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1.
Colchicine-induced chromosome doubling in Platanus acerifolia and its effect on plant morphology 总被引:1,自引:0,他引:1
We report the production of tetraploid plants of Platanus acerifolia, with the ultimate aim of improving the ornamental qualities of this important urban landscaping tree. Chromosome doubling
was achieved by the application of colchicine to either pre-soaked seed or to the apical meristems of young seedlings. Treatment
of the ungerminated seed was the more efficient method in terms of numbers of tetraploid seedlings (up to 40%, as determined
by chromosome counting of the root-tip nuclei) but this method produced no mature tetraploid plants due to the deleterious
effect of colchicine on subsequent root growth. When colchicine was applied directly to the apical growing tip of cotyledon-stage
seedlings, leaf and stem growth was temporarily affected but the plants eventually recovered. We conducted a preliminary screen
for putative tetraploids based on the observation in other plant species of a correlation of stomatal size and distribution
with ploidy. Plants containing significantly larger stomata and at a lower density across the lower leaf epidermis, were selected
for further analysis by flow cytometry and chromosome counting. These techniques confirmed that, of the 12 putative polyploids,
four were tetraploid, five were mixoploid and three were, in fact, diploid. Morphological differences of the tetraploids included
a more compact growth habit and broader, thicker leaves. These plants are being grown to full maturity in order to test their
potential for use in a breeding programme aimed at producing sterile triploid lines. 相似文献
2.
Genus Vaccinium,consisting of blueberries, cranberries, lingonberries and many related wild species, includes diploid, tetraploid, and hexaploid
species. Most evidence indicates that the tetraploid species are autotetraploids, with non-preferential bivalent chromosome
pairing. Although homoploid interspecific crosses usually produce numerous fertile hybrids if the parents are from the same
section of the genus, inter sectional crosses at the diploid level normally produce no seedlings, weak seedlings, or seedlings
that are very low in fertility. There is a strong but not complete triploid block within Vaccinium. Even with insections, tetraploid × diploid (and the reciprocal) crosses normally give only a few tetraploid and a few triploid
hybrids. Hexaploid × diploid crosses within sections are very hard to make, and the few hybrids that have been obtained are
pentaploid. The frequency of 2n gametes varies,both among genotypes within species and among species. Vaccinium pollen is normally shed in tetrads, and the frequency of large pollen grains shed in dyads can be used to estimate 2n gamete
frequency. Cultivated blueberries occur at both the tetraploid and the hexaploid levels, and there are important genetic resources
in the diploids. Unreduced gamete production has permitted transfer of genetic material from the diploid to the tetraploid
level and from the diploids and tetraploids to the hexaploid level via triploid hybrids. Intersectional crosses can occasionally
produce tetraploid Vaccinium hybrids that appear to behave as amphidiploids and have medium to high fertility. CommercialVaccinium cultivars are normally propagated by cuttings. Intersectional hybridization, chromosome doubling, and asexual propagation
could permit the production of novel hybrid combinations with value as ornamentals or in fruit production.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
3.
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
4.
Rodrigo Barba-Gonzalez Alex A. Van Silfhout Richard G. F. Visser Munikote S. Ramanna Jaap M. Van Tuyl 《Euphytica》2006,151(2):243-250
With the aim of utilizing allotriploid (2n = 3x = 36) lily hybrids (Lilium) in introgression breeding, different types of crosses were made. First, using diploid Asiatic lilies (2n = 2x = 24), reciprocal crosses (3x − 2x and 2x − 3x) were made with allotriploid hybrids (AOA) obtained by backcrosses of F1 Oriental × Asiatic hybrids (OA) to Asiatic cultivars (A). Secondly, the AOA allotriploids were crossed with allotetraploid (OAOA, 2n = 4x = 48), in 3x − 4x combination. Finally, the AOA allotriploids where crossed to 2n gamete producer F1 OA hybrids (3x − 2x (2n)). Two types of triploids were used as parents in the different types of crosses, derived from: (a) mitotic polyploidization and (b) sexual polyploidization. Ploidy level of the progeny was determined by estimating the DNA values through flowcytometry as well as chromosome counting. The aneuploid progeny plants from 3x − 2x and reciprocal crosses had approximate diploid levels and in 3x − 4x crosses and 3x − 2x (2n) the progeny had approximate tetraploid levels. Balanced euploid gametes (x, 2x and 3x) were formed in the AOA genotypes. Recombinant chromosomes were found in the progenies of all crosses, except in the case of 2x − 3x crosses through genomic in situ hybridization (GISH) analyses. Recombinant chromosomes occurred in the F1 OA hybrid when the triploid AOA hybrid was derived through sexual polyploidization, but not through mitotic polyploidization with two exceptions. Those recombinant chromosomes were transmitted to the progenies in variable frequencies. 相似文献
5.
