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1.
Chun-Jie Wang Lian-Quan Zhang Shou-Fen Dai You-Liang Zheng Huai-Gang Zhang Deng-Cai Liu 《Euphytica》2010,175(3):323-329
It is believed that unreduced gametes with somatic chromosome numbers play a predominant role in natural polyploidization.
Allohexaploid bread wheat originated from spontaneous hybridization of Triticum turgidum L. with Aegilops tauschii Coss. Unreduced gametes originating via meiotic restitution, including first-division restitution (FDR) and single-division
meiosis (SDM), are well documented in triploid F1 hybrids of T. turgidum with diploid Ae. tauschii (genomic constitution ABD, usually with 21 univalents in meiotic metaphase I). In this study, two T. turgidum lines known to carry genes for meiotic restitution were crossed to tetraploid Ae. tauschii. The resulting F1 hybrids (genomes ABDD), had seven pairs of homologous chromosomes and regularly formed 14 univalents and seven bivalents
at metaphase I. Neither FDR nor SDM were observed. The distribution of chromosome numbers among progeny obtained by self pollination
and a backcross to T. turgidum showed the absence of unreduced gametes. These results suggest that high homologous pairing interfered with meiotic restitution
and the formation of unreduced gametes. This may be related to asynchronous movement during meiosis between paired and unpaired
chromosomes or to uneven distribution of chromosomes in anaphases, resulting in nonviable gametes. 相似文献
2.
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
3.
Summary The meiotic behaviour of a hybrid between Triticum aestivum and the amphiploid Hordeum chilense x T. turgidum conv. durum, was studied using a C-banding staining method. This hybrid has the genome formula of AA BB D Hch with 2n=6x=42 chromosomes. The durum wheat chromosomes (genomes A and B) were easily recognized, whereas the D and Hch chromosomes were recognized as a whole. Meiotic pairing was homologous, as expected (14 bivalents from A and B genomes +14 univalents from D and Hch genomes). However, some pollen mother cells at metaphase-I presented pseudobivalents that could have been caused by either homoeologous or autosyndetic pairing amongst D and Hch chromosomes. 相似文献
4.
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
5.
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
6.
A synthetic amphidiploid species Cucumis hyriviis Chen & Kirkbride (2n = 4x = 38; genome designated as HHCC) has recently been created from an interspecific mating between C. sativus L. (2n = 2x = 14: genome designated as CC) and C. hystrx. Chakr. (2n = 2x = 24; genome designated as HH). This amphidiploid is resistant to root knot nematode, tolerant to low irradiance, and has higher nutritional value than standard processing cucumber cultivars. An allotriploid (2n = 3x = 26; HCC) was derived from a cross between C. sativus L. and C. hytivus Chen & Kirkbride. Diploid meiotic behaviour in C. sativus and C. hystrix involves the development of seven and 12 metaphase bivalents respectively. In the derived allotriploid. univalents. bivalents, and trivalents (at relatively low frequency) were observed at metaphase I indicating that some homeologues from the C and H genomes can synapse. Based on a comparative karyotype analysis of cucumber (i.e. chromosome size and pairing behaviour) and aliotriploid plants, the seven bivalents observed at metaphase I were ascertained to be cucumber homologues, while the 12 univalents were of C. hystrix origin thus confirming the allotriploid karyotypic constitution to be HCC. On average, the frequency of trivalents was 0.24 at diakinesis and 0.22 in 100 meiocytes at metaphase I. indicating the possibility of genetic exchange due to the homoeology between the C and H genomes. After simultaneous cytokinesis, only polyads were observed in pollen mother cells (PMCs) at telophase II, which led to the production of sterile pollen grains. Multi‐polarization of chromosomes was dominant at anaphase II. However. in about 20% PMCs. chromosomes separated to form a 7C + 1‐2H complement, suggesting a possible method for the production of alien addition cucumber‐C hystrix lines through further backcrossing of the allotriploid to diploid cucumber. 相似文献
7.
Among the progenies of a hybrid between common wheat Triticum aestivum L. cv. Yannong 15 and Thinopyron intermedium, plant E99018 was identified with the chromosome number 2n = 42 and stable agronomic traits. An analysis of the metaphase chromosome pairing indicated that it formed 21 bivalents but that 2 univalents were present in the F1 hybrid of this plant with common wheat. Resistance verification by race 15 and with mixed races of Blumeria graminis f. sp. tritici at the seedling and adult stages showed that at both stages, the plant was immune to powdery mildew. In situ hybridization with the genomic Th. intermedium and the St genome DNAs as probes and wheat DNA as a block has shown that it contained a pair of Th. intermedium chromosomes. On the basis of the hybridization pattern of the St genome probe to the critical chromosome, a conclusion was reached that this pair of chromosomes belonged to the E genome. Therefore, plant E99018 was a spontaneously formed substitution line. An analysis by 116 SSR markers indicated that the substituted wheat chromosome was 2D and the most likely substitution in E99018 is 2E(2D). 相似文献
8.
