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1.
Detailed karyotypes of Hydrangea macrophylla, Hydrangea paniculata and Hydrangea quercifolia were constructed on the basis of arm lengths and centromeric index, together with 45S rDNA fluorescence in situ hybridization. Although the chromosomes were small, they were well distinguishable for all species. Chromosome morphology and karyotypes were different for the three species. H. macrophylla had six metacentric (M), eight submetacentric (SM) and four subtelocentric (ST) chromosomes. The karyotype of H. paniculata contained seven M, 10 SM and one ST chromosomes and H. quercifolia had six M, 10 SM and two ST chromosomes. The variability among three species also was expressed by 45S rDNA signals. H. macrophylla had a nucleolar organizing region on chromosome 2, H. paniculata had 45S rDNA signals on chromosomes 2, 5 and 11 and H. quercifolia on chromosomes 3 and 8. Hybridization signal always was distally on the short arm but the strength of the signals was different for the three species. The chromosome portraits made in this study will be used to trace chromosome behaviour in interspecific hybrids resulting from breeding work between the three species.  相似文献   

2.
Meiosis in wide F1 hybrids in the tribe Triticeae is complex and irregular. Despite extensive research, the meiotic pathways in such hybrids remain largely unknown. In this study, the effect of the genotypes of disomic wheat–rye substitution lines on the regulation of meiosis in ABDR amphihaploids was analysed by comparing microsporogenesis and seed set under self pollination in hybrids of normal bread wheat (Triticum aestivum L.) and wheats with single chromosome substitutions 1R(1A), 1Rv(1A), 2R(2D)1, 2R(2D)2, 2R(2D)3, 5R(5D), 5R(5A), 6R(6A) with rye (Secale cereale L.). Three types of meiotic pathways were identified in the hybrids: reductional, equational, and equational+reductional. During the reductional type division, chromosomes randomly moved toward the poles at Anaphase I (AI) and separated sister chromatids at AII. Meiosis ended with tetrad formation, and the resulting plants were sterile ((2R(2D)1 × R, 2R(2D)2 × R). In the equational type division, the chromosomes aligned along the equator at Metaphase I and at AI separated into chromatids that moved toward the poles. This meiotic pathway led to dyad formation and partial fertility (especially in hybrids of 1Rv(1A) and 6R(6A)). In the equational+reductional pathway, some chromosomes divided in an equational manner while others were segregated reductionally within the same microsporocyte and this led to formation of tetrads with groups of uncoiled chromosomes. Comparison of the frequencies of each of the three meiotic pathways in different hybrid combinations suggests differences in contributions of individual chromosomes to the control of the entire meiotic process.  相似文献   

3.
An intergeneric cross has been made between Dendranthema crassum (kitam.) kitam. (2n = 90; ♀) and Crossostephium chinense (L.) Makino (2n = 18; ♂). Most of the hybrid embryos aborted at an early developmental stage. Using ovule rescue, it was possible to establish a single intergeneric hybrid plant showing 2n = 54 chromosomes. The leaf length, leaf width and epidermal hair density of the hybrid were all intermediate between those of the parents. However the flower diameter, number of tubular florets, epidermal hair height and epidermal hair length exceeded those of both parents. A genomic in situ hybridization approach was able to distinguish between the parental genomes in the hybrid plant.  相似文献   

