Genetic Diversity In Order Research Articles

Rooting screening in Eucalyptus dunnii clones: inverting the order in a clonal selection process

One of the main goals of a tree breeding program is to increase forest productivity, adaptation and profitability of forest plantations. Eucalyptus dunnii is a main species used for pulp production in Uruguay. Montes del Plata (MdP) is one of the largest forest companies in Uruguay and has been focused on the development, testing and deployment of E. dunnii clones to establish commercial plantations in Uruguay. MdP clonal strategy starts with the generation, testing and selection of families (Open-pollination and|or Control-pollination) with a breeding population with a wide genetic diversity in order to have a sustainable clonal program. Seeds from the best families are used for clonal development in a two-phase strategy that takes place in the company research nursery. On the first phase, all potential clones are screened for rooting and only the ones that root more than 60% go to the next phase. An average of 4,000 E. dunnii clones is evaluated every year, and 200 clones overpass 60% rooting threshold. This represents 5% of screened clones. The second phase is to produce plants in the nursey for the establishment of clonal trials in field, and, based on the performance, to select the candidate clones for deployment and breeding. Although the strategy and the breeding program are relatively young, promising results are seen. In the last 6 years, 1,225 E. dunnii clones developed by this rooting strategy were successfully established in clonal field trials. For species of Eucalyptus that have an undesirable trait of difficulty-to-root (recalcitrance), the screening of genotypes by rooting allows to establish in field testing clones with efficient clonal propagation. This way, the measurement and wood sampling in field trials is funnelled to clones that, if selected, could be scaled to clonal plantations.

Eucalyptus dunnii clonal strategy implementation in Montes del Plata

One of the main goals of a tree breeding program is to increase forest productivity, adaptation and profitability of forest plantations. Eucalyptus dunnii is a main species used for pulp production in Uruguay. Montes del Plata (MdP) is one of the largest forest companies in Uruguay and has been focused on the development, testing and deployment of E. dunnii clones to establish company plantations in Uruguay. On this presentation, the MdP ongoing clonal strategy for E. dunnii is presented. MdP clonal strategy starts with the generation, testing and selection of families in progeny tests (Open-pollination and Control-pollination) with a breeding population with a wide genetic diversity in order to have a sustainable clonal program. Seeds from the best families are used for clonal development in a two-phase strategy. In the first phase all potential clones are screened for rooting, in the company research nursery, and only the ones that root more than 60% go to the next phase, which is to produce plants for the establishment of clonal trials in field and, based on the performance, to select the candidate clones for deployment. On average, 4,000 clones|year are evaluated in the first phase, from which 200 go to clonal field trials every year. The strategy also includes a protocol for other traits assessment, like tree form, health and wood properties; the selection trait being tons of cellulose per tree (ADt). Wood properties are evaluated at early age using a company near infrared model (NIR). Then, values of predicted wood properties are projected to rotation age. This presentation will be complemented with extra information related to the different strategy phases in several posters. The MdP clonal strategy is a rolling front strategy, where clones from the best families are tested and selected for deployment and breeding to have continuous gain over time for E. dunnii.

EST-Microsatellite Types and Structural Scenarios in European Hake Fisheries.

