Interspecific F1 Hybrids Research Articles

Epitopes Of Tilapia Red Blood Cells. I. Species-Specific Antibodies For The Control Of Tilapia Breeding Stocks

Specific antisera against red blood cells of some tilapia species were obtained by reciprocal inter- specific and intergeneric immunizations. The antisera were used to confirm co-dominant expres- sion of epitopes in F1 interspecific hybrids and to identify the parental origin of three red tilapia strains. The antisera in all hybrids (Oreochromis niloticus x O. mossambicus, O. aureus x O. horno- rum, O. niloticus x S. galilaeus and O. niloticus x O. aureus) were positive to both parental strains. However, while all F1 hybrids of O. mossambicus x O. hornorum were positive to anti-O. mossambi- cus antiserum, only 50% were positive to anti-O. hornorum antiserum. In most cases, these results point to co-dominant expression of the species-specific epitopes in hybrids. In addition, the triple parental origins of the Philippine red tilapia (positive for O. aureus, O. mossambicus and O. niloticus epitopes) and of mossambicus red tilapia (positive for O. hornorum, O. mossambicus and O. niloticus epitopes) were assessed. The O. niloticus red tilapia, described as a purebred red variant of O. niloticus, was positive for both anti-O. niloticus and anti-O. aureus antibodies, with a significantly more intense reaction to the latter. A possible genetic basis of this last finding is discussed.

Plant regeneration from interspecific hybrid and backcross progeny of Helianthus eggertii × Helianthus annuus

An efficient protocol for plant regeneration from leaves of the interspecific hybrid Helianthus eggertii Small. × Helianthus annuus L. was developed. The regeneration capacity of the first backcross progeny is reported. Leaves from the F1 interspecific hybrid were cultured on Murashige and Skoog basal media (MS) supplemented with α-naphthalenacetic acid (NAA), N6-benzyladenine (BA), AgNO3, KNO3, casein hydrolysate and adenine sulfate. Embryo-like structures and/or shoots regeneration were observed on most of the tested media. The best results were obtained on media with a higher concentration of cytokinin (8.8 μM BA) and lower concentration of auxin (1.08 μM NAA). The addition of casein hydrolysate in the media increased the regeneration efficiency. Plant regeneration was achieved via somatic embryogenesis and direct organogenesis. The regeneration potential of leaf, stem and root explants of eighteen first backcross lines was studied. Most of the tested lines were highly regenerable and some of them had DNA content closely related to that of Helianthus annuus L.

Using the collection of wild species in sunflower breeding

We started to collect wild sunflower (Helianthus L) species in 1998. The main task of this collection is to promote the development of new breeding material. In particular, it was planned to use the wild species as resistance sources to the major diseases of sunflower and as Rf genes sources to the new CMS types. The collection consists presently of 140 accessions of annual wild species and 110 samples of 27 perennial ones. The assessment of the wild sunflowers collection for resistance to Sclerotinia (Sclerotinia sclerotiorum) Phomopsis {Phomopsis helianthi) and broomrape (Orobanche cumana) was carried out on artificial infectious backgrounds. Resistance to other diseases was estimated simultaneously under natural infection. The immunologic potential of the collection was assessed three times during the vegetative period: at early stages of ontogeny (first week of June), at full flowering (second week of August) and at the end of the vegetation period (fourth week of September). A group of 101 samples showed various types of resistance to a complex of diseases. F1 and F2 generations were produced from more than 100 cross combinations of sunflower inbred lines and wild annual species. The tolerance to Phomopsis in field conditions was recorded in the F1 and F2 interspecific hybrids. Also, several sources of fertility restoration for new CMS types (ANN1, ARG1, PEF1, GIG1 and RIG1) have been found among the accessions of wild annual sunflower species. Thus, certain samples from the collection may be useful for breeding to disease resistance. The development of new initial material for sunflower breeding has already started.

