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1.
One hundred and forty Mexican hawthorn (Crataegus spp.) accessions from six regions are preserved at the BGT-UACH germplasm bank (Mexico), comprising the most comprehensive living collection of Mexican hawthorns with different degrees of human management. The objective of this study was to assess the biodiversity of this valuable collection from morphological, molecular (microsatellite), and ethnobotanical viewpoints in order to delineate the most adequate strategy for the conservation of the native hawthorn germplasm in the present scenario of incipient establishment of commercial hawthorn plantations, which is likely to increase. Molecular characterisation revealed that the biodiversity was chiefly (90%) placed within the regions. Morphological characterisation indicated that the group from Chiapas was the most different germplasm pool compared with the other five. This was confirmed by molecular analysis, because in spite of the lack of a phylogeographical pattern, two germplasm pools were detected: one composed mainly by accessions from Chiapas and the other mainly by accessions from the other regions. The only clear differences among the regions in the ethnobotanical study were those derived from putting hawthorns into commercial cultivation, which occurred in just one region in the centre of the country (Mexico–Puebla–Tlaxcala). As a consequence, an ex situ conservation programme is necessary for those regions shifting patterns of cultivation from traditional to commercial, regardless of whether other on-farm programmes are also implemented. The germplasm collections within each region must be exhaustive due to their high genetic diversity.  相似文献   

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3.
Radix Campanumoeae (C. javanica Bl.) has been used in Miao herbal medicine to treat neurasthenia and consumptive disease for hundreds of years. Though Radix Campanumoeae shows great potential for utilization in medical studies, this herb crop has not been cultivated industrially in China. Many species in the Campanumoea genus are similar in phenotype; therefore, a karyotypic study would prove useful for clearly distinguishing Radix Campanumoeae from related species within the same genus, for germplasm preservation and for breeding Radix Campanumoeae. 10 accessions of four species in this genus and 5 accessions in 5 relative genera from SCSB were used for karyotype determination. The results showed a karyotype of 2n = 16 = 2m + 12sm + 1st in Campanumoea, and a karyotype of 2n = 18 = 6 m + 12sm in Cyclocodon. Based on the chromosome number and the karyotypic formula, we suggest that the Campanumoea genus can be divided into two genera, which is in agreement with results observed from pollen morphology and from homological usage in Chinese herbal medicine. The chromosome length in C. javanica subsp. javanica and C. javanica subsp. japonica Makino, ranged from 2.24 to 1.38 μm and 2.04 to 1.31 μm, respectively; and their haploid sets were almost identical (13.15 and 13.16 μm, respectively). This indicates that chromosomal rearrangements occur within chromosomes IV, V and VII without a net gain or loss of genetic material.  相似文献   

4.

Cotton (genus Gossypium) is an important agricultural crop around the world because of its fiber. Gossypium turneri Fryxell is a wild cotton species endemic to the state of Sonora (northwestern Mexico), whose status has been recently raised to endangered in the IUCN Red List. This species has invaluable characteristics that could be useful in the cultivated cotton gene pool. Despite its importance, G. turneri has been studied very little. To the best of our knowledge, no previous study has characterized its seed morphology and cytogenetics. Therefore, in the present study the seed morphology and karyotype of G. turneri were analyzed. Seeds of G. turneri have nonuniform oval shape and brown-gray color. This species produces short fibers attached to its seed surface that are not long enough for commercial use. Our seed sizes were greater than those previously described for G. turneri and other diploid cottons. The length and width of seeds were 8.80 mm and 4.83 mm, respectively. Traits such as embryo and seed coat were measured and carefully observed, and gossypol glands were observed only in the embryo during the evaluation of internal features of seeds. Cytogenetic analysis revealed 26 chromosomes (2n?=?2x?=?26) in mitotic cells of G. turneri. The karyotype analysis showed mainly metacentric (m), submetacentric (sm) and subtelocentric (st) chromosomes. Our results reveal important biological traits of G. turneri that could be considered in future studies to improve cultivated cotton.