Simple SummaryThe conservation of the maximum genetic background from all genomic regions matters for sustainability in the changing global scenario. This study focused the importance of integrating such genetic variation in order to infer meaningful units for management and sustainability. We show that knowledge that can be obtained from different marker types should be goal-oriented, i.e., remnant patterns of selection pressures and extreme drift episodes (directional markers, i.e., the evolutionary genetic background), current evolutionary novelty and adaptive potential for fisheries’ sustainability (balanced markers, i.e., the potential genetic drive of the species), and demographic dynamics of genetic relevance for fisheries’ management (neutral markers, i.e., the present-day fishery structure and connectivity). In particular, special attention should be paid to the variation in supergenes or balancing markers, which are a rich source of evolutionary novelty and can be crucial for species welfare and survival.A fishery’s structure and connectivity are priors to its effective management. A successful description of such processes depends on both the sampling design and the choice of adequate genetic markers. EST markers are perfusing the studies of marine metapopulations and are believed to provide access to functional polymorphisms. However, the assumed adaptive role of outlier EST loci might not be generalizable. EST-microsatellites represent the upper polymorphic boundary in these regions because of their high mutation rate. We have subclassified the polymorphisms of EST-microsatellites to assess their structural contribution in the European hake, a paradigmatic and highly mobile marine species (HMMS). Because of the counterbalanced forces between directional markers (15%) and balanced markers (23%), the whole marker set offers the same structural situation as the one observed with neutral markers (62%), i.e., k = 2 gene pools. In contrast to outlier EST- microsatellites, neutral EST subsets allow one to measure crucial population phenomena for fisheries’ management. The high inter-population divergence of outlier EST-microsatellites is compatible with drifted post-selection genomic regions rather than with ongoing local selective pressures. The structural scenario in hake is explainable by a limited gene flow across the Almería-Oran Front (AOF) and by the within-basin IBD pattern of connectivity plus drift-related demographic events. This study highlights how polymorphic properties of EST-microsatellite types can be useful to address mutually excluding research tasks in fisheries, i.e., to address its evolutionary history (directional markers or FAPS: Fossil Adaptive Polymorphic Systems); to delineate management units (neutral markers or NAPS: Non Adaptive Polymorphic Systems); or to ensure sustainability (balanced markers or APS: Adaptive Polymorphic Systems).

Genetic characterisation of centuries-old oak and linden trees using SSR markers

Abstract The main goal of this study was to identify the unique gene pool of old and historically valuable Quercus robur L. and Tilia cordata L. to be able to characterise their genetic diversity in order to determine the polymorphism by expressed sequence tag-single sequence repeat (EST-SSR) markers and identify the most valuable specimens. Morphological description, molecular genetic analysis, and statistical analysis were used in studies. The genetic distances between old-value trees of different Quercus L. and Tilia L. were determined based on EST-SSR markers and morphological characteristics. Using polymerase chain reaction (PCR), alleles of the expected size were obtained. It was determined that four to eight alleles were obtained by seven SSR markers in the studied Q. robur L. samples. According to the calculated value of the locus polymorphism index (polymorphism information content [PIC]), the most polymorphic was the marker SSRQrZAG 65; the PIC was 0.84. The lowest value of PIC was observed in the marker SSRQrZAG 11; the PIC was 0.69. Intragenetic polymorphism was detected for all studied markers. Among the studied samples of linden, two to five alleles were identified. It was found that the highest value of PIC was obtained for the marker Ts920 – 0.72. The least polymorphic was the marker Ts927 (PIC was 0.28), which is not only due to the small number of alleles, but also their uneven distribution in the sample. Intragenetic polymorphism was detected in four of the six markers analysed for T. cordata L. In this study, polymorphism was detected in all studied samples of Q. robur L. and T. cordata L., which allows to assess their genetic diversity based on the distribution of alleles.

Contribution to a reference library of DNA barcodes of Colombian freshwater fishes.

