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1.
Summary An autotetraploid population of caraway (Carum carvi L.) was produced by treating the growing points of young plants with a 0.2% colchicine solution. Selection on morphology, pollen size and pollen shape, followed by a selection on seed size proved to be an effective way to identify the mixoploid C0 plants. Three percent of the treated plants produced a tetraploid progeny. Moderate selection in the C1 and the C2 population resulted in an improvement of the average seed-set to the amount of 50% of the diploid control, with a range of 21–78%. The 1000-kernel weight of the tetraploid material was 7 g, compared to 3 g in the diploid control. The oil content of the autotetraploid seed was increased with 35.6%; the increase in carvone amounted to 6.9%. The results of the experiment indicate that breeding work in autotetraploid caraway may result in a new cultivar.  相似文献   

2.
The use of an 8x Vaccinium produced through doubling a tetraploid hybrid with colchicine was studied as a means of facilitating gene exchange between V. corymbosum L. and V. ashei Reade. Analysis included meiotic observations and crossability studies of the 8x plant, as well as attempting to develop 6x breeding lines. Meiotic analysis revealed the presence of micronuclei in Telphase II products and polyspory in sporads. In the crossability studies five 4x highbush plants were pollinated with 8x o2 4x pollen. Data gathered included: % fruit set, average weight/fruit, average number of seeds/fruit, average number of seedlings/pollination, and number of 6x seedlings. Octoploid pollinations were significantly lower than 4x pollinations in all parameters. One 6x plant was produced from the 4x-8x crosses but was found to be mitotically unstable, having somatic cells with chromosome numbers ranging from 48 to 168.  相似文献   

3.
Triploid tulips have agronomically desirable traits such as vigorous growth and large flower size, but only a portion of all cultivated tulips is triploid. To apply 2n pollen to polyploid breeding of tulips, the polyploidizing agent, nitrous oxide gas (N2O), was applied to bulbs. In tulips, meiosis in anthers occurs inside the bulbs from mid- to late-October. When meiosis in anthers (excised from bulbs) reached metaphase I, we treated other bulbs of the same clones with N2O for 24–48 h. Most of the treated plants produced pollen grains with a wide-ranging or bimodal size distribution, indicating a mixture of n, 2n and aneuploid pollen grains. The use of pollen containing a relatively high proportion of giant pollen grains tended to yield larger numbers of triploids in the progeny. The number of giant pollen grains could be increased when N2O-treated pollen grains were suspended in 10% sucrose and then sieved through a nylon mesh. Very few polyploids were observed in some cross combinations, even those involving pollen with a relatively high proportion of giant grains. Even so, this low polyploid yield most likely is due to a triploid block, because the capsules obtained in the crosses of the diploid×N2O-treated plants contained some abnormal seeds, which were mostly triploid. Embryo culture was useful in rescuing abnormal embryos. The present study reveals that 2n pollen can be produced at high frequency using N2O during tulip breeding.  相似文献   

4.
D. J. Luckett 《Euphytica》1989,42(1-2):177-182
Summary Seedlings of the cotton cultivar Sicot 1 were treated with either 1%, 2% or 5% colchicine in lanolin which was topically applied to the apical meristem four days after emergence. Of 293 1%-treated seedlings 64 survived to produce fertile C1 shoots which gave rise to 84 C2 single boll families. C2 and C3 generations were examined in field experiments for morphological variants and for a number of quantitative characters (yield components and fibre quality). No morphological mutants were seen but considerable heritable variation for metrical characters of economic importance was detected. Of 18 extreme C2 families consisting of 54 C3 progenies, 19 were shown in a replicated spaced-plant trial to be significantly different to the Sicot 1 parental material for at least one (usually more) characters. The 222 C3 progenies of the 66 non-extreme C2 families were tested in an unreplicated plot experiment and at least 14 were suspected of exhibiting variation in metrical characters. Although no light has been shed on the mechanism responsible for the production of variants by this method, it is argued that the colchicine technique results in higher levels of genetic variation than found in commercial cultivars; variation which can be readily exploited by cotton breeders.  相似文献   

