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1.
Meiosis and Pollen Viability in Helianthus tuberosus L. and its Hybrids with Cultivated Sunflower 总被引：1，自引：0，他引：1
The hexaploid species of Helianthus tuberosus is a potential source of resistance to several sunflower pathogens. But crossed with cultivated sunflower, it produces F, hybrids which have low values of fertility or even full sterility. Pollen viability and meiotic features were studied in 17 populations of the species H. tuberosus and in F1 hybrids. Significant differences in pollen viability existed between populations (47.1–98.8%). In the 15 FI hybrids, plant fertility ranged from 0 to 100 per combination, while pollen viability ranged from 12.4 to 57.1. Meiosis was almost normal in the analyzed species, and irregular in the F, hybrids. The highest percentage of meiocytes was with bivalents (85.9), but univalents (0.3) and multivalents (13.8) occurred as well. In metaphase and anaphase, the percentage of meiocytes with fast and lagging chromosomes was high. In anaphase, chromosome bridges were detected in 9.9 of the meiocytes. 相似文献
2.
Three diploid perennial sunflower species are useful for variety improvement: Helianthus mollis, because of sessile leaves, H. salicifolius, because of a high oil concentration, and H. maximiliani, a potential source of resistance to Sclerotinia sclerotiorum. The crossability of these species to cultivated sunflower was examined.Hybrids were obtained from eight combinations, with 3–15 F1 plants per combination. The F1's exhibited the dominant phenotype of the wild species. Pollen viability varied between 32.1 and 69.9%. Meiosis was irregular in the F1 hybrids. At diakinesis, bivalents (62.7–97.9% of meiocytes), univalents (0–31.23%), and multivalents (3.84–7.68%) were detected. At anaphase I, chromosome bridges were detected in 6.77 to 11.44% of meiocytes. Fast chromosomes in metaphase I, and lagging chromosomes in anaphase I and telophase II were evidenced in a high percentage of meiocytes. 相似文献
3.
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
4.
Creeping bentgrass (Agrostis
stolonifera L. or A. palustris Huds.) is a highly outcrossing allotetraploid species. It can form hybrids with a number of other Agrostis species and Polypogon genus. However, cytology and pollen grain fertility of the creeping bentgrass interspecific and intergeneric hybrids are
not well known. In this research, chromosome pairing behaviors during meiosis I in F1 and pollen viability of F1 hybrids, as well as seed set rate and seed germination rate of backcrosses were studied in hybrids between creeping bentgrass,
and other bentgrass species and three species of Polypogon genus. Abnormal chromosome pairing, laggard chromosomes, and premature segregation in F1 hybrids were found. Pollen viability ranged from 1.6 to 48.5% amongst F1 hybrids, significantly lower than that of the parents (85.5–94.1%). Some hybrids produced pollens of different sizes within
the same anther. Seed set following backcrosses using F1 hybrids as the male parent and creeping bentgrass as the recurrent parent was significantly lower than their parents. The
study of chromosome paring behaviors and progeny fecundity are important in utilizing the alien genes to improve bio-stress
and abio-stress resistance, and in assessing the potential transgene risks of creeping bentgrass. 相似文献
5.
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
6.