F. Pank F. Matzk U. Kästner W.D. Blüthner E. Foltys de Garcia A. Meister U. Ryschka G. Schumann 《Euphytica》2003,134(1):77-84
St. John's wort (Hypericum perforatumL.) is a medicinal crop plant that reproduces by apomixis. To study the reproductive diversity within the initial breeding
material, 656 plants from 92 accessions of the species were analysed by flow cytometric seed screening (FCSS) and compared
to 66 plants of cv. ‘Topaz’ as a control. Among plants from the 92 accessions, 16 were obligate sexuals, nine were obligate
apomicts and all remaining ones were facultative apomicts. Among controls, there were six obligate and 60 facultative apomicts.
Tests of reproductive pathways indicated that, in the investigated collection, all apomictic plants were tetraploid and all
sexual plants were diploid. A strategy for a cross breeding program in St. John's wort is illustrated by crossing one diploid
obligately sexual mother plant with six tetraploid facultative apomicts. All 91 F1 progeny obtained were triploid with 58% being obligate sexuals and 42%
facultative apomicts. To quantify the different routes of seed formation within facultatively apomictic individuals, the reproductive
pathways were reconstructed from about 30 single seeds from each of five tetraploid and two triploid plants using FCSS. The
frequency of seed formed by apomixis ranged from 54% to 67% among four tetraploid genotypes. One triploid and two tetraploids
formed 23% to 73% of the so-called BIII hybrids (fertilization of unreduced eggs) and one triploid was obligately sexual. The results show that while the mode of
reproduction in H. perforatum is highly variable, tetraploid obligate apomicts as well as diploid and triploid obligate sexuals can be selected as starting
material for breeding purposes.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
6.
Identification of tetraploid regenerants from cotyledons of diploid watermelon cultured in vitro 总被引:8,自引:0,他引:8
Summary Adventitious shoots were obtained from the diploid watermelon [Citrullus lanatus (Thunb.) Matsum. & Nakai] cultivars Dixielee, Jubilee II, Mickylee, Minilee, and Royal Sweet by culturing excised cotyledons on shoot regeneration medium for six weeks. Tetraploid and diploid regenerants were identified by counting the number of chloroplasts per guard cell pair from leaves of regenerated plants. Cross fertilization of putative tetraploids with diploid pollinators and the production of triploid seed confirmed the efficacy of this approach. The mean number of chloroplasts for tetraploid regenerants was 19.1 whereas diploids averaged 11.2. These values were similar to tetraploid and diploid plants from seed. Ovary diameter, petal, and anther diameter of male flowers, and leaf length by width ratio were also good indicators of plant ploidy. Progeny obtained from self-fertile tetraploids of Mickylee were crossed with various diploid pollinators to produce triploid hybrid seed. All triploid plants from tissue culture-derived tetraploids produced fruit comparable in quality to fruit produced by currently-available triploid hybrids, demonstrating that in vitro tetraploid induction can be used to produce high quality tetraploid plants for use in triploid hybrid seed production. 相似文献
7.