5.
Many diploid rose species and cultivars possess valuable traits that can be introgressed into modern tetraploid cultivars. Interspecific, interploidy crosses are possible, but triploid hybrids typically have limited fertility, hindering further breeding and selection. Tetraploidizing diploids before mating with tetraploids can alleviate fertility barriers. The efficiency of trifluralin was investigated for polyploidization of Rosa chinensis minima (2n = 2x = 14) seedlings. Treatments were trifluralin at 0.086% and 0.0086%, colchicine (0.5%), and distilled water and contained 2% dimethyl sulfoxide and a surfactant. Approximately 5 l of the treatment solution was applied to the apical meristem of seedlings (N = 337, 82–85 per treatment) in the process of cotyledon expansion. Guard cell length, pollen diameter, and root tip squashes of rooted cuttings were used to detect polyploidy in meristematic layer (L)I, LII, and LIII, respectively. Trifluralin (0.086%) was the most effective treatment for polyploidization (LI 20.2%, LII 12.9%, LIII 12.9%), followed by trifluralin (0.0086%) (LI 10.6%, LII 7.1%, LIII 4.7%) and colchicine (LI 2.4%, LII 0%, LIII 0%). Polyploidization consistently occurred from LI inward. Polyploids as a group had reduced pollen stainability and a lower leaflet length to width ratio than diploids. In addition, two diploid seedlings were identified which produce 2n pollen. Considerations in selecting germplasm and generating somatically-induced polyploids from seedlings versus clones for use in breeding are discussed.  相似文献   

6.
Investigations on interspecific crossability in two species of the genus Citrullus were studied based on their morphology, chromosome pairing and pollen fertility in their hybrids resulting from 12 combinations(including reciprocals). These have been utilized for tracing the phylogenetic relationship between the taxa and factors responsible for their differentiation. A collective evaluation of data on cross compatibility,morphology, chromosome association and pollen fertility indicated a close phylogenetic relationship between the species C. colocynthis (wild2n = 22) and C. vulgaris (cultivated 2n = 22). Significant differences for crossability and pollen fertility were observed between hybrids of C. colocynthis × C. vulgaris and reciprocals. Meiotic analysis of F1 hybrids revealed that these two species are freely crossable and provide normal chromosome association, involving an average of 9 to maximum 11 pairs of chromosomes. This indicated the possibility of high recombination and thereby genetic introgression of desirable traits. As both the species are of economic significance, breeding strategies can be developed for the genetic improvement of these species. This revised version was published online in August 2006 with corrections to the Cover Date.  相似文献   

7.
In the genus Brachiaria, genetic variation can be exploited directly from germplasm collections or released using sexual reproduction in normally apomictic polyploids. The discovery of a natural sexual polyploid accession H031 of Brachiaria humidicola collected in Africa, opened new opportunities to exploit the genetic variation in this species. This accession was crossed with an apomictic cultivar BRS Tupi with the same chromosome number (2n = 36) and 361 F1 hybrids were obtained. Following visual selection for leafiness, vigor, growth habit, and the mode of reproduction, 50 hybrids were selected for further agronomic evaluation. The parents and 45 of the 50 selected hybrids were evaluated for the regularity of meiosis. In the female parent (H031), meiosis was somewhat irregular, with 16.3% of abnormal tetrads, whereas the male (cv. BRS Tupi) meiosis was very regular, with only 3.1% of abnormal tetrads. Among hybrids (sexual and apomictic), the percentage of abnormal tetrads ranged from 15.8 to 98.3%. The abnormalities included irregular chromosome segregation, chromosome stickiness and the absence of cytokinesis. Considering that apomixis in the genus Brachiaria is pseudogamic, and that meiotic aberrations can compromise pollen viability, the results of this study present another parameter to aid selection for more stable microsporogenesis. Apomictic derivatives with stable meiosis are candidates for new cultivars whereas sexual hybrids can be retained in breeding for another round of recombination.  相似文献   

