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1.
Summary Interspecific substitutions of the nucleus of Helianthus annuus (2n=34) cv. Saturn into the cytoplasm of H. petiolaris (2n=34) by successive backcrossing, resulted in progenies with indehiscent anthers containing white, rather than normal yellow, pollen. Further backcrossing by cv. Saturn failed to restore pollen shed, suggesting that the male sterility was cytoplasmic. In vivo germination tests of pollen from 23 such plants from eight BC5 lines, indicated complete pollen sterility for 14 plants, but normal seed set, suggesting that female fertility was not affected. Meiosis in all plants examined was normal.Crosses between seven sources of pollen-fertility restorer, one collection of wild H. annuus, and an existing source of cytoplasmic male sterility, resulted in a high frequency of plants with normal pollen shed in all F1 progenies. However, no normal pollen shed was evident in F1 progenies for similar crosses between BC5 male-steriles and three of the seven restorer sources, nor for the single wild H. annuus evaluated. The foregoing suggests that the backcross substitution lines are a new source of cytoplasmic male sterility. The inheritance of restoration of pollen shed was complex and not fully elucidated. Some data suggested that two independent, complementary, dominant genes were required, but others indicated two to three independent, dominant genes.  相似文献   

2.
N. Inomata 《Euphytica》2003,133(1):57-64
The cytogenetic study was investigated in the intergeneric F1 hybrid, F2and backcross progenies (BC1). The plants used were Brassica juncea(2n=36) and Diplotaxis virgata(2n=18). Three intergeneric F1 hybrids between two species were produced through ovary culture. They showed 36 chromosomes. It might consist one genome of B. juncea and two genomes of D. virgata. The morphology of the leaves resembled that of B. juncea. The color of the petals was yellow that was like in D. virgata. The size of the petal was similar to that of B. juncea. The mean pollen fertility was15.3% and the chromosome associations in the first meiotic division were(0–1)IV+(0–2)III+(8–12)II+(12–20)I. Many F2 and BC1seeds were harvested after open pollination and backcross of the F1 hybrids withB. juncea, respectively. The F2seedlings showed different chromosome constitutions and the range was from 28 to54 chromosomes. Most seedlings had 38chromosomes followed by 36, 40 and 54. The BC1 seedlings also showed different chromosome constitutions and the range was from 29 to 62. Most seedlings had both 40and 54 chromosomes followed by 36, 46 and52. In the first meiotic division of F2 and BC1 plants, a high frequency of bivalent associations was observed in all the various kinds of somatic chromosomes. Many F3 and BC2 seeds were obtained by self-pollination and open pollination of both F2 and BC1 plants, and by backcrossing both F2 and BC1plants with B. juncea, respectively,especially, three type progeny with 36, 40or 54 chromosomes. The somatic chromosomes of the F3 and BC2 plants were further investigated. The bridge plants between B. juncea and D. virgata with 36 chromosomes may be utilized for breeding of other Brassica crops as well as B. juncea. This revised version was published online in July 2006 with corrections to the Cover Date.  相似文献   

3.
N. Inomata 《Euphytica》2005,145(1-2):87-93
Brassica napus (2n = 38) and Diplotaxis harra (2n = 26) were used to investigate gene transfer from D. harra to B. napus. Intergeneric F1 hybrids (dihaploid 2n = 32 chromosomes) were obtained through ovary culture. The chromosome associations in the first meiotic division was (0–2)III + (2–10)II + (12–28)I. Many seeds were harvested in the F1 hybrid after backcrossing with B. napus, and from open pollination of the F1 hybrid. Somatic chromosome numbers of BC1 and hybrid plants varied from 2n = 26 to 52. In the first meiotic division, high frequencies of bivalent association and relatively low pollen fertility were observed. BC2 plants generated from the BC1 plants with 2n = 38 chromosomes, 69.6% showed 2n = 38 chromosomes. Many aneuploids with addition and deletion of chromosomes were also obtained. A bridge plant between B. napus and D. harra with 2n = 32 chromosomes should be valuable material for the breeding of brassica crops.  相似文献   