Summary A significant correlation among chromosome number, chloroplast number and pollen grain size was observed using interspecific hybrids (2n=30,60), Arachis hypogaea (2n=40), A. stenosperma (PI 338280) (2n=20), A. batizocoi (PI 468329) (2n=20) and A. villosulicarpa Hoehne (PI 336984) (2n=20), representing four ploidy groups. Both chloroplast number in guard cells and pollen grain size were found to be positively correlated with ploidy, and provided a reliable method to distinguish diploid, triploid, tetraploid and hexaploid plants from each other regardless of their taxonomic backgrounds. These methods in combination with root-tip chromosome counts enabled us to confirm ploidy determinations on all three dissue layers, L1, L2 and L3 (guard cells, microsporocytes and root meristematic cells, respectively), and to detect the chimeric nature of some colchicine-treated tissue culture-derived plants. Screening pollen grains by size and the detection of highly stainable and viable, 30-chromosome pollen grains have enhanced the use of triploid hybrids in peanut breeding programs. 相似文献
8.
Masako Akutsu Satomi Kitamura Ryo Toda Ichiro Miyajima Keiichi Okazaki 《Euphytica》2007,155(1-2):143-152
Tetraploid varieties of lilies have superior agronomic traits such as large flowers and resistance to physiological disorders.
In the present study, we attempted to induce 2n pollen of Asiatic hybrid lilies by arresting the meiotic process with nitrous oxide (N2O) gas. To determine which meiotic stage is optimal for induction of 2n pollen, plants with attached buds at different meiotic stages were treated with N2O for 24 h in a pressure-tolerant cylinder. A few 2n pollen grains were induced using plants with anthers in prophase I, whereas mixed pollen grains of differing size were produced
using plants undergoing meiotic metaphase predominantly in anthers. Although normal lily pollen grains are elliptical, nitrous
oxide exposure induced giant pollen grains that appeared spherical. Flow cytometry analysis showed that the giant pollen grains
were diploid. When mixed pollen that included normal and giant pollen was crossed to tetraploid cultivars, the resulting seedlings
were tetraploid and aneuploid, indicating that the giant pollen grains were diploids that could generate tetraploid seedlings
through fusion to diploid eggs supplied from a tetraploid female parent. Thus, treatment with N2O is useful for the production of 2n lily pollen and may provide a new approach for tetraploid lily breeding. 相似文献
9.
Esdras M. Carbajal M. Carolina Zuleta Luellen Swayzer Brian M. Schwartz Maria Carolina Chavarro A. Carolina Ballen‐Taborda Susana R. Milla‐Lewis 《Plant Breeding》2019,138(6):958-966
St. Augustinegrass is well suited for lawns and commercial landscapes. While many genotypes are cross‐fertile, all cultivars are propagated vegetatively in sod production. To ensure varietal purity, development of sterile triploid hybrids by crossing tetraploid and diploid genotypes has been successfully used in other warm‐season turfgrasses. Applying this model in St. Augustinegrass would be beneficial to sod producers and turf managers who require purity for certification and uniformity for performance, respectively. This study was conducted to develop colchicine‐induced tetraploid lines of St. Augustinegrass. Seeds of cultivar ‘Raleigh’ were treated with four colchicine concentrations at four exposure times. A non‐treated control was included among the treatments. Seedlings that germinated were screened for genome size changes using flow cytometry. Line DSA 13005 and two progeny lines derived through selfing, DSA 16001 and DSA 16016, were corroborated as tetraploids (2n = 4x = 36) through chromosome counts. These lines will be used in future breeding efforts to attempt development of sterile triploid cultivars of St. Augustinegrass. 相似文献
10.
Shinji Kikuchi Miwako Iwasuna Aya Kobori Yasunori Tsutaki Akihiro Yoshida Yuri Murota Eisho Nishino Hidenori Sassa Takato Koba 《Breeding Science》2014,64(2):176-182
As the fruits of loquat (Eriobotrya japonica, 2n = 2x = 34) carry large seeds, the breeding of seedless loquat has long been a goal. The recent creation of triploid cultivars (2n = 3x = 51) and the application of gibberellins allow commercial production of seedless loquat, but the possibility of seed formation in triploid loquats has not been carefully investigated. Through crossing experiments and cytological observations of meiosis and pollen tube growth, we found that the triploid line 3N-N28 was essentially self-sterile, but developed seeds on pollination with pollen from diploid cultivars at rates of up to 5.5%. Almost half of the seedlings survived to 5 months, and carried diploid (2n = 34), tetraploid (2n = 68), or aneuploid chromosome numbers. Our results suggest that triploid loquat cultivars might retain the risk of seed formation. Protection from pollination by diploid cultivars or the development of new triploid cultivars will be necessary to ensure the production of seedless loquat fruits. 相似文献
11.
