Origins of the new allopolyploid species Senecio cambrensis (asteraceae) and its relationship to the canary islands endemic Senecio teneriffae

The distribution of a 330 bp cpDNA insertion was reexamined in British material of Senecio cambrensis (2n = 6x = 60), its two putative parental taxa, S. squalidus (2n = 2x = 20) and S. vulgaris (2n = 4x = 40), and the closely related Canary Islands' endemic S. teneriffae (2n = 6x = 60). This formed part of a test of the hypothesis that the Welsh form of S. cambrensis is derived from introduced S. teneriffae rather than having originated in Wales via allopolyploidy as previously supposed. It was established that the 330 bp insertion was carried by all plants of Welsh S. cambrensis and also S. teneriffae, but was absent from the cpDNA of Edinburgh S. cambrensis and all plants of British S. squalidus and S. vulgaris var. vulgaris surveyed. However, two of 19 individuals tested of S. vulgaris var. hibernicus also possessed the cpDNA insertion, indicating that it is present in British material of S. vulgaris, although at low frequency. The close similarity between S. teneriffae and S. cambrensis, especially the Welsh form of S. cambrensis, was confirmed by the results of a restriction analysis of rDNA, and also morphometric and crossing studies. However, isozyme analysis showed that S. teneriffae is monomorphic for βEST-3 and ACO-1 phenotypes that are not present in Welsh and Edinburgh S. cambrensis, nor in S. squalidus and S. vulgaris material surveyed. It is concluded that S. teneriffae and S. cambrensis are two closely related allohexaploid taxa that have very similar, but different origins. It is postulated that whereas S. cambrensis (in Wales and Edinburgh) is the allohexaploid of S. vulgaris and S. squalidus, S. teneriffae is possibly the allohexaploid of S. vulgaris and S. glaucus, the latter being a diploid species closely related to S. squalidus.     

Isozyme evidence and the origin ofSenecio vulgaris (Compositae)

An electrophoretic survey of isozyme variation was conducted to test the hypothesis thatSenecio vulgaris L. (2n = 40) is of autotetraploid origin fromS. vernalis Waldst. & Kit. (2n = 20). It was established thatS. vulgaris exhibited fixed heterozygosity at three loci examined, showed disomic inheritance at all polymorphic loci, and contained a gene (Est-1) and an allele (Aat-3b) which were not present in the single population ofS. vernalis surveyed. From this it is concluded thatS. vulgaris is not of autotetraploid origin. Instead, the genetic evidence is in keeping with an allopolyploid origin ofS. vulgaris with the possibility thatS. vernalis acted as one of its two parents.     

The origin ofSenecio vulgaris (Asteraceae)

Senecio vulgaris L. (2n = 40) is suggested to be of autotetraploid origin fromS. vernalis Waldst. & Kit. (2n = 20). This conclusion is based on results obtained from experimental hybridisations and cytological observations, and the consideration of morphological affinities, patterns of geographical distribution and hybrid formation under natural conditions. The morphological differences between the two species are related to a difference in the breeding system. WhilstS. vernalis is self-incompatible,S. vulgaris is self-compatible and strongly self-pollinating. Equally, other self-pollinating taxa traditionally associated withS. vulgaris are shown to have evolved independently from outbreeding relatives. Within a narrow frame of relationship, annual weeds have evolved in different cytotaxonomic circumstances.     

Ein Beitrag zur Zytotaxonomie der GattungSilene L. in Griechenland

Zusammenfassung Die Chromosomenzahlen vonS. cythnia, graeca, integripetala, insularis, rigidula undsedoides werden erstmals mitgeteilt. BeiS. fructicosa, colorata, conica ssp.sartorii, nicaeensis, nocturna undparadoxa konnten frühere Zählungen bestätigt werden. Alle Arten sind diploid mit 2n=24 Chromosomen.VonS. vulgaris ssp.vulgaris wurde eine tetraploide Pflanze mit einigen meiotischen Störungen gefunden.Zu einzelnen Arten werden kritische Bemerkungen zur Systematik und Zytologie gemacht.     

