Electrophoretic and molecular analysis of alpha-gliadins inAegilops species (Poaceae) belonging to the D genome cluster and in their putative progenitors

The D genome cluster includes six allopolyploidAegilops species having as pivotal genome that ofAegilops squarrosa. Alpha-gliadins, endosperm proteins coded by multigenic families, have been analyzed in the D genome species cluster and in their putative progenitors. They can be present or weakly expressed when analyzed in acid polyacrylamide gel electrophoresis. Molecular analysis has shown the possibility to distinguish subsp.strangulata from subsp.eusquarrosa and to confirm the presence ofAe. caudata and ofAe. umbellulata in the polyploidsAe. cylindrica andAe. juvenalis, respectively. Finally, introgression fromAe. longissima orAe. searsii in tetraploid and hexaploidAe. crassa, Ae. juvenalis, andAe. vavilovii is supposed.     

Electrophoretic survey of seedling esterases in wheats in relation to their phylogeny

Summary Evolutionary and ontogenetic variation of six seedling esterases of independent genetic control is studied in polyploid wheats and their diploid relatives by means of polyacrylamide gel electrophoresis. Four of them are shown to be controlled by homoeoallelic genes in chromosomes of third, sixth and seventh homoeologous groups.The isoesterase electrophoretic data are considered supporting a monophyletic origin of both the primitive tetraploid and the primitive hexaploid wheat from which contemporary taxa of polyploid wheats have emerged polyphyletically and polytopically through recurrent introgressive hybridization and accumulation of mutations. Ancestral diploids belonging or closely related to Triticum boeoticum, T. urartu, Aegilops speltoides and Ae. tauschii ssp. strangulata are genetically the most suitable genome donors of polyploid wheats. Diploids of the Emarginata subsection of the section Sitopsis, Aegilops longissima s.str., Ae. sharonensis, Ae. searsii and Ae. bicornis, are unsuitable for the role of the wheat B genome donors, being all fixed for the esterase B and D electromorphs different from those of tetraploid wheats.     

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.     

The structure of the Aegilops tauschii genepool and the evolution of hexaploid wheat

 Polymorphism in the lengths of restriction fragments at 53 single-copy loci, the rRNA locus Nor3, and the high-molecular-weight glutenin locus Glu1 was investigated in the D genome of hexaploid Triticum aestivum and that of Aegilops tauschii, the source of the T. aestivum D genome. The distribution of genetic variation in Ae. tauschii suggests gene flow between Ae. tauschii ssp. strangulata and ssp. tauschii in Iran but less in Transcaucasia. The “strangulata” genepool is wider than it appears on the basis of morphology and includes ssp. strangulata in Transcaucasia and southeastern (SE) Caspian Iran and ssp. tauschii in north-central Iran and southwestern (SW) Caspian Iran. In the latter region, Ae. tauschii morphological varieties ‘meyeri’ and ‘typica’ are equidistant to ssp. strangulata in Transcaucasia, and both belong to the “strangulata” genepool. A model of the evolution of Ae. tauschii is presented. On the geographic region basis, the D genomes of all investigated forms of T. aestivum are most closely related to the “strangulata” genepool in Transcaucasia, Armenia in particular, and SW Caspian Iran. It is suggested that the principal area of the origin of T. aestivum is Armenia, but the SW coastal area of the Caspian Sea and a corridor between the two areas may have played a role as well. Little genetic differentiation was found among the D genomes of all investigated free-threshing and hulled forms of T. aestivum, and all appear to share a single D-genome genepool, in spite of the fact that several Ae. tauschii parents were involved in the evolution of T. aestivum. Received: 17 November 1997 / Accepted: 17 March 1998     

Population structure of wild wheat D‐genome progenitor Aegilops tauschii Coss.: implications for intraspecific lineage diversification and evolution of common wheat