4.
We developed a new disomic addition line M11028‐1‐1‐5 (2n = 44 = 21” + 1”) from a cross between wheat cv. ‘7182’ and octoploid Tritileymus M47 (2n = 8x = 56, AABBDDN sNs ). Cytological observations demonstrated that M11028‐1‐1‐5 contained 44 chromosomes and formed 22 bivalents during meiotic metaphase I. The genomic in situ hybridization (GISH) investigations showed this line contained 42 wheat chromosomes and a pair of L. mollis chromosomes. SSR, EST and PCR‐based landmark unique gene (PLUG) markers were screened to determine the homoeologous relationships of the introduced L. mollis chromosomes in wheat background. Nine markers, i.e. Xwmc256, Xgpw312, Swes123, CD452568, BF483643, BQ169205, TNAC1748, TNAC1751 and TNAC1752, all of which were located on the homoeologous group 6 chromosomes of common wheat, amplified bands unique to L. mollis in M11028‐1‐1‐5. Gliadin analysis also confirmed that the added chromosomes in M11028‐1‐1‐5 were correlated with the sixth group chromosome. This indicated that M11028‐1‐1‐5 contained a pair of introduced L. mollis chromosome belonging to homoeologous group 6, which we designated it as Lm#6 Ns disomic addition line. This is the first report of a common wheat–L. mollis disomic addition line.  相似文献   

5.
The ability of 13 Nemesia species (six annual and seven perennial) to sexually hybridize was investigated. Six of the perennial Nemesia species investigated were inter-fertile with one another. Two of the annual species, N. macroceras and N. strumosa, were inter-fertile. Thirty three crosses were successful and resulted in viable seeds. The analysis of meiotic chromosome behaviour in interspecific hybrids indicated that Nemesia chromosomes in different parental species were homeologous. No evidence of chromosome inversions or chromosome translocations was observed during meiosis in interspecific hybrids between the six perennial Nemesia species. In the hybrids produced between N. macroceras and N. strumosa, a quadrivalent was observed during meiotic metaphase I, indicating that these two species differ by a reciprocal translocation. A successful hybridization was made between N. anisocarpa (annual) and N. foetans (perennial), producing two triploid hybrids. In the unsuccessful crosses, pollen tubes were observed entering ovaries and ovules, suggesting that post-fertilization barriers were preventing sexual hybridization. Many of these crosses produced nonviable, shrunken, empty seeds, suggesting that endosperm breakdown and embryo abortion prevent interspecific hybridization in unsuccessful crosses. The manipulation of ploidy levels in N. fruticans and N. strumosa and tissue culture of N. strumosa × N. fruticans ovules failed to overcome post-fertilization barriers between these species.  相似文献   

6.
Summary Some haploids isolated among the progeny from crosses involving several genotypically different motherplants of Beta vulgaris L., were used for an investigation on chromosome morphology of the genus Beta.The length of both the long and short arms proved to vary considerably for each chromosome, so that a representative idiogram of the 9 chromosomes could not be made. Staining the chromosomes according to the BSG-technique revealed only bands in the centromere regions. However, one chromosome with a narrow band in the short arm could be identified, which was supposed to be the nucleolar chromosome. The C-bands presumably correlate with the heterochromatic blocks as observed in mitotic and meiotic (pachytene) prophase.This study was part of a project on cytogenetics of interspecific hybrids resistent to beet cyst eelworm, supported by the Institute of Rational Sugar Production,Bergen op Zoom, the Netherlands.  相似文献   

7.
The nature of reproductive barriers and meiotic behaviour of chromosomes were studied in interspecific hybrids among the six rough-seeded Lupinus species. Out of 30 different interspecific crosses attempted in all possible combinations, eight produced viable F, seeds. These successful crosses involved L. cosentinii, L. digitatus, L. atlanticus and L. pilosus. Crosses of L. princei with other species resulted in shrivelled F, seed in all combinations. In contrast to previous reports, crosses of L. palaestinus with all other rough-seeded lupins were incompatible as no F1 hybrids were obtained. Barriers to interspecific reproduction were identified as nucleo-cytoplasmic and embryo-endosperm incompatibility in unsuccessful crosses, and chromosomal imbalances in F1 hybrids. Gene transfer is possible among L. cosentinii, L. digitatus and L. atlanticus, which produced F2 seed. Patterns of chromosome configurations in F1 meiotic cells suggested that these species have at least two genomes partially in common, but include inversions and translocations. The genome of L. atlanticus is closer to L. digitatus than to L. cosentinii, and that of L. pilosus is closer to L. atlanticus than to L. cosentinii. L. princei appears to have an isolated genome within the rough-seeded Lupinus species.  相似文献   