Recent hybrid origin and invasion of the British Isles by a self-incompatible species, Oxford ragwort (Senecio squalidus L., Asteraceae)

Senecio squalidus is a diploid hybrid species which originated in the British Isles following the introduction of material collected from a hybrid zone on Mount Etna, Sicily, approximately 300 years ago. Introduced hybrid material was cultivated in the Oxford Botanic Garden and gave rise to the stabilized diploid hybrid species, which later spread throughout much of the UK and into some parts of Ireland. Unusually for an invasive species, S. squalidus has a strong system of sporophytic self-incompatibility (SSI) that may have become modified as a result of its recent hybrid origin and spread. First, S. squalidus contains relatively few S alleles (between 2 and 6 S alleles within individual UK populations) compared to other species with SSI (estimates average ~17 S alleles per population). This most probably reflects the population bottleneck experienced by introduced hybrid material. Second, dominance relationships among S. squalidus S alleles are more extensive than those reported in other species with SSI. Third, although pseudo-self-compatibility occurs sporadically in S. squalidus, it is not widespread, indicating that SSI is maintained in the species despite potential mate availability restrictions imposed by low numbers of S alleles. Surveys of other forms of genetic diversity in S. squalidus show that allozyme variation is reduced relative to that within the progenitor species, but Randomly Amplified Polymorphic DNA variation is relatively high. Both types of genetic variation show little or no pattern of isolation-by-distance between populations in keeping with the recent range expansion of the species. During its spread in the British Isles, S. squalidus has hybridized with the native self-compatible (SC) tetraploid species, S. vulgaris, which has led to the origin of three new SC hybrid taxa: a radiate form of S. vulgaris (var. hibernicus), a tetrapoid hybrid species (S. eboracensis) and an allohexaploid (S. cambrensis).     

A new cytotype of Jacobaea vulgaris (Asteraceae): frequency,morphology and origin

Jacobaea vulgaris subsp. vulgaris (syn. Senecio jacobaea subsp. jacobaea) constitutes an intricate polyploid complex distributed in Europe. Four cytotypes have been reported in this species, three with euploid (diploid, tetraploid and octoploid; 2n=20, 40 and 80) and one with aneuploid (2n=32) chromosome numbers. Here we report that the diploid chromosome number (2n=20) reported from Bulgaria is due to misidentification with Jacobaea aquatica. On the other hand, we have discovered a new, hexaploid (2n=6x=60) cytotype within J. vulgaris subsp. vulgaris using flow cytometry. The new cytotype occurs within four sympatric populations of otherwise tetraploid and octoploid plants in Pannonia (one locality in the eastern Czech Republic and two localities in southwestern Slovakia) and in Podillya (one locality in western Ukraine). The frequency of hexaploid individuals within 76 studied populations is very low (only 10 of 693 analysed plants), and hexaploids probably represent hybrids between tetraploid and octoploid plants. Three mixed populations with hexaploid plants were subjected to detailed morphological and pollen fertility analyses. Multivariate morphometric analysis reveals partial separation of tetraploid and octoploid plants, whereas hexaploid individuals are similar in morphology to octoploids. In comparison with tetraploids, octoploids and hexaploids exhibit slightly longer ray florets, involucral bracts and tubular florets and more hairy outer achenes. Hexaploid plants display larger pollen grains and lower pollen fertility compared to tetraploids and octoploids.     

Chromosome studies in nine species of Austrian Symphyla (Myriapoda,Tracheata, Arthropoda)

The chromosomes of nine species of Austrian Symphyla, namely, Scutigerella causeyae, S. sp., S. sbordonii, S. palmonii, S. carpatica, S. seposita, Hanseniella nivea (fam. Scutigerellidae), Symphylella isabellae and S. vulgaris (fam. Scolopendrellidae) were studied using Giemsa-C-banding and fluorochrome staining techniques. Male diploid chromosome numbers range from 11 to 18. The mechanism of sex determination seems to be variable within this group: S. isabellae (2n=11) might have an XO-type, whereas the other species studied have even diploid chromosome numbers in the male sex. For S. causeyae, specimens with B-chromosomes and an obviously tetraploid form have been detected.     

Chloroplast DNA and isozyme evidence on the evolution ofSenecio vulgaris (Asteraceae)

