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1.
Cane JH 《Oecologia》2011,167(1):107-116
Pollinators, even floral generalists (=polyleges), typically specialize during individual foraging bouts, infrequently switching
between floral hosts. Such transient floral constancy restricts pollen flow, and thereby gene flow, to conspecific flowers
in mixed plant communities. Where incipient flowering species meet, however, weak cross-fertility and often similar floral
traits can yield mixed reproductive outcomes among pollinator-dependent species. In these cases, floral constancy by polyleges
sometimes serves as an ethological mating barrier. More often, their foraging infidelities instead facilitate host introgression
and hybridization. Many other bee species are oligolectic (taxonomic specialists for pollen). Oligoleges could be more discriminating
connoisseurs than polyleges when foraging among their limited set of related floral hosts. If true, greater foraging constancy
might ensue, contributing to positive assortative mating and disruptive selection, thereby facilitating speciation among their
interfertile floral hosts. To test this Connoisseur Hypothesis, nesting females of two species of oligolectic Osmia bees were presented with randomized mixed arrays of flowers of two sympatric species of their pollen host, Balsamorhiza, a genus known for hybridization. In a closely spaced grid, the females of both species preferred the larger flowered B. macrophylla, evidence for discrimination. However, both species’ females showed no floral constancy whatsoever during their individual
foraging bouts, switching randomly between species proportional to their floral preference. In a wider spaced array in which
the bouquets reflected natural plant spacing, foraging oligolectic bees often transferred pollen surrogates (fluorescent powders)
both between conspecific flowers (geitonogamy and xenogamy) and between the two Balsamorhiza species. The Connoisseur Hypothesis was therefore rejected. Foraging infidelity by these oligolectic Osmia bees will contribute to introgression and hybridization where interfertile species of Balsamorhiza meet and flower together. A literature review reveals that other plant genera whose species hybridize also attract numerous
oligolectic bees, providing independent opportunities to test the generality of this conclusion. 相似文献
2.
Artificial interspecific hybrids between large scale loach P. dabryanus and tetraploid pond loach M. anguillicaudatus (Cobitidae, Cypriniformes) are viable. To detect the occurrence of possible natural hybridization, genetic analyses by using
microsatellite markers were performed for natural populations of large scale loach and pond loach, the reciprocal laboratory
hybrids, and “supposed hybrids” with ambiguous morphology. The fertility of the artificial hybrids was also tested. At one
diagnostic microsatellite (Mac50), one out of 20 “supposed hybrids” was identified to be F1 hybrid between the two loach species because it had the same genotype as that of the laboratory hybrids. The triploid hybrids
between the two species were confirmed to be female-sterile. The results show that rare hybridization has occurred between
diploid large scale loach and tetraploid pond loach in nature although it may have little effect in genetic introgression.
This study is helpful for fish conservation and encourages further investigation on natural hybridization and introgression
of loaches. 相似文献
3.
Crop to weed transgene flow, which could result in more competitive weed populations, is an agricultural biosafety concern.
Crop Brassica napus to weedy Brassica rapa hybridization has been extensively characterized to better understand the transgene flow and its consequences. In this study,
weedy accessions of B. rapa were transformed with Bacillus thuringiensis (Bt) cry1Ac- and green fluorescence protein (gfp)-coding transgenes using Agrobacterium to assess ecological performance of the wild biotype relative to introgressed hybrids in which the transgenic parent was
the crop. Regenerated transgenic B. rapa events were characterized by progeny analysis, Bt protein enzyme-linked immunosorbent assay (ELISA), Southern blot analysis,
and GFP expression assay. GFP expression level and Bt protein concentration were significantly different between independent
transgenic B. rapa events. Similar reproductive productivity was observed in comparison between transgenic B. rapa events and B. rapa × B. napus introgressed hybrids in greenhouse and field experiments. In the greenhouse, Bt transgenic plants experienced significantly
less herbivory damage from the diamondback moth (Plutella xylostella). No differences were found in the field experiment under ambient, low, herbivore pressure. Directly transformed transgenic
B. rapa plants should be a helpful experimental control to better understand crop genetic load in introgressed transgenic weeds. 相似文献
4.
