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101.
E. Benavente J. Orellana B. Fernández-Calvín 《TAG. Theoretical and applied genetics. Theoretische und angewandte Genetik》1998,96(8):1200-1204
Wheat-wheat and wheat-rye homoeologous pairing at metaphase I and wheat-rye recombination at anaphase I were examined by
genomic in situ hybridization (GISH) in wild-type (Ph1Ph2) and mutant ph1b and ph2b wheat×rye hybrids. The metaphase-I analysis revealed that the relative contribution of wheat-rye chromosome associations
in ph2b wheat×rye was similar to that of the wild-type hybrid genotype but differed from the effect of the ph1b mutation. The greater pairing promotion effect of the ph1b mutation appears to be relatively more on distant homoeologous partner metaphase-I associations, whereas the lower promoting
effect of ph2b is evenly distributed among all types of homoeologous associations. This finding reveals that distinct mechanisms are involved
in the control of wheat homoeologous pairing by the two Ph genes. The frequency of wheat-rye recombination calculated from anaphase-I analysis was lower than expected from the metaphase-I
data. A greater discrepancy was found in ph2b than in ph1b wheat×rye hybrids, which may suggest a more distal chiasma localization in the former hybrid genotype.
Received: 20 June 1997 / Accepted: 9 December 1997 相似文献
102.
J. Chr Vogel S. J. Russell F. J. Rumsey J. A. Barrett Mary Gibby 《Plant biology (Stuttgart, Germany)》1998,111(3):241-246
Length polymorphism in a non-coding spacer (trnLUAA-trnFGAA) in the chloroplast DNA was used in the investigation of the origin of the most common and conspicuous European fern hybrid, Asplenium x alternifolium (Aspleniaceae, Pteridophyta). The origins of A. x alternifolium, the hybrid between A. trichomanes s.l. and A. septentrionale s.l. was studied at three ploidy levels, diploid, triploid and tetraploid. The cpDNA technique allowed us to investigate the mode of hybrid formation between sexual species for the first time over a wide geographic range and with a large sample size. Morphological variation in this hybrid has previously been attributed to different reciprocal parental combinations, and to the influence of chloroplast genes on morphogenesis. Our results demonstrate that one parent, A. septentrionale s.l., acts predominantly as the female parent in these hybrids, with only one population of A. x alternifolium showing reciprocal hybridity. The discovery of predominantly unidirectional hybrid formation in this hybrid may be explained by the different breeding systems of the parental taxa. The role of gametophyte ecology is also assessed. 相似文献
103.
Hybridization can occur naturally among diverging lineages as part of the evolutionary process leading to complete reproductive isolation, or it can result from range shifts and habitat alteration through global warming and/or other anthropogenic influences. Here we report a molecular cytogenetic investigation of hybridization between taxonomically distinct species of the Alcelaphini (Alcelaphus buselaphus 2n = 40 × Damaliscus lunatus 2n = 36) and the Tragelaphini (Tragelaphus strepsiceros 2n = 31/32 × Tragelaphus angasii 2n = 55/56). Cross-species fluorescence in situ hybridization provides unequivocal evidence of the scale of karyotypic difference distinguishing parental species. The findings suggest that although hybrid meiosis of the former cross would necessitate the formation of a chain of seven, a ring of four and one trivalent, the progeny follow Haldane''s rule showing F1 male sterility and female fertility. The tragelaphine F1 hybrid, a male, was similarly sterile and, given the 11 trivalents and chain of five anticipated in its meiosis, not unexpectedly so. We discuss these findings within the context of the broader evolutionary significance of hybridization in African antelope, and reflect on what these hold for our views of antelope species and their conservation. 相似文献
104.
