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Diversity, Volume 2, Issue 5 (May 2010) – 6 articles , Pages 701-836

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966 KiB  
Article
DNA Markers and FCSS Analyses Shed Light on the Genetic Diversity and Reproductive Strategy of Jatropha curcas L.
by Daria Gigliola Ambrosi, Giulio Galla, Marina Purelli, Tommaso Barbi, Andrea Fabbri, Sergio Lucretti, Timothy Francis Sharbel and Gianni Barcaccia
Diversity 2010, 2(5), 810-836; https://doi.org/10.3390/d2050810 - 25 May 2010
Cited by 43 | Viewed by 10236
Abstract
Jatropha curcas L. (2n = 2x = 22) is becoming a popular non-food oleaginous crop in several developed countries due to its proposed value in the biopharmaceutical industry. Despite the potentials of its oil-rich seeds as a renewable source of biodiesel [...] Read more.
Jatropha curcas L. (2n = 2x = 22) is becoming a popular non-food oleaginous crop in several developed countries due to its proposed value in the biopharmaceutical industry. Despite the potentials of its oil-rich seeds as a renewable source of biodiesel and an interest in large-scale cultivation, relatively little is known with respect to plant reproduction strategies and population dynamics. Here, genomic DNA markers and FCSS analyses were performed to gain insights into ploidy variation and heterozygosity levels of multiple accessions, and genomic relationships among commercial varieties of Jatropha grown in different geographical areas. The determination of ploidy and the differentiation of either pseudogamous or autonomous apomixis from sexuality were based on the seed DNA contents of embryo and endosperm. The presence of only a high 2C embryo peak and a smaller 3C endosperm peak (ratio 2:3) is consistent with an obligate sexual reproductive system. Because of the lack of either 4C or 5C endosperm DNA estimates, the occurrence of gametophytic apomixis seems unlikely in this species but adventitious embryony cannot be ruled out. The investigation of genetic variation within and between cultivated populations was carried out using dominant RAPD and Inter-SSR markers, and codominant SSR markers. Nei’s genetic diversity, corresponding to the expected heterozygosity, was equal to He = 0.3491 and the fixation index as low as Fst = 0.2042. The main finding is that seeds commercialized worldwide include a few closely related genotypes, which are not representative of the original Mexican gene pool, revealing high degrees of homozygosity for single varieties and very low genetic diversity between varieties. Full article
(This article belongs to the Special Issue Biological Diversity Assessed by Molecular Methods)
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463 KiB  
Article
A Molecular Survey of the Diversity of Microbial Communities in Different Amazonian Agricultural Model Systems
by Acácio A. Navarrete, Fabiana S. Cannavan, Rodrigo G. Taketani and Siu M. Tsai
Diversity 2010, 2(5), 787-809; https://doi.org/10.3390/d2050787 - 19 May 2010
Cited by 53 | Viewed by 10253
Abstract
The processes of land conversion and agricultural intensification are a significant cause of biodiversity loss, with consequent negative effects both on the environment and the sustainability of food production.The anthrosols associated with pre-Colombian settlements in the Amazonian region are examples of how anthropogenic [...] Read more.
The processes of land conversion and agricultural intensification are a significant cause of biodiversity loss, with consequent negative effects both on the environment and the sustainability of food production.The anthrosols associated with pre-Colombian settlements in the Amazonian region are examples of how anthropogenic activities may sustain the native populations against harsh tropical environments for human establishment, even without a previous intentionality of anthropic soil formation. In a case study (Model I—“Slash-and-Burn”) the community structures detected by automated ribosomal intergenic spacer analysis (ARISA) revealed that soil archaeal, bacterial and fungal communities are heterogeneous and each capable of responding differently to environmental characteristics. ARISA data evidenced considerable difference in structure existing between microbial communities in forest and agricultural soils. In a second study (Model II—“Anthropogenic Soil”), the bacterial community structures revealed by terminal restriction fragment length polymorphism (T-RFLP) differed among an Amazonian Dark Earth (ADE), black carbon (BC) and its adjacent non-anthropogenic oxisoil. The bacterial 16S rRNA gene (OTU) richness estimated by pyrosequencing was higher in ADE than BC. The most abundant bacterial phyla in ADE soils and BC were Proteobacteria—24% ADE, 15% BC; Acidobacteria—10% ADE, 21% BC; Actinobacteria—7% ADE, 12% BC; Verrucomicrobia, 8% ADE; 9% BC; Firmicutes—3% ADE, 8% BC. Overall, unclassified bacteria corresponded to 36% ADE, and 26% BC. Regardless of current land uses, our data suggest that soil microbial community structures may be strongly influenced by the historical soil management and that anthrosols in Amazonia, of anthropogenic origins, in addition to their capacity of enhancing crop yields, may also improve microbial diversity, with the support of the black carbon, which may sustain a particular and unique habitat for the microbes. Full article
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402 KiB  
Article
Genetic Diversity of the Pm3 Powdery Mildew Resistance Alleles in Wheat Gene Bank Accessions as Assessed by Molecular Markers
by Navreet K. Bhullar, Michael Mackay and Beat Keller
Diversity 2010, 2(5), 768-786; https://doi.org/10.3390/d2050768 - 19 May 2010
Cited by 22 | Viewed by 9599
Abstract
Genetic resources of crop plants are essential for crop breeding. They are conserved in gene banks in form of a large numbers of accessions. These accessions harbor allelic variants of agronomically important genes and molecular tools allow a rapid assessment of this allelic [...] Read more.