Yoko Yatabe Chie Tsutsumi Yumiko Hirayama Keigo Mori Noriaki Murakami Masahiro Kato 《Journal of plant research》2009,122(6):585-595
Rheophilous Osmunda lancea often hybridizes with a dryland ally, Osmunda japonica, to produce O. × intermedia, forming zonation in riverbanks and the adjacent dryland along flooding frequency clines. This study examined the genetic
structure of populations consisting of O. × intermedia and the two parental species by analyzing ten nuclear DNA markers [six cleaved amplified polymorphic sequence (CAPS) markers
and three simple sequence repeat (SSR) markers developed from an expressed sequence tag (EST) library, and the sequence of
the glyceraldehyde-3-phosphate dehydrogenase gene GapCp] and chloroplast DNA sequences. The results suggest that the nuclear genes of O. japonica and O. lancea are genetically differentiated despite shared polymorphism in their chloroplast DNA sequences. This discrepancy may be attributable
to natural selection and recent introgression, although it is not evident if introgression occurs between O. japonica and O. lancea in the examined populations. Our findings of putative F2 hybrids in O. × intermedia support its partial reproducibility, and also suggest that formation of later-generation hybrids generates morphological
variation in O. × intermedia. O. lancea plants collected from geographically distant localities were genetically very similar, and it is suggested that O. lancea originated monotopically. 相似文献
5.
Le Quoc Hung Takashi Asaeda Takeshi Fujino Bakari J. Mnaya 《Wetlands Ecology and Management》2007,15(2):105-111
The influence of Phragmites australis on the growth of Zizania latifolia, and the morphological characteristics of both species, were investigated at two nutrient levels. The experiment was carried
out over three growing seasons between May 2003 and December 2005. The experimental plot was longitudinally divided into two
equal halves, one of which was planted with Zizania latifolia (Zizania zone) and the other one with Phragmites australis (Phragmites zone). Four weeks after transplantation, the plot was again divided horizontally, perpendicular to the previous
division, and subject to low (LN) and high nutrient (HN) treatments. Measured growth indices of the two species were more
developed in the HN than in the LN treatments. Both species were observed to invade each other’s zone, but Phragmites latifolia seemed to out-compete Zizania latifolia individuals. This was evident from the decrease in below ground biomass of Zizania latifolia in the third growing season and deterioration in above ground organs with time. It was concluded that Phragmites australis out-competes Zizania latifolia due to better developed root and rhizome system. 相似文献
6.
Liangming Chen Zhigang Zhao Xi Liu Linglong Liu Ling Jiang Shijia Liu Wenwei Zhang Yihua Wang Yuqiang Liu Jianmin Wan 《Molecular breeding : new strategies in plant improvement》2011,27(2):247-258
The incomplete fertility of japonica × indica rice hybrids has inhibited breeders’ access to the substantial heterotic potential of these hybrids. As hybrid sterility
is caused by an allelic interaction at a small number of loci, it is possible to overcome it by simple introgression at the
major sterility loci. Here we report the use of marker-assisted backcrossing to transfer into the elite japonica cv. Zhendao88 a photoperiod-sensitive male sterility gene from cv. Lunhui422S (indica) and the yellow leaf gene from line Yellow249 (indica). The microsatellite markers RM276, RM455, RM141 and RM185 were used to tag the fertility genes S5, S8, S7 and S9, respectively. Line 509S is a true-breeding photoperiod-sensitive male sterile plant, which morphologically closely resembles
the japonica type. Genotypic analysis showed that the genome of line 509S comprises about 92% japonica DNA. Nevertheless, hybrids between line 509S and japonica varieties suffer from a level of hybrid sterility, although the line is highly cross-compatible with indica types, with the resulting hybrids expressing a significant degree of heterosis. Together, these results suggest that segment
substitution on fertility loci based on known information and marker-assisted selection are an effective approach for utilizing
the heterosis of rice inter-subspecies. 相似文献
7.
