Genetic Diversity Parameters Research Articles

Genetic and mating system assessment of translocation success of the long‐lived perennial shrub Lambertia orbifolia (Proteaceae)

There is an increasing need to establish populations of threatened plants in threat‐free habitat to prevent species extinction. The amount of genetic diversity in founding plants will influence whether the new population has the capacity to persist and evolve over time, and factors that influence the maintenance of genetic diversity, such as the mating systems, will also play a role in population persistence. We developed 13 nuclear microsatellite markers and used these to evaluate genetic diversity and mating system parameters of three translocated populations of two subspecies of Lambertia orbifolia, and compared these parameters to seven wild populations. Genetic diversity was maintained in the translocated population of L. orbifolia subsp. Scott River Plains, established using a single source population (Nar = 3.270 and He = 0.478 in translocated population; Nar = 3.280 and He = 0.534 in wild populations), and maintained or increased in the two admixed translocated populations of L. orbifolia subsp. orbifolia (Nar = 3.115, 3.830 and He = 0.511, 0.635 in translocated populations; Nar = 2.708 and He = 0.438 in wild populations) compared to wild populations of each subspecies. Mating system parameters were comparable between translocated and wild populations of L. orbifolia subsp. Scott River Plains indicating the likelihood of genetic diversity being maintained in future generations. However, there was increased selfing in translocated populations of L. orbifolia subsp. orbifolia, suggesting suboptimal pollination and high values for the inbreeding coefficient in these admixed populations (Fis = 0.474, 0.275), which may be an artifact of the Wahlund effect or from less fit (inbred) seedlings surviving ex situ propagation and translocation.

Genetic variability in mamey (Pouteria Sapota (Jaq.) H.E. Moore & Stearn) based on molecular markers and fruit morphology

The mamey (Pouteria sapota (Jacq.) H.E. Moore & Stearn) has been an important food source in Mexico and Central America from where it originates, as well as in other tropical areas of the world where it has been introduced. Despite the importance of this phytogenetic resource and the variability that has been previously reported, parameters of genetic variability and diversity have not been established that allow for sustainable development and commercial exploitation plans to be carried out. The objective of this work was to determine the genetic variability in a population of mamey from the state of Colima, based on molecular markers and characteristics of the fruit. A sample of plants from the state of Yucatán was used as reference germplasm with the origin. It was found that there is a high level of intrapopulation genetic variability and a considerable degree of differentiation in terms of allelic frequencies between the samples from Colima and Yucatán, the ISTR and ISSR markers proved to be useful in the segregation of the samples based on their origin.

Genetic Diversity and Population Genetic Structure of Ancient Platycladus orientalis L. (Cupressaceae) in the Middle Reaches of the Yellow River by Chloroplast Microsatellite Markers

Ancient trees are famous for their life spans of hundreds or even thousands of years. These trees are rare, a testament to history and are important for scientific research. Platycladus orientalis, with the longest life span and a beautiful trunk, has become the most widely planted tree species and is believed to be sacred in China. Extensive declines in habitat area and quality pose the greatest threats to the loss of genetic diversity of ancient P. orientalis trees in the middle reaches of the Yellow River. Strengthening the protection of P. orientalis genetic resources is of great significance for the long-term development of reasonable conservation and breeding strategies. To better understand the genetic diversity and population structure of P. orientalis, we successfully analyzed four polymorphic chloroplast simple sequence repeat (cpSSR) loci and applied them to diversity and population structure analyses of 202 individuals from 13 populations in the middle reaches of the Yellow River. Based on the cpSSR data, 16 alleles were detected across 202 individuals, and a moderate level of genetic diversity was inferred from the genetic diversity parameters (H = 0.367 and AR = 1.964). The mean pairwise genetic differentiation coefficient (Fst) between populations was 0.153, indicating relatively high genetic population differentiations. Analysis of molecular variance (AMOVA) showed that only 8% of the variation occurred among populations. Structure analysis divided the 13 P. orientalis populations into two groups with no significant geographic population structure, which was consistent with the unweighted pair group method with arithmetic mean (UPGMA) and Mantel test results. These results may indicate that transplanting and cultivation by ancient human activities are the main factors responsible for the revealed pattern of genetic differentiation of ancient P. orientalis populations. Our research is of great significance for the future establishment of protection schemes and scientific breeding of P. orientalis.