8.
To obtain a C1-population with a high percentage of tetraploids after colchicine treatment of turnips, a selection in the C0 can be used. A comparison is made between two criteria for this selection, viz. the average pollen grain size and the variation in pollen grain size.C0-selection on the basis of the average pollen grain size of five pollen grains per plant reduced the number of diploids in the C1 considerably. When the variation in pollen grain size of these five pollen grains is included as a selection-criterion the number of tetraploids in the C1 increased.The two methods are discussed in the light of the working efficiency and the genetical variation in the tetraploid C1-population. It is concluded that the character of the initial material should govern the choice of the selection criterion.  相似文献   

9.
Summary Sex expression in mulberry (Morus spp.) was recorded in 301 varieties, collected from diverse geographical origins, evolved varieties and polyploids maintained at Central Sericultural Research and Training Institute, Berhampore, West Bengal. India (24°6'N and 88°15'E) during 1991–93. Out of total varieties, 49 (16%) male, 161 (53%) female, 52 (17%) monoecious and 39 (13%) were bisexual. Parameters on flowering time, anthesis, floral characters, sex expression and sex reversal were recorded. The indigenous, evolved and polyploids showed early flowering (Jan–Feb) and exotic showed late flowering (Jan–April). The pollen grain viability, seed setting % and other floral behaviour were recorded.  相似文献   

10.
Summary The sensitivity of Fragaria seedlings to colchicine is dependent on the plant organ that is treated. Complete immersion of seedlings in a 1.5% colchicine solution results in total lethality, whereas the survival rates were more than 75% even at concentrations of 3.0% when only shoot apices were treated. High proportions of polyploids were isolated by treating shoot apices of seedlings with a 2.0% colchicine solution for 24–28 h. The dropper method is preferred to the tube method as it involves a minimum of manipulation and requires simple equipment. A differential response to colchicine was observed within and between different diploid species, diploid and tetraploid hybrids.  相似文献   

11.
Results of cytogenetic studies of 2 amphidiploids, O. glaberrima-sativa and O. sativa-breviligulata, are reported for the first time in the genus Oryza. All the 3 species have 2n=24 chromosomes. They were produced by treating buds of F1 stubbles with 0.1% colchicine solution.The gigas effect of polyploidy was observed in both the amphidiploids. While the F1 hybrids were completely sterile polyploidy resulted in 75.0% pollen fertility in both, with 47.0% spikelet fertility in O. glaberrima-sativa and 12.7% in O. sativa-breviligulata. Meiosis in the 2 amphidiploids was generally similar. Quadrivalents ranging from 0 to 12 were observed with 2 modes at 6IV and 8IV. The average number of IVs in the C2 and C3 generations ranged from 6.2 to 7.8. Segregation of characters was observed in the C2 and C3 generations in O. glaberrima-sativa. The C2 plants segregated for spikelet size and hairiness. Of the 4 C3 progenies studied, one segregated in the ratio 3:1 for the presence of anthocyanin pigmentation and hairiness of spikelets.The occurrence of IVs in high frequency and the segregation for differences in characters of the original parents noted in O. glaberrima-sativa are similar to the results reported from autotetraploids of O. sativa. It is suggested that these results point out to the rather close structural similarity in the chromosome complements of the 3 species and provide experimental evidence to the theory that the 2 cultivated species O. sativa and O. glaberrima have evolved independently from a common species O. perennis.  相似文献   

12.
Isolation distance is the main barrier to crop-to-crop gene-flow. A 3-year study assessed the maximum potential outcrossing under field conditions between two wheat cultivars (Triticum aestivum L.) and between wheat and durum wheat (Triticum turgidum L. var. durum). Outcrossing was measured by seed set on emasculated recipient plants placed at four sides with different distances from a 3 m × 3 m T. aestivum (cultivar Chinese Spring) pollen source. Frequencies of seed set at 0 m distance were 45% (37–56%) for T. aestivum cultivars and 18% (5–30%) with T. turgidum. These values agree with hybridization in non-limiting pollen conditions measured by manual crosses in greenhouse. The number of pollen grains and the outcrossing frequencies decreased at increasing distances influenced by the prevailing wind direction. Under semiarid conditions of this assay, viable pollen was found 14 m from the pollen source, with a maximum distance of 8 m at which cross-pollination decreases below 1%. Ambient conditions affect pollen viability, hybridization and pollen dispersal. Data presented in this paper emphasize the major role played by environmental conditions in outcrossing. Data obtained in one area may therefore not coincide with the prevailing situation in different locations and climates.  相似文献   