Summary Meiosis was studied in some triploid, tetraploid and hexaploid F1-hybrids from Solanum acaule x S. bulbocastanum and in a triploid F1-hybrid from S. acaule x S. tuberosum-haploid.The only anomaly found was stickiness at metaphase I, the degree of which appeared to be related to the proportion of the S. bulbocastanum chromosomes in the hybrids. No stickiness occurred at pre- and post-metaphase stages.A clear allosyndetic pairing between chromosomes of the two S. acaule genomes was observed in all triploid and tetraploid hybrids. These genomes apparently are closely related and little differentiated. The triploids S. acaule x S. bulbocastanum had 0–1 trivalent per cell, whereas 2–5 trivalents per cell were observed in the triploid S. acaule x S. tuberosum-haploid. Therefore S. acaule is more closely related to S. tuberosum L. than to S. bulbocastanum. A small amount of pairing between S. acaule and S. bulbocastanum is apparent from the occurrence of multivalents in all hybrids.Hexaploid F1's (2n=72) showed a nearly complete homologous pairing of chromosomes (35.2 bivalents per cell) and generally a normal separation of chromosomes at anaphase: 36-36. This offers an explanation for their high fertility. Triploid F1's from S. acaule x S. bulbocastanum have a high frequency of univalents leading to irregular separation of chromosomes at anaphase and consequently to unbalanced gametes and extreme sterility. In the tetraploid F1's (2n=48) nearly complete bivalent pairing was observed, 50% expectedly being homologous and 50% homoeologous pairing. Separation of chromosomes at anaphase was generally normal 24-24. In spite of this normal behaviour and allowing for tight stickiness at metaphase the tetraploids are very sterile. A satisfactory explanation cannot yet be given.Selfing and intercrossing hexaploid F1's gives normal berry set and many seeds per berry. However crosses with S. tuberosum and even those with the fertile hexaploid hybrid from 8x-S. acaule x 4x-S. tuberosum are little successful: berry set is far below normal and the berries are either parthenocarpic or contain only one or two seeds. These rather unexpected results warrant further investigation. Large-scale selfings and intercrosses of triploid and tetraploid hybrids have not been successful as yet. Among the female gametes of tetraploid hybrids a few appeared to be functional in crosses with hexaploid hybrids and in those with S. bulbocastanum. 相似文献
7.
Summary Three non-tuberous Solanum species of series Etuberosa-S. brevidens (brd), S. etuberosum (etb) and S. fernandezianum (frn)-upon selfing displayed compatible berry set but seed set varied and on an average was below normal. Also in crosses between species berry set was unhampered (apart from the crosses with short-styled frn as pollen plant), but the interspecific hybrid plants showed various degrees of sterility and a low average seed set upon selfing. Cytological investigations revealed that in pure species-plants semi-sterility regularly occurred and was invariably associated with multivalent associations (up to decavalents). This may account for the decreased seed set found after selfing and intercrossing. Meiosis in F1-hybrids was even more irregular, 75% of the pmc's showing multivalents involving from 4 to as many as 22 chromosomes in various complicated configurations in which even numbers of chromosomes were predominant. However, anaphase I separation was numerically balanced in more than 75% of the cells. Pollen stainability was very low in the hybrids.It is concluded that heterozygous translocations occur within each species and that the genomes of the species are differentiated by means of gross structural changes. In view of this and of the high chromosome pairing affinity the genome symbols E
1, E
2 and E
3 are proposed for etb, brd and frn, respectively.Crossability of the Etuberosa species with tuberous S. pinnatisectum (pnt) was slightly more successful (average 2.7 seeds/berry) than that of Etuberosa species hybrids with S. pinnatisectum (average 1.7 seed/berry). In the hybrids studied-etb × pnt, frn × pnt and (brd × etb) × pnt-a high frequency of univalents was the rule (range 6–16 per cell). In addition rod bivalents (4–8 per cell) and a low frequency of trivalents occurred (0–3 in the biparental hybrids and 1–4 in the trispecific hybrid).Utilization of the valuable characters of Etuberosa for potato breeding is dependent on the degree of gene exchange between Etuberosa chromosomes and chromosomes of tuberous species. In the diploid hybrids such exchange, though limited, may take place through bivalents and trivalents. As shown in this article such diploid hybrids are non-crossable because of complete male and female sterility. Only after doubling the number of chromosomes the hybrids are fertile and can be used for further crosses. 相似文献
8.
Gléia Laverde Ricci Alice Maria de Souza-Kaneshima Maria Suely Pagliarini Cacilda Borges do Valle 《Euphytica》2011,182(3):355-361
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
9.