Summary Eight different genotypes of the F1 hybrids between Oriental × Asiatic lily (Lilium) hybrids (2n = 2x = 24) were treated with nitrous oxide (N2O) gas under pressure for 24 and 48 hours. At the time of treatment, all plants possessed early meiotic stages in the anthers of the oldest flower buds. The mature flowers from treated plants were monitored for fertility through pollen germination in vitro as well as by using them in crosses with diploid Asiatic hybrids (2n = 2x = 24) both as male and female parents. In five out of the eight genotypes of OA hybrids there was evidence for the production of 2n pollen which germinated in vitro from either one or both treatments. The 2n pollen from three genotypes was successfully used in crosses. In two cases, the treated plants were successfully used as female parents which indicated the formation of 2n (or 2x) egg cells. From an analysis of 41 sexual polyploid progenies obtained from N2O treated plants it was shown that they were all euploids consisting of 34 triploids (2n = 3x = 36) and seven tetraploids (2n = 4x = 48). A detailed cytological analysis of 12 progeny plants through genomic in situ hybridization (GISH) proved that N2O had induced first division restitution gametes in most cases and in two cases they produced gametes through indeterminate meiotic restitution. There was evidence for intergenomic recombination in three cases. 相似文献
12.
Summary The possibility of combining anew the genomes of wild and cultivated progenitors of triploid S. x juzepczukii and pentaploid S. x curtilobum by following the known evolutionary pathway of these species was investigated.The resynthesis of S. x juzepczukii was easy, and a wide range of synthetic forms was bred. Among these were forms with higher frost resistance (-5°C) than has been found in natural S. x juzepczukii. The total tuber glycoalkaloid content of several synthetic hybrids was lower than or as low as that of natural clones. Most synthetic hybrids were more vigorous than natural S. x juzepczukii and produced about the same types of tubers as are found in the natural range of variation. The best diploid parents were found in the species S. goniocalyx.The attempt to resynthesize pentaploid S. x curtilobum has not been successful but tetraploid plants were obtained in the process. An explanation for the occurrence of tetraploids resulting from triploid x tetraploid and/or diploid crosses is offered.The newly bred tetraploids contain at least one genome from S. acaule (possibly two) and hybridize easily with ssp. andigena. They thus provide a means for the transfer of S. acaule germ plasm into the tetraploid cultivated gene pool which would profit from the frost resistance of S. acaule. 相似文献
13.
B. S. Ahloowalia 《Euphytica》1982,31(1):103-111
Summary Aneuploid plants of perennial ryegrass (Lolium perenne L.) with 2n=15 to 30 chromosomes were obtained by crossing a near-triploid (2n=3x+1=22) with a diploid or on open-pollination with diploids and tetraploids. Aneuploids occurred with a frequency of 83% in near triploid × diploid progeny and 92% on open-pollination with diploid and tetraploid plants. Aneuploid plants with 15 to 18 chromosomes resembled diploids in morphology and those with 19 to 30 chromosomes were akin to tetraploids. Meiotic studies suggested that most aneuploid plants resulted from transmission of aneuploid egg cells (n=8 to 23). Aneuploid plants with 2n=27 to 30 chromosomes in the progeny of 22×14 cross originated from unreduced egg cells. Plants with 19 to 21 chromosomes were recovered only by immature seed culture. Aneuploid plants with 26 to 30 chromosomes and triploids (2n=21) had higher pollen fertility and bigger seeds than plants with 15 to 22 chromosomes. 相似文献
14.
