Genetic Diversity Of Plant Species Research Articles

Genetic diversity within a newly identified population of Adenophora liliifolia (L.) A.DC. in Romania: implications for conservation

Adenophora liliifolia is a relict plant species, endangered at European level. Its occurrence in Romania is limited to a very few sites. The amount of genetic diversity of plant species is a valuable indicator of population, being the baseline in developing proper strategies for their conservation. Inter-simple sequence repeats (ISSRs) markers were used to analyze polymorphism in A. liliifolia genome and to evaluate the genetic diversity and accordingly, the state of a recently identified population. Five ISSR primers, specially designed for plants, and containing different simple sequence repeat motifs were tested. A total of 52 ISSR fragments were generated of which 41 were polymorphic (78.84%) and 32 (61.53%) specific to Adenophora genus. The value of Shannon’s index of genotypic diversity was 0.812. Jaccard similarity coefficient was calculated for pair wise comparisons among all individuals and ranged from 0.17 to 0.83. The genetic variability between individuals was 78.84% which suggests a relative high genetic differentiation. Although the level of genetic variability is moderate to high, the population is declining and exposed to demographic stochasticity. A possible cause is species germination requirements hampered by modification in vegetation structure and abundance. The population survival and reinforcement is conditioned by urgent measures for forest management in order to reduce herbaceous and shrubby vegetation and to limit mowing and grazing. Ex situ conservation measures are also proposed.

A Look into Genetic Diversity of Enset (Ensete ventricosum (Welw.) Cheesman) Using Transferable Microsatellite Sequences of Banana in Ethiopia

Microsatellite sequences are one of the best options for the study of genetic diversity in plant species. However, because of the high cost of their development, it is important to test whether existing sequences from related species can be exploited. Enset (Ensete ventricosum (Welw.) Cheesman) has remained largely unimproved partly due to lack of its genetic information, thus there is a need to study the genetic diversity of current accessions and build on it to develop new cultivars/varieties with desired agronomic traits. Transferability of 71 SSR loci from banana (Musa accuminata) to enset was investigated using 220 Enset accessions. Among the 71 SSRs tested, 12 (16.9%) were successfully transferable to enset. Eleven (16.9%) of these were used to examine the diversity of the 220 enset accessions that had been collected from eight different zones in Ethiopia.

Mutualistic fungal endophytes in the Triticeae - survey and description.

Grasses of the tribe Triticeae were screened to determine the presence of mutualistic epichloae fungal endophytes. Over 1500 accessions, from more than 250 species, encompassing 22 genera within the Triticeae were screened using immunodetection and direct staining/microscopy techniques. Only two genera, Elymus and Hordeum, were identified as harbouring epichloae endophytes with accessions native to a range of countries including Canada, China, Iran, Kazakhstan, Kyrgyzstan, Mongolia, Russia and the USA. Genetic analysis based on simple sequence repeat data revealed that the majority of endophytes cluster according to geographical regions rather than to host species; many strains isolated from Hordeum grouped with those derived from Elymus, and amongst the Elymus-derived strains, there was no clear correspondence between clustering topology and host species. This is the first detailed survey demonstrating the genetic diversity of epichloae endophytes within the Triticeae and highlights the importance of germplasm centres for not only preserving the genetic diversity of plant species but also the beneficial microorganisms they may contain.

Population history and gene dispersal inferred from spatial genetic structure of a Central African timber tree, Distemonanthus benthamianus (Caesalpinioideae).

African rainforests have undergone major distribution range shifts during the Quaternary, but few studies have investigated their impact on the genetic diversity of plant species and we lack knowledge on the extent of gene flow to predict how plant species can cope with such environmental changes. Analysis of the spatial genetic structure (SGS) of a species is an effective method to determine major directions of the demographic history of its populations and to estimate the extent of gene dispersal. This study characterises the SGS of an African tropical timber tree species, Distemonanthus benthamianus, at various spatial scales in Cameroon and Gabon. Displaying a large continuous distribution in the Lower Guinea domain, this is a model species to detect signs of past population fragmentation and recolonization, and to estimate the extent of gene dispersal. Ten microsatellite loci were used to genotype 295 adult trees sampled from eight populations. Three clearly differentiated gene pools were resolved at this regional scale and could be linked to the biogeographical history of the region, rather than to physical barriers to gene flow. A comparison with the distribution of gene pools observed for two other tree species living in the same region invalidates the basic assumption that all species share the same Quaternary refuges and recolonization pathways. In four populations, significant and similar patterns of SGS were detected. Indirect estimates of gene dispersal distances (sigma) obtained for three populations ranged from 400 to 1200 m, whereas neighbourhood size estimates ranged from 50 to 110.

