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1.
Variation for 24 morphological traits measured in a greenhouse environment and 36 randomly amplified polymorphic DNA (RAPD) markers was assessed among 318 wild octoploid strawberry (Fragariaspp.) genotypes from diverse habitats across the northern USA. RAPD marker frequencies and certain leaf and flower morphology traits (petiole color, leaf mass/area ratio, leaflet length and width, flower and receptacle diameter, petal width, flowers/inflorescence) were significantly different between the F. chiloensis-platypetala and F. virginiana-glauca species complexes. The proportion of variation accounted for by provenance effects was lower for the RAPD markers than for most morphological traits, especially in the F. virginiana-glauca species complex. Morphological traits of potential adaptive importance group the collection into provenances within each species-complex, and reflect the significant habitat and geographic differences across the region from which the germplasm was collected. Variation among populations within provenances was low for the molecular and most morphological traits, with a much larger amount of variability among plants within populations. Most of the variation for the presumably more selectively-neutral RAPD data was among plants within populations and populations within provenances rather than among the provenances that were recognized based on morphological traits, especially in the F. virginiana-glauca complex. Patterns of diversity for morphological traits must be considered, along with more selectively-neutral molecular characters such as RAPDs, to formulate effective sampling strategies and to properly estimate the quantity and apportionment of diversity within this germplasm.  相似文献   

2.
Phenotypic variation of agronomic characters in aromatic rice (Oryza sativa L.) was analyzed in order to elucidate the genetic diversity of the populations of rice landraces. Thirteen populations in Namdinh province, in the Red River Delta of Vietnam, were studied in both of farmers fields and an experimental field. Only small differences were found in agronomic characters among the populations, including populations containing different varieties. Variations among the populations in the frequency distributions of several characters suggested different degrees of diversity among the populations even among populations with the same variety name. The phenotypic profiles of farmers fields were different from those in an experimental field suggesting the environmental differences between them. One variety cultivated in the Myloc district had different phenotypic characters from the other varieties in the Haihau district more clearly in the experimental field. Since the small phenotypic variation in each of farm might be due to the genetic drift and selection by the farmers, on farm conservation of the landraces of rice is considered to be under a force to decrease phenotypic diversity. The present study suggests that the targeting several farms with different phenotypic profiles contribute to the conservation of regional genetic diversity of the landraces of rice.  相似文献   

3.
The extent and patterns of distribution of genetic variation among 80 sorghum (Sorghum bicolor (L.) Moench) germplasm accessions from Ethiopia and Eritrea were investigated using RAPD with 20 oligonucleotide primers. The primers generated a total of 147 polymorphic bands across the 80 accessions with a mean of 7.35 bands per primer. Estimation of the extent of variation by the Shannon-Weaver diversity index revealed an intermediate level of overall variation (H = 53), although the levels varied among regions of origin of the accessions. Partitioning of the total variation revealed considerable variation (77%) within the region of origin of the accessions and the remainder (23%) among regions of origin. Similarly, a large portion (94%) of the total variation was found within the adaptation zones compared to among the adaptation zones (6%). The results suggest a weak differentiation of the sorghum material both on regional and agro-ecological bases, which could be ascribed to the high rate of outcrossing in cultivated sorghum and its free natural hybridization with its wild and weedy relatives, as well as to seed movement by humans. The average genetic dissimilarity was found to be 36% among the 80 accessions and 13% among the 15 regions of origin. Cluster analysis failed to group accessions of the same region or the same adaptation zone, which further confirmed the weak differentiation of the material studied. The clustering pattern of the regions of origin was broadly concordant with previous clustering patterns obtained using morphological characters, in which regions with broad agro-climatic conditions were grouped together.  相似文献   

