Genetic diversity and phenotypic variation in marginal populations of the locally endangered speciesHordeum secalinum (Poaceae)

Electrophoresis was used to compare variation in hordein polypeptide patterns and isozymes in five marginal populations ofHordeum secalinum (four Swedish and one Danish population) and four populations along the Atlantic coast from Denmark to Spain. Hordein patterns were uniform within and among Swedish and Danish populations whereas the materials from France and Spain were divergent. The banding patterns for nine isozymes (AAT, IDH, MDH, PGD, GPI, ME, ACP, EST, and PRX) agreed with those reported for otherHordeum species. All putative loci were monomorphic with the exception of PRX, which showed three different phenotypes. The five marginal populations varied in seed set and cultivated plants differed in phenological traits.Dedicated to emer. Univ.-Prof. DrFriedrich Ehrendorfer on the occasion of his 70th birthday     

Structural and numerical chromosomal polymorphism in natural populations ofAlopecurus (Poaceae)

Considerable structural and numerical chromosomal variation has been found in natural populations ofAlopecurus. Interchange heterozygotes, identified by multivalent formation during meiosis, have been recovered in four out of six species studied and are reported for the first time in the diploidsA. bulbosus, andA. myosuroides, and the tetraploidA. pratensis. B chromosomes have been found in two species,A. pratensis andA. myosuroides and also in inter-specific hybrids betweenA. pratensis andA. arundinaceus. The characteristics, distribution and meiotic behaviour of both interchange heterozygotes and B chromosomes are described.     

Allozyme variation within and between populations inLolium (Poaceae)

Isozyme analysis was used to determine genetic variation within and between populations of sevenLolium species. All populations from the inbreeding species (L. temulentum, L. remotum, L. loliaceum, andL. persicum) were completely fixed for all enzymes scored. They also contained, for four of the five enzyme systems studied, exactly the same allelic variant. The three cross-breeding species showed large within-population variation and much less between-population variation. The great similarity of the allozymic variants found in all species, made the division of the genusLolium into species on basis of allozymic data difficult. It was not possible to separate the different inbreeding species from each other. Within the cross-breeding groupL. multiflorum andL. rigidum could be distinguished fromL. perenne. L. multiflorum, andL. rigidum could, with more difficulty, also be separated from each other. Allelic variation could have more relation with the provenance of the populations than with taxonomic classification.Genetic variation inLolium spp. II. For first part see Pl. Syst. Evol. 188: 87–99.     

Microsatellite polymorphism and genetic differentiation in three Norwegian populations of Elymus alaskanus (Poaceae)

 Variation at seven microsatellite loci was investigated in three local E. alaskanus populations from Norway and microsatellite variation was compared with allozyme variation. The percentage of polymorphic loci was 81%, the mean number of alleles per polymorphic locus was 5.7 and expected heterozygosity was 0.37. An F-statistic analysis revealed an overall 48% deficit of heterozygotes over Hardy-Weinberg expectations. Gene diversity is mainly explained by the within population component. The averaged between population differentiation coefficient, F _st , over 7 loci is only 0.13, which accounts for only 13% of the whole diversity and was contrary to allozyme analysis. The mean genetic distance between populations was 0.12. However, a χ² -test showed that allele frequencies were different (p < 0.05) among the populations at 5 of the 7 loci. In comparison with the genetic variation detected by allozymes, microsatellite loci showed higher levels of genetic variation. Microsatellite analysis revealed that population H10576 possesses the lowest genetic variation among the tested three populations, which concur with allozyme analysis. The dendrogram generated by microsatellites agreed very well with allozymic data. Our results suggest that natural selection may be an important factor in shaping the genetic diversity in these three local E. alaskanus populations. Possible explanations for deficit heterozygosity and incongruence between microsatellites and allozymes are discussed. Received November 6, 2001; accepted April 24, 2002 Published online: November 14, 2002 Addresses of the authors: Genlou Sun (e-mail: Genlou.sun@STMARYS.CA), Biology Department, Saint Mary's University, Halifax. Nova Scotia, B3H 3C3, Canada. B. Salomon, R. von Bothmer, Department of Crop Science, The Swedish University of Agricultural Sciences, P.O. Box 44, SE-230 53, Alnarp, Sweden.     