Rapid loss of genetic variation in a founding population of Primula elatior (Primulaceae) after colonization

Land-use changes and associated extinction/colonization dynamics can have a large impact on population genetic diversity of plant species. The aim of this study was to investigate genetic diversity in a founding population of the self-incompatible forest herb Primula elatior and to elucidate the processes that affect genetic diversity shortly after colonization. AFLP markers were used to analyse genetic diversity across three age classes and spatial genetic structure within a founding population of P. elatior in a recently established stand in central Belgium. Parentage analyses were used to assess the amount of gene flow from outside the population and to investigate the contribution of mother plants to future generations. The genetic diversity of second and third generation plants was significantly reduced compared with that of first generation plants. Significant spatial genetic structure was observed. Parentage analyses showed that < 20 % of the youngest individuals originated from parents outside the study population and that > 50 % of first and second generation plants did not contribute to seedling recruitment. These results suggest that a small effective population size and genetic drift can lead to rapid decline of genetic diversity of offspring in founding populations shortly after colonization. This multigenerational study also highlights that considerable amounts of gene flow seem to be required to counterbalance genetic drift and to sustain high levels of genetic diversity after colonization in recently established stands.

Long distance pollen‐mediated gene flow at a landscape level: the weed beet as a case study

Gene flow is a crucial parameter that can affect the organization of genetic diversity in plant species. It has important implications in terms of conservation of genetic resources and of gene exchanges between crop to wild relatives and within crop species complex. In the Beta vulgaris complex, hybridization between crop and wild beets in seed production areas is well documented and the role of the ensuing hybrids, weed beets, as bridges towards wild forms in sugar beet production areas have been shown. Indeed, in contrast to cultivated beets that are bi-annual, weed beets can bolt, flower and reproduce in the same crop season. Nonetheless, the extent of pollen gene dispersal through weedy lineages remains unknown. In this study, the focus is directed towards weed-to-weed gene flow, and we report the results of a pollen-dispersal analysis within an agricultural landscape composed of five sugar beet fields with different levels of infestation by weed beets. Our results, based on paternity analysis of 3240 progenies from 135 maternal plants using 10 microsatellite loci, clearly demonstrate that even if weedy plants are mostly pollinated by individuals from the same field, some mating events occur between weed beets situated several kilometres apart (up to 9.6 km), with rates of interfield-detected paternities ranging from 11.3% to 17.5%. Moreover, we show that pollen flow appears to be more restricted when individuals are aggregated as most mating events occurred only for short-distance classes. The best-fit dispersal curves were fat-tailed geometric functions for populations exhibiting low densities of weed beets and thin-tailed Weibull function for fields with weed beet high densities. Thus, weed beet populations characterized by low density with geographically isolated individuals may be difficult to detect but are likely to act as pollen traps for pollen emitted by close and remote fields. Hence, it appears evident that interfield pollen-mediated gene flow between weed beets is almost unavoidable and could contribute to the diffusion of (trans)genes in the agricultural landscape.

Tubulin-based polymorphism (TBP): a new tool, based on functionally relevant sequences, to assess genetic diversity in plant species.

TBP (tubulin-based polymorphism) is a new molecular marker based tool that relies on the presence of intron-specific DNA polymorphisms of the plant beta-tubulin gene family. The multifunctional and essential role of the tubulin proteins is reflected in the conservation of regions within their primary amino acid sequence. The ubiquitous nature of this gene family can be exploited using primers that amplify the first intron of different beta-tubulin isotypes, revealing specific fingerprints. The method is rapid, simple, and reliable and does not require preliminary sequence information of the plant genome of interest. The ability of TBP to discriminate between accessions and species in oilseed rape, coffee, and lotus is shown. In all cases, TBP was able to detect specific genetic polymorphisms in the context of a simplified and readily appreciable pattern of DNA amplification. The application of TBP for assessing genetic diversity and genome origins in disseminated plant landraces rather than in highly inbred cultivated species is also discussed.

Chloroplast diversity in Vouacapoua americana (Caesalpiniaceae), a neotropical forest tree.

The chloroplast genome has been widely used to describe genetic diversity in plant species. Its maternal inheritance in numerous angiosperm species and low mutation rate are suitable characters when inferring historical events such as possible recolonization routes. Here we have studied chloroplast DNA variation using PCR-RFLP (polymerase chain reaction-restriction fragment length polymorphism) with seven pairs of primers and four restriction enzymes in 14 populations of Vouacapoua americana (Caesalpiniaceae) a neotropical tree sampled throughout French Guiana. Population diversity (Hs), total gene diversity (Ht) and differentiation among populations (GST) were estimated using Nei's method as 0.09, 0.87 and 0.89, respectively. This is consistent with the limited gene flow associated with synzoochory in this species. The genetic structure observed in the north of French Guiana suggests that historical events such as contractions and recent recolonizations have had a large impact on the distribution of genetic diversity in this species.

Plant Life Histories: Ecology, Phylogeny and Evolution.