13.
Fenny Dane  T. Tsuchiya 《Euphytica》1979,28(3):563-567
summary Meiotic chromosome studies of polyploid Cucumis species revealed the presence of bivalent chromosome configurations in the tetraploid C. aculeatus and C. zeyheri and hexaploid C. figarei, while a maximum of ten quadrivalents were observed in pollen mother cells of a tetraploid species, C. heptadactylus.Allotetraploidy was not accompanied by an increase in the number of pores per pollen grain, but the autotetraploid and hexaploid species showed a relatively high percentage of 4-porate pollen. The pollen fertility of the tetraploid species was normal.Contribution from the Department of Horticulture and Department of Agronomy. Supported by the Colorado State University Experiment Station and published as Scientific Series Paper No 2403.Former Graduate Research Assistant, Department of Horticulture (present address, 1030 Sanders St., Auburn, Alabama 36830 USA) and Professor, Department of Agronomy, respectively.  相似文献   

14.
Cross compatibility between Abelmoschus esculentus and A. moschatus   总被引：1，自引：0，他引：1  
Interspecific cross compatibility between cultivated and wild okra (Abelmoschus esculentus and A. moschatus) and pollen tube growth behaviour in the crosses among a local cultivar of A. esculentus, A. moschatus and their F1s were studied. Fruit set was observed in all the crosses except one and seed setting was absent in two of the crosses which set fruit. All seed produced were shrivelled but F1 plants were obtained from two crosses where cultivated okra was used as the seed parent. The F1 plants were perennial in nature with very low pollen viability and seed set. A high percentage of pollen germination and profuse pollen tube penetration in the style were observed in the cross A. esculentus × A. moschatus but low pollen tube penetration with abnormal pollen tubes was observed in the reciprocal cross. The number of pollen tubes was very low but they appeared to be normal in the backcross A. esculentus × F1, but were generally abnormal in the reciprocal cross. Both pre- and postzygotic barriers seemed to occur in crosses between the two species. The present studies indicate that these barriers can be overcome and desirable characters from A. moschatus transferred to cultivated okra using conventional hybridisation techniques. This revised version was published online in July 2006 with corrections to the Cover Date.  相似文献   

15.
J. B. O. Owuor 《Euphytica》1985,34(2):355-360
Summary Melosis was studied in Coffea arabica, in induced tetraploid C. canephora, in their F1 hybrid (arabusta hybrid) and in backcross generations of the hybrid with C. arabica as recurrent parent. Irregularities were observed, consisting of univalents (especially in the arabusta hybrid), multivalents (especially in tetraploid C. canephora) and uneven distribution of chromosomes at first anaphase. Chromosome distribution was improved by backcrossing. Meiotic irregularities wer negatively correlated with pollen fertility.  相似文献   

16.
Viability and storage of bromeliad pollen   总被引：7，自引：1，他引：6  
Several bromeliad species from two different subfamilies, were used to develop a reliable method to evaluate pollen viability. Pollen germination on a medium containing 20% sucrose, 0.001%H3BO3 and 0.5% agar was comparable to germination on a compatible stigma. Maximum germination was reached within 2 to 10 hours depending on the species. Based on this test, six species were considered as being good pollen donors with germination percentages between 49%and 83%. Furthermore, pollen from these species and cultivars could be stored in liquid nitrogen (–196 °C) without a considerable loss of viability. For all species, a dehydration period of 4 hours prior to cryopreservation and a rehydration period of 1 hour after cryostorage were essential. Greenhouse humidity influenced anther moisture content and cryostorability. This revised version was published online in July 2006 with corrections to the Cover Date.  相似文献   