BackgroundThe Barcode of Life initiative was originally motivated by the large number of species, taxonomic difficulties and the limited number of expert taxonomists. Colombia has 1,610 freshwater fish species and comprises the second largest diversity of this group in the world. As genetic information continues to be limited, we constructed a reference collection of DNA sequences of Colombian freshwater fishes deposited in the Ichthyology Collection of the University of Antioquia (CIUA), thus joining the multiple efforts that have been made in the country to contribute to the knowledge of genetic diversity in order to strengthen the inventories of biological collections and facilitate the solution of taxonomic issues in the future.New informationThis study contributes to the knowledge on the DNA barcodes and occurrence records of 96 species of Colombian freshwater fishes. Fifty-seven of the species represented in this dataset were already available in the Barcode Of Life Data System (BOLD System), while 39 correspond to new species to the BOLD System. Forty-nine specimens were collected in the Atrato River Basin and 708 in the Magdalena-Cauca asin during the period 2010-2020. Two species (Loricariichthysbrunneus (Hancock, 1828) and Poeciliasphenops Valenciennes, 1846) are considered exotic to the Atrato, Cauca and Magdalena Basins and four species (Oncorhynchusmykiss (Walbaum, 1792), Oreochromisniloticus (Linnaeus, 1758), Parachromisfriedrichsthalii (Heckel, 1840) and Xiphophorushelleri Heckel, 1848) are exotic to the Colombian hydrogeographic regions. All specimens are deposited in CIUA and have their DNA barcodes made publicly available in the BOLD online database. The geographical distribution dataset can be freely accessed through the Global Biodiversity Information Facility (GBIF).

High Genetic Diversity of Shorea acuminata Dyer in the Rehabilitated Area of a Degraded Lowland Dipterocarp Tropical Rainforest

The United Nation’s Decade on Ecosystem Restoration 2021–2030 aims to halt ecosystem degradation to achieve Sustainable Development Goals (SDGs) by 2030. In Malaysia, the concept of sustainable forest management (SFM) has been practiced since 1901. In this study, we evaluated the genetic diversity of the native dipterocarp timber tree Shorea acuminata in a rehabilitated area at Kenaboi Forest Reserve (Kenaboi FR). The rehabilitated area was formerly a degraded forest managed with the taungya restoration system for 50 years. All trees with diameter at breast height (DBH) of 5 cm and over were measured, tagged and identified in a one-hectare study plot. A total of 132 inner bark samples were collected for DNA extraction. Four SSR markers (Sle280, Sle392, Sle475 and Sle566) and two EST-SSR markers (SleE07 and SleE16) were used to analyse 95 good-quality DNA samples. Genetic diversity parameters including maternal contribution were determined for 75 samples. The genetic diversity of big trees (He = 0.656 ± 0.19) and small trees (He = 0.652 ± 0.17) were high and both were in genetic equilibrium, with Fis values of the big trees being 0.035 and small trees being 0.164. Clustering analysis based on Jaccard’s similarity values (at 95% confidence level) confirmed that big trees in the Kenaboi FR rehabilitated area had originated from genetically diverse seed trees of the Sungai Menyala Forest Reserve which were used as the planting stock for the taungya restoration system. Maternal contribution showed that the allele contribution of the small trees came from the planted S. acuminata trees within the study area. The high genetic diversity of small trees in this study provides strong evidence that the existing big trees would be suitable for a genetically diverse seed collection to rehabilitate other degraded forests. Sustainable forest management must emphasise genetic diversity in order to ensure the resilience of rehabilitated forest ecosystems.

Stressful social environment and financial strain drive depressive symptoms, and reveal the effects of a FKBP5 variant and male sex, in African Americans living in Tallahassee.

The World Health Organization estimates that almost 300 million people suffer from depression worldwide. African Americans are understudied for depression-related phenotypes despite widespread racial disparities. In our study of African Americans, we integrated information on psychosocial stressors with genetic variation in order to better understand how these factors associated with depressive symptoms. Our research strategy combined information on financial strain and social networks with genetic data to investigate variation in symptoms of depression (CES-D scores). We collected self-report data on depressive symptoms, financial strain (difficulty paying bills) and personal social networks (a model of an individual's social environment), and we genotyped genetic variants in five genes previously implicated in depressive disorders (HTR1a, BDNF, GNB3, SLC6A4, and FKBP5) in 128 African Americans residing in Tallahassee, Florida. We tested for direct and gene-environment interactive effects of the psychosocial stressors and genetic variants on depressive symptoms. Significant associations were identified between high CES-D scores and a stressful social environment (i.e., a high percentage of people in participants' social network who were a source of stress) and high financial strain. Only one genetic variant (rs1360780 in FKBP5) was significantly associated with CES-D scores and only when psychosocial stressors were included in the model; the T allele had an additive effect on depressive symptoms. Sex was also significantly associated with CES-D score in the model with psychosocial stressors and genetic variants; males had higher CES-D scores. No significant interactive effects were detected. A stressful social environment and material disadvantage increase depressive symptoms in the study population. Additional associations with FKBP5 and male sex were revealed in models that included both psychosocial and genetic data. Our results suggest that incorporating psychosocial stressors may empower future genetic association studies and help clarify the biological consequences of social and financial stress.