Rhizobium specificity of Trifolium ambiguum M. Bieb × T. repens L. hybrid clovers

Growth of full-sib families of an F1 interspecific hybrid between Trifolium ambiguum M.Bieb and T. repens L, and two generations of backcross hybrids (BC1F2 and BC2F1) with T. repens as the recurrent parent, were compared to their parental species. Plants were grown in a N-free medium and inoculated with Rhizobium leguminosarum biovar trifolii rhizobia effective on T. ambiguum or T. repens. Hybridisation produced progeny that nodulated with rhizobia from either T. ambiguum or T. repens, but plant growth varied. Mean weights of T. repens and hybrids, particularly F1 and BC1F2, were higher when inoculated with a mixture of strains isolated from field grown T. repens than with the New Zealand inoculant strain for T. repens. When inoculated with the mix of rhizobia from T. repens, mean weights were 242, 189, 132, 125, and 100 mg/plant for T. repens, BC2F1, BC1F2, F1 and T. ambiguum, respectively. However, although the mean weight of BC2F1 lines was significantly less than T. repens, there was considerable variation in individual full-sib families indicating the potential to select within BC2F1 hybrids for high plant growth/symbiotic nitrogen fixation. The weight of T. ambiguumplants inoculated with the New Zealand inoculant strain for hexaploid T. ambiguum was similar to T. repens inoculated with the mix of rhizobia from T. repens (253 and 242 mg/plant, respectively). Mean fresh weights of F1 hybrid plants were similar when inoculated with rhizobia for T. ambiguum or T. repens (125 and 130 mg/plant, respectively). However, weight of T. repens, BC1F2 and BC2F1 hybrids inoculated with rhizobia for T. ambiguum were all less than 90 mg/plant. There was a significant relationship between plant fresh weight and ethylene production. The results indicate that measuring weights of inoculated plants growing in N-free media is a rapid initial method of screening a range of plant germplasm for plant growth/symbiotic nitrogen fixation rates.

Transmission genetics of chromatin from a synthetic amphidiploid to cultivated peanut (Arachis hypogaea L.). broadening the gene pool of a monophyletic polyploid species.

Polyploidy creates severe genetic bottlenecks, contributing to the genetic vulnerability of leading crops. Cultivated peanut is thought to be of monophyletic origin, harboring relatively little genetic diversity. To introduce variability from diploid wild species into tetraploid cultivated Arachis hypogaea, a synthetic amphidiploid [[A. batizocoi K9484 x (A. cardenasii GKP10017 x A. diogoi GKP10602)](4x)] was used as donor parent to generate a backcross population of 78 progeny. Three hundred seventy RFLP loci were mapped onto 23 linkage groups, spanning 2210 cM. Chromatin derived from the two A-genome diploid ancestors (A. cardenasii and A. diogoi) comprised mosaic chromosomes, reflecting crossing over in the diploid A-genome interspecific F(1) hybrid. Recombination between chromosomes in the tetraploid progeny was similar to chromosome pairing reported for A. hypogaea, with recombination generally between chromosomes of the same subgenomic affinity. Segregation distortion was observed for 25% of the markers, distributed over 20 linkage groups. Unexpectedly, 68% of the markers deviating from expected segregation showed an excess of the synthetic parent allele. Genetic consequences, relationship to species origins, and significance for comparative genetics are discussed.

Seedling herbivory by slugs in a willow hybrid system: developmental changes in damage, chemical defense, and plant performance.

We evaluated feeding preference and damage by the slug, Arion subfuscus, on seedlings of two willow species, Salix sericea and S. eriocephala, and their F1 interspecific hybrids. Trays of seedlings were placed in the field and excised leaves were presented to slugs in choice tests. Slugs preferred feeding on and caused the most damage to S. eriocephala seedlings. S. sericea seedlings were least preferred and least damaged. F1 hybrid seedlings were intermediate in preference and damage. Slug preference of and damage to these seedlings decreased over time, suggesting developmental changes in resistance. Seedlings were sampled for phenolic glycoside and tannin chemistry weekly to coincide with the field and laboratory experiments. Concentrations of phenolic glycosides and tannins increased linearly with seedling age, coincident with changes in slug preference and damage, indicating a developmental change in defense. Slug deterrence was not detected at low concentrations of salicortin when painted on leaves or discs, but both salicortin and condensed tannins deterred slug feeding at concentrations between 50 and 100mg/g, levels found in adult willows. Seedling performance was related to damage inflicted by slugs. Due to lower levels of damage when exposed to slugs in the field, S. sericea plants had significantly greater biomass than S. eriocephala plants. Biomass of F1 hybrids was equal to S. sericea when damaged. However, undamaged S. eriocephala and F1 hybrid plants had the greatest biomass. Because F1 hybrid seedlings performed as well as the most fit parent in all cases, slugs could be an important selective factor favoring introgression of defensive traits between these willow species.