鹅观草属的几个新组合

本文报道了禾本科鹅观草属的三个种级新组合和四个变种级新组合。即大丛鹅观草Roegneria magnicaespis (D.F.Cui)L.B.Cai;新疆鹅观草Roegneria sinkiangensis(D.F.Cui)L.B.Cai;阿尔泰鹅观草Roegneria altaica(D.F.Cui)L.B.Cai;短芒鹅观草Roegneria glaberrima var.breviarista (D.F.Cui)L.B.Cai;林缘鹅观草Roegneria mutabilis var.nemoralis (D.F.Cui)L.B.Cai;多花鹅观草Roegneria abolinii var.pluriflora (D.F.Cui)L.B.Cai和曲芒鹅观草Roegneria tschimganica var.glabrispicula (D.F.Cui)L.B.Cai。     

拟鹅观草属3种植物的核型研究

对禾本科小麦族拟鹅观草属物种Pseudoroegneria geniculata、P.geniculata ssp.scythica和P.geniculata ssp.pruinifera的核型进行了研究.结果显示:P.geniculata和P.geniculata ssp.scythica为四倍体物种,P.geniculata ssp.pruinifera为六倍体物种;P.geniculata、P.geniculata ssp.scythica和P.geniculata ssp.pruinifera的核型公式分别为2n=4x=28=18m(2sat)+10sm(2sat)、2n=4x=28=28m(2sat)和2n=6x=42=36m(6sat)+6sm(2sat);P.geniculata和P.geniculata ssp.pruinifera为2A核型,而P.geniculata ssp.scythica为1A核型.研究表明:3种植物的核型存在差异;P.geniculata ssp.pruinifera的核型为首次报道,其核型明显不同于P.geniculata和P.geniculata ssp.scythica.     

Structuring of genetic variation inHordeum spontaneum (Poaceae): Genotypic variation within populations

Samples from eleven populations of wild barley were examined for metric growth and reproductive traits in a common garden field trial. Descendants of these plants were examined for electrophoretically determined genotypes. In most cases each population had one or more predominant electrophoretically detectable genotypes and many infrequent genotypes. Analysis of variance ofHordeum spontaneum shows that the between-population variance component contributed the bulk of the observed variation in metric traits, with only a small proportion of the total variation contributed by the between-genotype within-population variance component. Nevertheless, a full 20% of the F values for the among genotype analysis were significant at the 5% level. In addition, using discriminant analysis, electrophoretically determined genotypes could be easily distinguished on the basis of trait (i.e., metric) measurements. The joint use of electrophoresis (to identify genotypes) and of trait measurements is a powerful tool for investigating intrapopulation genetic variation.     

Hybridization between tetraploid species of Alopecurus L. (Poaceae): morphological studies of natural and artificial hybrids

The morphology of individuals of mixed natural populations of three species of Alopecurus, A. pratensis, A. geniculars and A. arundinaceus , is described. It is suggested that plants morphologically intermediate between the parental species are hybrids or of hybrid origin. Hybridization occurs more readily between A. pratensis and A. arundinaceus than between A. pratensis and A. geniculate , since intermediate forms were recovered from all mixed populations of A. pratensis and A. arundinaceus. The intermediate forms occur only in a few populations of A. pratensis and A. geniculars where an appropriate habitat is available. Evidence of backcrossing and therefore introgression comes from the continuum of intermediate forms that exists between the species. Scatter diagrams for individual populations show distinct differences in the degree of introgression. Observations on artificially produced hybrids are similar to those on naturally occurring hybrids.     

Hybridization between tetraploid species of Alopecurus L. (Poaceae): chromosome behaviour of natural and artificial hybrids

The meiotic behaviour of plants from mixed populations of Alopecurus pratensis × A. geniculatus and of A. pratensis × A. arundinaceus ( 2n = 4×(= 28) is reported together with observations on some artificially produced hybrids. This meiotic behaviour is correlated with the degree of hybridity as shown by the hybrid index values of the plant. In A. pratensis × A. geniculatus hybrids there are marked differences between populations in the degree of meiotic disturbance and in one population there was an almost complete breakdown of meiosis. Alopecurus pratensis × A. arundinaceus hybrids show fairly regular meiotic pairing but in most plants there are a few univalent chromosomes at metaphase I. Artificially produced hybrids of A. pratensis × A. aequalis gave meiotic configurations that suggest that the genomes of the parent species are very similar. Taken together with the results from artificially produced hybrids of A. pratensis × A. geniculatus , it is suggested that bivalent-promoting mechanisms reduce multivalent formation both in the species and the hybrids. The interaction of different genotypes involved in the control of meiosis may account for the variation in meiotic behaviour in the different populations of hybrids. Pollen fertility is reduced in most populations of hybrids and likely to be an important factor permitting introgressive hybridization.     