Interspecific hybrid plants between Melilotus altissima (yellow flowers) and either M. alba (white flowers) or M. taurica
(white flowers) and between M. suaveolens (yellow flowers) and M. wolgica (white flowers) which were inviable because of heavy
chlorosis, were grown successfully by in vitro culture and reached the flowering stage. Pollen fertility of hybrid plants
between M. altissima and M. alba was about 46% whereas hybrids between M. altissima and M. taurica and between M. suaveolens
and M. wolgica showed about 25% and 18% of pollen fertility, respectively. All F1s did not set any selfed seeds. Observing the pairing of chromosomes at metaphase I in the hybrid plants, it was revealed
that the genomes of M. altissima and M. alba differ by a reciprocal translocation. This result could account for the partial
sterility of pollen in the F1 hybrids. On the other hand, hybrid plants between M. altissima and M. taurica and between M. suaveolens and M. wolgica showed
normal pairing of chromosomes though pollen fertility of the hybrids was very low, suggesting that low pollen fertility was
controlled by sterility gene(s). These results demonstrate that M. altissima and 7 other species of the subgenus Eumelilotus
share the same chromosomal constitution. The only exception, M. alba, differs from the other 8 species by a segmental interchange.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
10.
Interspecific hybrids and backcross generations between the wild perennial species Helianthus resinosus, Helianthus paucifiorus, Helianthus laevigatus, Helianthus nuttallii ssp. nuttallii T. & G. and Helianthus giganteus, resistant to broomrape (Orobanche cernua) and susceptible inbred lines were obtained to study crossability to cultivated sunflower and the transmission and expression of resistance to this parasitic weed. Conventional crosses with all the species tested were successful except for the crosses with diploid H. giganteus, for which embryo rescue techniques were needed to overcome hybrid incompatibility. Pollen viability and seed set were highest for F1 hybrids with hexaploid species and lowest for those with the diploid H. giganteus. We evaluated F1, BC1F1, some BC2F1 plants and the wild and cultivated parents. The wild species and interspecific hybrids were resistant to broomrape infection except for H. nuttallii, which showed segregation, indicating that the resistance is dominant. The crossability and resistance of F1, and back-cross generations of species with different ploidy levels indicate that the transfer of broomrape resistance to cultivated sunflower is feasible. 相似文献
11.
Triticale is generally treated as a self‐pollinating crop and line breeding is practised. Hybrid breeding has been discussed for some time, but there is little information for winter triticale. This study investigated heterosis for eight agronomic traits in F1 and F2 hybrids grown together with their parents as drilled plots in three environments. On average, grain yield heterosis was 12.5 dt/ha (a relative 10.5%) compared with the mid‐parent value for F1 hybrids, and 6.2 dt/ha (5.0%) for F2 hybrids and withawide range of 4.4–17.1 dt/ha for F1 hybrids. A positive contribution to the heterosis of yield was made by kernels/spike and 1000‐kernel weight, whereas spikes/m2 showed negative heterosis. Hybrid plants in F1 and F2 were taller than mid‐parents (8.3 cm and 5.3 cm, respectively), with a tendency to earlier heading. The negative heterosis for falling number in F1 and F2 hybrids could be a problem for commercial production of triticale hybrids. By selecting parents for combining ability and the identification of heterotic patterns, grain yield heterosis of 20% appears feasible. 相似文献
12.