Genomic in situ hybridization (GISH) discriminates between the A and the B genomes in diploid and tetraploid Setaria species

Genomic in situ hybridization (GISH) was used to investigate genomic relationships between different Setaria species of the foxtail millet gene pool (S. italica) and one interspecific F1 hybrid. The GISH patterns obtained on the two diploid species S. viridis (genome A) and S. adhaerans (genome B), and on their F1 hybrid showed clear differentiation between these two genomes except at the nucleolar organizing regions. Similar GISH patterns allowed differentiation of S. italica from S. adhaerans. However, GISH patterns did not distinguish between the genomes of S. italica and its putative wild ancestor S. viridis. GISH was also applied to polyploid Setaria species and enabled confirmation of the assumed allotetraploid nature of S. faberii and demonstration that both S. verticillata and S. verticillata var. ambigua were also allotetraploids. All these tetraploid species contained two sets of 18 chromosomes each, one from genome A and the other from genome B. Only one polyploid species, S. pumila, was shown to bear an unknown genomic composition that is not closely related either to genome A or to genome B.Key words: Setaria, genomic in situ hybridization, genome analysis.

Allopolyploidy-induced rapid genome evolution in the wheat (Aegilops-Triticum) group.

To better understand genetic events that accompany allopolyploid formation, we studied the rate and time of elimination of eight DNA sequences in F1 hybrids and newly formed allopolyploids of Aegilops and TRITICUM: In total, 35 interspecific and intergeneric F1 hybrids and 22 derived allopolyploids were analyzed and compared with their direct parental plants. The studied sequences exist in all the diploid species of the Triticeae but occur in only one genome, either in one homologous pair (chromosome-specific sequences [CSSs]) or in several pairs of the same genome (genome-specific sequences [GSSs]), in the polyploid wheats. It was found that rapid elimination of CSSs and GSSs is a general phenomenon in newly synthesized allopolyploids. Elimination of GSSs was already initiated in F1 plants and was completed in the second or third allopolyploid generation, whereas elimination of CSSs started in the first allopolyploid generation and was completed in the second or third generation. Sequence elimination started earlier in allopolyploids whose genome constitution was analogous to natural polyploids compared with allopolyploids that do not occur in nature. Elimination is a nonrandom and reproducible event whose direction was determined by the genomic combination of the hybrid or the allopolyploid. It was not affected by the genotype of the parental plants, by their cytoplasm, or by the ploidy level, and it did not result from intergenomic recombination. Allopolyploidy-induced sequence elimination occurred in a sizable fraction of the genome and in sequences that were apparently noncoding. This finding suggests a role in augmenting the differentiation of homoeologous chromosomes at the polyploid level, thereby providing the physical basis for the diploid-like meiotic behavior of newly formed allopolyploids. In our view, this rapid genome adjustment may have contributed to the successful establishment of newly formed allopolyploids as new species.

Inheritance of the delayed gland morphogenesis trait in Australian wild species ofGossypium

Five Australian wild cotton species with the delayed gland morphogenesis trait, as well asG arboreum, G davidsonii and four different gland genotypes ofG hirsutum, Gl2Gl2Gl3Gl2, Gl2Gl2gl3gl3, gl2gl2Gl3G3, and gl2gl2gl3gl3, were used in this experiment and 10 interspecific hybrids were obtained by the crossing among them. According to the gland expression on the seeds and plants of the interspecific hybrids, the inheritance of the delayed gland morphogenesis trait of Australian wild cotton species was opened out as follows: ( i ) the inheritance of the delayed gland morphogenesis trait was almost the same among the 5 Australian wild cotton species, and the gene or genes which controlled this trait may be located in the same loci. (ii) The glandless seed trait of the Australian wild cotton species was dominant over the glanded seed trait ofG arboreum, a genome A species, and the seeds of interspecific hybrid F1 between them were glandless. However, it was recessive over the glanded character of genome D species,G davidsonii, and their F1 was a typical glanded one. (iii) The glandless seed trait of the Australian wild cotton species was recessive or incomplete dominant over the glanded cotton but dominant over the glandless cotton ofG hirsutum, and the glandless genes (gl2gl2gl3gl3 of upland cotton had great weakening effect on the glanded plant trait of the Australian wild cotton species on the other hand. For the two main glanded genes of upland cotton, the delayed gland morphogenesis trait of the Australian wild cotton species was dominant epistatic over glandless genes, gl2gl2gl3gl3, and one of the glanded genes, Gl2Gl2, but was recessive epistatic over the other glanded gene, Gl3Gl3. Therefore, it is much convenient to use Gl2Gl2gl3gl3 as the upland cotton parent in the interspecific hybridization and backcrossing afterward, in order to produce the upland cotton germplasm with glandless seeds and glanded plant trait.