人工诱导雌核发育日本白鲫

分别用遗传失活的散鳞镜鲤(Cyprinus carpio L.)、团头鲂(Megalobrama amblycephala)精子诱导日本白鲫(Carassius cuvieri)进行雌核发育.未经冷休克处理,用UV照射过的镜鲤的精子(其最佳UV照射剂量为4 200 mJ/cm2)与日本白鲫卵子受精获得(32.4±3.3)%雌核发育单倍体和(0.7±0.3)%杂交二倍体,而照射过的团头鲂精子(其最佳UV照射剂量为3 600mJ/cm2)与日本白鲫卵子受精得到了(33.8±1.4)%雌核发育单倍体和(0.5-±0.3)%杂交二倍体.日本白鲫卵子分别经灭活的镜鲤、团头鲂的精子激活(精子经各自最佳UV剂量处理),施以冷休克处理(受精后2min,0-4℃,40min),其孵化率分别为(27.8±2.1)%和(29.4±3.3)%,发育到摄食期,其正常的雌核发育二倍体鱼苗分别为(15.7±3.4)%和(23.6±4.1)%,在镜鲤实验组中,其正常的雌核发育二倍体鱼苗占孵化鱼苗总数的56%,这比团头鲂实验组中正常雌核发育二倍体鱼苗的比率(达到80%)低,结果表明诱导日本白鲫雌核发育,与母本遗传关系远的团头鲂精子较镜鲤的更有效.从染色体数目、外形特征和性腺结构等方面证实雌核发育后代的生物学特性.雌核发育日本白鲫全为雌性,这表明其雌性是同配XX型.雌核发育日本白鲫在生产上将有着潜在的价值,如比普通日本白鲫长得更快,抗病能力强等.所有的雌核发育日本白鲫的染色体数目都是100,而所有的团头鲂与日本白鲫的杂交后代都是三倍体(3n=124),新三倍体鱼在鱼类养殖和理论研究中将存在潜在的价值.     

Delimitation and classification ofBromus fasciculatus (Poaceae)

The syntypes ofBromus madritensis var.delilei Boiss. comprise two different elements: specimens ofB. haussknechtii Boiss. and ofB. fasciculatus C. Presl s.l. By its lectotypification and on the basis of new morphological characters, the validation ofB. fasciculatus subsp.delilei (Boiss.)H. Scholz 1971 was substantiated. This subspecies represents the eastern marginal segregate of the south-Mediterranean species.B. fasciculatus var.alexandrinus Thell. is a minor variant of the typical subspecies.Dedicated to Prof.K. H. Rechinger on the occasion of his 80th birthday.     

羊茅属(禾本科)新类群

描述了山东产羊茅属的2个新类群,即毛鞘羊茅和崂山小颖羊茅。毛鞘羊茅与羊茅相近,表现在叶片内卷成线状,圆锥花序紧缩成穗状,外稃背部粗糙,区别在于具有向上膜质的叶耳,叶鞘密被倒向的微毛,小穗长7-10mm,第1外稃长4-5mm,顶端具0.5-1mm长的芒或无,内稃脊光滑;崂山小颖羊茅与原变种的区别在于第1颖卵状披针形,长1.5-2mm,具2-3脉。     

Extremely high cytoplasmic diversity in natural and breeding populations of Lolium (Poaceae)

Ten chloroplast microsatellite markers were used to characterise chloroplast genetic diversity at allelic and haplotypic level in 104 accessions of Lolium perenne, other Lolium species, Festuca species and x Festulolium cultivars. Furthermore, genetic relationships between the accessions and biogeographic distribution of haplotypes were investigated using a range of Nei's population genetic diversity measures and analysis of molecular variance (AMOVA). An extremely high number (511) of haplotypes was detected in 1575 individuals. Nei's gene diversity values among L. perenne accessions ranged between 0 and 0.333. Much of the L. perenne European ecotype diversity (61%), as calculated using AMOVA, could be attributed to within-population variance and this is likely caused by, and maintained by, high levels of natural and anthropogenic seed dispersal. Plastid gene pools and maternal lineages for L. perenne could be clearly identified. Evidence was found, using AMOVA, to show a likely migration route of L. perenne from Southern regions of Europe northwards.     