Chloroplast DNA (cpDNA) and isozyme variation were analyzed over a range of populations of two infraspecific taxa of the tetraploidSenecio vulgaris. The isozyme data were supportive of the hypothesis that the weedy and cosmopolitanS. vulgaris var.vulgaris is an evolutionary derivative ofS. vulgaris subsp.denticulatus from the coasts of W Europe and montane altitudes in S Spain and Sicily. The two taxa exhibited a very high genetic identity with subsp.denticulatus containing slightly more isozyme diversity than was found in var.vulgaris. — Three cpDNA haplotypes (A, B, C) already known from other Mediterranean diploid species ofSenecio were resolved in var.vulgaris, and an additional fourth haplotype (E) was found in subsp.denticulatus. Two alternative hypotheses were chosen to account for the origin and maintenance of the observed cpDNA composition ofS. vulgaris. It either reflects (1) the retention of an ancestral polymorphism which stems from the recurrent and polytopic formation of ancestral tetraploid lineages; or (2)S. vulgaris originally was characterized by haplotype E, and haplotypes A, B and C were acquired through repeated introgressive hybridization with related diploid species. The finding that very low levels of nuclear (isozyme) diversity were present in both taxa ofS. vulgaris examined supports the second of these two hypotheses; however, more detailed analysis of nuclear genetic diversity is required before a firm conclusion can be reached on this matter.Dedicated to emer. Univ.-Prof. DrFriedrich Ehrendorfer on the occasion of his 70th birthday     

Description de Syphabulea mascomai n. sp. et analyse du genre Syphabulea

Syphabulea mascomai n. sp., parasite de Sciurus vulgaris (L.) en Espagne, est décrite. S. mascomai se distingue des autres espèces du genre par: (i) la grande taille de ses oeufs; (ii) la taille relativement réduite de l'opercule de ces oeufs; (iii) par les particularités de l'ornementation du crochet accessoire au gubernaculum. La systématique et la répartition géographique des espèces du genre Syphabulea Gubanov, 1964 sont discutées. L'espèce type du genre est Syphabulea tjanschani (Ablasov, 1962) n. comb. [= Syphacia sp. d'Ablasov in Skrjabin et al. (1960); =Syphacia tjanschani Ablasov, 1962; =S. toschevi Petrov & Bayanov, 1962; =S. thompsoni sensu Li (1933); =S. thompsoni sensu Gubanov (1964); = Syphabulea sobolevi Gubanov, 1964]. Le genre Syphabulea n'était jusqu'ici connu que dans le région orientale, la région néarctique, et l'Est de la région paléarctique. La découverte d'un nouveau Syphabulea dans la péninsule ibérique, dont la faune parasitaire présente des caractères endémiques et relictuels, montre que la présence de ce genre dans la région paléarctique est probablement ancienne. Le genre Syphabulea est sympatrique du genre Rodentoxyuris Quentin & Tenora, 1975, lui aussi spécifique de Rongeurs Sciuroidea, dans une partie importante de la région holarctique. Syphabulea mascomai n. sp., parasitic in the caecum and large intestine of Sciurus vulgaris (L.) in Spain, is described. S. mascomai is characterised by: (i) its very large eggs; (ii) a shorter operculum on the eggs; and (iii) by the peculiar shape of the ornamentation of the accessory piece of gubernaculum. The systematics and the zoogeographical range of the genus Syphabulea Gubanov, 1964 are discussed. The type-species of the genus is: Syphabulea tjanschani (Ablasov, 1962) n. comb. [=Syphacia sp. of Ablasov in Skrjabin et al. (1960); =Syphacia tjanschani Ablasov, 1962; =S. toschevi Petrov & Bayanov, 1962, = S. thompsoni sensu Li (1933); =S. thompsoni sensu Gubanov (1964); =Syphabulea sobolevi Gubanov, 1964]. Until now the genus Syphabulea was known only from the Oriental region, from the Nearctic region and from the asiatic part of the Palearctic region. The discovery of a new species from Spain, an area in which the parasitological fauna exhibits endemic and relictual characteristics, indicates that this genus has probably been present in this part of Europe for quite a long time. The zoogeographical range of genus Syphabulea involves most of the Holarctic region, where it is sympatric with Rodentoxyuris Quentin & Tenora, 1975, another genus parasitic in the Sciuroidea.Se describe a Syphabulea mascomai n. sp. como parásito de Sciurus vulgaris (L.) en España. S. mascomai se distingue de las otras especies del género por: (i) el gran tamaño del los huevos; (ii) el tamaño, relavitamente reducido, del operculo de los huevos; (iii) las características de la ornemantación del gancho accesorio del gubernáculo. Se discute la sistemática y la repartición geográfica de las especies del género Syphabulea Gubanov, 1964. La especie tipo es: Syphabulea tjanschani (Ablasov, 1962) n. comb. [= Syphacia sp. del Ablasov in Skrjabin et al. (1960); =Syphacia tjanschani Ablasov, 1962; =S. toschevi Petrov & Bayanov, 1962; =S. thompsoni sensu Li (1933); =S. thompsoni sensu Gubanov (1964); = Syphabulea sobolevi Gubanov, 1964]. Hasta el presente se tenían datos del género Syphabulea en la Región Oriental, la Región Neártica y en el este de la Región Paleártica. El hallazgo de Syphabulea en la Península Ibérica, donde las parasitofaunas presentan características endémicas y relictuales, viene a sugerir que la presencia del género en la Región Paleártica es muy antigua. El género Syphabulea es simpátrico del género Rodentoxyuris Quentin & Tenora, 1975, tambien específico de Roedores Sciuroidea en la mayor parte de la Región Holártica.     