Aegilops tauschii Coss. is the D‐genome progenitor of hexaploid wheat. Aegilops tauschii, a wild diploid species, has a wide natural species range in central Eurasia, spreading from Turkey to western China. Amplified fragment length polymorphism (AFLP) analysis using a total of 122 accessions of Ae. tauschii was conducted to clarify the population structure of this widespread wild wheat species. Phylogenetic and principal component analyses revealed two major lineages in Ae. tauschii. Bayesian population structure analyses based on the AFLP data showed that lineages one (L1) and two (L2) were respectively significantly divided into six and three sublineages. Only four out of the six L1 sublineages were diverged from those of western habitats in the Transcaucasia and northern Iran region to eastern habitats such as Pakistan and Afghanistan. Other sublineages including L2 were distributed to a limited extent in the western region. Subspecies strangulata seemed to be differentiated in one sublineage of L2. Among three major haplogroups (HG7, HG9 and HG16) previously identified in the Ae. tauschii population based on chloroplast variation, HG7 accessions were widely distributed to both L1 and L2, HG9 accessions were restricted to L2, and HG16 accessions belonged to L1, suggesting that HG9 and HG16 were formed from HG7 after divergence of the first two lineages of the nuclear genome. These results on the population structure of Ae. tauschii and the genealogical relationship among Ae. tauschii accessions should provide important agricultural and evolutionary knowledge on genetic resources and conservation of natural genetic diversity.     

Electrophoretic variation in esterases and peroxidases of native greek diploidAegilops species(Ae. caudata andAe. comosa,Poaceae)

The esterase and peroxidase patterns in five varieties ofAegilops caudata (genome type C) andAe. comosa (genome type M) were studied in order to elucidate the phylogenetic relationships within and between the two groups. The electrostarch gel electrophoresis technique was applied to extracts of shoot and root of 4-day-old seedlings, and the electropherograms were evaluated by gel densitometer traces. Inspite of considerable isozyme polymorphism, closer relationships in the banding patterns were found between different varieties of a single species than between varieties of the two different species. Esterase and peroxidase patterns of the twoAe. caudata varieties (caudata andpolyathera) are very similar and prove their close phylogenetic relationship. The isozyme affinities withinAe. comosa varieties are illustrated by the seriessubventricosa—biaristata—thessalica. The latter endemic variety has quite a number of characteristic bands and is relatively isolated. Altogether, the electrophoretic data agree well with morphological and cytological similarities (Zhukovsky 1928,Eig 1929,Karataglis 1973, 1975b).     

A high-density genetic linkage map of Aegilops tauschii, the D-genome progenitor of bread wheat

 Aegilops tauschii is the diploid D-genome progenitor of bread wheat (Triticum aestivum L. em Thell, 2n=6x=42, AABBDD). A genetic linkage map of the Ae. tauschii genome was constructed, composed of 546 loci. One hundred and thirty two loci (24%) gave distorted segregation ratios. Sixty nine probes (13%) detected multiple copies in the genome. One hundred and twenty three of the 157 markers shared between the Ae. tauschii genetic and T. aestivum physical maps were colinear. The discrepancy in the order of five markers on the Ae. tauschii 3DS genetic map versus the T. aestivum 3D physical map indicated a possible inversion. Further work is needed to verify the discrepancies in the order of markers on the 4D, 5D and 7D Ae. tauschii genetic maps versus the physical and genetic maps of T. aestivum. Using common markers, 164 agronomically important genes were assigned to specific regions on Ae. tauschii linkage, and T. aestivum physical, maps. This information may be useful for map-based cloning and marker-assisted plant breeding. Received: 23 March 1998 / Accepted: 27 October 1998     

On the taxonomic position ofSilene thebana (Caryophyllaceae)

Silene thebana Orph. exBoiss. is transferred as a subspecies toS. fabaria (L.)Sm., resulting in the new combinationS. fabaria (L.)Sm. subsp.thebana (Orph. exBoiss.)Melzh. The chromosome count of 2n = 24 is recorded for the first time for this taxon.Dedicated to Prof. DrK. H. Rechinger on the occasion of his 80th birthday, 16th October 1986.     