Elsje Kleynhans Des E. Conlong John S. Terblanche 《Entomologia Experimentalis et Applicata》2014,150(2):113-122
Understanding tolerance of thermal extremes by pest insects is essential for developing integrated management strategies, as tolerance traits can provide insights into constraints on activity and survival. A major question in thermal biology is whether thermal limits vary systematically with microclimate variation, or whether other biotic or abiotic factors can influence these limits in a predictable manner. Here, we report the results of experiments determining thermal limits to activity and survival at extreme temperatures in the stalk borer Eldana saccharina Walker (Lepidoptera: Pyralidae), collected from either Saccharum spp. hybrids (sugarcane) (Poaceae) or Cyperus papyrus L. (Cyperaceae) and then reared under standard conditions in the laboratory for 1–2 generations. Chill‐coma temperature (CTmin), critical thermal maximum (CTmax), lower lethal temperatures (LLT), and freezing temperature between E. saccharina collected from the two host plants were compared. CTmin and CTmax of E. saccharina moths collected from sugarcane were significantly lower than those from C. papyrus (CTmin = 2.8 ± 0.4 vs. 3.9 ± 0.4 °C; CTmax = 44.6 ± 0.1 vs. 44.9 ± 0.2 °C). By contrast, LLT of moths and freezing temperatures of pupae did not vary with host plant [LLT for 50% (LT50) of the moth population, when collected from sugarcane: ?3.2 ± 0.5 °C, from C. papyrus: ?3.9 ± 0.8 °C]. Freezing temperatures of pupae collected from C. papyrus were ?18.0 ± 1.0 °C and of those from sugarcane ?17.5 ± 1.8 °C. The E. saccharina which experienced the lowest minimum temperature (in C. papyrus) did not have the lowest CTmin, although the highest estimate of CTmax was found in E. saccharina collected from C. papyrus and this was also the microsite which reported the highest maximum temperatures. These results therefore suggest that host plant may strongly mediate lower critical thermal limits, but not necessarily LLT or freezing temperatures. These results have significant implications for ongoing pest management and thermal biology of these and other insects. 相似文献
105.
Xi-yan Yang Xian-long Zhang Shuang-xia Jin Li-li Fu Ling-gang Wang 《Plant Cell, Tissue and Organ Culture》2007,89(2-3):225-235
Asymmetric somatic hybrids were obtained between Gossypium hirsutum Coker 201 and wild cotton G. klozschianum Anderss. An investigation on the effect of ultraviolet (UV) irradiation on donor protoplasts was carried out, and the lethal
dose was determined to be 38.7 J cm−2. We firstly screened the putative hybrids by the color of the calli produced, followed by morphological, cytological, and
molecular analysis of putative hybrid plants. Most regenerated plants derived from fused protoplasts displayed a recipient-like
morphology, while some showed an intermediate phenotype between Coker 201 and G. klozschianum. Chromosome numbers in these somatic hybrids ranged from 54 to 74. The hybrids were verified by random amplified polymorphic
DNA (RAPD) and simple sequence repeat (SSR). Absence or co-existence of parents’ genome DNA fragments was identified through
molecular analysis. The heredity of cytoplasm was investigated by cleaved amplified polymorphic sequence (CAPS) analysis using
mitochondrial and chloroplast universal primer pairs. The results indicated that recombination and rearrangements might have
occurred in some regions of mitochondria (mt) and chloroplast (cp) DNA. To our knowledge, this is the first report about asymmetric
protoplast fusion in cotton, and the hybrids obtained would be useful for breeding programs. 相似文献
106.