4.
A field experiment was conducted in Tanzania for two seasons to assess the genetic diversity of bambara groundnut landraces based on morphological characters. One hundred accessions collected from a wide range of agricultural zones in the country were evaluated in a 10 × 10 triple lattice block design at Maruku station in Bukoba, Tanzania. For the qualitative characters evaluated, considerable morphological variations were observed for growth habit, pod shape and pod colour. Quantitative morphological characters such as peduncle length, number of leaves per plant, terminal leaflet width, terminal leaflet length, petiole length, plant spread, plant length, pod width, seed length, seed width, number of pods per plant, shelling percentage and days to 50% flowering showed significant variation among accessions for the two test seasons. Multivariate analysis for 15 quantitative morphological traits that showed significant variation indicated that the first four PCs with eigenvalues ≥1 accounted for 63.0 and 65.0% of the total variance among the accessions during the two test seasons, respectively. The most important loadings for PC1 and PC2 for the two seasons were terminal leaflet width, terminal leaflet length, petiole length, plant spread, plant height and pod length, pod width, seed length, seed width, numbers of pods per plant. Cluster analysis grouped bambara groundnut accessions into three major groups with respect to their geographic origins. Based on this present study, bambara groundnut landraces from Tanzania displayed a considerable diversity for morphological and agronomic traits useful for germplasm management and utilization into crop improvement.  相似文献   

5.
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6.
Weedy rice (Oryza sativa f. spontanea Baker) is one of the most serious weeds in direct-seeded rice production; adversely affecting rice areas and yield in Thailand. The objectives of this study were to evaluate the level of morphological and agronomical variation and the level and pattern of genetic diversity and population structure of weedy rice populations in Thailand. Sixty-three weedy rice populations collected from three rice production areas of Thailand were sampled over four rice cultivation seasons to study phenotypic characteristics, genetic diversity and population structure. All analysis included comparison with seven cultivated rice varieties and seven local common wild rice populations. The results demonstrated considerable genetic and morphological variation, population structure, and changing dynamics of Thai weedy rice populations, both within and between regions and growing seasons. Phenotypic and genotypic variations and population structure of weedy rice populations changed temporally, with a trend over five years toward greater similarity to companion crop rice varieties. The ongoing gene flow, combined with ecological conditions created by farmers’ selection and agronomic practices, may enhance fitness and adaptability of weedy rice populations and stimulate the evolution of invasiveness in weedy rice plants. The adaptive evolution of weedy rice tended to parallel cultivated rice for high adaptation to the agronomic practices, possibly including selection for crop mimicry, which has led to the convergence of weedy populations phenotypically and genetically with the companion crop rice.  相似文献   

7.
Summary Electrophoresis was carried out for six isozyme systems on 175 accessions of the seven morphological forms of Chamaecytisus proliferus (L. fil.) Link (Fabaceae: Genisteae) from the Canary Islands. Previous studies have shown that there is clear differentiation into morphological and ecological forms. The underlying genetic variation as visualised by studying isozymes does not reflect this. While substantial genetic diversity can be identified, this was found to be as much within as between morphological forms. This genetic diversity was found to decrease from east to west, and reflects the pattern of variation remaining after colonisation of the individual islands, which is assumed to have progressed in the same direction. Subsequently, adaptive radiation has given rise to the overlying morphological variation as exhibited in the seven morphological forms.In terms of in situ conservation, overall genetic diversity can be easily conserved in the abundant populations occurring in the east of the archipelago, while more attention is required for conservation of the much rarer morphological forms found in the west, despite their relative lack of isozyme diversity.Abbreviations ACO aconitase - ADH alcohol dehydrogenase - IDH Asocitrate dehydrogenase - MDH malate dehydrogenase - PGD 6-phosphogluconate dehydrogenase - PGM phosphoglucomutase - CA cluster analysis - PCA principal component analysis  相似文献   

8.
Broadening the genetic base upon which the breeding of durumwheat relies is a growing concern in Italy. Exotic materials canrepresent valuable sources of adaptive features and they have beenrepeatedly exploited in the past for direct utilisation and/orintrogression by crossing into existing germplasm. An increase of theavailable genetic variation for the breeding also appearsenvisageable in terms of end-product quality. This studyassessed the variation in germplasm from eastern Europe countries,which could represent novel gene sources for durum wheat improvementin Italy, and verified the presence of variants of potential interestfor agronomical and quality characteristics to be possibly exploitedfor breeding. Fifty-nine landraces from the former USSR and 91from Bulgaria were grown in Sicily and evaluated for agronomicaltraits, spike morphological characteristics (possibly bearingsome taxonomic relevance), and protein composition at three lociencoding for glutenin subunits responsible of flour quality features.The results suggested a similar overall diversity in the two groupsconsidering either the variance of the agronomical characters, or thediversity index (H) across morphological traits, orthe frequency distribution of electrophoretic patterns of gluteninsubunits encoded at three loci. Genotypes of potential usefulness asdonors of positive agronomical or quality attributes were found inboth germplasm groups, although the agronomical characteristics ofthe exotic genotypes rarely matched those required by the breeding inthe target area. Conversely, the genetic variation found at the threeloci involved in the composition of glutenin subunits appeared ofgreater relevance for the breeding in Italy.  相似文献   