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
9.
Summary Crosses between a wild species C. chacoense and three cultivated species of chili pepper viz. C. annuum, C. frutescens and C. chinense yielded hybrids when C. chacoense was the seed parent but the reciprocal crosses were unsuccessful. C. chacoense × C. annuum F1 hybrids were partly fertile and therefore an F2 population could be raised; the other two F1 hybrids were totally sterile. Chromosome pairing in the F1 plants resulted largely in bivalents and a few multivalents and univalents. The genomes of the four species share large homologies and the role of chromosome structural changes in genome differentiation is suggested. Hybrid sterility is the major reproductive isolation mechanism. 相似文献
10.
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
11.
S. Tokumasu 《Euphytica》1976,25(1):463-470
Summary Amphidiploids (Brassicoraphanus) were produced by means of colchicine treatment of F1 hybrids between Brassica japonica
Sieb. and Raphanus sativus L. The cytology of the amphidiploids was studied from F1 to F3 generations. Some plants had the euploid chromosome number 2n=38, whereas others had the aneuploid number 2n=37. One or two of either quadrivalents or trivalents, as well as some univalents, were seen in most of the plants examined. All the plants showed a low seed fertility. In F3 generation there arose some yellow-flowered plants, all of which showed a higher seed fertility than normal white-flowered plants. It is postulated that the change of flower colour might originate in the segmental exchange of only partially homologous chromosomes following multivalent formation. A gene causing white flower colour was perhaps closely linked to a gene causing sterility, and both genes were probably excluded together through the segmental exchange of the chromosomes. Therefore, it can be said that the increase of fertility was induced by cytological irregularity. 相似文献
12.
Cajanus reticulatus var. grandifolius, endemic to Australia and a wild relative of the cultivated species, C. cajan, was successfully crossed with the latter as the female parent. The major wild species characters such as persistent stipules,
long pod hairs, pod shattering, brown seeds with grey speckles, and presence of seed strophiole were dominant in the hybrid.
For growth and branching habit, and leaflet, flower, pod, and seed size, the hybrid was intermediate between the parents.
The meiotic cells of the hybrid were found to have quadrivalents, trivalents, univalents,and showed reduced chromosome pairing
as revealed by the increased number of rod bivalents per cell at metaphase-I, and stickiness and precocious movement of chromosomes
to poles in the second division. In comparison to the parents, the hybrid had fewer pods and seeds. However,these anomalies
in the interspecific hybrid are not significant enough to preclude the gene transfer from C. reticulatus to the cultivated species through a sexual route.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
13.
Summary Results of reciprocal crosses between Solanum verrucosum (2n=2x=24) and S. bulbocastanum (2n=2x=24) are described in terms of pollen tube behaviour in styles, of berry and seed set, of fertility and of meiotic behaviour of the F1 hybrids. Pollen tube growth of S. verrucosum is strongly inhibited in styles of S. bulbocastanum, whereas no inhibition is observed in the reciprocal cross. Therefore S. bulbocastanum x S. verrucosum fails to set berries or seeds, whereas the reciprocal cross produces both berries (54.4% berry set) and seeds (0.3 per berry). Only 14.6% of the seeds germinate. Both the diploid and corresponding tetraploid hybrid plants are vigorous, flower abundantly, have a rather regular meiosis (mainly rod bivalents), but show a high degree of cytoplasmic-genic male sterility. Crossability of the diploid hybrid plants is nil when used as pollen parents and near to zero when used as pistillate parents. The barriers to hybridization of the parent species (unilateral inhibition of pollen tube growth, somatoplastic sterility, cytoplasmic-genic male sterility and structural differences of the parental chromosomes) are discussed and methods are suggested to overcome these barriers. 相似文献
14.
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
15.
Summary The meiotic behaviour of five tetraploid wheat strains x Elytricum fertile (2n=42 chromosomes, AABBD(SH) genomes) F1 hybrids has been analysed. Multivalent associations were observed in the hybrids which could be attributed to Elymus sibiricus L. gene (s) somewhat suppressing the activity of the wheat homoelogous pairing control system. This interaction depends on the wheat genotype. The effect was particularly notable when Triticum turgidum var. salomonis was the wheat parent. The possibility of gene transfer from Elymus to wheat is discussed. 相似文献
16.
Summary An intergeneric hybrid (2n=38) between Gossypium hirsutum L. (2n=52) × Hibiscus panduraeformis
Burm. (2n=24) was obtained by pollinating about 2000 flower buds of G. hirsutum var. Gregg Male Sterile with pollen from H. panduraeformis. The F1 hybrid was intermediate in plant habit, but possessed gossypol glands and nectaries on the leaves, bolls containing seeds with fuzz and lint as dominant characters of G. hirsutum. Flowers with yellow corolla and anthers; purple petal spot, profuse growth of epidermal hairs on all plant parts including the boll sutures, and jassid tolerance were dominant characters of H. panduraeformis. The partial fertility of the F1 indicated the possibilities of combining jassid and drought tolerance of H. panduraeformis with the desired economic characters of G. hirsutum for rainfed cultivation.The F1 hybrid showed various meiotic irreguarities and about 40% pollen sterility. Formation of the normal bivalents occurred quite frequently suggesting a close relationship between the parental species. The sterility observed in the hybrid may be due to small structural differences between the chromosomes of the two genera and meiotic abnormalities. 相似文献
17.