Protein patterns and their association with photosynthetic pigment content, agronomic behavior, and origin of purslane accessions (Portulaca oleracea L.).

In this study, the proteomic, morphometric, and photosynthetic pigment data of purslane (Portulaca oleracea) accessions were combined together to show their impact on genetic variation in order to establish a relationship between protein patterns and phenotypic behavior of the plant. Seeds of 18 collected purslane accessions were cultivated based on a completely randomized design with three replicates. Before the flowering stage, the data on morphology, photosynthetic pigment content, and seed proteins were obtained. The results showed a significant difference among purslane accessions in terms of the most studied agronomic characteristics and the content of photosynthetic pigments and proteins. The cluster analysis of the 18 purslane accessions based on agronomic data, and photosynthetic pigment content, and protein pattern data produced three main clusters. Moreover, the seed protein analysis revealed that the two polymorphic protein bands of size 40 kDa (protein "a") and 30 kDa (protein "b") effectively diversified the agronomic, photosynthetic pigment, and phylogenetic relationships among the purslane accessions. Interestingly, protein "a" was produced in plants growing in low altitude areas and played a suppressive role for TDW, while protein "b" was produced in plants growing in high altitude areas and functioned as an activator agent for this trait. Overall, the outcomes of the present study indicated the presence of high genetic variability (77.6%) among the purslane accessions. These findings suggest that these proteins should be sequenced for further proteomic analyses and can be used for hybridization to generate useful recombinants in segregating generations and improve breeding varieties of P. oleracea.

Forests of Greece, Their Multiple Functions and Uses, Sustainable Management and Biodiversity Conservation in the Face of Climate Change

This is a review paper based on national and international literature, national inventories and empirical approach. A general overview of the forests, forest management and forest biodiversity of Greece are briefly summarized. The distribution of the main forest species and their ecosystems in the Geographic regions of Greece is presented in a tabular form. Their multiple functions and uses, their management type/regime, their risks and threats, protection and conservation measures are also synoptically described. Furthermore, adaptive forest management and silviculture as well as management of genetic diversity in order to face climate change are also analysed. Research priority areas on biodiversity and challenges for biodiversity research and related policy in Greece have been summarized. The new Rural Development Program (2014-2020), which is currently in the final phase of implementation, will take into consideration the forest itself and forest-related European and National legal obligations. Finally, major conclusions and research priority areas on future management and conservation of forests are highlighted.

The Effect of Gamma Co 60 Radiation on Soybean (Glycine max(L.) Merr) Shade Tolerants

Soybean is one of important national commodities for food and industry. Gamma rays are electromagnetic waves that have very strong penetrating power. One of the sources of gamma rays is from 60Co. With its strong penetration power, gamma rays can be used in plant breeding to create new genetic diversity in order to develop high-yielding varieties. Irradiation of gamma rays at 300 Gy dose on Denna 2 variety soybean was conducted, then it was planted as M1 plant and later continued to be planted as M2. In M2 generation, mutant lines was selected based on early maturity, better than of the parent variety.The criteria used was harvest age between 75-81 days, the plants should look robust and strong stems. Harvesting days of parent varieties (Denna 2) was 81 days, while the mutant strains obtained were between 75-81 days. Likewise, for the plant height, the parent variety was 42.30 cm, whereas mutant lines of 38,56 cm in average, making it more resistant to logging. The average pods for parent was 36.37 pods and mutant lines of 55.24 pods. In selected shade tolerant soybean of the M3 generation early aged mutan lines shade tolerant days, of the parent variety Denna 2 days.