Cytotaxonomy and breeding system of the genusBiscutella (Cruciferae)

Chromosome counts were determined for 46 populations ofBiscutella representing 28 taxa. The genus was found to contain diploid taxa with 2n = 12, 16 and 18, tetraploid taxa with 2n = 36 and hexaploid taxa having 2n = 54.B. laevigata L. s. l. consists of diploid and tetraploid populations which are poorly differentiated morphologically. TetraploidB. laevigata s. l. and hexaploidB. variegata Boiss. & Reuter (s. l.) are characterized by chromosomal instability. The variation in chromosome numbers and the occurrence of polyploidy is discussed in relation to the taxonomy of the genus. An investigation of the breeding system showed that most of the annual species were self-compatible and partly inbreeding and most of the perennial species self-incompatible and, therefore, outbreeding, while one annual species,B. cichoriifolia Loisel., showed both systems.     

Phylogenetic Relationships and Intraspecific Variation of D-Genome Aegilops L. as Revealed by RAPD Analysis

RAPD analysis was carried out to study the genetic variation and phylogenetic relationships of polyploid Aegilops species, which contain the D genome as a component of the alloploid genome, and diploid Aegilops tauschii, which is a putative donor of the D genome for common wheat. In total, 74 accessions of six D-genome Aegilops species were examined. The highest intraspecific variation (0.03–0.21) was observed for Ae. tauschii. Intraspecific distances between accessions ranged 0.007–0.067 in Ae. cylindrica, 0.017–0.047 in Ae. vavilovii, and 0–0.053 inAe. juvenalis.Likewise, Ae. ventricosaand Ae. crassa showed low intraspecific polymorphism. The among-accession difference in alloploidAe. ventricosa (genome D^vN^v) was similar to that of one parental species, Ae. uniaristata (N), and substantially lower than in the other parent, Ae. tauschii (D). The among-accession difference in Ae. cylindrica(C^cD^c) was considerably lower than in either parent, Ae. tauschii (D) orAe. caudata (C). With the exception of Ae. cylindrica, all D-genome species—Ae. tauschii (D),Ae. ventricosa (D^vN^v), Ae. crassa (X^crD^cr1 and X^crD^cr1D^cr2), Ae. juvenalis (X^jD^jU^j), andAe. vavilovii (X^vaD^vaS^va)—formed a single polymorphic cluster, which was distinct from clusters of other species. The only exception, Ae. cylindrica(C^cD^c), did not group with the other D-genome species, but clustered withAe. caudata (C), a donor of the C genome. The cluster of these two species was clearly distinct from the cluster of the other D-genome species and close to a cluster of Ae. umbellulata (genome U) and Ae. ovata (genome U^gM^g). Thus, RAPD analysis for the first time was used to estimate and to compare the interpopulation polymorphism and to establish the phylogenetic relationships of all diploid and alloploid D-genome Aegilops species.     

A taxonomical revision ofThymus sect.Teucrioides (Lamiaceae)

TheThymus teucrioides Boiss. & Spruner aggregate is revised and the following new taxa, all from the alpine zone in the Greek mountains, are described:Th. leucospermus Hartvig from the calcareous mountains of Pindhos and Mt Parnassos in Sterea Ellas,Th. rechingeri Hartvig with the subsp.macrocalyx Hartvig from calcareous mountains in Sterea Ellas and N Peloponnissos, andTh. teucrioides subsp.alpinus Hartvig from the serpentine areas of N Pindhos. In the variableTh. teucrioides s. str. many characters have turned out to be markedly geographically correlated and many local populations can be distinguished by a particular combination of characters.Dedicated to Prof.K. H. Rechinger on the occasion of his 80th birthday.     