Three tetraploid (2n= 4x= 28) wheat Triticum turgidum L. landrace morphotypes (= genotypes) from Ethiopia were found to carry a variant karyotype directly discernible under the microscope. This was possible because the rearrangement involved one of the satellited chromosomes. Giemsa C-banding revealed that the rearrangement resulted from a 5BS.6BS(5BL.6BL) centric reciprocal translation. The banding pattern on 5BL was polymorphic, suggesting that this translocation might have occurred more than once. There was little C-band polymorphism for the remaining chromosomes, except for 2A. As pure lines, all three morphotypes showed normal chromosome pairing at metaphase I (MI) in pollen mother cells (PMCs). indicating that they are genomically stable. Meiotic analyses of F1 hybrids and F2 segregates derived from crosses with tester varieties clearly indicated that one of them (B-l–9) carried another translocation. However, we were not successful in delecting the chromosomes involved, presumably the interchanged segments did nol include C-banding regions. By using T5BS.6BS, direct evidence for segregation distortion against translocation homozygotes in intervarietal hybrids was obtained. The distorted segregation was attributed lo zygotic selection. No aneuploid plants were obtained from the F2 segregates. However, translocation heterozygotes resulting in unstable meiosis were abundant in the F2 generation. The implications of the results in using the indigenous landraces in hybridization breeding are discussed. 相似文献
13.
Anther culture in the breeding process of winter wheat. III. Ability of winter wheat F1 populations with the two heterozygous 1AL–IAS/1AL–IRS and 1BL–1BS/1BL–IRS chromosome pairs Application of anther culture to four F1 hybrids between the IBL–IRS (‘Amigo’) and several 1BL–IRS wheat-rye translocation forms yielded 129 green pollen plants in an average embryo induction frequency of 17.6 %. A total of 2632 anthers was inoculated. 25 % and 42 % of the regenerated plants were haploid and spontaneously doubled haploid, and 33 % had abnormal chromosomal structure. After chromosome doubling treatment 87% of all pollen plants set seeds. By means of multiple peroxidases and Giemsa C-banding patterns, the anther culture progeny could be further classified into 16 plants without the short arm of IR-chromosome of rye, 21 IAL–IRS and 50 1BL–IRS translocation lines and into 16 IAL–IRS, IBL–IRS double translocation lines according to the four possible characteristic types of F2 gametes of the tested F1 hybrids. Advantages of the haploid technique for the selection of desirable traits and the meaning of the IRS genes in wheat are discussed. 相似文献
14.
The meiotic behaviour of 13 spontaneous interspecific F1 hybrids of Amaranthus was studied. The hybrids between species with n= 16 chromosomes had 16 bivalents but varied considerably in pollen stainability (0–55%). These results suggest the existence of cryptic structural hybridity. The hybrids involving A. cruentus (n = 17) and species with n = 16 (A. caudatus and A. quitensis) always formed 15II+1 III with very low pollen stainability (5–7%). Further observations indicated that Amaranthus species are allotetraploids with basic numbers of x= 8 and x= 9 but exhibit x= 16 and x= 17 as secondary basic numbers, as demonstrated by (a) the frequent presence of 811 + 171 in the meiosis of the hybrid A. spinosus (n = 17) × A. hybridus (n= 16); and the occurrence of secondary associations between bivalents in MI. Genomic formulae are proposed for each species, on the basis of the meiotic behaviour of the hybrids studied. 相似文献
15.
Embryo rescue techniques were used to obtain hybrids between Sinapis alba L. (white mustard) and Brassica napus L. (oilseed rape) with the goal of improving the disease tolerance of oilseed rape. Hybrid plants with 31 or 43 chromosomes were only recovered, when S. alba, was used as the female parent. One hybrid was obtained from the cross S. alba L. cv. ‘Kirby’×B. napus L. cv. ‘Topas’, while 26 hybrids were obtained, when various S. alba L. cultivars were pollinated with the rapid cycling B. napus line CrGC 5006. All F1, hybrid plants were male sterile; however, the first generation backcross to B. napus L., also obtained by embryo rescue, produced plants with 50 chromosomes and 61–84 % pollen viability. Second backcross generation seed was produced by normal sexual crossing. Preliminary cytological analyses of pollen mother cells of hybrid plants suggests the possibility of genetic exchange between the two species. 相似文献
16.