Genetic diversity in Japanese populations of the Eurasian Collared Dove

BackgroundEurasian Collared Dove (Streptopelia decaocto) is a species distributed in the Eurasian continent and North Africa, and inhabiting mainly in Saitama Prefecture in Japan. Eurasian Collared Dove is one of the most prosperous invaders in the world, and Japanese Eurasian Collared Dove has also been introduced from overseas. The Japanese population has declined to one-hundredth over 30 years and is being protected. In this study, we analyzed its genetic diversity in order to understand the genetic differences between wild populations of Eurasian Collared Dove and those bred in zoos.MethodsA sequence of about 1.9 kb mtDNA was determined for 20 wild Eurasian Collared Doves living in Saitama, Japan and 20 zoo-bred Eurasian Collared Doves, and population genetic analysis was performed.ResultsIn the COI gene, 778 bp had the same sequence in all the 40 individuals examined, and no mutation sites could be confirmed. In the control region, two base substitution sites were confirmed in 1140 bp long sequence. Three haplotypes were detected in 20 individuals in wild, whereas all 20 zoo-bred individuals possessed the same haplotypes possessed in the wild population.ConclusionHaplotypes of zoo-bred individuals were also retained among the wild individuals, confirming that no genetic problems could occur if the zoo-bred individuals were released to the wild for the Japanese Eurasian Collared Dove propagation program.

Salt Tolerance Associated With Molecular Markers in Alfalfa

Background: Breeding for salinity tolerance in open-pollinated crops depends on broad genetic variation in order to select for vigorous plants under salinity stress. Objective: To compare the yield of some local alfalfa cultivars under saline and non-saline soils and to develop molecular genetic markers associated with salt tolerance using RAPD and ISSR analysis, thereby providing a basis for alfalfa salt-tolerance breeding and research. Methods: A two years field trial was carried out during 2013/14 and 2014/15 in Galbana Village at Sahl El-Tina site., North Sinai Governorate with 13 cuts after establishing period. Three local parental cultivars, nine selected populations for salt stress under different stress levels (three initial EC’s: 8.73, 10.63 and 12.43 dSm-1), a new tolerant pop, and three exotic varieties were included in the experiment under initial EC’s (10.83). Results: Under Egyptian conditions, local cultivars: Siwa and Ismaelia were qualified as more adapted to salinity stress conditions than the exotic cultivars. New tolerant pop. ranked as the top yielding across all tested parental populations followed by Siwa and Ismaelia tolerant selected populations. New valley population had the lowest fresh, dry and protein yield overall studied populations. The tolerant selected populations were out yielded than their parental cultivars. A total of 16 alfalfa populations were analyzed at the molecular level to develop molecular markers associated with salt tolerance using seven RAPD and five ISSR primers. All primers succeeded to generate reproducible polymorphic DNA products. RAPD primers produced eight positive specific markers and six negative specific markers for salt tolerance in alfalfa population Sinai-1, while ISSR primers produced 12 positive specific markers and six negative specific markers for salt tolerance in alfalfa. The dendrograms were generated using pooled RAPD, ISSR, and the combined analysis of their data divided the alfalfa populations into two main clusters. The first cluster consisted of population Sinai 1 alone, while the second one contains all other evaluated populations. Conclusion: The new tolerant pop. could be considered as a new promising population and more adapted to salt stress.

The impact of genetic diversity on the accuracy of DNA barcoding to identify species: A study on the genus Phellodendron.