Genome differentiation in Aegilops. 3. Evolution of the D-genome cluster

 Six polyploid Aegilops species containing the D genome were studied by C-banding and fluorescence in situ hybridization (FISH) using clones pTa71 (18S-5.8S-26S rDNA), pTa794 (5S rDNA), and pAs1 (non-coding repetitive DNA sequence) as probes. The C-banding and pAs1-FISH patterns of Ae. cylindrica chromosomes were identical to those of the parental species. However, inactivation of the NOR on chromosome 5D with a simultaneous decrease in the size of the pTa71-FISH site was observed. The N^v and D^v genomes of Ae. ventricosa were somewhat modified as compared with the N genome of Ae. uniaristata and the D genome of Ae. tauschii. Modifications included minor changes in the C-banding and pAs1-FISH patterns, complete deletion of the NOR on chromosome 5D^v, and the loss of several minor 18S-5.8S-26S rDNA loci on N^v genome chromosomes. According to C-banding and FISH analyses, the D^cr1 genome of Ae. crassa is more similar to the D^v genome of Ae. ventricosa than to the D genome of Ae. tauschii. Mapping of the 18S-5.8S-26S rDNA and 5S rDNA loci by multicolor FISH suggests that the second (X^cr) genome of tetraploid Ae. crassa is a derivative of the S genome (section Emarginata of the Sitopsis group). Both genomes of Ae. crassa were significantly modified as the result of chromosomal rearrangements and redistribution of highly repetitive DNA sequences. Hexaploid Ae. crassa and Ae. vavilovii arose from the hybridization of chromosomal type N of tetraploid Ae. crassa with Ae. tauschii and Ae. searsii, respectively. Chromosomal type T1 of tetraploid Ae. crassa and Ae. umbellulata were the ancestral forms of Ae. juvenalis. The high level of genome modification in Ae. juvenalis indicates that it is the oldest hexaploid species in this group. The occurrence of hexaploid Ae. crassa was accompanied by a species-specific translocation between chromosomes 4D^cr1 and 7X^cr. No chromosome changes relative to the parental species were detected in Ae. vavilovii, however, its intraspecific diversity was accompanied by a translocation between chromosomes 3X^cr and 3D^cr1. Received July 24, 2001 Accepted October 1, 2001     

Inter- and intraplant C-banding polymorphism in one population ofAegilops comosa subsp.comosa var.comosa (Poaceae)

The Giemsa C-banding pattern of the chromosomes of the native self-pollinatedAegilops comosa subsp.comosa var.comosa was studied. Six of the seven chromosomes of the haploid genome were found to be polymorphic for C-banding patterns. Chromosome A had four variants, chromosome E three variants and each of the chromosomes B, D, and F two variants. Chromosomes E and G were polymorphic for arm length and arm ratio.This paper is part of the doctoral dissertation ofA. Georgiou.     

Chloroplast and nuclear microsatellite analysis of Aegilops cylindrica

Aegilops cylindrica Host (2n=4x=28, genome CCDD) is an allotetraploid formed by hybridization between the diploid species Ae. tauschii Coss. (2n=2x=14, genome DD) and Ae. markgrafii (Greuter) Hammer (2n=2x=14, genome CC). Previous research has shown that Ae. tauschii contributed its cytoplasm to Ae. cylindrica. However, our analysis with chloroplast microsatellite markers showed that 1 of the 36 Ae. cylindrica accessions studied, TK 116 (PI 486249), had a plastome derived from Ae. markgrafii rather than Ae. tauschii. Thus, Ae. markgrafii has also contributed its cytoplasm to Ae. cylindrica. Our analysis of chloroplast and nuclear microsatellite markers also suggests that D-type plastome and the D genome in Ae. cylindrica were closely related to, and were probably derived from, the tauschii gene pool of Ae. tauschii. A determination of the likely source of the C genome and the C-type plastome in Ae. cylindrica was not possible.     

Heteromerikarpie und Fruchtpolymorphismus beiMicroparacaryum,gen. nov., (Boraginaceae)

Microparacaryum (M. Pop. exH. Riedl)Hilger & Podlech is described as a new genus of theBoraginaceae-Cynoglosseae. It comprises the annual species hitherto included inParacaryum (DC.)Boiss. andMattiastrum (Boiss.)Brand. Distribution maps are given for all 3 genera.Microparacaryum consists of two species,M. salsum (Boiss.)Hilger & Podlech (M. s.) andM. intermedium (Fresen.)Hilger & Podlech (M. i.). ParticularlyM. i. is a very variable species, and most of the species formerly recognized belong here. Scattered all over the range of the genus, plants occur with nutlets exhibiting flat or incurved marginal wings, often in mixed populations. This fruit polymorphism is taxonomically treated by recognizing formae. In addition, the following new infraspecific taxa and combinations are described:M. i. var.intermedium formaparacaryoides Hilger & Podlech,M. i. var.stellatum (H. Riedl)Hilger & Podlech,M. i. var.stellatum formamattiastroides Hilger & Podlech,M. s. formamattiastroides Hilger & Podlech.