9.
Taro (Colocasia esculenta (L.) Schott), cultivated in Vêtuboso, a village of northern Vanuatu, Melanesia, was surveyed to: (1) assess the extent of morphological and molecular variation being maintained by growers at the village level and, (2) compare this diversity with the diversity found in the crops in Vanuatu. Ethnobotanical data were combined with AFLP analysis to elucidate possible sources of variation. Folk assessment of variation is based on: (a) morphological characteristics (11 characters), (b) names and (c) classification according to habitat, uses, origin and agronomic adaptation. This 3-fold approach allowed growers to differentiate 96 morphotypes, all of which are given distinct vernacular names. AFLP fingerprints successfully differentiated all these 96 morphotypes which do not present a significant intra-clonal variation. But genetic results showed no clear groupings according to geographic origin or habitat of morphotypes and stated that the diversity found within the village was comparable with the overall diversity found in Vanuatu. Local nomenclature and stories associated with each cultivar suggested three sources of diversity: introductions (38%), somatic mutations (15%) and sexual recombinations (48%). AFLP results confirm folk beliefs about origin at least for three pairs of mutants. The 11 so-called wild forms analysed by AFLP were suggested to be feral, escapes from domestication. A dynamic in situ conservation strategy (DISC), favouring a broadening of the national genetic base, was discussed for taro.  相似文献   

10.
There is considerable wealth of genetical and morphological variation in tetraploid wheat collected from Ethiopia by past expeditions. Several authors have speculated on the reasons for this concentration of diversity so far removed from the centre of origin of wheats in West Asia. The present study reports results of evaluation carried out on material collected in the early 1970's from Ethiopia. The landraces from the two provinces Shewa and Tigray were found to be distinctly different. This divergence was attributed to the differences in environmental conditions between them. Wide differentiation among landraces within each province was also present. The Ethiopian farmer's practice of growing composite cultivars in the field has resulted in bulk samples of Ethiopian landraces containing several agrotypes. The proportion of total variance due to differences among agrotypes within landraces was by far the greatest found in this study, followed in most cases by the variation among landrace populations within provinces which exceeded, in turn, the variation between province gene pools. The optimal strategy for further germplasm collections and implications for improvement and conservation in locally-based community gene banks are discussed.  相似文献   

11.
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12.
Morphological spike diversity of Omani wheat   总被引：2，自引：2，他引：0  
Little is known about the diversity of field crops in Oman. The objective of this study therefore was to characterize wheat accessions from this country using individual spikes collected from different wheat cultivation areas. The phenotypic assessment of 15 qualitative and 17 quantitative characters showed variations among Omani wheat landraces. The standardized phenotypic diversity index (H′) was with 0.66 higher for quantitative characters than for qualitative characters (0.52) in tetraploid wheats and with 0.63 and 0.62, respectively, in hexaploid wheats. Overall, the morphological data revealed a surprisingly high diversity among landraces and showed that simple morphological characters can be used for an effective characterization of diversity in Omani wheat.  相似文献   