Preface Part I. Phylogenetic Perspectives: 1. Comparing plants and connecting traits J. Silvertown, and M. Dodd 2. Phylogenetic uncertainties and sensitivity analyses in comparative biology M. Donoghue, and D. Ackerly 3. Comparative ecology of the native and alien floras of the British Isles M. J. Crawley, P. H. Harvey, and A. Purvis Part II. Reproductive Traits: 4. The comparative biology of pollination and mating in flowering plants S. C. H. Barrett, L. D. Harder, and A. C. Worley 5. How does self-pollination evolve? Inferences from floral ecology and molecular genetic variation S. C. H. Barrett, L. D. Harder, and A. C. Worley 6. Effects of life history traits on genetic diversity in plant species J. L. Hamrick, and M. J. W. Godt Part III. Evolutionary Ecology of Seed Dormancy and Seed Size: 7. Evolutionary ecology of seed dormancy and seed size J. L. Hamrick, and M. J. W. Godt 8. Comparative ecology of seed size and dispersal M. Westoby, M. Leishman, and J. Lord 9. Packaging and provisioning on plant reproduction D. L. Venable Part IV. Recruitment and Growth: 10. Comparative ecology of clonal plants J. M. van Groenendael, L. Klimes, J. Klimesova, and R. J. J. Hendriks 11. Life history variation in plants: an exploration of the fast-slow continuum hypothesis M. Franco and J. Silvertown 12. Life history evolution in heterogenous environments: a review of theory R. M. Sibly Part V. Interaction: 13. Plant-insect feeding associations D. Futuyma, and C. Mitter 14. Trends in the evolution of root-microbe symbioses A. H. Fitter, and B. Moyersoen 15. Competitive ability: definitions, contingency and correlated traits D. Goldberg Index.

Comparative analysis of genetic similarity among maize inbred lines detected by RFLPs, RAPDs, SSRs, and AFLPs

DNA-based fingerprinting technologies have proven useful in genetic similarity studies. RFLP is still most commonly used in the estimation of genetic diversity in plant species, but the recently developed PCR-based marker techniques, RAPDs, SSRs and AFLPs, are playing an increasingly important role in these investigations. Using a set of 33 maize inbred lines we report on a comparison of techniques to evaluate their informativeness and applicability for the study of genetic diversity. The four assays differed in the amount of polymorphism detected. The information content, measured by the expected heterozygosity and the average number of alleles, was higher for SSRs, while the lowest level of polymorphism was obtained with AFLPs. However, AFLPs were the most efficient marker system because of their capacity to reveal several bands in a single amplification. In fact, the assay efficiency index was more than ten-fold higher for AFLPs compared to the other methods. Except for RAPDs, the genetic similarity trees were highly correlated. SSR and AFLP technologies can replace RFLP marker in genetic similarity studies because of their comparable accuracy in genotyping inbred lines selected by pedigree. Bootstrap analysis revealed that, in the set of lines analysed, the number of markers used was sufficient for a reliable estimation of genetic similarity and for a meaningful comparison of marker technologies.

Effects of life history traits on genetic diversity in plant species

Seven two-trait combinations (e.g. breeding system and seed dispersal mechanism) of five life history characteristics were used to analyse interspecific variation in the level and distribution of allozyme genetic diversity in seed plants. Highly significant differences were seen among categories for all seven comparisons. Life form and breeding system had highly significant influences on genetic diversity and its distribution. Regardless of other traits, outcrossing species tended to be more genetically diverse and had less genetic differentiation among their populations. Similarly, woody plants have less among population differentiation and somewhat more genetic diversity than non-woody species with similar life history traits. An analysis of twelve plant families indicated that species within families with predominately outcrossing, woody species had more genetic diversity and less interpopulation differentiation than species within families with predominately herbaceous species.

Genetic Diversity of Plant Species in Glacier National Park: Implications for Management

Genetic diversity, as the fundamental resource of Glacier National Park (GNP), is central to the characterization of biodiversity present in GNP. Preserving the genetic variation in species maintains their intrinsic flexibility to deal with variable abiotic and biotic environments. Although often not readily apparent as visible morphologic (phenotypic) differences, genetic variation may occur 1) between individuals within a population and 2) between populations of a species. Managers need to consider these two components of genetic variation when mediating the effects of human disturbance in GNP. However, very little is currently known about these levels of genetic organization in GNP species. Our three year project examines the presence and patterns of genetic variation in two GNP species: strawberry (Fragaria virginiana Duchesne) and mountain brome (Bromus carinatus Hook. and Arn.). We are quantifying the amount and distribution of genetic and phenotypic variation using quantitative genetic and electrophoretic methods and are identifying phenotypic characters subject to natural selection, i.e., those characters important for survival and reproduction differences in populations.

Genetic Diversity of Plant Species in Glacier National Park: Implications for Management

Glacier National Park (GNP) is responsible for the management and preservation of biological diversity in the natural populations of plants and animals occurring within its boundaries. Information on existing levels of genetic variation within and among populations is a prerequisite for developing management strategies to maintain genetic diversity and to perform revegetation activities. We are using two methods to assess levels of genetic diversity and differentiation among populations: quantitative genetic analysis and isozyme (electrophoresis) analysis. To examine whether patterns of genetic variation and adaptation to local environments require that sites be revegetated with plants collected from nearby natural populations, or alternatively, whether transplants could be obtained from other sources; we are focussing on three experimental areas: 1. quantitative genetics; 2. electrophoresis, and 3. natural selection.