Susceptibility of parent and interspecific F1 hybrid pine trees to tip moth damage in a coastal North Carolina planting

Tip moth damage among families of parent pine species and their interspecific F1 hybrids was quantitatively assessed in a coastal planting in North Carolina. Three slash pine (Pinus elliotti var. elliotti Engelm.), two loblolly pine (Pinus taeda L.), and four interspecific F1 hybrid pine families were used. The F1 hybrids were as susceptible to damage by Nantucket pine tip moth (Rhyacionia frustrana (Comst.)), as was their susceptible loblolly pine parent. Their phenotypes support a dominant or partially dominant mode of inheritance for susceptibility. The phenotype of one slash pine family was not statistically different from the phenotypes of the loblolly and F1 hybrid pines. The high susceptibility of that one slash pine family appeared to be intrinsic, even though slash pine is considered resistant to tip moth damage. Tip moth damage on the two other slash pine families was significantly lower.

Método de obtenção de híbridos interespecíficos entre Lycopersicon esculentum e L. peruvianum

A transferência de genes da espécie silvestre Lycopersicon peruvianum para a espécie L. esculentum por processo convencional de hibridação é limitada por incompatibilidade. O objetivo deste trabalho foi desenvolver um método de obtenção de híbridos entre essas duas espécies, mediante a técnica de cultura de óvulos, tendo em vista o interesse em transferir genes presentes em acessos de L. peruvianum que conferem resistência a Septoria lycopersici. Foram utilizados os acessos CNPH 946, CNPH 947 e CNPH 948 de L. peruvianum e as cultivares Floradade e Ipa-5 de L. esculentum. Sementes híbridas de frutos com 25-68 dias após a polinização foram colocadas para germinar inicialmente em meio de cultura Murashige & Skoog (MS), e posteriormente em meio HLH. As sementes foram incubadas no escuro a 25°C. Só foram regenerados os híbridos provenientes das sementes colocadas para germinar em meio HLH. Dezesseis híbridos foram obtidos de 1.573 óvulos, sendo de 1% a taxa de regeneração de plantas híbridas. As características morfológicas dos híbridos F1 quando comparadas com os dois genitores indicaram que as plantas eram realmente resultado da hibridação entre L. esculentum e L. peruvianum.

Genomic in situ hybridization (GISH) discriminates between the A and the B genomes in diploid and tetraploid <i>Setaria</i> species

Genomic in situ hybridization (GISH) was used to investigate genomic relationships between different Setaria species of the foxtail millet gene pool (S. italica) and one interspecific F1 hybrid. The GISH patterns obtained on the two diploid species S. viridis (genome A) and S. adhaerans (genome B), and on their F1 hybrid showed clear differentiation between these two genomes except at the nucleolar organizing regions. Similar GISH patterns allowed differentiation of S. italica from S. adhaerans. However, GISH patterns did not distinguish between the genomes of S. italica and its putative wild ancestor S. viridis. GISH was also applied to polyploid Setaria species and enabled confirmation of the assumed allotetraploid nature of S. faberii and demonstration that both S. verticillata and S. verticillata var. ambigua were also allotetraploids. All these tetraploid species contained two sets of 18 chromosomes each, one from genome A and the other from genome B. Only one polyploid species, S. pumila, was shown to bear an unknown genomic composition that is not closely related either to genome A or to genome B.

Esterase isozymes are useful to track introgression between Allium fistulosum L. and A. cepa L.

Polyacrylamide gel electrophoresis (PAGE) was used to study the polymorphism of esterases in Allium cepa L. and A. fistulosum L. Two varieties of each species, an A. fistulosum × A. cepa interspecific F1 hybrid, and (A. fistulosum × A. cepa) hybrid derivatives were analyzed for determination of banding patterns upon staining with α- and β-napthyl acetate substrates of esterase. Complex band patterns were observed. In total, 10 bands were detected between A. cepa and A. fistulosum — five inA. cepa, six in A. fistulosum with only one band common to both species. With the exception of one band unique to A. fistulosum which appeared only when stained with α-substrate, extracts of both A. cepa and A. fistulosum leaf tissue exhibited the same bands when stained with both α- and β-substrates. Bands stained with the different systems are distinguished by color: α-substrate always appeared black, while bands stained to β-substrate are always red. Esterase bands were assigned into 5 presumptive loci of four zones of activity with according to the migration distance of the bands from the front, color of each band upon staining with α- and β-substrates, and segregation observed in crosses and hybrid derivatives. Esterase enzymes detected in this study appear to be monomeric. Polymorphisms were identified between A. cepa and A. fistulosum by esterase banding patterns. Esterase enzymes provide an additional marker in monitoring introgression of foreign germplasm in interspecific onion breeding.