In our early experiments, a variety of Bupleurum scorzonerifolium-like somatic hybrid plants were obtained from protoplast fusion between Arabidopsis thaliana and UV-treated/untreated B. scorzonerifolium. To compare the effects of UV and γ-ray irradiation on the B. scorzonerifolium partner and obtain Arabidopsis-like hybrids, we designed a novel combination of somatic hybridization between A. thaliana and B. scorzonerifolium. Before protoplast isolation and fusion, the suspension cells of B. scorzonerifolium were irradiated by gamma ray (60Co, 50 Gy with 1.3 Gy min−1). Both parental protoplasts lost regeneration capacity, but over 100 somatic hybrids restored the capacity and developed
to Arabidopsis-like inflorescences and flowers with some characteristics of B. scorzonerifolium. Some hybrid flowers showed yellow sepal, petal, or carpel, whose color was similar to the petal of B. scorzonerifolium; the others had silique of Arabidopsis with angularity of B. scorzonerifolium, and their parts possessed five stamens, the same as B. scorzonerifolium. Cytological analysis showed that three hybrids had Arabidopsis-like karyotypes. Random Amplified Polymorphic DNA (RAPD) and Simple Sequence Repeats (SSR) profiles revealed that both parental
fragments were amplified from these hybrids. These results indicated chromatin introgression from B. scorzonerifolium to A. thaliana, which may be related to the complementation of hybrid inflorescence and flower generation. 相似文献
8.
This paper discusses a number of experiments performed, involving the fusion by an electric field of mesophyll protoplasts
from Solanum tuberosum cv. Bintje, S. tuberosum dihaploid clones 243, 299 and the wild tuberous disease-resistant species S. bulbocastanum and S. pinnatisectum. Three fusion experiments (S. bulbocastanum + S. tuberosum dihaploid 243, S. pinnatisectum + S. tuberosum cv. Bintje and S. pinnatisectum + S. tuberosum dihaploid 299) yielded 542 calli, the 52 ones of which produced shoots. Obtained regenerants were estimated by the flow-cytometry (FC)
and RAPD analysis to determine hybrid plants.The utilisation of the FC as a useful method for detecting somatic hybrids is
also discussed in this paper. The combination S. bulbocastanum + S. tuberosum dihaploid 243 led to the creation of eight somatic hybrids, the combination S. pinnatisectum + S. tuberosum cv. Bintje yielded four somatic hybrids and the combination S. pinnatisectum + S. tuberosum dihaploid 299 resulted in no hybrid regenerants. Morphology in vitro, growth vigour and production of tuber-like structures
were evaluated in hybrid plants. Plants were transferred in vivo for further estimation (acclimatization, habitus evaluation
and tuberization ability). 相似文献
9.
X. H. Shan X. F. Ou Z. L. Liu Y. Z. Dong X. Y. Lin X. W. Li B. Liu 《TAG. Theoretical and applied genetics. Theoretische und angewandte Genetik》2009,119(7):1325-1333
We have reported previously that the most active miniature inverted terminal repeat transposable element (MITE) of rice, mPing, was transpositionally mobilized in several rice recombinant inbred lines (RILs) derived from an introgressive hybridization
between rice and wild rice (Zizania latifolia Griseb.). To further study the phenomenon of hybridization-induced mPing activity, we undertook the present study to investigate the element’s behavior in a highly asymmetric somatic nuclear hybrid
(SH6) of rice and Z. latifolia, which is similar in genomic composition to that of the RILs, though probably contains more introgressed alien chromatins
from the donor species than the RILs. We found that mPing, together with its transposase-donor, Pong, underwent rampant transpositional activation in the somatic hybrid (SH6). Because possible effects of protoplast isolation
and cell culture can be ruled out, we attribute the transpositional activation of mPing and Pong in SH6 to the process of asymmetric somatic hybridization, namely, one-step introgression of multiple chromatin segments
of the donor species Z. latifolia into the recipient rice genome. A salient feature of mPing transposition in the somatic hybrid is that the element’s activation was accompanied by massive loss of its original copies,
i.e., abortive transpositions, which was not observed in previously reported cases of mPing activity. These data not only corroborated our earlier finding that wide hybridization and introgression may trigger transpositional
activation of otherwise quiescent transposable elements, but also suggest that transpositional mobilization of a MITE like
mPing can be accompanied by dramatic reduction of its original copy numbers under certain conditions, thus provide novel insights
into the dynamics of MITEs in the course of genome evolution. 相似文献
10.