Genetic variability and relationship among different accessions of Froriepia subpinata Bail (Gijavash) an endangered medicinal plant from Iran revealed by ISSR and IRAP markers

The genetic variability of Froriepia subpinata Ledeb. Bail., an endangered Iranian endemic species, has been estimated with a total of 52 accessions using 20 markers including ISSR and IRAP. The results showed the polymorphic band produced by primers was 82.3%. The best mean values of genetic diversity parameters observed in ISSRs markers, being UBC873, UBC811, and UBC873 the best primers tested. The similarity range among accessions was 34.45% to 93.3%. The cluster analysis classified the accessions into five main groups that in totally, accessions with similarity in region generally were clustered in the same group. Overall, present study could provide elementary information for formulation of conservation strategies and invaluable elementary genetic information for next breeding or designing conservation programs.

Genetic Diversity of Campomanesia adamantium and Its Correlation with Land Use and Land Cover

(1) Background: Campomanesia adamantium is an endemic species of the Cerrado and this biome has been under threat by its constant degradation. The genetic diversity of C. adamantium was characterized using species-specific microsatellites in two different time periods and correlations of these parameters of genetic diversity with the land use and land cover data. (2) Methods: We used 10 microsatellite loci to analyze C. adamantium from five populations, collected in 2011 and 2017. Maps of land use and land cover of the collection sites in both years were generated and subsequently correlated with genetic diversity. (3) Results: No significant loss of genetic diversity was observed in the analyzed period and a positive inbreeding coefficient was observed in all populations. AMOVA and STRUCTURE showed that there is no population structure between years and populations. Significant Pearson correlations were observed in 2017 between parameters of genetic diversity and land use and land cover, with a positive correlation between expected heterozygosity and secondary vegetation, and a negative correlation between inbreeding coefficient and exposed soil. (4) Conclusions: There was no decline in genetic diversity from 2011 to 2017. The high rates of the inbreeding coefficient could lead, for the species, in the long run, to an inbreeding depression as the Cerrado fragmentation might cause a population bottleneck.

Monitoring genetic diversity acrossPinus tabuliformisseed orchard generations using SSR markers

The maintenance of genetic diversity across seed orchard generations is an important management objective. Here, we used Pinus tabuliformis Carrière as a model to explore the extent of genetic diversity across the species’ breeding activities through their corresponding seed orchard generations. We utilized a large number of simple sequence repeat (SSR) markers selected from P. tabuliformis transcriptomic data, and then assessed the effect of marker number on genetic diversity and genetic relationships of individuals across orchard generations. In total, we designed 125 SSR markers, of which 39 were polymorphic and used in the present study. The genetic diversity and genetic distance parameters tended to increase with an increase in loci number and a stable trend was reached at 24 SSRs. The selected optimal 24 SSR markers were further used to assess the genetic diversity across seed orchard generations, and a decreasing trend was detected with the advancement of orchard’s generations. Genetic distance analysis indicated that individuals in the 2nd generation orchard were more closely related compared with those of the 1st generation and the 1.5 generation. This study provided valuable information on the effect of selection and breeding on genetic diversity and highlighted its role for effective seed orchard management.