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5.
The genus Zea (teosinte) has a native distribution from Mexico to Nicaragua (Meso-America region) and studies on teosinte species may help improve our understanding of maize genetics, population genetics, genome evolution and crop evolution. Moreover, since F1 hybrids between teosinte and maize are fertile, all teosinte species can potentially contribute to maize breeding in the form of traits such as resistance or tolerance to heavy metals in the soil and other adverse environmental conditions. Gene flow between maize and teosinte occurs in Mexico and Central America. This study analysed the genetic diversity of teosintes by using the microsatellite technique on a total of 120 individuals from six different species and 21 Simple Sequence Repeats (SSR). A total of 109 alleles were found and the number of alleles per locus ranged from 2 to 7. The genetic diversity varied between all species from 0.514 to 0.572, with a mean value of 0.548 (Nei index). Rare and unique alleles were detected in all species, with the highest frequencies found in Zea diploperennis Iltis, Doebley et Guzman, Zea perennis (Hitchc.) Reeves et Mangelsdorf and Zea nicaraguensis Iltis et Benz, which had more than seven rare alleles each. Analysis of molecular variance revealed that 19.87% of the variation between species was statistically significant (P < 0.001). When the different species were compared with the Wright (Fst) value, genetic variation between species was confirmed. The data also revealed a moderate rate gene flow between the species. Genetic diversity was found to be somewhat higher in Central America than in Mexico.  相似文献   

6.
Nicotiana section Suaveolentes (Solanaceae) currently includes 28 species and subspecies that are endemic to Australasia and the South Pacific and one African species, N. africana. The section is monophyletic and of allotetraploid origin, but relationships among the species in it and its diploid progenitors are poorly understood. Here we report chromosome numbers for 20 of the 29 taxa from the Suaveolentes, including a count for one recently proposed species for which no number has previously been available. Many of the published chromosome numbers for the Suaveolentes are confirmed in this study. However, six counts were different from the published numbers including n = 15 for N. maritima and N. suaveolens, which is a new chromosome number for the genus. Nicotiana goodspeedii and N. rotundifolia were n = 16, and the same number was found in the suggested species N. sp. ‘Corunna’. Nicotiana suaveolens contains polyploid races of n = 32 and here we report the probable existence of an n = 31 race as well. Karyotypic variation within species and within the section is apparently much greater than previously thought and further investigation is warranted.  相似文献   

7.
Background, aim, and scope  Polycyclic aromatic hydrocarbons (PAHs) are ubiquitous environmental pollutants. They are formed during pyrogenic and diagenetic processes and are components of petrogenic materials such as oils and coals. To identify PAH sources, several studies have employed forensic methods, which may be costly to execute. Although a large number of possible forensic methods are available (e.g., total ion chromatograms, PAH ratios, PAH alkyl homologue series, isoalkanes and isoprenoids, steranes and terpanes, stable isotope ratios, n-alkanes), one has to decide which method is the appropriate cost effective screening approach. In this study, three approaches were tested and compared by measuring (1) an extended PAH spectrum (i.e., 45 instead of the common 16 EPA-PAHs), (2) PAH ratios and (3) n-alkanes to determine if point sources are distinguishable from non-point sources, and if an individual source can be distinguished from a multiple source contaminated site in the study area. In addition, the study evaluated whether these methods are sufficient for source identification of selected samples, and if they constitute a sound strategy for source identification prior to the selection of more cost intensive methods. Materials and methods  Eighteen samples with previously characterized PAH point sources (previously characterized point sources in the Mosel and Saar region) were analyzed. Additionally, three river bank soils of Mosel and Saar rivers with known non-point PAH sources were investigated. The point sources were two gasworks, a tar impregnation facility, a creosoted timber, an acid tar, a tank farm, and a diesel contaminated site. Non-point sources were hard coal particles and atmospheric inputs in river bank soils. All samples were extracted with hexane and acetone, analyzed with a gas chromatograph coupled to a mass spectrometer for PAH distribution patterns and ratios. n-Alkanes were measured by a gas chromatograph equipped with a flame ionization detector. Results  Samples collected from point sources and non-point sources were analyzed by the use of three forensic methods, i.e., PAH patterns of an extended PAH spectrum, PAH ratios and n-alkanes. Identification by PAH patterns alone was insufficient for the non-point sources and some point sources, since the n-alkanes must be measured, as well. The use of PAH ratios with only 16 EPA-PAHs is less indicative in determining multiple sources because source assignments (or categories) change depending on the ratio used. Discussion  This study showed that by employing an extended PAH spectrum it is possible to fingerprint and distinguish sources. The use of alkylated PAHs is essential for identifying petrogenic sources. It is insufficient to rely exclusively on either the common 16 EPA-PAHs or the ratios to the parent PAHs when identifying non-point sources. Source identification using PAH ratios is only reliable if both parent and alkylated PAHs are measured. n-Alkane analyses provide more detailed information about petrogenic sources by verifying the presence of oils, diesel, gasoline, or coal in non-point sources. Conclusions  The three methods tested were deemed sufficient to distinguish between point and non-point PAH sources in the samples investigated. The use of an extended PAH spectrum provides the first step toward identifying possible sources. It simplifies the decision whether additional forensic methods should be necessary for more detailed source identification. Recommendations and perspectives  The determination of PAH alkyl homologue series, biomarkers, and isotopes is often advised (Kaplan et al., Environ Forensics 2:231–248, 2001; Oros and Simoneit, Fuel 79:515–536, 2000; Wang and Fingas, Mar Pollut Bull 47:423–452, 2003). The methods involved are complex and often expensive. We recommend a relatively uncomplicated and cost-effective method (i.e., extended PAH spectrum) before further and more expensive forensic investigations are to be conducted. Additional research with an extended sample set should be carried out to validate these findings for other sources and sites. Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users.  相似文献   