Induction of Gynogenesis in Japanese Crucian Carp (Carassius cuvieri)

Diploid gynogenesis was induced in Japanese crucian carp (Carassius cuvieri) eggs using UV-irradiated genetically inactive spermatozoa from mirror carp (Cyprinus carpio L.) or blunt snout bream (Megalobrama amblycephala), with or without cold shock. The optimal radiation dosage was 4200 mJ/cm² and 3600 mJ/cm² for mirror carp and blunt snout bream sperm, respectively. At this dosage and without cold shock, the yields were (32.4±3.3)% vs. (33.8±1.4)% gynogenetic haploids and (0.7±0.3)% vs. (0.5±0.3)% hybrid diploids, respectively. At the optimal UV dosage but with cold shock (2 min after fertilization, 0-4°C for 40 min), the hatching rates were (27.8±2.1)% and (29.4±3.3)%, respectively. From hatching to feeding, (15.7±3.4)% and (23.6±4.1)% normal gynogenetic diploids were recorded, respectively. Survival of normal gynogenetic diploids was 56% out of the hatched fry when using irradiated spermatozoa of mirror carp, which was lower than that (up to 80%) when using irradiated spermatozoa of blunt snout bream. This indicated that the sperm of blunt snout bream, with distant genetic relation to the maternal Japanese crucian carp, was more effective than that of mirror carp to induce diploid gynogenesis. The nature of the gynogenetic progeny was identified with external appearance, chromosome number and gonad structure. The presence of only females in gynogenetic progeny probably suggested XX genotype in the female Japanese crucian carp. The gynogenetic diploids have potential values such as faster growth and stronger disease resistance than the normal Japanese crucian carp. All gynogenetic progeny possessed 100 chromosomes whereas all J x B crosses were triploid with 124 chromosomes. The formation of the new triploid hybrids in J x B crosses may be useful in aquaculture.     

Selective adaptation to copper of populations ofAgrostis tenuis andFestuca rubra (Poaceae)

Populations ofAgrostis Tenuis andFestuca rubra, tolerant and non-tolerant towards Zn and Pb, were studied in regard to their adaptability by natural selection, towards a third metal (Cu) and the time required for the appearance of such tolerance. It was found that Zn and Pb tolerant and non-tolerant populations are likely to select the character of Cu-tolerance within the course of only one generation. More specifically, Zn and Pb tolerant populations show a better adaptability compared with non-tolerant ones. The amount of tolerance to copper obtained by artificial selection is comparable with that of populations growing naturally on copper mines.     

RAPD variation in wild populations of four species of the genus Hordeum (Poaceae)

 The genetic variation of 102 natural populations of wild barley growing in Spain was assessed using RAPDs (random amplified polymorphic DNA). The plant material included the annual species H. marinum subsp. marinum (22 populations) and subsp. gussoneanum (14), H. murinum subsp. murinum (7) and subsp. leporinum (35), and the perennial species H. bulbosum (17) and H. secalinum (7). Ten of the tested 64 arbitrary 10-mer primers amplified polymorphic DNA in all taxonomic units. Analyses was performed within and between populations, species and subspecies. The primers gave a total of 250 RAPD products. The level of polymorphism varied between taxonomic units depending on the primers employed and the plant reproductive system. In general, the most variable were the allogamous species H. secalinum and H. bulbosum and the autogamous H. marinum subsp. marinum. Among the amplified bands, 69 (27%) were shared by at least two different taxonomic units. The remaining bands were specific. The results demonstrate differences in the degree of similarity between taxonomic units. Jaccard’s similarity coefficients for interval measure within and between populations were used to produce a cluster diagram using the unweighted pair-group method (UPGMA). The different populations of the species and subspecies of Hordeum fell into three groups. The first group contained the populations belonging to both subspecies of H. marinum, plus those of H. secalinum. The populations of H. marinum subsp. gussoneanum were very closely associated. Those of H. marinum subsp. marinum were grouped in a broad cluster. The second group, occupying the innermost position of the tree, was very closely associated with the populations of both subspecies of H. murinum. The third branch segregated H. bulbosum. A series of RAPD markers were investigated by cleaving the amplified products of the same size with restriction endonucleases that recognize targets of 4- or 6-bp. The production of equivalent fragments following cleavage by the same enzyme would seem to demonstrate their homology in samples from different individuals, populations or taxonomic units. Received: 18 May 1997 / Accepted: 22 August 1997     

Progenitor-derivative relationships of Hordeum polyploids (Poaceae, Triticeae) inferred from sequences of TOPO6, a nuclear low-copy gene region