4.
Summary Resistance toMeliodogyne chitwoodi races 1 (MC1) and 2 (MC2) andM. hapla (MH) derived fromSolanum bulbocastanum was introduced into the cultivated potato gene pool through somatic fusion. The initial F1 hybrids showed resistance to the three nematodes. Resistance to reproduction on roots by MC1 was accompanied by resistance to tuber damage in F1 clones. Tuber damage sometimes occurred, however, in hybrids of BC1 progeny resistant to reproduction on roots when MC2 and MH were the challenging nematodes. Resistance to reproduction was transferred into BC1 individuals, but a greater proportion of BC1 progeny was resistant to MC1 than to MC2 or MH. Resistance to MC1 appears to be dominant and discretely inherited. F1 and BC1 progeny were pollen sterile, but seed were produced from crosses using cultivated tetraploid pollen sources. Approximately 11 and 33 per cent of pollinations produced berries on F1 and BC1 pistillate parents, respectively. Seed yield increased fourfold overall in crosses with F1 compared to BC1 individuals.Abbreviations MC1 Meloidogyne chitwoodi race 1 - MC2 Meloidogyne chitwoodi race 2 - MH Meloidogyne hapla - Rf Reproductive factor  相似文献   

5.
The African rice Oryza glaberrima, traditionally cultivated since more than 3.500 years, is of poor agronomic performance but resistant/tolerant to various stresses and diseases. The introduction of these characters into O. sativa cultivars is difficult since crossing barriers cause spikelet sterility in F1. Backcrossing can restore fertility and recently facilitated the development of fertile O. glaberrima × O. sativa ssp. japonica hybrid progenies for rain fed systems. With the objective to gain access to African rice germplasm for improvement of irrigated rice, crosses were performed with eighteen O. glaberrima and twenty O. sativa ssp. indica accessions. In total about one hundred F1-hybrid grains were obtained. The F1 plants were all completely sterile and backcrossing (BC) to O. sativa was performed in order to restore spikelet fertility. Monitoring of Tog5681 × IR64 hybrid progenies under field conditions revealed a broad genetic diversity within the BC1 and BC2 populations. Some BC1 and BC2 progeny plants outperformed the O. sativa parent, indicating that the heterozygocity level and complementary gene action after two backcrosses are still sufficient to positively influence plant vigor. Spikelet fertility of progenies was highly variable, but almost complete fertility was already observed within the BC1F2 population. High spikelet fertility was preserved in one out of two analyzed BC1F3 families and inmost of the BC2F3 families. The ability to restore spikelet fertility within few generations and the potential of the genetic diversity present in interspecific progenies facilitates the development of plant types specifically designed for the African irrigated and lowland environment. This revised version was published online in August 2006 with corrections to the Cover Date.  相似文献   

6.
Summary Cajanus platycarpus, an incompatible wild species from the tertiary gene pool of pigeonpea (C. cajan (L.) Millspaugh), has many desirable characteristics for the improvement of cultivated varieties. To necessitate such transfers, embryo rescue techniques were used to obtain F1 hybrids. The F1 hybrids were treated with colchicine to obtain tetraploid hybrids, that were selfed to obtain F2, F3 and F4 progenies. All of the hybrids and subsequent progenies had an intermediate morphology between the two parents. Backcrossing of the tetraploid hybrids with cultivated pigeonpea was not possible given embryo abortion, with smaller aborted embryos than those obtained in the F0 parental cross.As a route of introgression, diploid F1 hybrids were backcrossed with cultivated pigeonpea and BC1 progeny obtained by in vitro culture of aborting embryos. BC2 plants were obtained by normal, mature seed germination. Although embryo rescue techniques had to be used to obtain F1 and BC1 plants, it was possible to produce BC2 and subsequent generations through direct mature seed. Every backcross to cultivated pigeonpea increased pollen fertility and the formation of mature seeds.Special project assistant till December, 2003.  相似文献   