11.
Kouichi Kawamura Masashi Kubota Miki Furukawa Yasushi Harada 《Conservation Genetics》2007,8(5):1163-1176
The amago salmon, Oncorhynchus masou ishikawae, is an endemic subspecies of O. masou in Japan. Owing to the extensive stocking of hatchery fish throughout Japan, indigenous populations of O. m. ishikawae are now on the verge of extinction. We examined the genetic effects of stocking hatchery fish on wild populations in the
River Koza, Japan, using microsatellite and mitochondrial DNA (mtDNA) markers. For mtDNA, haplotype mt1, which is common in
wild populations, was present exclusively in isolated wild populations assumed to be unaffected by previous stocking, while
it was never observed in hatchery fish. Genetic diversity was much higher in wild populations in the stocked area, which shared
many mtDNA haplotypes with hatchery fish, than in isolated wild populations with haplotype mt1. Pairwise F
ST estimates based on microsatellites showed significant differentiation among the isolated populations with many microsatellite
loci monomorphic. Significant deviation from Hardy–Weinberg equilibrium was observed in wild populations in the area subject
to stocking, where a Bayesian-based assignment test showed a high level of introgression with hatchery fish. These results
suggest that wild populations with haplotype mt1, which became isolated through anthropogenic environmental change in the
1950–1960s, represent indigenous populations of O. m. ishikawae in the River Koza. They have low genetic diversity, most likely caused by genetic bottlenecks following damming and environmental
deterioration, while stocking of hatchery fish over the past 30 years apparently had a large impact on the genetic structure
of wild populations in the main channel of the River Koza. 相似文献
12.
von Korff M Wang H Léon J Pillen K 《TAG. Theoretical and applied genetics. Theoretische und angewandte Genetik》2004,109(8):1736-1745
In the present paper, we report on the selection of two sets of candidate introgression lines (pre-ILs) in spring barley. Two BC2DH populations, S42 and T42, were generated by introgressing an accession of Hordeum vulgare ssp. spontaneum (ISR42-8, from Israel) into two different spring barley cultivars, Scarlett (S) and Thuringia (T). From these BC2DH populations two sets with 49 (S42) and 43 (T42) pre-ILs were selected, and their genomic architecture as revealed by SSR marker analysis was characterised. The selected pre-ILs cover at least 98.1% (S42) and 93.0% (T42) of the exotic genome in overlapping introgressions and contain on average 2 (S42) and 1.5 (T42) additional non-target introgressions. In order to illustrate a potential application and validation of these pre-ILs, the phenotypic effect of the exotic introgression at the locus of the major photoperiod response gene Ppd-H1 was analysed. Pre-ILs carrying the introgression at the Ppd-H1 locus flowered significantly earlier than the elite parents, and the introgression maintained its effect across the two genetic backgrounds and across four tested environments. The selected pre-ILs represent a first promising step towards the assessment and utilization of genetic variation present in exotic barley. They may promote the breeding progress, serve for the verification of QTL effects and provide a valuable resource for the unravelling of gene function, e.g. by expression profiling or map-based cloning. 相似文献
13.