风毛菊属6种植物的核型分析

采用常规压片技术对分布于横断山区菊科(Compositae)风毛菊属(Saussurea DC.)的6种植物进行染色体数目和核型分析。结果表明:尖苞雪莲（S.polycolea var.acutisquama）核型公式为:2n=2x=32=20m+12sm,属2B型;球花雪莲核（S.globosa）型公式为:2n=2x=34=16m+18sm,属2B型;重齿风毛菊(S.katochaete)核型公式为:2n=2x=32=8m+18sm+6st,属3B型;柱茎风毛菊(S.columnaris)核型公式为:2n=2x=32=24m+8sm,属2B型;禾叶风毛菊(S.graminea)核型公式为:2n=2x=28=8m+18sm+2st,属3B型;长毛风毛菊(S.hieracioides)核型公式为:2n=2x=32=12m+16sm+4st,属2B型。6个种染色体中均未发现随体。其中尖苞雪莲和柱茎风毛菊染色体为首次报道。     

The purification and some properties of cocoa necrosis virus, a serotype of tomato black ring virus

Cocoa necrosis virus (CNV) was transmitted by sap inoculation to twelve of twenty-one species tested. It was propagated and assayed in Phaseolus vulgaris. Sap from P. vulgaris was infective after dilution to 10^-3but not 10^-4, after 10 min at 60 d?C but not 65 d?C, and after 4 but not 7 days at 20–24 d?C. Lyophilized sap from P. vulgaris was infective after 2 years in vacuo. Virus was prepared by extracting infected leaves of P. vulgaris with 0.1 M phosphate (pH 7.5) containing 0.05 M ethylene diamine tetra-acetate and 0.02 M thioglycollate. After clarification with n-butanol, virus was purified by precipitation with polyethylene glycol and several cycles of differential centrifugation. Such preparations were very infective and contained numerous particles, 24–26 nm in diameter with a hexagonal profile, which sedimented as two components with sedimentation coefficients (Sd?_20,w) of 101 S and 129 S. The absorption spectra of both components with maximum and minimum absorption at 259 and 240 nm respectively were typical of nucleoproteins (101 S component, A 260/280 = 1.63; A 260/240 = 1.40:129 S component, A260/280 = 1.78; A260/240 = 1.58) and indicated nucleic acid contents of ca. 35% for the 129 S component and ca. 20% for the 101 S component; values calculated from the sedimentation coefficients were 41 and 30% respectively. Only the 129 S component seemed to be infective and was not more so when mixed with 101 S component. Both components contained a single protein subunit weighing ca. 60000 daltons. Under certain conditions sap fractionated without butanol gave virus preparations containing empty protein shells (54 S) and small spherical particles (20–30 S) ca. 12 nm diameter. CNV is a serotype of tomato blackring virus and is distantly related to Hungarian chrome mosaic virus. The cryptogram of CNV is */*:*/(35–41):S/S:S/*.     

Chromosomes of Syrphidae

This report describes the karyotypes of five species of the tribe Sericomyiini (Diptera, Syrphidae). The five species are: Sericomyia chalcopyga Lw. (2n=12), S. chrysotoxoides Mq. (2n=10), S. lata (Coq.) (2n = 12), S. militaris Walker (2n=12) and S. sp. 1 (2n=10). Polytene chromosomes of Arctophila flagrans O. S. are illustrated.Dedicated to Prof. J. Seiler on the occasion of his 80th birthday.     