7.
To further understand the nature of hybrid sterility between Oryza sativa and Oryza glaberrima, quantitative trait loci (QTL) controlling hybrid sterility between the two cultivated rice species were detected in BC1F1 and advanced backcross populations. A genetic map was constructed using the BC1F1 population derived from a cross between WAB450-16, an O. sativa cultivar, and CG14, an O. glaberrima cultivar. Seven main-effect QTLs for pollen and spikelet sterility were detected in the BC1F1. Forty-four sterility NILs (BC6F1) were developed via successive backcrosses using pollen sterility plants as female and WAB450-16 as the recurrent parent. Seven NILs, in which the target QTL regions were heterozygous while the other QTL regions as well as most of the reminder of the genome were homozygous for the WAB450-16 allele, were selected as the QTL identification materials. BC7F1 for the seven NILs showed a continuous variation in pollen and spikelet fertility. The four identified pollen sterility QTLs were located one each on chromosomes 1, 3, 7 and 7. Pollen sterility loci qSS-3 and qSS-7a were on chromosomes 3 and 7, respectively, which coincides with the previously identified S19, and S20, while loci qSS-1 and qSS-7b on chromosomes 1 and 7L appear distinct from all previously reported loci. An epistatic interaction controlling the hybrid sterility was detected between qSS-1 and qSS-7a.  相似文献   

8.
Although 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.  相似文献   

9.
Summary Three triticale lines, Siskiyou, M2A-Beagle, and OK 77842 have been reported to possess resistance to bacterial leaf streak caused by Xanthomonas campestris, pv. translucens (Xct.). The three resistant lines were crossed to susceptible lines and crossed with each other. F2, BC1-F1, BC2-F1 plants were inoculated with a mixture of two Xct strains. The segregation data indicate the presence of a single dominant gene in each of the three resistant lines to bacterial leaf streak. These three genes are either the same or closely linked herein designated as Xct1.  相似文献   

10.
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. This revised version was published online in August 2006 with corrections to the Cover Date.  相似文献   

11.
Characterization of transgenic male sterility in alfalfa   总被引：6，自引：0，他引：6  
Dependable male sterility would help to make hybrid cultivar development a reality in alfalfa once higher levels of heterosis are attained. Alfalfa plants obtained by genetic transformation with a construct containing the Barnase gene under the control of a tobacco anther tapetum specific promoter were studied. Vacuolization and degeneration of the tapetal cell cytoplasm at a premeiotic stage of development were observed in all five transformed plants (T0)examined, but the severity of the abnormalities varied greatly among pollen sacs of a genotype. During the meiotic stage, some pollen sacs showed reduction in size, and the tapetum generally appeared thinner when compared to those of the non transgenic plants; tapetal cells showed abnormal vacuolization and signs of cytoplasm degeneration. Despite this, some microspores were formed and some pollen grains were shed in all the T0 plants, but these were highly variable in size and had very low in vitro germinability. Self-fertility was negligible. The T0 plants were crossed with one or two unrelated non transgenic male-fertile plants. Mendelian segregation was observed with two exceptions. Instability of the trait in F1 progenies was noticed, varying for different T0 parents. F1 plants exhibiting higher sterility than the primary transformants were observed, indicating that it should be possible to obtain good male sterile plants by backcrossing this trait into different genetic backgrounds. The possible use of this transgenic male sterility in alfalfa breeding is briefly discussed. This revised version was published online in July 2006 with corrections to the Cover Date.  相似文献   