Philip J. Kauth Michael E. Kane Wagner A. Vendrame 《In vitro cellular & developmental biology. Plant》2011,47(1):148-156
Seed responses to temperature are often essential to the study of germination ecology, but the ecological role of temperature
in orchid seed germination remains uncertain. The response of orchid seeds to cold stratification have been studied, but the
exact physiological role remains unclear. No studies exist that compare the effects of either cold stratification or temperature
on germination among distant populations of the same species. In two separate experiments, the role of temperature (25, 22/11,
27/15, 29/19, 33/24°C) and chilling at 10°C on in vitro seed germination were investigated using distant populations of Calopogon tuberosus var. tuberosus. Cooler temperatures promoted germination of Michigan seeds; warmer temperatures promoted germination of South Carolina and
north central Florida seeds. South Florida seed germination was highest under both warm and cool temperatures. More advanced
seedling development generally occurred at higher temperatures with the exception of south Florida seedlings, in which the
warmest temperature suppressed development. Fluctuating diurnal temperatures were more beneficial for germination compared
to constant temperatures. Cold stratification had a positive effect on germination among all populations, but South Carolina
seeds required the longest chilling treatments to obtain maximum germination. Results from the cold stratification experiment
indicate that a physiological dormancy is present, but the degree of dormancy varies across the species range. The variable
responses among populations may indicate ecotypic differentiation. 相似文献
14.
Jagesh K. Tiwari Poonam D. Sarkar SK. Pandey Jai Gopal S. Raj Kumar 《Plant Cell, Tissue and Organ Culture》2010,103(2):175-187
Interspecific potato somatic hybrids between Solanum tuberosum L. (di)haploid C-13 and 1 endosperm balance number non-tuberous wild species S. etuberosum Lindl. were produced by protoplasts electrofusion. The objective was to transfer virus resistance from this wild species
into the cultivated potatoes. Post-fusion products were cultured in VKM medium followed by regeneration of calli in MS13 K medium at 20°C under a 16-h photoperiod, and regenerants were multiplied on MS medium. Twenty-one somatic hybrids were
confirmed by RAPD, SSR and cytoplasm (chloroplast/mitochondria) type analysis possessing species-specific diagnostic bands
of corresponding parents. Tetraploid nature of these somatic hybrids was determined through flow cytometry analysis. Somatic
hybrids showed intermediate phenotypes (plant, leaves and floral morphology) to their parents in glass-house grown plants.
All the somatic hybrids were male-fertile. ELISA assay of somatic hybrids after artificial inoculation of Potato virus Y (PVY)
infection reveals high PVY resistance. 相似文献
15.
The possibility to obtain diploid hybrids by pollination of allotetraploid wild potato species Solanum acaule and S. stoloniferum plants with fertile pollen of S. tuberosum dihaploids was demonstrated for the first time. Dihaploid hybrids have arisen with comparatively high frequency (from 12.5 to 33.3%). They were characterized by high regularity of meiosis and high fertility. They easily crossed with S. tuberosum dihaploids, forming viable progeny. This seems prospective for effective introgression of valuable genetic gene pool of wild allotetraploid potato species in breeding material of S. tuberosum on the diploid level. 相似文献
16.
17.
Bottecchia M Oliveira SG Bauzer LG Souza NA Ward RD Garner KJ Kyriacou CP Peixoto AA 《Journal of molecular evolution》2004,58(6):754-761
Genes involved in the reproductive isolation are particularly useful as molecular markers in speciation studies. Lutzomyia longipalpis (Diptera: Psychodidae: Phlebotominae), a putative species complex, is a vector of visceral leishmaniasis in Latin America. We isolated from this species a fragment homologous to cacophony, a Drosophila gene that encodes features of the lovesong, an acoustic signal that is important in the sexual isolation of closely related species and known to vary considerably among L. longipalpis putative siblings species. Using an intron of the sandfly cacophony as a marker, we analyzed the molecular variation and sequence divergence among five populations of L. longipalpis from Brazil, three allopatric (Jacobina, Lapinha and Natal) and two putative sympatric sibling species from the locality of Sobral. A high level of polymorphism was found and analysis of the data indicates that very little gene flow is occurring among the populations of Jacobina, Lapinha, and Natal. A high level of differentiation was also observed between the two putative sympatric species of Sobral, one of which seems to be the same sibling species found in Natal, while the other is somewhat more related to Jacobina and Lapinha. However, the amount of estimated gene flow among the Sobral siblings is about seven times higher than the previously estimated for period, another lovesong gene, perhaps indicating that introgression might be affecting cacophony more than period. The results suggest that L. longipalpis is not a single species in Brazil, but it is yet not clear whether the different populations studied deserve species status rather than representing an incipient speciation process. 相似文献
18.