     

Genome relationship betweenPsathyrostachys huashanica andP. fragilis (Poaceae)

Hybrids between the Chinese endemic speciesPsathyrostachys huashanica Keng and the SW. Asian speciesP. fragilis (Boiss.)Nevski (all 2n = 14) developed normally but were completely sterile. Meiotic analyses revealed a high chiasma frequency indicating that the two species as well asP. juncea (Fisch.)Nevski share the same basic genome (called N). The hybrid nature of the plants was established through karyotype analysis and Giemsa C-banding.     

A comparative analysis of the composition and organization of two subtelomeric repeat families in <Emphasis Type="Italic">Aegilops speltoides</Emphasis>Tausch. and related species

The structural organization and evolution of two tandemly repeated families, Spelt1 and Spelt52, located in the subtelomeric regions of Aegilops speltoides chromosomes were studied. The Spelt1 family of sequences with a monomer length of 178 bp was characterized by cloning and sequence analysis of polymerase chain reaction (PCR) products. Members of the Spelt1 family revealed sequence similarities exceeding 95\%. This conservation has remained despite divergence of species in Aegilops section Sitopsis and after independent multiple amplification events in the genome of Ae. speltoides. Sequences representing the Spelt52 family were cloned, sequenced and compared with other sequences in databases. The Spelt52 repeat family contains monomers of two types, Spelt52.1 and Spelt52.2. The two monomers share a homologous stretch of 280 bp and have two regions without sequence similarity of 96 bp and 110 bp, respectively. PCR analysis was conducted to 15 lines in Ae. speltoidesTausch., Ae. longissimaSchw.&Mushc.,Ae. sharonensisEig.,Ae. bicornis(Forssk)Jaub.&Sp., andAe. searsii Feld.&Kis. using primers to the homologous and non- homologous regions of Spelt52 family. Intraspecies and interspecies differences in the occurrence and abundance of combinations of Spelt52.1 and Spelt52.2 monomers were detected. The use of primers to telomeric and subtelomeric repeats followed by Southern hybridization, cloning, and sequence analysis demonstrated that Spelt1 and Spelt52 are localized close to each other and to telomeric repeats. The efficiency of a PCR approach for the analysis of telomeric/subtelomeric junction regions of chromosomes is discussed.     

Geographic patterns of histone H1 encoding genes allelic variation in <Emphasis Type="Italic">Aegilops tauschii</Emphasis> Coss. (Poaceae)

An electrophoretic analysis of histone H1 of Aegilops tauschii was carried out using the collection of 303 accessions (156 of ssp. tauschii and 147 of ssp. stangulata) representing all the species range. Three, four and six allelic variants were found for Hst1, Hst2 and Hst3 locus, respectively. The level of histone H1 allelic variability in ssp. strangulata was considerably higher than in ssp. tauschii. Expected heterozygosity (H_E) for the loci Hst1, Hst2 and Hst3 made up 0.066, 0.484 and 0.224 respectively in ssp. strangulata vs. 0.024, 0.051 and 0.214 in ssp. tauschii. Besides the most common haplotype, Hst1 ¹⁰⁰⁰, Hst2 ¹⁰⁰⁰, Hst3 ¹⁰⁰⁰, five other haplotypes with frequencies of occurrence higher than 0.02 were found in ssp. strangulata, and only one such haplotype—in ssp. tauschii. The most part of histone H1 variation in ssp. tauschii was in the western part of the area. In ssp. strangulata, the alleles Hst2 ⁹⁸⁸ and Hst2 ⁹⁷³ were found only in Caucasia, and the allele Hst1 ¹⁰⁴³—only in Precaspian Iran and south-eastern Azerbaijan. Histone H1 variation patterns in Ae. tauschii are very similar to those of non-coding sequences of chloroplast DNA. Therefore, histone H1 allelic variation in this species seems to be mostly neutral. Nevertheless, the evidences were pointed out, revealing that some part of variation at Hst2 locus in ssp. strangulata could be adaptive. It seems that Hst2 ¹⁰²⁶ allele is disadvantageous in western Precaspian Iran, the region with the high annual rainfall, and being eliminated by natural selection.