Summary The formation of triploids in 4x×2x crosses was studied in primitive potato varieties from the Andes of Peru and Bolivia. Triploid frequencies were as high as 80–100% in some crosses, although the actual number of seeds was low. The triploid block varied according to the tetraploid parent, and was never entirely absent. The likelihood of triploid formation was studied in 4x×2x crosses where pollen from both tetraploids and diploids of known genotype was used. Even though the diploids were chosen for their non-production of 2n gametes, as detected in pollen grain size, 66% of the hybrids were tetraploid. The amount and probability of gene-flow between the tetraploid and diploid gene-pools, either directly through 2n gametes or through triploid bridges was examined. Most of the 20 cultivars of S. x chaucha produced seed in crosses with tetraploids and diploids, although the fertility of the latter crosses was four times higher. The female fertility of some of the triploids thus allows them to exchange genes with the tetraploids and diploids, although gene-flow occurs more rapidly through direct transfer from diploids to tetraploids via 2n gametes. 相似文献
15.
The widespread occurrence of 2ngametes (i.e. gametes with the somatic chromosome number) in the Medicago sativa-coerulea-falcata complex supports the concept that gene flow from diploid to tetraploid species occurs continuously in nature and plays a
key role in alfalfa evolution. Breeders realized early that gene transfer between ploidy levels via 2n pollen and 2n eggs would have had potential use in cultivated alfalfa improvement. Cytological investigations provided insights into the
types of meiotic abnormalities responsible for the production of 2n gametes. Alterations were defined as genetically equivalent to first (FDR) or second division restitution(SDR) mechanisms.
For breeding purposes,data have proven that 2n gametes of the FDR type are more advantageous than those obtained by SDR for transferring parental heterozygosity and retaining
epistatic interactions. The use of diploid meiotic mutants that produce 2ngametes is now recognized as one of the most effective methods available for exploiting heterosis and introgressing wild germplasm
traits into cultivated tetraploid alfalfa via unilateral (USP) and bilateral sexual polyploidization (BSP) schemes. Both2n egg and 2n pollen producers could be used for direct gene transfer from wild diploid relatives into cultivated alfalfa by means of 2x-4x and4x-2x crosses. Although data have shown that forage yield improvement can be achieved when plants are sexually tetraploidized,
problems related to reduced plant fertility and seed production remain largely unexplained. Apomixis has the potential of
cloning plants through seed and thus provides a unique opportunity for developing superior tetraploid cultivars with permanently
fixed heterosis and epistatic effects. A main goal in alfalfa breeding could be the introduction of functional apomixis (i.e.
Apomeiosis and parthenogenesis) in cultivated alfalfa stocks. In the future, the efficiency of alfalfa breeding programs based
on the use of reproductive mutants could be improved by direct selection at the genotype level using RFLPs and PCR-based markers.
Suitable DNA markers and detailed linkage maps of alfalfa mutants should help to discover apomictic mutants and address basic
genetic issues such as the extent of genomicre combination in polyploid hybrids and the effect of sexual polyploidization
on heterosis. Molecular markers have recently been used in alfalfa for studying the inheritance of 2n gamete formation and identifying polymorphisms associated to genes involved in meiotic abnormalities. Molecular tagging of
2n egg and 2n pollen formation not only should explain the genetic control and regulation of these traits, but may also be an essential
step towards marker-assisted selection of 2n gamete producers and implementation of USP and BSP breeding schemes. Future perspectives include strategies for the map-based
cloning of genomic DNA markers,and screening of EST mini-libraries related to flowers at different developmental stages from
meiotic mutants and wild-type scan lead to the identification of mRNAs and thus of candidate genes that control 2n gamete formation in alfalfa.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
16.
Ploidy races in Actinidia chinensis 总被引:3,自引:0,他引:3
Summary Ploidy levels were examined in 26 accessions of Actinidia chinensis: 20 accessions were diploid (2n=2x=58) and 6 accessions were tetraploid (2n=4x=116). There was no evidence of variation in ploidy level within an accession. Our results are consistent with tetraploid A. chinensis coming from a restricted part of China.Interploid crosses within A. chinensis produced only low numbers of seedlings which were mainly triploid. Crossing hexaploid A. deliciosa with pollen of tetraploid A. chinensis produced a large family of plants and those checked were pentaploid.Counts on 83 genotypes of different ploidy levels (2x, 3x, 4x, and 5x) confirmed that the basic chromosome number in Actinidia is 29. 相似文献
17.