Fine mapping of S32(t), a new gene causing hybrid embryo sac sterility in a Chinese landrace rice (Oryza sativa L.) 总被引:2,自引:0,他引:2
Li D Chen L Jiang L Zhu S Zhao Z Liu S Su N Zhai H Ikehashi H Wan J 《TAG. Theoretical and applied genetics. Theoretische und angewandte Genetik》2007,114(3):515-524
Ketan Nangka, the donor of wide compatibility genes, showed sterility when crossed to Tuanguzao, a landrace rice from Yunnan
province, China. Genetic and cytological analyses revealed that the semi-sterility was primarily caused by partial abortion
of the embryo sac. Genome-wide analysis of the linkage map constructed from the backcross population of Tuanguzao/Ketan Nangka//Ketan
Nangka identified two independent loci responsible for the hybrid sterility located on chromosomes 2 and 5, which explained
18.6 and 20.1% of phenotypic variance, respectively. The gene on chromosome 5 mapped to the previously reported sterility
gene S31(t), while the gene on chromosome 2, a new hybrid sterility gene, was tentatively designated as S32(t). The BC1F2 was developed for further confirmation and fine mapping of S32(t). The gene S32(t) was precisely mapped to the same region as that detected in the BC1F1 but its position was narrowed down to an interval of about 1.9 cM between markers RM236 and RM12475. By assaying the recombinant
events in the BC1F2, S32(t) was further narrowed down to a 64 kb region on the same PAC clone. Sequence analysis of this fragment revealed seven predicted
open reading frames, four of which encoded known proteins and three encoded putative proteins. Further analyses showed that
wide-compatibility variety Dular had neutral alleles at loci S31(t) and S32(t) that can overcome the sterilities caused by these two genes. These results are useful for map-based cloning of S32(t) and for marker-assisted transferring of the neutral allele in hybrid rice breeding. 相似文献
107.
Alexandra Leitão Raquel Chaves Sara Santos Henrique Guedes-Pinto Pierre Boudry 《Journal of experimental marine biology and ecology》2007,343(2):253-260
The taxonomic status of the two commercially important cupped oysters, Crassostrea angulata, the Portuguese oyster (Lamarck, 1819) and Crassostrea gigas, the Japanese oyster (Thunberg, 1793) has long been in question. The recent observation of the hybridization between C. gigas and C. angulata and the production of fertile F1s led us to search for cytogenetic evidence of both parental genomes in the interspecific hybrids. The cytogenetic characterization of the hybrids was performed by the use of restriction endonuclease treatments. This technique has recently shown the potential for individual chromosome identification by banding in oysters. Chromosomes of C. gigas, C. angulata and their hybrids were treated with two different restriction enzymes (ApaI and HaeIII), stained with Giemsa, and examined for banding patterns. These chromosome markers allowed the parental haploid sets to be identified in the hybrids. The analysis of the banded karyotypes of the interspecific hybrids showed that for each chromosome pair, one of the homologues presented a banding pattern consistent with that of C. gigas and the other homologue presented a banding pattern consistent with that of C. angulata. These cytogenetic results substantiate the reported interspecific hybridization between C. gigas and C. angulata. In view of these results and taking into account the present expansion of C. gigas aquaculture in southern Europe, the question of the need for preservation of pure C. angulata stocks should be raised as only a few populations remain in the south of Spain and Portugal. Recently, changes in the genetic composition of populations in southern Portugal have indeed been observed, showing that human activities have created contact zones between the two taxa while no natural sympatric zones exist in Europe. 相似文献
108.
Morten Skage Anders Hobæk Štĕpánka Ruthová Barbara Keller Adam Petrusek Jaromír Sed’a Piet Spaak 《Hydrobiologia》2007,594(1):19-32
A collaborative research effort was undertaken to evaluate the robustness of a recently developed genetic tool for species
identification of members in the morphologically variable Daphnia longispina species complex. This genetic method, based on restriction fragment length polymorphism (RFLP) of the internal transcribed
spacer region (ITS) of nuclear ribosomal DNA (rDNA) with restriction enzymes Mwo I and Sau96 I [Billiones et al., 2004. Hydrobiologia 526: 43–53], was applied to many different European populations. Results were
compared with two or more independently obtained characters (morphology, allozymes, mitochondrial DNA (mtDNA), or cloned rDNA-ITS
sequences). Individuals of most taxa were readily identified, but unexpected ITS-RFLP patterns were found in many individuals
indicated by other markers to be D. galeata or one of its hybrids. Among 43 investigated D. galeata populations (902 specimen analysed by ITS-RFLP), deviant RFLP fragment patterns occurred in 26 (i.e., more than half) of
the populations. The deviant patterns could be attributed to the loss of one single restriction site in the ITS2 region. This
loss made the distinction of D. galeata from other species unreliable, and F1 hybrids could not be identified. Future users should be aware of this shortcoming of
the Billions et al. [2004. Hydrobiologia 526: 43–53] protocol. As a solution to this problem, we present an improved genetic
identification protocol based on a simple double digestion of the rDNA-ITS region with the restriction enzymes BsrB I and EagI. Sequence analyses of rDNA-ITS clones and preliminary testing indicate that the new protocol is unaffected by the rDNA variation
which troubled the Mwo I/Sau96 I protocol. Further, the new protocol identifies all European species of the D. longispina complex, as well as their F1 hybrids. However, a wider screening is required to verify its general utility for all species,
since yet unknown variation may occur.