Luciana Delgado-Benarroch Barry Causier Julia Weiss Marcos Egea-Cortines 《Planta》2009,229(6):1219-1229
Control of organ size is the product of coordinated cell division and expansion. In plants where one of these pathways is
perturbed, organ size is often unaffected as compensation mechanisms are brought into play. The number of founder cells in
organ primordia, dividing cells, and the period of cell proliferation determine cell number in lateral organs. We have identified
the Antirrhinum FORMOSA (FO) gene as a specific regulator of floral size. Analysis of cell size and number in the fo mutant, which has increased flower size, indicates that FO is an organ-specific inhibitor of cell division and activator of cell expansion. Increased cell number in fo floral organs correlated with upregulation of genes involved in the cell cycle. In Arabidopsis the AINTEGUMENTA (ANT) gene promotes cell division. In the fo mutant increased cell number also correlates with upregulation of an Antirrhinum ANT-like gene (Am-ANT) in inflorescences that is very closely related to ANT and shares a similar expression pattern, suggesting that they may be functional equivalents. Increased cell proliferation
is thought to be compensated for by reduced cell expansion to maintain organ size. In Arabidopsis petal cell expansion is inhibited by the BIGPETAL (BPE) gene, and in the fo mutant reduced cell size corresponded to upregulation of an Antirrhinum BPE-like gene (Am-BPE). Our data suggest that FO inhibits cell proliferation by negatively regulating Am-ANT, and acts upstream of Am-BPE to coordinate floral organ size. This demonstrates that organ size is modulated by the organ-specific control of both general
and local gene networks.
Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users. 相似文献
19.
Interspecific somatic hybrids between a dihaploid potato clone H-8105 susceptible to Phytophthora infestans (Mont.) de Bary and a resistant diploid tuberizing species Solanum bulbocastanum were generated and analysed. Only ten regenerants displaying the intermediate morphology with dominating characteristics
of the wild parent (simple leaves, anthocyanin pigmentation) were produced in 15 weeks after a single PEG-mediated fusion
event. The RAPD patterns confirmed the hybridity of all of them. The hybrids rooted poorly and grew slowly in vitro. The cytological analysis revealed a high degree of aneuploidy in the hybrids with morphological and growth anomalies in vitro, while the morphologically normal hybrids were tetraploids. All the S. bulbocastanum (+) H-8105 hybrids were unstable in culture and three of them were consequently lost during three years of propagation in vitro. The possible reasons for instability of somatic hybrids between the distantly related species are discussed. 相似文献
20.
Habitat fragmentation can affect levels of herbivory in plant populations if plants and herbivores are differentially affected
by fragmentation. Moreover, if herbivores are top–down controlled by predators or parasitoids, herbivory may also be affected
by differential effects of fragmentation on herbivores and their natural enemies. We used natural Silene latifolia populations to examine the effects of plant population size and isolation on the level of herbivory by the seed predating
noctuid Hadena bicruris and the rate of parasitism of the herbivore by its parasitoids. In addition, we examined oviposition rate, herbivory and
parasitism in differently sized experimental populations. In natural populations, the level of herbivory increased and the
rate of parasitism decreased with decreasing plant population size and increasing degree of isolation. The number of parasitoid
species also declined with decreasing plant population size. In the experimental populations, the level of herbivory was also
higher in smaller populations, in accordance with higher oviposition rates, but was not accompanied by lower rates of parasitism.
Similarly, oviposition rate and herbivory, but not parasitism rate, increased near the edges of populations. These results
suggests that in this system with the well dispersing herbivore H. bicruris, habitat fragmentation increases herbivory of the plant through a behavioural response of the moth that leads to higher oviposition
rates in fragmented populations with a reduced population size, increased isolation and higher edge-to-interior ratio. Although
the rate of parasitism and the number of parasitoid species declined with decreasing population size in the natural populations,
we argue that in this system it is unlikely that this decline made a major contribution to increased herbivory. 相似文献