Role of fructose-1,6-bisphosphatase, fructose phosphotransferase, and phosphofructokinase in saccharide metabolism of four C3 grassland species under elevated CO2

We studied the effects of 15-months of elevated (700 μmol mol⁻¹) CO₂ concentration (EC) on the CO₂ assimilation rate, saccharide content, and the activity of key enzymes in the regulation of saccharide metabolism (glycolysis and gluconeogenesis) of four C₃ perennial temperate grassland species, the dicots Filipendula vulgaris and Salvia nemorosa and the monocots Festuca rupicola and Dactylis glomerata. The acclimation of photosynthesis to EC was downward in F. rupicola and D. glomerata whereas it was upward in F. vulgaris and S. nemorosa. At EC, F. rupicola and F. vulgaris leaves accumulated starch while soluble sugar contents were higher in F. vulgaris and D. glomerata. EC decreased pyrophosphate-D-fructose-6-phosphate l-phosphotransferase (PFP, EC 2.7.1.90) activity assayed with Fru-2,6-P₂ in F. vulgaris and D. glomerata and increased it in F. rupicola and S. nemorosa. Growth in EC decreased phosphofructokinase (PFK, EC 2.7.1.11) activity in all four species, the decrease being smallest in S. nemorosa and greatest in F. rupicola. With Fru-2,6-P2 in the assay medium, EC increased the PFP/PFK ratio, except in F. vulgaris. Cytosolic fructose-1,6-bisphosphatase (Fru-1,6-P₂ase, EC 3.1.3.11) was inhibited by EC, the effect being greatest in F. vulgaris and smallest in F. rupicola. Glucose-6-phosphate dehydrogenase (G6PDH EC 1.1.1.49) activity was decreased by growth EC in the four species. Activity ratios of Fru-1,6-P₂ase to PFP and PFK suggest that EC may shift sugar metabolism towards glycolysis in the dicots.     

Patterns of genetic diversity in the red squirrel (Sciurus vulgaris L.): Footprints of biogeographic history and artificial introductions

British S. vulgaris are classified as aseparate subspecies, S. v. leucourus, tomainland Europe. While S. vulgaris is notunder threat across most of its Eurasian range,in Britain, Ireland and Italy populations aredeclining, mainly due to the introduction ofthe American grey squirrel (S.carolinensis). In this study, we conducted anextensive survey of mitochondrial DNA variationin British S. vulgaris populations and apreliminary survey of continental Europeanpopulations. Our main aims were to determinethe extent to which any populations of S.vulgaris in Britain are partially or whollythe product of artificial translocation of redsquirrels from continental Europe, and whethercontinental population variation will provideinformation on post-glacial reafforestationpatterns in Europe. We found that the majorityof extant populations of British S.vulgaris are of continental ancestry, manywith a very recent (last 40 years) Scandinavianancestry. The Scandinavian haplotype hasrapidly become the most dominant innortheastern Britain, despite not appearing innorthern English populations until 1966. Thissuggests that these squirrels may have anadaptive advantage in the non-native sprucedominated conifer plantations of northernEngland. Our preliminary examination ofcontinental populations demonstrated that theyare sufficiently differentiated to allow aphylogeographic study of this species.     

Chemical composition of the cell wall in some green algae species

Cell walls of two strains ofChlorella vulgaris (from fresh water, F, and saline water, S) and ofKirchneriella lunaris contained various proportion of saccharides and proteins (highest percentage in dry matter was found inK. lunaris). They differed also in presence of individual monosaccharides (5 inC. vulgaris F, 8 inC. vulgaris S and 6 inK. lunaris) and amino acids (11 in C.vulgaris F, 6 in C.vulgaris S and 7 inK. lunaris). Common substances were rhamnose, cystine, proline, glutamic acid and leucine. Communicated by Z. ŠESTáK     

Karyology of theScorzonera (Compositae) species from the Iberian Peninsula

A karyological study of 15 taxa ofScorzonera L. from the Iberian Peninsula has been made. The chromosome numbers found inS. hispanica var.pinnatifida, S. baetica, S. reverchonii, S. angustifolia, S. laciniata var.calcitrapifolia and var.subulata (2n = 14) are new. Diploid cytotypes with 2n = 14 and 2n = 12 prevail, andS. hispanica var.crispatula is the only taxon which exhibits autopolyploidy (2n = 14, 28). x = 7 is considered to be the base chromosome number within the genus, with x = 6 being derived from it by translocation. This and detailed karyotype analyses allow to group the Iberian Peninsula species ofScorzonera into three groups.     