Summary A comparison was made of the meiotic stability and reproductive behaviour ofTriticale hexaploide cv. Rosner andT. aestivum cv. Pitic in response to two temperature regimes (15° and 30°C) imposed continuously from premeiosis to maturity. Mean frequencies of MI open bivalents, univalents, and lagging chromosomes at AI were significantly higher in Rosner than in Pitic. Such irregularity would appear to arise from the asynchronous disjunction of chromosomes between Metaphase I and Anaphase I, resulting in meiotic disturbances and a high frequency of abnormal microspores. Despite such abnormalities, floret fertility was equivalent to that observed in Pitic, and the proportion of aneuploids recovered in the progeny, although greater than expected in wheat, was much lower than would be predicted. It is suggested that there is a strong certation effect in the transmission of aneuploid microspores and that the irregularities observed during microsporogenesis do not apply directly to megasporogenesis.No appreciable effect of temperature on meiotic chromosome behaviour during microsporogenesis was observed in either wheat or Triticale. In Triticale, high temperatures (30°C) substantially reduced spikelet fertility, and in contrast, low temperature (15°C) increased the frequency of aneuploids.Contribution No 232, Department of Plant Science, University of Manitoba, Winnipeg 19, Manitoba, Canada 相似文献
18.
Summary The regular meiotic behaviour of the cultivated oat Avena sativa (2n=6x=42) is genetically controlled. The factors which control the diploid-like meiotic behaviour also restrict the amount of pairing that occurs between alien chromosomes and their homoeologues in A.sativa, and hence increases the difficulties of introducing desirable variation from wild species into the cultivated oat. A genotype of the diploid species A.longiglumis which interferes with the regular meiotic behaviour of A. sativa can be used to induce pairing between alien chromosomes and their corresponding chromosomes in A. sativa. Using this procedure the dominant gene conferring mildew resistance has been transferred from the tetraploid weed species A. barbata into the cultivated oat. 相似文献
19.
L. K. Bharathi Vinod A. D. Munshi T. K. Behera Shanti-Chandrashekaran J. J. Kattukunnel A. B. Das Vishalnath 《Euphytica》2010,176(1):79-85
Teasle gourd [Momordica subangulata Blume subsp. renigera (G. Don) de Wilde, 2n = 56] exhibits morphological characters found in both M. dioica (2n = 28) and M. cochinchinensis (2n = 28). Morphological analysis of M. subangulata subsp. renigera suggests an allopolyploid origin. We present evidence elucidating the genomic relationships between M. dioica, M. cochinchinensis and M. subangulata subsp. renigera. A triploid M. dioica × M. subangulata subsp. renigera hybrid had an average of 12.76 bivalents, 13.84 univalents and 0.88 trivalents at metaphase I, while the M. cochinchinensis × M. subangulata subsp. renigera hybrid had an average of 13.08 bivalents, 12.96 univalents and 0.96 trivalents. F1 hybrids of the two diploid species (M. dioica × M. cochinchinensis) showed an average of 9.12 bivalents and 9.76 univalents, suggesting that the genomes of these species are only partially
homologous. A higher number of bivalents in the triploid hybrids suggests that M. subangulata subsp. renigera is a segmental allopolyploid of M. dioica and M. cochinchinensis and that its genomes have diverged from the parental genomes. 相似文献
20.
Nicotiana glauca is of potential interest to breeders as it carries resistance to black root rot of tobacco. Cytological investigations of sexual interspecific hybrids of N. tabacum T′T′TT (2n = 4x = 48) cv. ‘Wiślica’ × N. glauca GG (2n = 2x = 24) were carried out. The analyses of chromosome association at diakinesis and metaphase I in the PMCs of amphihaploid F1 T′TG (2n = 3x = 36) revealed low variable pairing with 0–5 bivalents. The sterile amphihaploids F1 were converted into partial female fertile amphidiploids T′T′TTGG by chromosome doubling. Among 36 mature plants obtained, 15 were found to have chromosome numbers (2n = 6x = 72) and were verified as amphidiploids, 9 had (2n = 6x = 70 or 71) chromosomes while the remaining 12 were haploid. True amphidiploids, in spite of quite high chromosome pairing during meiosis, were very different in pollen fertility, ranging from 0% to 85%. Male fertility disturbances did not correlate with the degree of female fertility upon pollination with N. tabacum. Sesquidiploids T′TG (2n = 5x = 60) obtained from backcrossing the amphidiploids to parental tobacco showed more than 22 bivalents, 10–12 univalents and occasional multivalents that indicated the possibility of interchange events between N. tabacum and N. glauca genomes. 相似文献