12.
Cytological modes of the origin of 2n gametes were investigated in six different genotypes of F1 hybrids between Oriental and Asiatic (OA) lilies (Lilium, 2n = 2x = 24). Chromosome pairing between the parental genomes was very low, the average frequency range from 0.3 to 1.2 bivalents per cell among the genotypes. Within a genotype the frequency of bivalents varied from 0 to 6 in some cases. The normally occurring haploid pollen grains were totally sterile. In contrast, in different genotypes, variable percentages of 2n pollen were found and shown to be fertile as estimated from pollen germination. A cytological analysis of Metaphase I and subsequent stages of meiosis using genomic in situ hybridization (GISH) revealed that there was intergenomic recombination between the alien genomes. Following Metaphase I stage, three different types of abnormal cytological events led to the formation of 2n pollen: (i) Post-Metaphase I division (PMI), (ii) Post-Metaphase II division (PMII) and (iii) Asymmetric Cytokinesis of the pollen mother cell followed by chromosome division. All three cytological events led to first division restitution (FDR) gametes. Based on in vitro pollen germination it was proved for two genotypes that 2n pollen was viable only during the first day of anthesis. It was possible to use 2n pollen successfully for backcrossing. Implications of 2n pollen for intergenomic recombination in BC1 progenies are discussed.  相似文献   

13.
The main goal of this work was to introduce resistance genes for rust, caused by Uromyces appendiculatus, and anthracnose, caused by Colletotrichum lindemuthianum, in an adapted common bean cultivar through marker-assisted backcrossing. DNA fingerprinting was used to select plants genetically closer to the recurrent parent which were also resistant to rust and to race 89 of C. lindemuthianum. DNA samples extracted from the resistant parent (cv. Ouro Negro), the recurrent parent (cv. Rudá), and from BC1, BC2 and BC3 resistant plants were amplified by the RAPD technique. The relative genetic distances in relation to the recurrent parent varied between 9 and 59% for BC1, 7 and 33% for BC2, and 0 and 7% for BC3 resistant plants. After only three backcrosses, five lines resistant to rust and anthracnose with, approximately, 0% genetic distance in relation to the recurrent parent were obtained. These lines underwent field yield tests in two consecutive growing seasons and three of them presented a good yield performance, surpassing in that sense their parents and most of the reference cultivars tested.  相似文献   

14.
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   

15.
Summary The possibilities to transfer important traits and in particular resistance to the beet cyst nematode (Heterodera schachtii, abbrev. BCN) from Raphanus sativus to Brassica napus were investigated. For these studies B. napus, R. sativus, the bridging hybrid ×Brassicoraphanus (Raparadish) as well as offspring of the cross ×Brassicoraphanus (Raparadish) ×B. napus were used. Reciprocal crosses between B. napus and R. sativus were unsuccessful, also with the use of embryo rescue. Crosses between ×Brassicoraphanus as female parent and B. napus resulted in a large number of F1 hybrids, whereas the reciprocal cross yielded mainly matromorphic plants. BC1, BC2 and BC3 plants were obtained from backcrosses with B. napus, which was used as the male parent. F1 hybrids and BC plants showed a large variation for morphology and male and female fertility. Cuttings of some F1 and BC1 plants, obtained from crosses involving resistant plants of ×Brassicoraphanus, were found to possess a level of resistance similar to that of the resistant parent. These results and indications for meiotic pairing between chromosomes of genome R with those of the genomes A and/or C suggest that introgression of the BCN-resistance of Raphanus into B. napus may be achieved.  相似文献   

16.
Inheritance of black leaf mold resistance in tomato   总被引：1，自引：0，他引：1  
Summary Inheritance of black leaf mold (BLM) (caused by Pseudocercospora fuligena) resistance was studied in four crosses involving two resistant Lycopersicon accessions (PI134417, L. hirsutum and PI254655, L. esculentum) and four susceptible Asian Vegetable Research and Development Center tomato lines (CLN657BC1F2-267-0-3-12-7, CL143-0-10-3-0-1-10, CLN698BC1F2-358-4-13 and CL5915-93D4-1-0-3). For each cross, six generations, i.e. P1, P2, F1, F2, BC1F1 and BC1F2 were evaluated following inoculations with isolate Pf-2 of P. fuligena. Chi-square analyses of the data based on the ratio of resistant to susceptible plants in the F2 in three of four crosses gave a good fit to a segregation ratio of 1 R : 15 S, and BC1F2 data in three of four crosses gave an acceptable fit to the segregation ratio of 1 R : 63 S. The results indicate that resistance to BLM may be conditioned by two recessive genes acting epistatically in both PI134417 and PI254655.  相似文献   