8.
Two colchicine-induced tetraploid lines, one belonging to Pisum sativum and the other to the wild species Pisum fulvum, were compared with their corresponding diploids and among themselves for chromosome number, meiotic behaviour and for pollen and pod fertility. For both lines, five generations were analyzed; the tetraploid level was maintained throughout the generations. In P. fulvum, aneuploids with 27, 29 and 30 chromosomes were observed, while in P. sativum aneuploids with 29 chromomes were found. Meiotic analysis evidenced a higher number of quadrivalents and a lower number of univalents in P. fulvum. This particular chromosomal behaviour may also have been responsible for determining the higher pollen and pod fertility in P. fulvum. Wild species of this genus seem to have better tolerance for ploidy variations.  相似文献   

9.
Summary The meiotic pairing behaviour at metaphase I of a Triticum aestivum×Triticum monococcum hybrid has been studied by means of the C-banding technique to ascertain the homology between the chromosomes in the A genome of the two species. The technique allowed the A and B genome chromosomes and the 2D, 3D and 5D chromosomes to be identified. Differences in the level of chromosome pairing in the A genome were noted. The T. monococcum 4A chromosome did not pair with any of the T. aestivum chromosomes in any of the metaphase I cells analysed. Two reciprocal translocations between the 2B and 2D chromosomes on one side and the 2A and 3D on the other side have been identified. The usefulness of the C-banding technique in the study of chromosome homology among species related to wheat is discussed.  相似文献   

10.
Sexuality is correlated with diploidy and apomixis with polyploidy in the Brachiaria genus. Brachiaria ruziziensis is a key species in Brachiaria breeding due to its obligate sexuality and intrinsic agronomic qualities. Interspecific crosses in the genus became feasible only when a few diploid accessions of B. ruziziensis were artificially tetraploidized and remained sexual. Hybridization has been done since, using natural tetraploid apomictic accessions of B. brizantha or B. decumbens as pollen donors. Twenty two accessions of B. ruziziensis from the Embrapa Beef Cattle germplasm collection (Campo Grande, MS, Brazil) were cytologically analyzed: 16 are natural diploids (2n = 2x = 18) and six are artificially induced tetraploids (2n = 4x = 36). The meiotic behavior in the 16 diploid accessions varied. The mean of meiotic abnormalities per accession ranged from zero to 24.46%. Meiotic behavior in the induced tetraploid accessions also varied with the mean of meiotic abnormalities ranging from 5.20% to 54.71%. The most common abnormalities observed in both the diploid and the tetraploid accessions, were those related to irregular chromosome segregation. In one tetraploid accession, with a high frequency of those, other irregularities involving chromosome orientation at metaphase plate and chromosome convergence to the poles, a meiotic mutation known as divergent spindle, were recorded. Meiotic behavior should be considered in selecting potential genitors for breeding.  相似文献   

11.
Hugh Thomas  W. Powell  T. Aung 《Euphytica》1980,29(3):635-640
Summary The regular meiotic behaviour of the cultivated oat Avena sativa (2n=6x=42) is genetically controlled. The factors which control the diploid-like meiotic behaviour also restrict the amount of pairing that occurs between alien chromosomes and their homoeologues in A.sativa, and hence increases the difficulties of introducing desirable variation from wild species into the cultivated oat. A genotype of the diploid species A.longiglumis which interferes with the regular meiotic behaviour of A. sativa can be used to induce pairing between alien chromosomes and their corresponding chromosomes in A. sativa. Using this procedure the dominant gene conferring mildew resistance has been transferred from the tetraploid weed species A. barbata into the cultivated oat.  相似文献   