DNA barcoding is widely used in species identification, but there is considerable controversy regarding the extent of sampling in research methods. Some scholars have proposed that this small sample size underestimates the intraspecific genetic diversity, which would impact on the accuracy of DNA barcoding to identify species. In study, we selected all Phellodendron species (including P. amurense Rupr., P. chinense Schneid., and P. chinense var. glabriusculum Schneid.) as the materials, collected 59 P. amurense samples from 35 populations greatly to represent the genetic diversity, and analyzed the haplotype, genetic distance, barcoding gap, and Neighbor‐Joining (NJ) trees based on psbA‐trnH and internal transcribed spacer gene sequences. Additionally, a sampling simulation was conducted to assess the correlation between genetic diversity and the number of populations. Finally, analysis of critical geographical populations was performed. Based on analysis of haplotype, genetic distance, barcoding gap, and NJ trees, we found that eight P. amurense samples impacted on the effectiveness of DNA barcoding, which genetic information were very important to identify Phellodendron species. Moreover, the result of the NJ tree analysis performed the small‐scale P. amurense sample size did not completely match the objective phylogenetic relationship in Phellodendron. In simulation sampling analysis, the data showed the genetic diversity indexes at the same population level gradually decreased and stabilized as the number of simulation sampling populations increased. We found that 1–2 samples from over 24 populations based on uniform geographical distribution could represent 80% of the genetic diversity of P. amurense and ensure authenticity and reliability of DNA barcoding. Thus, we proposed it is particularly important adequately samples to cover infraspecific genetic diversity in order to ensure identification accuracy of DNA barcoding.

Evaluation of the genetic variability of faba bean (Vicia faba L.) genotypes using agronomic traits and molecular markers

BackgroundBreeding programs need to work with magnitudes of genetic variation in order to achieve the best results. In this study, we have estimated the genetic diversity and evaluated the field performance of 18 faba bean genotypes from different origins, during the 2014–2015 and 2015–2016 growing seasons.ResultsThe field evaluations revealed that the faba bean genotypes showed enough variation for their agronomic thoughtful parameters. ALB was noted as being the genotype that was the tallest (126.25 cm), but the superlative genotypes were L251 and L252 for a high number of seeds per plant (72.25) and the maximum seed yield per plant (56.40 g). The estimations of the genetic diversity between all of the faba bean genotypes were done using eight sequence-related amplified polymorphism (SRAP)-combined primers. The number of different alleles amplified for each polymorphic marker, ranged from 2 to 9, was observed by SRAP genotyping, with polymorphic information contents (PIC) between 0.445and 0.896, and discrimination power (DP) with an average of 0.125 per allele.ConclusionsAcross both years, the best grain yields were gathered from the L25, L252, and L182 genotypes, in descending order, whereas the ALB genotype had the lowest grain yield in comparison with the other genotypes. The cluster analysis of faba bean genotypes was generally based on not only the origin but also the genetic background.

MORPHOMETRIC ANALYSIS OF FRUITS AND SEEDS OF Annona crassiflora Mart. (ANNONACEAE) FROM CENTRAL BRAZIL

ABSTRACT With the existing reduction of the vegetation cover of the Cerrado, several tree species have their areas of occurrence diminished, and as a consequence, they lose part of their genetic diversity. To counter this scenario it is necessary to know the genetic diversity in order to base projects and practical conservation measures. Thus, the objective of this work was to investigate the genetic variability of Annona crassiflora by means of morphometric data of fruits and seeds in four populations in central Brazil. In total, 152 fruits were obtained from 73 matrices, of which the height, diameter, fruit mass, mass of 100 seeds and number of seeds per fruit were measured. The fruits were stripped and the seed removed to measure their height, width and thickness. The hierarchical cluster study showed the grouping of 11 small groups and two large groups, and in these two large groups there are representatives of the four populations sampled. This shows that there is no specific division of populations, indicating high genetic variability. The fruits of the Buritis population were, as a rule, significantly larger than those of other populations, which may indicate genetic distancing or different environmental conditions of pollination and dispersion. This pattern was not observed in the seed size analysis, although there was a statistical difference between the populations. In general, the largest dimensions were found in the populations of Planaltina and Buritis. Therefore, the analyzes indicate high genetic diversity and fruits/seeds with larger dimensions in the best-preserved state.