17.
The male sterile plants that segregated in a BC5F2 of `C. sericeus × C. cajan var. TT-5' population were maintained by sib mating. The male sterile plants were crossed with ICPL-85012.Approximately 50% of the F1 plants were sterile. F2 plants derived from the fertile F1 plants did not segregate for male sterility. The reciprocal hybrid i.e. ICPL-85012 × Fertile derivatives from C. sericeus × TT-5, did not express male sterility. However, among the 12 F2 plant to row progenies, two segregated 25% male sterile plants and remaining 10 did not segregate. The segregation pattern in subsequent progenies revealed that the sterility was under control of a single recessive allele. Studies on the backcross and their BC1F2 and BC1F3progenies revealed another sterility gene which was found to be dominant in inheritance. This paper shows that what was thought to be cytoplasmic male sterility from C. sericeus cytoplasm is actually a single dominant gene possibly acting in concert with a single recessive gene to mimic cytoplasmic male sterility. This revised version was published online in July 2006 with corrections to the Cover Date.  相似文献   

18.
Haploid selection for traits related to pollen cold tolerance in tomato was performed in segregating populations derived from a Lycopersicon esculentum × L. pennellii hybrid. BC1 populations were obtained by combining normal and low temperature treatments on two stages of pollen development: pollen formation, and germination and pollen tube growth. F1 hybrids were cultivated under low and normal temperatures and their pollen was used to pollinate L. esculentum plants at low and normal temperatures. The four BC1 populations obtained were tested for the quality and quantity of pollen produced at low temperatures. The population obtained by cold treatment at both stages had a significantly improved pollen germination ability at low temperatures. The two other coldselected BC1 populations showed no differences compared with the unselected BC population. A second cycle of pollen selection, corresponding to BC2, was applied in order to test its persistence in the subsequent generations and the possibility to further improve the character. This second cycle showed no improvement although some plants retained the high pollen germination ability at low temperatures that was observed in the first cycle. Hence, gametophytic selection of some characters related with tomato pollen performance may be feasible, at least for the first cycle of selection.  相似文献   

19.
Summary Sunflower lines breeding true for very high oleic acid content in their oil (average levels higher than 85%) were crossed with standard sunflower lines with mean oleic acid levels of 30%. Analysis of the oil of F1 seeds indicated dominance for high oleic levels and control of the genotype of the embryo. Segregating generations were obtained selfing heterozygous high oleic BCnF1 plants from several generations of a backcrossing program to incorporate the high oleic character to standard inbred lines and testcrossing these plants to low oleic material. Analysis of F2 and testcrossed seeds showed three kind of segregations, in both F2 and testcrossed populations, with different proportions of low, intermediate and high oleic types. Genetic analysis of these data supported the hypothesis, that the high oleic character is controlled by three dominant complementary genes OL1, OL2 and OL3. Additional data showing F1 seeds with intermediate oleic content and segregations for high oleic in progenies of intermediate types, suggest the presence of major factors modifying high oleic acid content.  相似文献   

20.
Summary Atrazine resistant Brassica napus × B. oleracea F1 hybrids were backcrossed to both parental species. The backcrosses to B. napus produced seeds in both directions but results were much better when the F1 hybrid was the pollen parent. Backcrosses to B. oleracea failed completely but BC1s were rescued by embryo culture both from a tetraploid hybrid (2n = 4x = 37; A1C1CC) and sesquidiploid hybrids (2n = 3x = 8; A1C1C). Progeny of crosses between the tetraploid hybrid and B. oleracea had between 25 and 28 chromosomes. That of crosses between the sesquidiploid hybrid and B. oleracea had between 21 and 27. A few plants that had chromosome counts outside the expected range may have originated from either diploid parthenogenesis, unreduced gametes or spontaneous chromosome doubling during in vitro culture. Pollen stainability of the BC1s ranged from 0% to 91.5%. All the BC1s to B. oleracea were resistant to atrazine.  相似文献   

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