N. Inomata 《Plant Breeding》2002,121(2):174-176
In this cytogenetic study the progeny of all crosses were investigated in F1, F2 and backcross (BC1) hybrids. Brassica napus and F1 hybrids between B. napus and B. oleracea, and between B. napus and three wild relatives of B. oleracea (B. bourgeaui, B. cretica and B. montana). Each of the wild relatives has 18 somatic chromosomes. Interspecific F1 hybrids were obtained through ovary culture mean. These had 28 and 37 chromosomes and their mean pollen fertility was 10.7% and 93.0%, respectively. Many F2 and BC1 seeds were harvested from the F1 hybrids with 37 chromosomes after self‐pollination and open pollination of the F1 hybrids, and backcrossing with B. napus. Many aneuploids were obtained in the F2 and BC1 plants. It is evident from these investigations that the F1 hybrids may serve as bridge plants to improve B. napus and other Brassica crops. 相似文献
17.
Summary Morphological and cytogenetical studies were carried out on the F1 and F2 hybrids and backcross derivatives of the interspecific cross Capsicum baccatum L. x C. frutescens L. The F1 and F2 hybrids displayed irregular meiosis with a maximum association of eight chromosomes in the former and one quadrivalent in the latter with the appropriate number of bivalents and univalents. It is inferred that C. baccatum differs from C. frutescens (yellow) by at least tow or three interchanges and from the white cultivar by a single interchange. Structural repatterning of chromosomes, erratic meiotic behaviour, genes for pollen sterility, segregational imbalances following intergenomic recombination are believed to be major factors causing sterility in the hybrids. The two species are sympatric and natural hybrids have not been realised. 相似文献
18.
Transgene introgression from transgenic rapeseed (Brassica napus) to different varieties of B. juncea was assessed in this study. Crossability between a transgenic rapeseed line Z7B10 (pollen donor) and 80 cultivars of 16 B. juncea varieties (including two wild accessions) was estimated by artificial pollination in a greenhouse. As a result, interspecific crossability between the transgenic Z7B10 line and the 80 B. juncea cultivars varied considerably, with seeds per flower from 0.00–10.67. Seed germination rates of the interspecific F1 hybrids ranged from 49.0%–89.3%. The estimated frequencies of natural gene flow from the transgenic Z7B10 line to 10 B. juncea cultivars with different uses in the experiment field varied from 0.08% to 0.93%. The natural F1 hybrids were highly sterile, with seeds per silique ranging from 0.27 to 1.03. In addition, seeds per flower of hybrid descendants varied from 0.02 to 0.22 when F1 hybrids were self‐pollinated, and those ranged from 0.03 to 0.30 when F1 hybrids were backcrossed with their corresponding B. juncea parents. Results of this study suggest a low level of transgene introgression from transgenic rapeseed to different B. juncea varieties, which provides a sound scientific basis for the safety management of coexisting transgenic B. napus and B. juncea varieties in China. 相似文献
19.
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
20.
Summary Autotetraploid (2n=4x=28) pearl millet inbred lines, Tift 23BE and Tift 239DB, have been developed for use in crosses with other polyploid Pennisetum species. Each line set less than 1% and 3% selfed and open-pollinated seed, respectively. Seed germination was usually less than 17%. First generation (F1) hybrids between the two inbreds set up to 61% seed while up to 40% of the seed from hybrids germinated.Seed weight per inflorescence for two planting dates averaged 0.32 g and 3.06 g for the two inbreds and the second generation F2 progeny, respectively. One hundred seed weight was also significantly higher (0.78 g vs 0.48 g) in the F2 progeny, probably due better endosperm development. Chromosome behavior and pollen stainability were similar in the inbred parents and hybrids. However, the hybrids shed more pollen than the inbred parents.Heterosis was evident in the F1 hybrids and F2 progeny which showed significant increases in plant height, leaf length, leaf width, and inflorescence length in addition to fertility improvement. 相似文献