12.
Summary In this study a new trigeneric hybrid involving species from the Triticum, Secale and Leymus was produced by crossing octoploid triticale (Jinsong49) with octoploid tritileymus (950059). The chromosome constitution of the parental amphiploid, trigeneric hybrid and its progenies were studied. Genomic in situ hybridization (GISH) analysis showed that Jinsong49 and 950059 had 44 wheat chromosomes, and 12 rye chromosomes, 12 L. mollis chromosomes respectively. The mean meiotic configuration of trigeneric hybrid F1 was 13.17 I + 20.82 II + 0.37 III + 0.02 IV. GISH results indicated the trigeneric hybrid F1 had 6 rye chromosomes and 6 Leymus chromosomes. In the selfed derivatives of the trigeneric hybrids, while the number of selfed generation increased, the mean number of chromosomes tends to decrease gradually and slowly. GISH results revealed that most plant tested in the progeny population had 8–12 rye chromosomes, and no Leymus chromosomes were detected. The results indicated that rye chromosomes can be preferentially transmitted in the progenies of trigeneric hybrid than Leymus chromosomes.  相似文献   

13.
Uniformly abnormal meiotic behaviour was observed in 12 F1-plants from a cross between Solanum etuberosum (non-tuberous) and S. pinnatisectum (tuberous). Per pollen mother cell at MI an average was found of 3.64 bivalents (all rodshaped, 1–2 per cell, heteromorphic), 16.64 univalents (scattered haphazardly on a continuous bipolar spindle) and 0.03 trivalents (all Y-shaped). Lagging chromosomes and precocious division of univalents very frequently occurs, leading to unequal distribution of chromosomes, aneuploid gametes and male sterility. Heteromorphic bivalents at MI, loops in bivalents at pachytene and non-disjunction in one hybrid plant, point to a highly abnormal meiotic behaviour. The occurrence of few trivalents is discussed.Considering that according to the literature nearly normal pairing was observed in the intergeneric F1-hybrids Lycopersicon esculentum × Solanum lycopersicoides and L. esculentum x S. pennellii, the lack of chromosome pairing in an interspecific F1-hybrid, of which both Solanum parents belong to the same section, is paradoxical to a plant breeder and might even be conspicuous to a taxonomist.  相似文献   

14.
Wheat (Triticum aestivum L.) breeders often utilize alien sources to supply new genetic variation to their breeding programs. However, the alien gene complexes have not always behaved as desired when placed into a wheat background. The introgressed genes of interest may be linked to undesirable genes, expressed at low levels or not at all. The short arm of rye (Secale cereale L.) chromosome one (1RS) contains many valuable genes for wheat improvement. In order to study rye gene response to varying copy number, wheat lines were constructed which contained zero, two or four doses of 1RS. The meiotic behavior of rye chromosome 1R, and wheat/rye translocation chromosomes, 1AL/1RS and 1BL/1RS was studied in the F1 hybrids between wheat lines carrying 1R or the translocation chromosomes. The IRS arm was transmitted at a very high frequency; 98 % of the F2 plants had at least one of the chromosomes with a IRS arm. In addition, 44 % of the F2 plants received at least one copy of the chromosomes from each parent. Analysis of the meiotic behavior of the IRS arm suggested that few euploid wheat gametes were formed. Therefore, most of the pollen must have contained IRS. It is unknown whether the lack of euploid wheat pollen could account for the high transmission frequency of the rye chromosomes. There may have been differential survival of the embryos receiving the rye chromosome as well.  相似文献   