Guest editor: Piet Spaak
Cladocera: Proceedings of the 7th International Symposium on Cladocera 相似文献
109.
Cytogenetic studies on two F1 hybrids of autotetraploid rice varieties showing extremely high level of heterosis 总被引:1,自引:0,他引:1
L. Luan S. B. Tu W. B. Long X. Wang Y. H. Liu F. L. Kong T. He W. G. Yan M. Q. Yu 《Plant Systematics and Evolution》2007,267(1-4):205-213
Mechanisms of two F1 hybrids (D46A × DTP-4 and D46A × Dminghui63) of autotetraploid rice (2n = 4x = 48) showing extremely
high pollen fertility 87.40% and 85.97%, respectively, seed set 82.00% and 79.00%, respectively and extremely high level of
heterosis were analyzed cytologically. The chromosome pairing of D46A × DTP-4 and D46A × Dminghui63 was normal at metaphase
I(MI), and had almost no I or III, with an average of 0.020I +14.36 II 6.44rod+7.91ring) +0.01III + 4.80 IV + 0.01VIII and
0.06 I + 17.67 II (11.01rod + 6.67ring)] + 0.06 III +3.10IV+0.01VI, respectively. The most frequent chromosome configurations
were 10II+7IV and 12II+bIV. The bivalent frequency was less frequent in hybrids than that in restoring parents, and the same
results were gained from univalents, trivalent and multivalents. However, the quadrivalent frequency was significantly higher
in hybrids than that in restoring parents at MI. The other meiotic phases progressed normally, except for low percentages
of PMCs with lagging chromosomes at AI and low percentages of PMCs with micronuclei at telophaseI (TI) and telophaseII (TII).
PMCs with lagging chromosomes at AI and PMCs with micronuclei at TI and TII showed negative correlation between pollen fertility
and seed set. Above 90% of the PMCs could form normal microspores, which resulted in the production of viable pollen grains,
abnormal microspores were observed including penta-fission and hexa-fission. Based on these results we suggest that the two
F1 hybrids had better behaviors of chromosome pairing and genetic stability than autotetraploid rice and other autotetraploid
plants ever studied. 相似文献
110.
Moghaddam AM Roudier F Seifert M Bérard C Magniette ML Ashtiyani RK Houben A Colot V Mette MF 《The Plant journal : for cell and molecular biology》2011,67(4):691-700
Plant genomes are earmarked with defined patterns of chromatin marks. Little is known about the stability of these epigenomes when related, but distinct genomes are brought together by intra‐species hybridization. Arabidopsis thaliana accessions and their reciprocal hybrids were used as a model system to investigate the dynamics of histone modification patterns. The genome‐wide distribution of histone modifications H3K4me2 and H3K27me3 in the inbred parental accessions Col‐0, C24 and Cvi and their hybrid offspring was compared by chromatin immunoprecipitation in combination with genome tiling array hybridization. The analysis revealed that, in addition to DNA sequence polymorphisms, chromatin modification variations exist among accessions of A. thaliana. The range of these variations was higher for H3K27me3 (typically a repressive mark) than for H3K4me2 (typically an active mark). H3K4me2 and H3K27me3 were rather stable in response to intra‐species hybridization, with mainly additive inheritance in hybrid offspring. In conclusion, intra‐species hybridization does not result in gross changes to chromatin modifications. 相似文献