Veerle Lamote Joost Baert Isabel Roldán-Ruiz Marc De Loose Erik Van Bockstaele 《Euphytica》2002,123(2):159-164
Several genotypes of Lolium perenne (2n = 2x = 14) were screenedfor the production of 2n eggs. In each cross a diploid genotype, used asfemale parent, was pollinated with a tetraploid genotype. All interploidycrosses were made in isolation cages. Flow cytometrical analysis of theprogeny of 154 diploid plants revealed 28 tetraploid descendants. Theseoffspring plants were harvested on 15 different diploid mother plants.Amplified Fragment Length Polymorphism (AFLP) markers were used tocheck the parenthood of these tetraploids. Two seedlings died, theremaining plants could, after AFLP fingerprinting, be identified as meiotictetraploids. The results obtained allowed to conclude that the tetraploidprogeny plants harvested on 15 diploid mother plants were the result ofthe fertilisation of an unreduced egg by a reduced pollen grain of thetetraploid plant. 相似文献
18.
Nadeem Khan Shujun Zhou M. S. Ramanna Paul Arens Jeronimo Herrera Richard G. F. Visser Jaap M. Van Tuyl 《Euphytica》2009,166(3):399-409
Ploidy level and intergenomic recombination was studied in interspecific hybrids between Longiflorum × Asiatic lilies (LA
hybrid) backcross to Asiatic parents in order to assess the possibility for analytic breeding in lily. By backcrossing the
diploid (2n = 2x = 24) F1 interspecific hybrid between Longiflorum × Asiatic lilies to Asiatic parents, 104 BC1 progeny plants were produced.
Among these, there were 27 diploids, 73 triploids (2n = 2x = 36) and 4 aneuploids (2x − 1, 2x + 2 or 2x + 3). In addition, by backcrossing triploid BC1 (LAA) plants to diploid Asiatic parents in 2x − 3x and reciprocal combinations, 14 diploid BC2 progenies were produced. Genomic in situ hybridization (GISH) was performed to
study the intergenomic recombination and karyotype composition. GISH indicated extensive intergenomic recombination among
the chromosomes in LA hybrids. A large number of Longiflorum chromosomes were transmitted to the BC1 progenies from LA hybrids.
However, very few Longiflorum chromosomes were transmitted from the BC1 triploid (LAA) plants to the BC2 progenies. The occurrence
of diploid plants in the BC progenies of LA hybrids has opened the prospects of analytic breeding in lilies. In this approach,
the selection of superior genotypes can be carried out at the diploid level and polyploid forms are synthesized from superior
diploid parents. The advantages of analytic breeding are evident: (a) a maximum level of heterozygosity can be attained in
the synthetic polyploids and (b) introgression can be achieved with a minimum of linkage drag. Based on GISH results the potential
application of analytic breeding in lily allopolyploids has been discussed. 相似文献
19.
Maria Suely Pagliarini Claudicéia Risso-Pascotto Alice Maria de Souza-Kaneshima Cacilda Borges do Valle 《Euphytica》2008,164(1):181-187
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
20.
In vitro induction of tetraploids in Phlox subulata L. 总被引:2,自引:0,他引:2
Tetraploid plants of Phlox subulata L. were induced successfully by treating shoot tips in vitro with colchicine. Shoot tips excised from in vitro shoots were
treated with four different concentrations of colchicine (0.005, 0.01, 0.02, 0.04%) in solid MS medium supplemented with 4.54 μM
TDZ and 0.49 μM IBA for 10, 20 or 30 days, respectively. The survival rates of shoots tips were affected by the concentration
of colchicine and the duration of treatment. High concentration and longer duration reduced survival of the shoot tips, but
the effect of duration of colchicine was more than that of concentration. Tetraploid plants were obtained in all of the treatments,
but the percentages of tetraploids varied among different treatments, from 25.0% to 75.0%. The most efficient condition for
inducing tetraploids was to treat shoot tips with 0.005% colchicine for 20 days, with 30.0% survival rate of shoot tips and
6 tetraploid plants out of 10 plants examined. The rooted tetraploid plants were transplanted successfully in a solar greenhouse.
Under the same growing condition, significant varieties in flower bud and flower sizes were detected between 2x and 4x plants. The flower diameters of tetraploid and diploid plants were 2.91 cm and 2.24 cm, respectively. 相似文献