13.
The fact that the intraspecific genetic differentiation in neutral genetic markers and genes coding for adaptive traits are not typically correlated has caused a great deal of conceptual and practical trouble in delimitation of conservation units. Although the importance of combining information on adaptive genetic divergence with information on historical and recent gene flow in the delimitation of conservation units has been recognized, integrated empirical studies to this end are still rare. We explored the evidence for the specific conservation status of two freshwater three-spined stickleback (Gasterosteus aculeatus) populations on the Adriatic side of the Balkan Peninsula by comparing their phenotypic and genetic characteristics to those of other representative European populations. Apart from focusing on the neutral genetic divergence in mitochondrial DNA sequences and microsatellite markers, we also compared the patterns of morphological differentiation (i.e. bony armour development) resulting from adaptation to freshwater environments. The Balkanic populations formed two distinct groups with regard to neutral genetic variation and had the least developed bony armour of all the examined populations. All morphometric analyses identified the two Balkanic populations as phenotypically – and hence most likely also ecologically – clearly distinct from other European three-spined stickleback populations. These results suggest that the two Balkanic populations (River Neretva and River Zeta) fulfil the most stringent criteria (i.e. lack of genetic and ecological exchangeability) to be classified as conservation units distinct from other European three-spined stickleback populations.  相似文献   

14.
Taxa of conservation interest are frequently identified using morphological or ecological characters. These characters are assumed to represent evolutionary importance, population structure and/or phylogenetic relationships in such organisms. We tested this assumption using two species complexes of the moth genus Hemileuca (Saturniidae). Both have populations threatened by habitat loss and need conservation protection. Legislation protects one taxon with apparent ecological differences. We sequenced 624 base pairs of mtDNA from the COI gene for geographically distant populations of the Hemileuca maia species complex and the H. electra species complex. Resultant phylogenies contradict prior assumptions about relationships in both species complexes. The legislatively protected Bog Buckmoth is paraphyletic with widespread H. maia, and its use of a novel hostplant seems to be a local adaptation. Divergent morphology and hostplant use among H. electra subspecies are associated with modest genetic divergence (0.48%). However, a group of unrecognized populations that are morphologically similar and geographically close to H. electra electra have mtDNA that is divergent by an average of 4.1%. There is disagreement regarding prioritization of ecological divergence over neutral genetic distance in conservation. We place ecological variation in a phylogenetic context and recommend that exploration of genetic relationships be undertaken when populations are threatened. Adaptive ecological variation should be evaluated in a phylogenetic context to understand its conservation importance. This study illustrates the importance both of phylogenetic context and the use of independent characters in assessing biodiversity for conservation prioritization.  相似文献   

15.
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16.
Following a legume collection mission to south-west Turkey in 1996, five species of Trifolium were analysed for genetic variation within and between species in eleven morphological and flowering characters. The five species included two outcrossing species, T. michelianum and T. resupinatum, and three inbreeding species, T. clypeatum, T. glomeratum and T. tomentosum. The genetic diversity found was related to climate and edaphic factors. All five species showed significant amounts of genetic differentiation between sites and the species could be separated morphologically by principal components analysis and cluster analysis. The most significant source of genetic variation was found to be related to geographical distribution with those species which were widely distributed across south-west Turkey exhibiting much greater amounts of genetic variation between sites, than those which had a narrow distribution. The breeding system was found to be less important, but only the morphology of the outbreeding species showed any environmental clines in relation to climate. A multiple regression analysis was computed to estimate the effect of growing season on the days to flowering of each of the species.  相似文献   

17.
A characterization of 10,105 accessions of hexaploid cultivated oat (Avena sativa L. sensu lato) from 85 countries of the Plant Gene Resources of Canada (PGRC) collection was conducted at Saskatoon, Saskatchewan, Canada. Eight environmentally stable morphological characters (panicle type, panicle erectness, panicle density, lemma colour, dorsal awn of lemma, ligula, major infraspecific group), differentiated into 18 character states, were used to define genetically distinct morphological groups. Comparisons of oat diversity from different countries, among the major infraspecific groups and among Canadian oat cultivars registered between 1886 and 2002 were possible. The 10,105 accessions represented 118 different morphological groups. The number of accessions in each morphological group was unevenly distributed with the 13 most frequent morphological groups including 90% of the accessions. The most frequent morphological groups in the PGRC collection were identical with the most frequent types of Canadian oat cultivars. The greatest richness of diversity was found in oat from countries with temperate climates and intensive oat breeding programmes. The oat accessions comprised 8,754 accessions of common hulled oat, 183 accessions of hull-less oat and 1,168 accessions of red oat. For red oat (A. byzantina C. Koch), West Asia was richest in diversity. The USA could be considered a secondary centre of diversity for red oat and Canada a secondary centre of diversity for hull-less oat. Morphological diversity of oat cultivars released in Canada increased during the twentieth century. The morphological groups were related to formal taxonomical infraspecific classifications of A. sativa. Applications of the concept of defining morphological groups for phenotyping a large germplasm collection are demonstrated discussed.  相似文献   