8.
As a country, Mexico presents an especially wide range of fruit germplasm diversity. Tepexi de Rodríguez, Puebla, Mexico, belongs to The Tehuacán-Cuicatlán Valley, which is an arid zone recognized to have a flora diversity. In that place, wild plum (Ximenia americana L. var. americana; Olacaceae), locally named “tihuixocote” grows mainly in backyards, the fruit of this species is appreciated by native people due to its taste, which is reported to be a mixture between sweet and sour. Fruit from 15 trees were characterized by measuring bio-physical and bio-chemical parameters, including weight, diameter (equatorial and polar), relationship equatorial/polar diameters, total sugar, soluble solid content and phenolic compounds. The results of this study indicate variability for these various wild plum fruit characteristics among trees growing in a reduced territorial space.  相似文献   

9.
Differences in alpha and beta bat diversity among montane rainforest and five shaded coffee plantations under different management regimes, as well as some environmental factors and vegetation parameters influencing bat richness, were evaluated for the first time in southeastern Chiapas, Mexico. In each site, bats were captured every 2 months from March 2004 to July 2005, with six mist-nets, during two nights, using the capture-recapture method. We captured 2970 individuals of 43 bat species. Montane rainforest had the greatest alpha diversity (H′ = 2.681; n = 37), whereas alpha diversity was similar among coffee plantations (H′ = 2.229-2.364; n = 23-26). The number of frugivorous and nectarivorous species was similar among the sites; the greatest exchange in species composition (beta diversity) occurred for insectivorous bats, which reduce their number in coffee plantations as pesticides are incorporated. Bat richness species was significantly related to the number of vegetation strata, height, and cover of trees. We suggest that coffee plantations could act as corridors, facilitating connection among different elements of the landscape in the Sierra Madre de Chiapas for some frugivorous and nectarivorous bats.  相似文献   