15.
Interspecific hybridization is an important approach to broaden the genetic base and create novel plant forms in breeding programs. However, interspecific hybridization in Ipomoea is very difficult due to the cross incompatibility. Here we report two novel interspecific F1 hybrids between I. batatas (L.) Lam. (2n = 6x = 90) and two wild species, I. grandifolia (2n = 2x = 30) and I. purpurea (2n = 2x = 30). Hybridization was stimulated by applying plant growth hormones. Morphological, molecular and cytological tests were conducted to confirm their hybridity. We found that the two hybrids were quite distinctive in leaf color and morphology, and yielded intermediate sizes of storage roots compared to their respective parents. Inter-simple sequence repeat analysis showed that the unique DNA bands from the wild parents could be detected in these two hybrids. The cluster analysis also showed that the two F1 hybrids were closer to I. batatas in phylogeny relationship. The number of chromosomes of the two hybrids was both 60, indicating that the hybrids were tetraploid. The meiotic configuration analysis of the H1 of I. batatas × I. grandifolia revealed the occurrence of 17.58I + 14.28II + 1.36III + 2.48IV at metaphase I in average chromosome association per pollen mother cells (PMCs), 4.26I + 18.32II + 2.56III + 3.12IV was average meiotic configuration in the H2 of I. batatas × I. purpurea. Both hybrids appeared to be polyads and multi-microcytes at tetrad phase and differed in their pollen fertility.  相似文献   

16.
N. Watanabe  S.F. Koval 《Euphytica》2003,129(3):259-265
The chlorophyll a:b ratio of chlorina mutants is much higher than that of wild type plants. Physical mapping of the chlorina mutant loci (cn-A1, cn-B1 and cn-D1) of common wheat (Triticum aestivum L.) and durum wheat (T. turgidum L.) was carried out with partial deletion lines of Chinese Spring(CS) of the long arms of homoeologous group7 chromosomes. F1 plants of partial deletion lines with near-isogenic lines (ANK-32A and ANK-32B) of the spring bread wheat Novosibirskaya 67 and a near-isogenicline of durum wheat LD222, ANW-7B were evaluated for chlorophyll a:b ratio of the leaves. Hemizygous and heterozygous plants were more easily distinguished by chlorophyll a:b ratio than by visual observation. The dose effects of the chlorina loci on chlorophyll a:b ratio were also confirmed. The position of the allele on the chromosome was localized by fraction length, the comparative values between whole chromosome and partially deleted chromosome. The locus cn-A1 was localized on the region of 83% distal from the centromere on the long arm of chromosome 7A, cn-B1 locus was localized on the region between 69% and 78% distal from the centromere on the long arm of chromosome 7B, and cn-D1 locus was localized on the region between 76% and 77% distal from the centromere on the long arm of chromosome 7D. We consider the map derived by deletion mapping is more accurate than the map calculated from recombination frequency. This revised version was published online in July 2006 with corrections to the Cover Date.  相似文献   

17.
New tri-species hybrids (GOS) in the genus Pennisetum involving the cultivated species pearl millet (P. glaucum L.) and two wild species, viz. P. squamulatum Fresen and P. orientale L. C. Rich, are reported. Six hybrid plants were recovered after crossing a backcross hybrid (2n = 3x = 23, GGO) between P. glaucum (2n = 2x = 14, GG) and P. orientale (2n = 2x = 18, OO) with F1s (2n = 6x = 42, GGSSSS) between P. glaucum (2n = 4x = 28, GGGG) and P. squamulatum (2n = 8x = 56, SSSSSSSS). The hybrids were perennial, morphologically intermediate to their parents, and represented characters from the three contributing species. The hybrids contained 2n = 44 chromosomes (GGGSSO) representing 21, 14 and nine chromosomes from P. glaucum, P. squamulatum and P. orientale, respectively. Meiotic and flow-cytometric analysis suggested origin of these hybrids from unreduced female and reduced male gametes. Average chromosome configuration (8.42I + 14.32II + 1.62III + 0.52IV) at Meiosis showed limited inter-genomic pairing indicating absence of significant homology between the three genomes. The hybrids were male sterile (except one) and highly aposporous. P. orientale was identified to induce apospory in hybrid background with P. glaucum at diploid and above levels, though it was quantitatively affected by genomic doses from sexual parent. A case of inducible and recurrent apospory is presented whereby a transition from Polygonum-type sexual embryo-sacs to Panicum-type aposporous embryo-sacs was observed in diploid interspecific hybrids. Results supported independent origin and partitioning of the three apomixis-components (apomeiosis, parthenogenesis, and functional endosperm development), reported for the first time in Pennisetum. Potential utilization of GOS hybrids in understanding genome interactions involved in complex traits, such as perenniality and apomixis, is discussed.  相似文献   