18.
Phenotypic diversity was assessed for quantitative and qualitative traits in a salt-tolerant subset of the international safflower (Carthamus tinctorius L.) germplasm collection originating from 11 countries in three regions (Central Asia, Southwest Asia and Africa) of the Middle East. Phenotypically, the germplasm, among and within regions, was highly variable, especially for rosette- and yield-related traits. Frequency of desirable variants of seven agronomically important traits ranged from 14% for long rosette period to 50% for no or few spines. Level of population differentiation was high for number of capitula per plant (30%), whereas most traits partitioned their diversity (82–87%) within populations. Region-specific nonrandom associations among sets of qualitative traits and the existence of broad morphological and phenotypic diversity in this germplasm were supported by the large number of log-linear models needed to describe qualitative trait associations, the high number of principal components needed to account for total variability, and the low discriminatory power of phenotypic traits among germplasm from regions and countries in the Middle East. These results suggest that adaptation of the species to the wide spatial and temporal variation in the Middle East resulted in a multitude of ecotypes and in enormous amount of local variation. A multivariate selection criterion for high biological and seed yield, long rosette period and no or few spines identified five accessions from Southwest Asia that can be introduced into subsistence farming systems as a multipurpose crop under saline agriculture.  相似文献   

19.
Native species show adaptive traits that are difficult to find in introduced species. The Pampas region in Argentina is a valuable nature reserve of grasses and Paspalum dilatatum Poir. is one of the most important grasses found there. Based on ploidy level and on morphological traits, five biotypes of P. dilatatum have been described. Two of them were included in this study: a tetraploid biotype with sexual reproduction and a pentaploid biotype with apomictic reproduction. We analyzed the genetic diversity in eight native populations from the Salado basin, Argentina, using both quantitative traits and molecular data (RAPD) with these aims: to obtain information of the degree of phenotypic variation in that area, to know which the pattern of distribution of this variation is and to look for association between molecular markers with populational or biotypic differentiation. Cluster analysis based on morphological data grouped the individuals of the different populations by ploidy level. Molecular markers showed the inverse situation because individuals were grouped by geographic origin as opposed to biotype. Moreover, since RAPD did not discriminate between biotypes with sexual or apomictic reproduction, they are probably not associated with mating system. The results let us conclude that polygenic traits such as LP, LBSR, NRT and NSP can discriminate between biotypes and molecular markers such as bands 12, 40, 19 and 46 can be used to discriminate among populations, probably because they detect neutral variation. The article is part of a thesis presented by María Victoria García in partial fulfillment of the requirements for the Doctor’s degree, Facultad de Ciencias Naturales y Museo, Universidad Nacional de La Plata, La Plata, Argentina.  相似文献   

20.
The wide morphological variation of Aegilops tauschii has led to the distinction of different subspecies; a typical ssp. tauschii and a second ssp. strangulata. However some researchers pointed out the existance of the intermediate form among morphologically distinguished subspecies. Distribution, diversity and the relationship between different subspecies and the intermediate form were evaluated in the Iranian Ae. tauschii collection. This collection was classified to 15 different populations according to morphological similarities and the collecting origin of accessions. The highest variation was found in tauschii population of Golestan followed by tauschii populations of Gilan and Ardebill, whereas the lowest variation was observed in tauschii populations of central Iran. Two discriminant functions suggested that the length of rachis node and spikelet glume, particularly, the length/width ratios of these traits had the highest impact on identification of different forms. Mahalanobis distances (D 2 ) between the two subspecies along with intermediate form on the multidimensional scaling plot showed that the intermediate form is more similar to ssp. tauschii than ssp. strangulata. Although, the diversity within the ssp. strangulata was not very high, it widely affected the diversity of Iranian accessions of Ae. tauschii through continues crossing with the more diversed subspecies, tauschii, during thousands of years. This fact had lead to expansion of its distribution from its origin to Northern Khorasan, Northern Semnan and Eastern Ardebill by producing the intermediate form.  相似文献   

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