10.
Lima bean (Phaseolus lunatus L.) is an important crop in traditional Mayan agriculture of the Yucatan Peninsula, Mexico, its Mesoamerican center of diversity. Genetic erosion in this species is currently a threat in this region out of 3 of 21 landraces dominate 71.24% of the cultivated area, and 12 are rare landraces grown only in 6.29%. Using 90 ISSR loci, we estimated the diversity and genetic relationships for 21 landraces to analyzing their risk of genetic erosion, and generate data for their in situ conservation. Total genetic diversity was high (h = 0.29), however it was lower than wild gene pool reported (h = 0.69). The abundant landraces had genetic diversity values lower (h = 0.13, I = 0.17) than the common (h = 0.26, I = 0.33) and rare landraces (h = 0.24, I = 0.27). However, the rare landraces are in a higher risk of genetic erosion due to local extinction. The cluster analysis showed no groups corresponding to morpho-phenological characteristics, geographic origin or traditional classification, which resulted from high inter-landraces gene flow levels. The molecular data confirmed that the domesticated Lima bean pool of the Yucatan Peninsula has a high risk of genetic erosion. If current tendencies in landrace cultivation continue, many will no longer be planted within two to three generations, with a consequent loss of their alleles. Programs urgently need to be established for in situ conservation of Lima bean landraces in this region.  相似文献   

11.
Solanum pimpinellifolium, due to its close relationship to S. lycopersicum, has been a genetic source for many commercially important tomato traits. It is a wild species found in the coastal areas of Peru and Ecuador. In this study, the genetic variation of S. pimpinellifolium was studied using the diversity found in 10 microsatellites in 248 plants spread throughout its entire distribution area, including Ecuador, which has been underrepresented in previous studies. Peruvian and Ecuadorian accessions are genetically quite differentiated. A possible cause of these differences could be the non-uniform nature of the coastal Ecuadorian and Peruvian climates, seeing as an important correlation between genetic differentiation and climate has been found. In addition, Ecuadorian and south Peruvian accessions have a lower genetic diversity and a higher homozygosity due to their higher autogamy, lower population size, and possible colonization bottlenecks. The Galápagos Islands population is an extreme case, with no diversity, likely caused by a recent colonization from the northern continental Ecuadorian region where genetically identical plants have been found. Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users. Elena Zuriaga and José M. Blanca contributed equally to this work.  相似文献   

12.
The karyomorphology of 18 Epimedium species were reported in this study. Among 18 species, the karyomorphology of eight taxa, namely E. ecalcaratum, E. pauciflorum, E. lishihchenii, E. dolichostemon, E. pudingense, E. baojingense, E. yingjiangense and E. shuichengense were reported for the first time. The chromosome numbers of all species studied are 2n = 2x = 12, except E. yingjiangense 2n = 4x = 24. Tetraploid was reported in genus Epimedium for the first time. All the Epimedium species, investigated in the present research, have a uniform karyotype with two types of chromosome, metacentric and submetacentric, except E. leptorrhizum and E. sagittatum, of which the sixth pair of chromosomes were subteleocentric. A secondary constriction was commonly found on the proximal side of the short arm of the chromosome pair 1 or 2. The karyotype symmetry of all investigated species was relatively primitive 1A, 2A or 3A. The speciation, infrageneric and intergeneric relationship of Epimedium in Berberidaceae were discussed.  相似文献   

13.
Sequences of the internal transcribed spacers (ITS) of nuclear ribosomal DNA were analysed to precise their length (637–643 bp) and resolve phylogenetic relationships among eight Mediterranean species of the genus Hedysarum (Fabaceae). The infra-specific variability levels of the ITS sequences of spontaneous population of H. coronarium proved a lack of polymorphism both in the length and in the sequences examined in this species. Hence, a consensus ITS sequence characterising each Hedysarum species has been investigated for analysis of inter-specific polymorphisms. The level of variation of ITS sequence was high enough to make the ITS1 and ITS2 a useful tool for phylogenetic reconstruction. However, ITS2 seems to be relatively more polymorphic and more informative than ITS1 regarding length or GC percent. The phylogenic relationships in the genus Hedysarum based on ITS1 and ITS2 sequences taken independently or together, are discussed in the context of current work in molecular biosystematics. Results exhibited the distinctiveness of the two H. spinosissimum subspecies (i.e. H. spinosissimum ssp. capitatum and H. spinosissimum ssp. spinosissimum). In addition, the great similarity of the ITS sequences between H. coronarium (the only cultivated species of the genus) and H. carnosum suggests the usefulness of the latter in selection programmes to improve pastoral production in semi-arid areas.  相似文献   