Population Genetic Structure of Ural Black Pied Cattle

The variability of 15 microsatellite loci was analyzed in 15 786 cattle individuals of Black Pied, Holstein, and Tagil breeds bred in the Urals. It was demonstrated that modern population of Holstein Black Pied cattle contained in pedigree farm of Sverdlovsk, Kurgan, Tyumen, and Chelyabinsk oblasts, Perm krai, and the Republic of Udmurtia represents a single population. Genetic differentiation of calves born in Sverdlovsk oblast in the period 2008–2019 and Holstein bulls contained in AO Uralplemtsentr does not differ statistically significantly from zero, which makes it possible to assert that the modern cattle population of the region belongs to the Holstein breed. A statistically significant decrease in the parameters of genetic diversity of the dairy cattle population from Sverdlovsk oblast in the period 2010–2019 was demonstrated, which indicates an increase in inbreeding in the population.

Genetic characterization and parentage assignment of Egyptian Arabian horses based on two microsatellite panels

The present study aimed to investigate the powerfulness of the two microsatellite panels (ISAG against TKY) for genetic characterization and parentage assignment of closely related Arabian horse families. A total of 41 Egyptian Arabian horse samples representing eight sire families were analyzed by two panels (12 markers of ISAG against 12 markers of TKY). The basic measurements of genetic diversity and parentage were estimated. The TKY panel showed higher genetic diversity parameters (Na = 6.250; Ne = 3.33; HO = 0.655; HE = 0.691; PIC = 0.6335) than ISAG Panel (Na = 5.000; Ne = 2.994; HO = 0.646; HE = 0.657; PIC = 0.601). The parentage assignment of the eight sire families by using the two panels was successfully indicated by their higher power of exclusion 0.99999 and 0.99998, for TKY and ISAG panels, respectively. TKY panel will continue to be an additional and confirmatory panel in single system exclusion within the ISAG panel. Cervus software provided an accurate and rapid method in the assignment of Arabian horse parentage.

Genetic diversity of Eragrostis tef accessions collected from acid soil-affected areas and cross-amplification of SSR markers linked to Al-toxicity tolerance in cereals

ABSTRACT The aim of this study was to assess the extent of genetic diversity among and within tef populations collected from acid-affected soils in Ethiopia, and to test the cross-amplification of markers linked to Al-toxicity tolerance in other cereals. Forty-two tef genotypes were studied using 33 highly polymorphic SSRs. About 55% of the amplified putative alleles were effective in discriminating the genotypes. The mean PIC value was 0.66, suggesting that the majority of the markers had high discriminatory power. The population structure analysis revealed the presence of two genetically distinct populations and clearly distinguished landraces from the rest. A significant difference in genetic diversity parameters was observed between the two inferred populations. The landraces consistently had higher values for all of the diversity parameters and had contrastingly a higher value of private alleles. The AMOVA showed highly significant (P = 0.001) genetic variation among tef populations and among genotypes, with variance contribution of 17% and 67%, respectively. Eighty-two percent of the Al-toxicity tolerance markers amplified 84 alleles. This finding suggests the possibility of in-situ preservation of rare alleles that may confer acid tolerance through the improvement of available landraces in acid affected soils. Thus, urgent efforts are needed to collect accessions from areas with acid-affected soils.

Development of novel microsatellite marker panel in threatened tetraploid mahseer, Tor tor (Hamilton 1822) for insights into its genetic diversity and population structure