Plant species effect on the spatial patterns of soil properties in the Mu-us desert ecosystem,Inner Mongolia,China

Although Artemisia ordosica Krasch. and Sabina vulgaris Ant. are the dominant shrub species in the Mu-us desert ecosystem, they differ in their botanical traits. We investigated the spatial patterns of soil properties using geostatistical analysis to examine the effect of plant species on these spatial patterns. Comparison among three microsite types (under A. ordosica, under S. vulgaris, and the opening between vegetation) showed that A. ordosica generally had less effect than S. vulgaris on local soil properties. The long life-span, prostrate life-form, and evergreen leaf-habit of S. vulgaris may lead to a higher accumulation of organic and fine materials under S. vulgaris. The range of spatial autocorrelation found in the mass of organic matter on the soil surface was smaller than that of the coverage of S. vulgaris (11.5 m) which corresponded to the canopy patch size of this species, and was longer than the canopy patch size of A. ordosica. The ranges of total C and N, and pH (11.7–15.6 m) were similar to that of S. vulgaris. The range of available P (106.3 m) was comparable to that of the coverage of A. ordosica (86.2 m) considered to be the scale of the distribution of this species. The ranges of silt+clay and exchangeable K, Ca, and Mg (31.0–46.7 m) were not related to plant presence, and were similar to that of topography (43.1 m).     

基于荧光原位杂交的藜属植物核型分析

为精确地识别藜属植物染色体组的核型特征,该文研究了4种来自青海高原的野生藜属植物(灰绿藜、藜、菊叶香藜及杂配藜)和1种从美国引进的栽培藜麦品种PI614932-HX(3)基于染色体荧光原位杂交(rDNA FISH)的核型。利用5S rDNA和45S rDNA对5种藜属植物有丝分裂中期的染色体进行FISH研究。藜属植物的核型分析结果表明:(1)藜属植物中存在二倍体(2n=2x=18)和四倍体(2n=4x=36)两种倍性,藜麦和灰绿藜为四倍体,其余3种为二倍体。(2)藜麦、灰绿藜、藜、菊叶香藜及杂配藜的核型公式分别为2n=4x=36=34m(2AST)+2sm,2n=4x=36=32m(4AST)+4sm,2n=2x=18=16m(4AST)+2sm,2n=2x=18=18m及2n=2x=18=16m+2sm。(3)染色体由大部分的中部着丝粒染色体(m)和少部分近中部着丝粒染色体(sm)组成。(4)核型类型除了菊叶香藜为1B以外,其余均属于2B类型。(5)在藜麦、灰绿藜及藜中具有分布位置不同、数量不等的双随体。5S rDNA、45S rDNA FISH结果表明:(1)藜麦和灰绿藜的染色体上存在2对5S rDNA位点和1对45S rDNA位点,藜、杂配藜的染色体上存在1对5S rDNA位点和1对45S rDNA位点,菊叶香藜的染色体上只存在1对5S rDNA位点。(2)5S rDNA和45S rDNA位点均位于染色体的短臂上。该研究首次获得了藜属植物基于5S rDNA和45S rDNA荧光原位杂交核型,为藜属植物亲缘关系研究和细胞生物学研究提供了分子细胞遗传学依据。     

Cytogenetic analysis of Lycopersicon esculentum (+) Solanum etuberosum somatic hybrids and their androgenetic regenerants

The aim of the study was to characterize genomic relationships among cultivated tomato (Lycopersicon esculentum Mill.) (2n=2x=24) and diploid (2n=2x=24) non-tuberous wild Solanum species (S. etuberosum Lindl.). Using genomic in situ hybridization (GISH) of mitotic and meiotic chromosomes, we analyzed intergeneric somatic hybrids between tomato and S. etuberosum. Of the five somatic hybrids, two plants were amphidiploids (2n=4x=48) mostly forming intragenomic bivalents in their microsporocytes, with a very low frequency of multivalents involving the chromosomes of tomato and S. etuberosum (less than 0.2 per meiocyte). Tomato chromosomes showed preferential elimination during subsequent meiotic divisions of the amphidiploids. Transmission of the parental chromosomes into microspores was also evaluated by GISH analysis of androgenic plants produced by direct embryogenesis from the amphidiploid somatic hybrids. Of the four androgenic regenerants, three were diploids (2n=2x=24 or 2n=2x+1=25) derived from reduced male gametes of the somatic hybrids, and one plant was a hypertetraploid (2n=4x+4=52). GISH revealed that each anther-derived plant had a unique chromosome composition. The prospects for introgression of desirable traits from S. etuberosum into the gene pool of cultivated tomato are discussed. Received: 2 August 2000 / Accepted: 4 December 2000