14.
Genetic erosion has been evaluated at the landrace level in the past, principally because the loss of landraces is believed to generate erosion at the allelic level; however, few studies had tested this hypothesis in the crop’s centers of diversity and domestication. Using microsatellite markers, we analyzed for genetic erosion in lima bean (Phaseolus lunatus) landraces over time in samples collected in 1979 and in 2007 in northeast Campeche, in the Yucatan peninsula, Mexico, an important diversity center and part of the putative domestication area for this crop. We found that the lima bean genetic pool from 1979 had a higher genetic diversity than the one for the 2007 pool (Nei’s diversity, H = 0.18 and 0.05, respectively). Although this result could not to be explained using a bottleneck analysis, a cluster analysis showed that the alleles present in 1979 were not the same as those found in 2007, indicating an allelic displacement in the genetic pool of the lima bean landraces in the last 30 years. This displacement could be due to the introduction of improved varieties or landraces, resulting in a displacement of local varieties or to changes in the Mayan criteria for selection of germplasm or both. This study showed that the loss of landraces can generate both quantitative and qualitative changes in the genetic pool of the domesticated species. Such changes are very important to consider when planning ex situ and in situ programs to conserve crop diversity in their domestication areas.  相似文献   

15.
The ‘Morelos’ accessions of Amaranthus from Mexico demonstrate taxonomic ambiguity at the basic morphologic level. The main cause is the enormous morphological and genetic variation exhibited by the species in the genus. Although basic morphological criteria can be applied to herbarium specimens or germplasm collections for quick taxonomic identification, the morphological data alone can be misleading. To ascertain the taxonomic identity of the ‘Morelos’ accessions and their hypothesized species affiliation to Amaranthus caudatus or Amaranthus cruentus, we conducted a comparative analysis of phylogenetic relationships among these taxa/accessions using amplified fragment length polymorphism (AFLP) and micromorphology methods. Based on AFLP data, all the controversial ‘Morelos’ accessions can be consistently placed into a single A. cruentus species clade, which is clearly separated from the A. caudatus species clade. The AFLP-based phylogenetic relationship of ‘Morelos’ and delimitation of A. cruentus and A. caudatus are further supported by micromorphology, showing that the combination of these techniques can provide more reliable data for germplasm identification than each method used alone.  相似文献   

16.
In Mexico and all over the world, the number of studies on the species of the Jatropha genus has increased because of the use of its seed oil to produce biodiesel. However, the knowledge of the taxonomy, distribution, and ethnobotany of these and related species is incomplete. This article presents the distribution of the genus in Mexico according to its internationally accepted taxonomic identity. The distribution is linked to environmental variables such as elevation, climate type, soil, and soil moisture patterns. In addition to showing the current taxonomical knowledge in Mexico, this article discusses its biogeography, its traditional uses and the research lines to follow in further study of the genus. The distribution results show that some species are broadly adapted; as a consequence, they are present in many different environments. Species such as J. dioica, J. curcas, J. cordata, J. cinerea and J. gaumeri are distributed in areas with well defined environmental conditions. However, the distribution of species such as J. riojae has not yet been ascertained. Three areas with high species richness were identified, and they are very important for the study and conservation of the genus. Mexico is a global center of diversity for this genus. Food and medicinal uses have been reported for some species. This article concludes with recommendations for further study to improve the knowledge of this genus in Mexico.  相似文献   