Diversity and spatial genetic structure of natural Moroccan Quercus susber L. assessed by ISSR markers for conservation.

Morocco is one of the most important regions of the world in terms of Quercus suber L. number and variation. This species is in decline due to several factors, which can lead to permanent loss of this resource. It would be essential to evaluate the genetic diversity in order to conserve maximum genetic variability of this species. The genetic diversity and differentiation of 16 sites from five regions representing the entire range of Moroccan Cork Oak were assessed. Twenty-three ISSR primers used generated 985 polymorphic fragments with an average of 42.8 bands per primer and showed 100% of polymorphism. The 173 individuals revealed a moderate level of genetic diversity at species level (I = 0.27, He = 0.161). The AMOVA showed that the highest level of diversity occurred within populations (64%), this was also confirmed by the coefficient of differentiation (Gst = 0.47). The estimated gene flow (Nm = 0.56) and the Mantel test revealed a significant correlation between geographic and genetic diversity (r = 0.266; p = 0.001). This genetic structure was further shown by the topology of the UPGMA, sPCA and STRUCTURE analysis. In addition, a core collection of 34 genotypes was established representing the essential diversity detected. This research advocates populations and individuals to preserve in order to improve and conserve this resource in the future.

RAPD ANALYSIS OF GENETIC VARIATION IN NATURAL POPULATIONS OF AEGILOPS SP. FROM SOUTH ADRIATIC

New challenges that food production is facing, requires novel approach inagricultural strategy. The scissors of growing demand for food and the limits of theEarth's resources are forcing plant breeders to run for the new borders, utilizing allthe available genetic variation in order to create fruitful and economically soundcultivars. Aegilops sp. (Poaceae) is a potential source of genetic variation for wheatimprovement. RAPD marker analysis was used in order to distinguish and evaluatedifferent genotypes of Aegilops sp. population samples from the collectiongathered during few years’ expeditions in South Adriatic, along the coastal, littoraland the inland parts of Montenegro. Ten randomly amplified polymorphic DNAmarkers (RAPDs) were tested: OPA-05, OPA-08, OPB-06, OPA-02, OPA-07,OPA-25, OPB-07, OPB-18, OPC-06, OPC-10 to examine genetic structuring on 18samples of 6 populations of different Aegilops sp. According to global AMOVA,75% of total gene diversity was attributable mostly to diversity within population(ΦPT =0.205 p=0.001), indicating that the groups of studied goat grass populationswere seemingly to differing genetically. In contrast, 25% of the variation camefrom variation among populations. According to PCoA, the distribution of 18 goatgrass accessions by Principal Coordinate Analysis shows 3 distinct groups. PCoaxis 1, PCo axis 2, and PCo axis 3 account for 20.8%, 18.2% and 14.1% of thevariation, respectively. The results showed that RAPD markers could be aconvenient tool for investigating genetic variation and for detecting geneticstructuring of populations. Genetic variability formed under natural selection wasentrenched.

Molecular Diversity in Selected Banana Clones (<i>Musa AAA</i> “Cavendish”) Adapted to the Subtropical Environment of Formosa Province (Argentina)

Banana production dates from the 1920s in Argentina. Rhizomes were introduced and dispersed by immigrants from bordering countries in the Northern provinces. There is scarce information on its genetic diversity to assist in crop breeding programs; hence studies of genetic structure between populations and individuals are fundamental for future use. Molecular markers assess the diversity of the crop. This study employed Amplified Fragment Length Polymorphism to investigate the genetic variation in local banana plants from farmer’s fields. Forty-four rhizomes (selected from a total of 860 plants for being stable for production) were used as plant material and 6 primer combinations selected in a previous report were used. Polymorphic fragments present in a given genotype were assigned 1 and those absent were assigned 0. The matrix generated was analyzed by univariate and multivariate analysis. A total 540 bands were scored, of which 100% were polymorphic. The number of the pattern duplicated bands was 23 and twenty-one amplicons were exclusive to banana plants collected in the same farmer’s field. Hierarchical clustering and principal coordinates analyses showed differences between genotypes. The cophenetic correlation of the cluster was 0.63 while the 18% of the total molecular variation was explained by the two principal coordinates. These analyses evidence genetic diversity of the crop according to farmer’s field. In agreement to this observation, analysis of molecular variance revealed that 8.9% of the variation was found among farmer populations and 91.1% within farmer populations. In conclusion, introduction of banana into the subtropical zone was associated with a broader genetic variation in order to increase the genetic homeostasis necessary for adapting the crop to the suboptimal environment of Northeastern Argentinean Formosa Province.