18.
Pollen viability and male meiosis in intraspecific hybrids of Hydrangea aspera subsp. aspera Kawakami group (2n = 2x = 36) and subsp. sargentiana (2n = 2x = 34) were investigated. Although it had been assumed that they were sterile, pollen viability was observed; it varied from 2.5% to 12.1%. The production of gametes with different chromosome numbers was implied by the analysis of the dispersion of the diameter distribution of pollen grains. Analysis of male meiosis made it possible to identify the origins with two major categories of meiotic aberrations: abnormal chromosome distribution (early chromosome migration at metaphase, lagging chromosomes at anaphase, micronuclei at telophase), leading to the formation of unbalanced tetrads and/or ones with supernumerary microspores; and abnormal spindle orientation in metaphase II (tripolar, fused and parallel spindles), leading to the formation of dyads or triads. The mode of 2n pollen formation is of the First Division Restitution type. The high level of parental heterozygosity that is normally associated with them should facilitate the transfer of a polygenic trait in breeding programme.  相似文献   

19.
Interspecific hybridization plays a crucial role in plant genetics and breeding. The efficiency of interspecific crosses to a considerable extent depends on the genetic relatedness of genomes from parental species. Interspecific hybrids involving Brassica maurorum (2n = 16, MM) and two Brassica crop species, viz B. rapa (2n = 20, AA) and B. napus (2n = 38, AACC), were produced and analyzed for their meiotic chromosome pairings in pollen mother cells (PMCs) by using genomic in situ hybridization (GISH) with the labeled DNA of B. maurorum (MM) as probe. In hybrids B. maurorum × B. rapa (2n = 18, MA), all chromosomes remained unpaired in 28% PMCs, and the maximum of autosyndetic bivalents was two and one among the chromosomes of A and M genomes, with the average per cell being 0.27 and 0.12, respectively. Up to two allosyndetic bivalents between A and M genomes appeared, averagely 0.48 per cell. In hybrids B. maurorum × B. napus (2n = 27, MAC), the maximum of autosyndetic bivalents in M genome was two and the average was 0.11, while the maximum of allosyndetic bivalents between M and A/C genomes was two and the average was 0.78. The 2–7 bivalents formed by A/C-genome chromosomes showed their high homology. The results were compared and discussed with the chromosome pairings in the hybrids of B. maurorum with B. juncea and B. carinata with respect to the genome relationships and the potential for chromosome recombination.  相似文献   

20.
Spontaneous chromosome doubling via union of unreduced (2n) gametes has been thought to be the way that common wheat (Triticum aestivum L.) was originated from the hybridization of T. turgidum L. with Ae. tauschii Cosson. Previous works have observed unreduced gametes in F1 hybrids of Ae. tauschii with six of the eight T. turgidum subspecies. It is not clear, however, whether the formation of these unreduced gametes is a norm in the F1 hybrids. In the present study, we tried to answer this question by assessing the occurrence frequency of unreduced gametes in 115 T. turgidum–Ae. tauschii hybrid combinations, involving 76 genotypes of seven T. turgdium subspecies and 24 Ae. tauschii accessions. Our data show that these hybrid combinations differed significantly (P ≤ 0.01, F = 11.40) in selfed seedset, an indicator for production of unreduced gametes. This study clearly showed that meiotic restitution genes are widely distributed within T. turgidum. However, significant differences were found between as well as within T. turgidum subspecies and in the interaction of the T. turgidum genotypes with those of Ae. taushii. The possible application of the meiotic restitution genes from T. turgidum in production of double haploids is also discussed.  相似文献   

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