Polyploidization is a major mechanism of speciation in plants. Within the barley genus Hordeum, approximately half of the taxa are polyploids. While for diploid species a good hypothesis of phylogenetic relationships exists, there is little information available for the polyploids (4×, 6×) of Hordeum. Relationships among all 33 diploid and polyploid Hordeum species were analyzed with the low-copy nuclear marker region TOPO6 for 341 Hordeum individuals and eight outgroup species. PCR products were either directly sequenced or cloned and on average 12 clones per individual were included in phylogenetic analyses. In most diploid Hordeum species TOPO6 is probably a single-copy locus. Most sequences found in polyploid individuals phylogenetically cluster together with sequences derived from diploid species and thus allow the identification of parental taxa of polyploids. Four groups of sequences occurring only in polyploid taxa are interpreted as footprints of extinct diploid taxa, which contributed to allopolyploid evolution. Our analysis identifies three key species involved in the evolution of the American polyploids of the genus. (i) All but one of the American tetraploids have a TOPO6 copy originating from the Central Asian diploid H. roshevitzii, the second copy clustering with different American diploid species. (ii) All hexaploid species from the New World have a copy of an extinct close relative of H. californicum and (iii) possess the TOPO6 sequence pattern of tetraploid H. jubatum, each with an additional copy derived from different American diploids. Tetraploid H. bulbosum is an autopolyploid, while the assumed autopolyploid H. brevisubulatum (4×, 6×) was identified as allopolyploid throughout most of its distribution area. The use of a proof-reading DNA polymerase in PCR reduced the proportion of chimerical sequences in polyploids in comparison to Taq polymerase.     

Loss of genetic variation in geographically marginal populations of Atriplex tatarica (Chenopodiaceae)

BACKGROUND AND AIMS: Genetic variability was estimated for Atriplex tatarica from 25 populations in the Czech Republic. Since its north-western range margin is in central Europe, a relationship between marginality and low within-population genetic diversity was tested in accordance with the Central-Marginal Model. METHODS: Population genetic diversity was expressed by assessing patterns of variation at 13 putatively neutral allozyme loci (comprising 30 putative alleles) within and between 25 natural populations of A. tatarica along a north-west-south-east transect in the Czech Republic. KEY RESULTS: Atriplex tatarica is a species of human-made habitats with a mixed mating system and wide geographic distribution. Overall, A. tatarica displayed moderate levels of genetic diversity in comparison with other herbaceous plants. The percentage of loci that were polymorphic was 47.1%, with average values of 1.55, 0.151 and 0.155 for the average number of alleles per polymorphic locus (A), observed heterozygosity (Ho) and expected heterozygosity (He), respectively. There was only weak evidence of inbreeding within populations (FIS=0.031) and significant population differentiation (FST=0.214). Analysis of the data provides no evidence for isolation-by-distance for the whole study area. However, Mantel tests were highly significant for the marginal Bohemian region and non-significant for the central Moravian region. While northern populations of A. tatarica showed significantly lower allelic richness (A=1.462) than populations from the southern part of the study area (A=1.615), they did not differ in observed heterozygosity (Ho), gene diversity (HS), inbreeding within populations (FIS) or population differentiation (FST), despite generally lower values of particular genetic measurements in the marginal region. CONCLUSIONS: Genetic diversity, with the exception of allelic richness, was not significantly lower at the margins of the species' range. This, therefore, provides only weak support for the predictions of the Central-Marginal Model.     

The origin and evolution of Eragrostis tef (Poaceae) and related polyploids: evidence from nuclear waxy and plastid rps16

Tef (Eragrostis tef; Poaceae) is an allotetraploid (2n = 4x = 40) cereal crop whose origin within the large genus Eragrostis is unknown. Previous studies have suggested a total of 14 wild Eragrostis species as potential progenitors. Phylogenetic analysis of sequence data from the nuclear gene waxy and the plastid locus rps16 strongly supports the widely held hypothesis of a close relationship between tef and E. pilosa, a wild allotetraploid. Eragrostis heteromera, another previously proposed progenitor, is shown by the waxy data to be a close relative of one of the tef genomes. Other putative progenitors included in the taxon sample are not supported as closely related to tef. Plastid sequences from five varieties of tef and four E. pilosa accessions are identical and therefore are uninformative with respect to the question of multiple origins of these polyploids. The waxy phylogeny also resolves the relationships among other allopolyploids, supporting a close relationship between the morphologically similar allotetraploids E. macilenta, E. minor, and E. mexicana. Eragrostis cilianensis, another morphologically similar allopolyploid, appears to have shared one diploid progenitor with these species but derived its other genome from an unrelated diploid.