DISCOVERING GENETIC MODIFIERS OF ALZHEIMER’S DISEASE USING NOVEL MOUSE MODELS

Recent studies of familial AD cases suggest genetic factors can delay the onset and progression of cognitive deficits by decades. Therefore, these genetic factors may provide key targets for treatment and prevention of AD. However, significant barriers restrict our ability to discover the genetic mechanisms of resilience using conventional approaches. Resilient individuals are often asymptomatic and thus escape the attention of medical geneticists. Animal models of AD provide a powerful resource for longitudinal and in-depth analyses, but traditionally are only studied on one genetic background. These limitations create a critical need for innovative approaches that take advantage of ‘high-risk’ FAD mutations in animal models in combination with genetic diversity in order to identify resilient genetic backgrounds that can be used to gain a better understanding of molecular mechanisms underlying resilience. To discover genetic modifiers of FAD, we generated a novel mouse panel of genetically diverse mice carrying FAD mutations in APP and PS1. Mice were phenotyped across the lifespan using construct valid cognitive and neuropathological assays, and genetic interval mapping was used to identify loci associated with resilience to cognitive decline and Aβ pathology. We observed wide variation in the age at onset and severity of AD symptoms in our FAD mouse population, which parallels variation observed in humans with high-risk FAD mutations. Results from our genetic interval mapping identified multiple genomic regions associated with resilience or susceptibility to AD, including the APOE locus and two novel quantitative trait loci. As our goal is to discover novel genes and molecular networks that govern human AD resilience, genes and molecular networks underlying resilience to AD in our mouse studies will be integrated with existing human genetic data to prioritize candidates with high translational relevance. High-priority genes associated with resilience to AD in human cohorts will be targeted via genome-editing in relevant mouse models for functional validation. Since clinical and pathological hallmarks of FAD parallel those of sporadic late-onset AD cases, we expect modifiers discovered in our mouse studies will broadly generalize to all forms of AD.

Genome size comparison in Colobanthus quitensis populations show differences in species ploidy

Colobanthus quitensis is the only native dicotyledoneae in the Antarctic; therefore, it is the object of ample research regarding tolerance mechanisms to its extreme habitat. This species also represents a wide geographical distribution, from 68°S to 17°N and from 0 m a.s.l. in the south to 4200 m a.s.l. in the north of its distribution area. As the described habitats for different populations coincide in their extreme abiotic characteristics, there has been increasing interest in studying different populations in recent years, as well as the existence of phenotypic or genetic variability among them. In contrast, very little is known about its genome; knowledge of genome size and ploidy levels allows the development of strategies to generate information in population studies related to structure, gene flow and genetic diversity in order to describe phenotypic characteristics. Several studies have related genome size to the ecological requirements of the species distributed through an ample environmental gradient. For several years now, flow cytometry has become a simple method to determine genome size in a wide variety of species. In this paper, we determine genome size for three C. quitensis populations. The populations of Arctowski and La Marisma (Punta Arenas) have 2C = 1.95 pg, while the Conguillio population reported 2C = 0.84 pg, approximately half as much. This may evidence different ploidy levels between the populations, creating new questions with regard to the number of chromosomes and the possible existence of endopoliploidy. This would be related to the distribution and the adaptive mechanisms of this species throughout its wide distribution.