Susceptibility of parent and interspecific F1 hybrid pine trees to tip moth damage in a coastal North Carolina planting

Susceptibility of parent and interspecific F1 hybrid pine trees to tip moth damage in a coastal North Carolina planting

Allele-specific loss or imbalance of chromosomes 9, 15, and 16 in B-cell tumors from interspecific F1 hybrid mice carrying Emu-c-myc or N-myc transgenes.

Mice carrying an immunoglobulin enhancer (Emu-) linked c- or N-myc transgene develop fatal monoclonal or oligoclonal pre-B or B-cell lymphomas. This indicates that, beside the Emu-activated myc gene, additional genetic changes are required for tumor development. To trace these additional changes, we carried out a genome-wide search for loss of heterozygosity (LOH) and allelic imbalance (AI). This was done at 53 microsatellite markers in a panel of 34 lymphomas and four plasmacytomas from c- or N-myc transgene carrying (BALB/c x Mus spretus)F1 hybrids. An additional 43 lymphomas and three plasmacytomas from non-transgenic F1 mice were also investigated. Losses of one or more spretus-derived chromosome 9 markers were detected in 19 of 23 (83%) of the lymphomas, but in none of the four plasmacytomas that developed in N-myc F1 mice. No LOH-9 was found in any of the 11 lymphomas from Emu-c-myc F1 mice and only in 1 of 46 (2%) tumors derived from non-transgenic (BALB/c x spretus)F1 hybrid controls. These results suggest that a gene on spretus chromosome 9 confers resistance to the development of N-myc but not c-myc-induced lymphomas. AI of chromosome 15 markers (AI-15) was detected in 57 of 77 (74%) lymphomas and in 5 of 7 (72%) plasmacytomas, independently of the transgenic status and the mode of induction. All of the lymphomas and plasmacytomas with AI-15 revealed a relative gain of the spretus-derived D15Mit6 allele (located at 13.7 cM from the centromere), together with a gain of the BALB/c allele of the more distal (29.6 cM) D15Mit64 marker, suggesting somatic recombination. LOH in the region close to c-myc was detected in a proportion of tumors with AI-15. The observation of complex genetic alterations includes somatic recombination, AI and LOH involving chromosome 15 in tumors induced by a myc transgene. This indicates that at least two genes in addition to c-myc on this chromosome can be involved in lymphoma development.

A New Synthetic Species of Cucumis (Cucurbitaceae) from Interspecific Hybridization and Chromosome Doubling

A new synthetic species,Cucumis hytivus J.-F. Chen & J. H. Kirkbr. (2n=38), obtained by doubling the number of chromosomes in the sterile interspecific F1 hybrid (2n=19) betweenC. sativus L. (2n=14) andC. hystrix Chakr. (2n=24), is described.

444 Forcing Requirements of Seed-propagated Easter Lilies

Seed-propagated lilies have the potential to revolutionize Easter lily production, eliminating clonal disease transmission, costly production and shipping. Five F1 interspecific hybrids, Lilium × formolongo (L. longiflorum × L. formosanum), were evaluated to establish an initial forcing schedule. The hybrids included `Raizan Herald', `Augusta F1', `Raizan No. 1', `Raizan No. 2', and `Raizan No. 3'. Two hundred seeds/hybrid were sown in early July in plug trays. Ten weeks after sowing, seedlings were transplanted into 3-inch pots. At the 20-week stage, the seedlings were repotted into 6-inch standard pots for the final production phase. All hybrids had low germination rates (<20%). Hybrids were grown under two photoperiod treatments (short, long days) at 21 °C with n = 10 reps/hybrid/treatment. Plants were evaluated for no. days to visible bud, leaf unfolding rate, final plant height, leaf number, bud count, flowering dates, and the no. of shoots/bulb. Ten weeks after sowing, hybrids had one to four leaves/plant. At 20 weeks, the leaf number had increased to as many as 40. Despite the lack of a cold treatment, most hybrids initiated flower buds. Visible bud date occurred as early as 20 weeks after sowing. Photoperiod had no effect on leaf number, stem height, and flower bud initiation. Plant height exceeded 15 inches by week 16 in most hybrids, indicating the need for plant growth regulator applications. The next steps in product development for seed-propagated Easter lilies will be outlined.