Genetic resources of crop plants are essential for crop breeding. They are conserved in gene banks in form of a large numbers of accessions. These accessions harbor allelic variants of agronomically important genes and molecular tools allow a rapid assessment of this allelic diversity. Here, we have screened a collection of 1005 wheat gene bank accessions for powdery mildew resistance and a molecular characterization for functional alleles at the wheat powdery mildew resistance locus Pm3 was carried out mostly on the resistant accessions. The two analyzed sets of accessions consisted of 733 accessions originating from 20 different countries and 272 landraces originating specifically from Afghanistan. The Pm3 haplotype (indicating the presence of a Pm3-type of gene, susceptible or resistant) was found to be abundantly present in both sets. The accessions with a Pm3 haplotype were further screened for the presence of the functional Pm3a to Pm3g alleles using allele-specific molecular markers. Pm3b and Pm3c were the most frequently found alleles while the other five alleles were detected only in few accessions (Pm3d, Pm3e, Pm3f) or not detected at all (Pm3a, Pm3g). The data further showed that Pm3b is the major source of Pm3-mediated powdery mildew resistance in wheat accessions from Afghanistan. Susceptible allelic variants of Pm3 were found to be widespread in the wheat gene pool. The presented molecular analysis of Pm3 alleles in a diverse set of wheat accessions indicates that several alleles have defined geographical origins. Possibly, the widespread Pm3b and Pm3c alleles evolved relatively early in wheat cultivation, allowing their subsequent diffusion into a broad set of wheat lines. Full article
(This article belongs to the Special Issue Assessment of Plant Genetic Diversity)
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1160 KiB  
Article
From Points to Forecasts: Predicting Invasive Species Habitat Suitability in the Near Term
by Tracy R. Holcombe, Thomas J. Stohlgren and Catherine S. Jarnevich
Diversity 2010, 2(5), 738-767; https://doi.org/10.3390/d2050738 - 12 May 2010
Cited by 14 | Viewed by 8829
Abstract
We used near-term climate scenarios for the continental United States, to model 12 invasive plants species. We created three potential habitat suitability models for each species using maximum entropy modeling: (1) current; (2) 2020; and (3) 2035. Area under the curve values for [...] Read more.
We used near-term climate scenarios for the continental United States, to model 12 invasive plants species. We created three potential habitat suitability models for each species using maximum entropy modeling: (1) current; (2) 2020; and (3) 2035. Area under the curve values for the models ranged from 0.92 to 0.70, with 10 of the 12 being above 0.83 suggesting strong and predictable species-environment matching. Change in area between the current potential habitat and 2035 ranged from a potential habitat loss of about 217,000 km2, to a potential habitat gain of about 133,000 km2. Full article
(This article belongs to the Special Issue Diversity Theories and Perspectives)
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276 KiB  
Review
Ecological Processes and Contemporary Coral Reef Management
by Angela Dikou
Diversity 2010, 2(5), 717-737; https://doi.org/10.3390/d2050717 - 11 May 2010
Cited by 7 | Viewed by 10568
Abstract
Top-down controls of complex foodwebs maintain the balance among the critical groups of corals, algae, and herbivores, thus allowing the persistence of corals reefs as three-dimensional, biogenic structures with high biodiversity, heterogeneity, resistance, resilience and connectivity, and the delivery of essential goods and [...] Read more.
Top-down controls of complex foodwebs maintain the balance among the critical groups of corals, algae, and herbivores, thus allowing the persistence of corals reefs as three-dimensional, biogenic structures with high biodiversity, heterogeneity, resistance, resilience and connectivity, and the delivery of essential goods and services to societies. On contemporary reefs world-wide, however, top-down controls have been weakened due to reduction in herbivory levels (overfishing or disease outbreak) while bottom-up controls have increased due to water quality degradation (increase in sediment and nutrient load) and climate forcing (seawater warming and acidification) leading to algal-dominated alternate benthic states of coral reefs, which are indicative of a trajectory towards ecological extinction. Management to reverse common trajectories of degradation for coral reefs necessitates a shift from optimization in marine resource use and conservation towards building socio-economic resilience into coral reef systems while attending to the most manageable human impacts (fishing and water quality) and the global-scale causes (climate change). Full article
(This article belongs to the Special Issue Spatial and Temporal Benthic Diversity Patterns)
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183 KiB  
Article
Distinctiveness of Bean Landraces in Italy: the Case Study of the ‘Badda’ Bean
by Giulia Paniconi, Federica Gianfilippi, Pietro Mosconi and Andrea Mazzucato
Diversity 2010, 2(5), 701-716; https://doi.org/10.3390/d2050701 - 05 May 2010
Cited by 4 | Viewed by 7633
Abstract
In this study, we present the morphological and molecular characterization of the ‘Badda’ bean, a landrace of outstanding organoleptic qualities that is diffused in the area of Polizzi in the province of Palermo in Sicily, Italy. This landrace is entitled to [...] Read more.
In this study, we present the morphological and molecular characterization of the ‘Badda’ bean, a landrace of outstanding organoleptic qualities that is diffused in the area of Polizzi in the province of Palermo in Sicily, Italy. This landrace is entitled to be valorized in the local market and therefore needs a thorough description to draw criteria to establish its distinctiveness from landraces with morphological and geographical proximity. Three ‘Badda’ accessions, representing the morphological variability within the landrace, have been evaluated together with suitable references. With the help of morpho-physiological traits, digital scanning of apical leaflets and ISSR molecular markers, we describe a spectrum of descriptors useful to distinguish the ‘Badda’ accessions among themselves and from similar landraces. Full article
(This article belongs to the Special Issue Biological Diversity Assessed by Molecular Methods)
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