17.
Northeast China is known as an important distribution region of the genus Lilium, with ten native species reported among the 55 species found in the whole country so far. This paper is about the distribution, collection, classification and evaluation of the Lilium germplasm collected from this area. The accessions were identified and classified into six species and three variants, including Lilium lancifolium Thunb., L. pumilum DC., L. dauricum Ker-Gawl, L. cernuum Komar., L. amabile Palib., L. distichum Nakai, L. concolor Salisb. var. buschianum (Lodd.) Baker, L. concolor Salisb. var. megalanthum Wang et Tang, and L. leichtlinii Hook. f. var. maximowiczii (Regel) Baker. Nevertheless, the species L. callosum Sieb. has not been collected by now. Chromosome counts showed that L. lancifolium was triploid (2n = 3x = 36) and the other species were diploid (2n = 2x = 24). Besides L. distichum, chromosome number variations were observed in the root-tip cells among the other eight species. Haploid cells (2n = x = 12) were discovered in L. lancifolium. B-chromosomes were observed in L. lancifolium, L. dauricum, L. pumilum, L. concolor var. buschianum and L. concolor var. megalanthum. The analytic hierarchy process was employed to evaluate ornamental characteristics and potential utilization of nine identified species. It seemed that L. lancifolium, L. cernuum, L. pumilum and L. concolor var. buschianum had better ornamental value and utilization potential than others.  相似文献   

18.
The karyomorphology for eight diploid species of Arachis belonging to three sections has been described for the first time, Sect. Extranervosae: A. macedoi (2n = 20m) and A. retusa (2n = 14m + 6sm); Sect. Heteranthae: A. sylvestris (2n = 16m + 4sm); Sect. Procumbentes: A. chiquitana (2n = 18m + 2sm); Sect. Arachis: A. cruziana (2n = 18m + 2sm), A. herzogii (2n = 18m + 2sm), A. simpsonii (2n = 20m) and A. williamsii (2n = 20m). A pair of satellited chromosomes was observed in all species. A chromosomes were found in A. chiquitana, A. herzogii and A. simpsonii. Karyotypic differences between sections were observed, but not enough to establish a characteristic karyotype pattern for each section. However, the species may be differentiated by the presence of A chromosomes, the type and position of satellites, and the karyotype formulae. These results are discussed with regard to karyotype evolution in Arachis to contribute to understanding the role of chromosome changes in the evolution of the genus.  相似文献   

19.
Juniperus procera is economically highly important but threatened tree species. It is the only species among 67 taxa in the genus Juniperus that naturally grows in Africa and south of the equator extending up to 18°S in Zimbabwe. Ethiopia is assumed to host the largest J. procera populations, which are also believed to have high genetic variation owing to their wide ecological amplitude. This study assessed genetic variation at AFLPs of J. procera populations in the Ethiopian highlands. In the study six populations, namely Chilimo, Goba, Menagesha-Suba, Wef-Washa, Yabelo and Ziquala were included. A total of 20–24 trees from each population were investigated based on 128 AFLP band positions. AMOVA revealed that most of the variation (94%) resided within populations of J. procera suggesting extensive gene flow among populations which is attributable to the outcrossing mating system and effective gene transport mechanisms of the species. However, genetic differentiation among populations was still significant (P < 0.05), and the differentiation was significantly (P < 0.05) correlated with geographic distance. All population pairs were significantly (P < 0.05) differentiated except for Menagesha-Suba and Wef-Washa. These two populations also showed the highest gene diversity (H j = 0.301 and H j = 0.297, respectively). These results are in accordance with historical records that claim the establishment of the Menagesha-Suba juniper population as plantation of seedlings from Wef-Washa back in fifteenth century.  相似文献   

20.
The genetic relatedness among 51 accessions, 14 species of the genus Zingiber and genetic variability of a clonally propagated species, Zingiber montanum (Koenig) Link ex Dietr., from Thailand were studied using random amplified polymorphic DNA (RAPD) profiles. Twenty-nine random primers gave reproducible amplification banding patterns of 607 polymorphic bands out of 611 scored bands accounting for 99.40% polymorphism across the genotypes. Jaccard’s coefficient of similarity varied from 0.119 to 0.970, indicative of distant genetic relatedness among the genotype studied. UPGMA clustering indicated eight distinct clusters of Zingiber, with a high cophenetic correlation (r = 1.00) value. Genetic variability in Z. montanum was exhibited by the collections from six regions of Thailand. High molecular variance (87%) within collection regions of Z. montanum accessions was displayed by AMOVA and also explained the significant divergence among the sample from six collection regions. Our results indicate that RAPD technique is useful for detecting the genetic relatedness within and among species of Zingiber and that high diversity exists in the clonally propagated species, Z. montanum.  相似文献   

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