations of backcross. Introgression was evident from
11, 8 and 7 linkage groups of G. sturtianum, G. raimondii and G. thurberi respectively. The types of introgression revealed by RFLP probes are discussed, and breeding schemes to enhance recombination
are proposed. The ability to trace DNA segments of known chromosomal locations from the donor G. sturtianum through segregating generations is a starting point to map the ”low-gossypol seed and high-gossypol plant” traits.
Received: 5 January 1999 / Accepted: 17 June 1999 相似文献
18.
K. C. Armstrong W. A. Keller 《TAG. Theoretical and applied genetics. Theoretische und angewandte Genetik》1981,59(1):49-52
Summary The maximum chromosome pairing observed in haploids of Brassica campestris was two bivalents plus one trivalent but differences were observed in the chromosome pairing frequencies of the four haploids studied. This pairing supports the theorem that the species is hexasomic for one chromosome, tetrasomic for two and disomic for three others but it is emphasized that some of the observed pairing might be explained by a phenomenon other than homology. 相似文献
19.
Toppino L Mennella G Rizza F D'Alessandro A Sihachakr D Rotino GL 《The Journal of heredity》2008,99(3):304-315
Gene exchanges between Solanum melongena and its allied relative Solanum aethiopicum are a crucial prerequisite for introgression of useful traits from the allied species into the cultivated eggplant. In order to evaluate the extent of genetic recombination between the 2 species, biochemical and molecular markers were employed. A dihaploid population obtained through anther culture of the corresponding tetraploid somatic hybrids was genetically analyzed. The extent of disomic/tetrasomic inheritance and segregation ratios of 3 isozyme systems and intersimple sequence repeat (ISSR) markers were evaluated. The dihaploids, being derived from microspores, allowed for simple, complete, and accurate analyses. The segregation of 280 ISSR markers (110 aethiopicum-specific, 104 melongena-specific, and 66 monomorphic) were evaluated in 71 dihaploids. According to the genetic constitution (simplex/duplex/triplex), almost 64% of the fragments revealed the tetrasomic and/or disomic inheritance. With regard to the assigned species-specific fragments, 68% and 4% were unambiguously the result of tetrasomic and disomic inheritance, respectively. Twenty-four of the 66 monomorphic ISSRs were inherited according to random chromatid segregation. The phenotypes of glucose-6-phosphate dehydrogenase (G-6-PDH), 6-phosphogluconate dehydrogenase (6-PGDH), and shikimate dehydrogenase (SKDH) were studied in 70 dihaploids and inferences were made about the allelic state of their 5 loci. The isozyme markers segregated in the dihaploids in a distorted manner, their segregations did not fit in with any of the expected segregation ratios. However, tetrasomic inheritance might be suggested for G-6-PDH 2 and SKDH 1 loci. Our results demonstrated that gene exchanges occurred readily in the somatic hybrids between S. melongena and S. aethiopicum gr. Gilo. 相似文献
20.
Microsatellite Analysis of Genetic Variation and Population Genetic Differentiation in Autotetraploid and Diploid Rice 总被引:1,自引:0,他引:1
Genetic diversity and population genetic structure of autotetraploid and diploid populations of rice collected from Chengdu
Institute of Biology, Chinese Academy of Sciences, were studied based on 36 microsatellite loci. Among 50 varieties, a moderate
to high level of genetic diversity was observed at the population level, with the number of alleles per locus (A
e) ranging from 2 to 6 (mean 3.028) and polymorphism information content ranging from 0.04 to 0.76 (mean 0.366). The expected
heterozygosity (H
e) varied from 0.04 to 0.76 (mean 0.370) and Shannon’s index (I) from 0.098 to 1.613 (mean 0.649). The autotetraploid populations showed slightly higher levels of A
e, H
e, and I than the diploid populations. Rare alleles were observed at most of the simple sequence repeat loci in one or more of the
50 accessions, and a core fingerprint database of the autotetraploid and diploid rice was constructed. The F-statistics showed genetic variability mainly among autotetraploid populations rather than diploid populations (F
st = 0.066). Cluster analysis of the 50 accessions showed four major groups. Group I contained all of the autotetraploid and
diploid indica maintainer lines and an autotetraploid and its original diploid indica male sterile lines. Group II contained only the original IR accessions. Group III was more diverse than either Group II or
Group IV, comprising both autotetraploid and diploid indica restoring lines. Group IV included a japonica cluster of the autotetraploid and diploid rices. Furthermore, genetic differences at the single-locus and two-locus levels,
as well as components due to allelic and gametic differentiation, were revealed between autotetraploid and diploid varieties.
This analysis indicated that the gene pools of diploid and autotetraploid rice were somewhat dissimilar, as variation exists
that distinguishes autotetraploid from diploid rices. Using this variation, we can breed new autotetraploid varieties with
some important agricultural characters that were not found in the original diploid rice varieties. 相似文献