17.
Summary Low temperature and humidity were used for the storage of pollen of four species of Fragaria (2n=14, 42 and 56) and two species of Potentilla (2n=14). The stainability of Fragaria pollen was assessed over a number of years by use of aceto-carmine stain and its viability by cross-pollinations; stainability of Potentilla pollen was assessed by acetocarmine. Fragaria pollen so stored remained stainable for seven years and showed the ability to set seed for three years. over the latter period, aceto-carmine staining gave a reasonable prediction of seed set produced by the stored pollen of Fragaria and so is of value in estimating pollen viability in that genus. Potentilla pollen remained stainable for three years.  相似文献   

18.
The first success at interspecific hybridization between cultivated sunflower(H. annuus) and a diploid perennial species, H. simulans is reported. The F1s from both direct and reciprocal directions exhibited dominance of the wild species phenotype and were pollen sterile. Meiosis was irregular in the F1 hybrids and both univalents and multivalents were observed. Multiplication of the interspecific hybrids was achieved through in vitro culture of nodal sections on Murashige & Skoog medium supplemented with 0.5 mg l-1 benzyladenine. Fertility of the interspecific hybrids was improved by subjecting the in vitro proliferating shoots to 0.001% colchicine incorporated in the shoot multiplication medium. The amphiploids serve as fertile bridges and facilitate interspecific gene transfer through conventional breeding. This revised version was published online in July 2006 with corrections to the Cover Date.  相似文献   

19.
Summary InDactylis glomerata L. subsp.lusitanica, triploid and tetraploid plants were obtained by bilateral sexual polyploidization in crosses between diploid parents known to produce 2n gametes. The polyploid and diploid progeny were compared for allozyme diversity (allele number and heterozygosity), phenological (pollen fertility, inflorescence emergence date), cellular (stomatic cell size) and morphological characters (vegetative biomass, seed weight, total seed number per plant, panicle number and seed number per panicle length) in four contrasting growing conditions. Stomatal cell size and the total number of alleles were significantly lower in diploids than in polyploids which sometimes recovered more than two distinct alleles at a locus via 2n gametes possessing heterozygous loci. Pollen fertility was similar in diploids and tetraploids, but significantly lower in the triploids. Seed weight was significantly higher in polyploids, although the average number of seeds per panicle length and the total number of seeds was higher in the diploid sibs. No phenological differences occurred among ploidy levels whereas such differences were observed inDactylis in all the natural areas of sympatry between diploids and their related polyploids. Our results provide evidence for an instantaneous effect of polyploidization on certain traits and suggest that natural selection would act subsequently on several other traits to allow the establishment of new polyploids.  相似文献   

20.
Summary Seeds of tetraploid Solanum acaule (2n=48) and diploid S. bulbocastanum (2n=24) were germinated in petri-dishes on filter paper soaked in 0.3% colchicine. An additional treatment with 0.3% colchicine was applied one month after sowing at four successive days in the axils of the cotyledons of the seedlings. S. acaule appeared much more sensitive to colchicine (14 surviving seedlings from 500 seeds) than S. bulbocastanum (109 surviving seedlings from 450 seeds). Six S. acaule plants with 2n=96 chromosomes were obtained against 38 S. bulbocastanum plants with 2n=48 chromosomes.The ploidy level in each of the three germ layers L1, L2, L3 was determined in 113 plants of S. bulbocastanum and the following results were obtained. Four of the eight possible ploidy types were detected, viz 2x-2x-2x (72 plants), 4x-2x-2x (3 plants), 2x-4x-4x (9 plants) and 4x-4x-4x (29 plants). Doubling the number of chromosomes resulted in a highly significant increase of the number of chloroplasts in the guard cells of stomata and a greatly significant decrease in the proportion of trimerous pollen, male fertility and leaf index. The variability for all characters studied, except for leaf index, was clearly lowest in the 2x-2x-2x group. All plants with a 2x-L2 were highly male fertile and self-incompatible, also in the three bud stages tested. Male fertility of the plants with 4x-L2 varied greatly: 12 plants had more than 90% stainability, 5 plants must be considered male sterile. All non-sterile plants with 4x-L2 were found to be self-compatible, pointing to a gametophytic system of incompatibility in S. bulbocastanum.  相似文献   

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