Recombinant chromosomes of advanced backcross plants between Allium cepa L. and A. fistulosum L. revealed by in situ hybridization

Cytological analysis of (Allium cepa L.×Allium fistulosum L.)×A. cepa L. F1BC3 plants revealed most plants were diploid with 16 chromosomes. Karyotypes of these plants showed recombinant chromosomes. Fluorescence and genomic in situ hybridization patterns of interspecific F1 hybrid and F1BC3 plants revealed A. fistulosum chromosomes or chromosomal segments. A highly repetitive 376-bp DNA sequence and genomic DNA of A. fistulosum revealed similar telomeric hybridization sites when hybridized onto A. fistulosum chromosomes. Cytogenetic evidence showed that A. fistulosum DNA has recombined into the A. cepa genome.

Allele-specific loss or imbalance of chromosomes 9, 15, and 16 in B-cell tumors from interspecific F1 hybrid mice carrying e?-c-myc or N-myc transgenes

Mice carrying an immunoglobulin enhancer (Emu-) linked c- or N-myc transgene develop fatal monoclonal or oligoclonal pre-B or B-cell lymphomas. This indicates that, beside the Emu-activated myc gene, additional genetic changes are required for tumor development. To trace these additional changes, we carried out a genome-wide search for loss of heterozygosity (LOH) and allelic imbalance (AI). This was done at 53 microsatellite markers in a panel of 34 lymphomas and four plasmacytomas from c- or N-myc transgene carrying (BALB/c x Mus spretus)F1 hybrids. An additional 43 lymphomas and three plasmacytomas from non-transgenic F1 mice were also investigated. Losses of one or more spretus-derived chromosome 9 markers were detected in 19 of 23 (83%) of the lymphomas, but in none of the four plasmacytomas that developed in N-myc F1 mice. No LOH-9 was found in any of the 11 lymphomas from Emu-c-myc F1 mice and only in 1 of 46 (2%) tumors derived from non-transgenic (BALB/c x spretus)F1 hybrid controls. These results suggest that a gene on spretus chromosome 9 confers resistance to the development of N-myc but not c-myc-induced lymphomas. AI of chromosome 15 markers (AI-15) was detected in 57 of 77 (74%) lymphomas and in 5 of 7 (72%) plasmacytomas, independently of the transgenic status and the mode of induction. All of the lymphomas and plasmacytomas with AI-15 revealed a relative gain of the spretus-derived D15Mit6 allele (located at 13.7 cM from the centromere), together with a gain of the BALB/c allele of the more distal (29.6 cM) D15Mit64 marker, suggesting somatic recombination. LOH in the region close to c-myc was detected in a proportion of tumors with AI-15. The observation of complex genetic alterations includes somatic recombination, AI and LOH involving chromosome 15 in tumors induced by a myc transgene. This indicates that at least two genes in addition to c-myc on this chromosome can be involved in lymphoma development.

Cytogenetic study of Helianthus laevigatus and its F1 and BC1F1 hybrids with cultivated sunflower, Helianthus annuus

AbstractAlthough the wild sunflower species Helianthus laevigatus has not been extensively studied it may be considered for sunflower breeding as a potential source of desirable genes for Sclerotinia stalk rot resistance and high contents of proteins and linoleic acid in the seed.A set of six H. laevigatus populations was crossed to cultivated sun~ower lines and produced nine F1 (2‐14 plants) and 66 BC1F1 hybrid combinations (1‐13 plants). Male sterility occurred in F1 and BC1F1 hybrid combinations and pollen viability was lower in the progenies than in the parents (51.6‐77.2%in F1 and in F1 and 4.8‐34.0% in BC1F1). Meiosis was normal in the H. laevigatus populations It was found that this tetraploid species also occurred in a hexaploid form Numerous irregularities were observed in the meiosis of the F1 interspecific hybrids During diakinesis, quadrivalents and hexavalents were recorded in addition to bivalents Dislocated chromosomes and chromosome bridges were present in the other phases The chromosome number in F1 was 68 (tetraploid). Irregularities in chromosome pairing were observed in the interspecific hybrids at BC1F1. There were many univalents, and trivalents quadrivalents and hexavalents were also present The chromosome number in the BC1F1 generation ranged from 34 to 60. The occurrence of meiotic irregularities in the F1 and BC1F1 interspecific hybrids indicates that H. laevigatus and the cultivated sunflower differ in genome constitution.