BackgroundTor tor (Hamilton 1922), a natural polyploid fish species, is commonly known as the red-fin or deep bodied mahseer and is the type species of the Tor genus. It was assessed as ‘Near Threatened’ in the IUCN Red List, due to rapidly declining populations in wild and recently reassessed as Data Deficient. To generate the genetic structure information in this species, co-dominant markers face polyploidy specific hitches in genotyping, such as auto/tetrasomy, double reduction and missing dosage information. ObjectiveIn the present study, a total of 25 polymorphic microsatellite loci was developed through long- read single molecule, real time (SMRT) sequencing technology, to genotype 139 T. tor samples from six natural riverine populations of India, to determine intra-specific genetic variation in this species. ResultsUpon sequencing 1.5 kb SMRT bell library, the clustering and assembly of high-quality CCS reads resulted into 9746 contigs and 2129 contained repeat sequences. The majority of repeats were dinucleotide (67.8%), followed by trinucleotide (21.4%) and tetranucleotide (10.7%). Out a total of 118 SSR loci primers designed, 25 loci showed polymorphism. The microsatellite genotype analyses with these loci indicated T. tor as an auto-tetraploid, with tetrasomy segregation and occurrence of double reduction. The microsatellite loci identified were highly polymorphic (average PIC 0.6687).. The genetic diversity parameters, observed and expected heterozygosities ranged from 0.1268 to 0.5047 and from 0.4989 to 0.9212, respectively, whereas inbreeding (FIS) values from 0.2334 to 0.8379. The average ρ statistics value of 0.0739 (p = 0.00) indicated the presence of genetic structure in the natural population, and along with pair-wise ρ statistics and DAPC analysis pointed to the occurrence of three genetic stocks. ConclusionThe identified microsatellite loci were found to be useful in generating information on genetic diversity and fine scale population structure of tetraploid T. tor, which would be valuable for conservation and management of this threatened species.

Population Structure of Sable in the Baikal Mountain Land: Analysis of Genetic and Phenotypic Traits

The genetic and phenotypic structure (according to the fur color) of 14 sable samples from the Baikal mountain land (BML) has been studied by analyzing 257 animals for 11 microsatellite loci and evaluating over 12 000 pelts with respect to seven standard color categories. It has been found that the population structure of sable in the region is heterogeneous both phenotypically and genetically. An isolated population group of sable with dark fur inhabits Zabaikalsky krai (Uletovsky, Petrovsk-Zabaikalsky, and Krasnochikoysky districts). The Khamar-Daban Ridge in the south of Lake Baikal is inhabited by a sable population with a high genetic diversity and the lightest fur color in the study region, which is most likely due to its contacts with the East Sayan population. The other BML samples have a relatively high genetic diversity and intermediate parameters of fur color, which may result from their large-scale intraregional translocations and migrations. The results of comparative tests suggest an indirect correlation between the phenotypic and genetic structures in samples from at least seven sable populations inhabiting the study region.

Genetic Diversity and Structure of Apomictic and Sexually Reproducing Lindera Species (Lauraceae) in Japan

Research Highlights: genetic diversity in populations were compared among related shrub species with different reproductive systems. Background and Objectives: Lindera species are dioecious trees or shrubs that produce seeds by mating of males and females. To evaluate the importance of genetic diversity for the persistence of natural populations, we compared genetic information among four Lindera species in Japan. Three are dioecious shrubs (Lindera praecox, Lindera umbellata, and Lindera obtusiloba) that produce seeds by sexual reproduction. The remaining species, Lindera glauca, reproduces by apomixis; only female plants are found in Japan. Materials and Methods: all four species were sampled across a wide geographic area, from Tohoku to Kyushu, Japan. Single nucleotide polymorphisms (SNPs) were detected by multiplexed ISSR genotyping by sequencing (MIG-seq) and the resulting genetic diversity parameters were compared among populations. Results: in all sexually reproducing species, the values of observed heterozygosity were close to the expected ones and the inbreeding coefficients were nearly 0. These results were supposed to be caused by their obligate outcrossing. The genetic difference increased, in ascending order, between a mother plant and its seeds, within populations, and across geographic space. We observed a substantial geographic component in the genetic structure of these species. For L. glauca, the genetic difference between a mother and its seeds, within populations, and across space were not significantly different from what would be expected from PCR errors. Genetic diversity within and among populations of L. glauca was extremely low. Conclusions: apomixis has the advantage of being able to found populations from a single individual, without mating, which may outweigh the disadvantages associated with the extremely low genetic diversity of L. glauca. This may explain why this species is so widely distributed in Japan. Provided that the current genotypes remain suited to environmental conditions, L. glauca may not be constrained by its limited genetic diversity.

Genetic Structure of Some Iranian, New and Old Worlds Linum Usitatissimum L. Populations

In current evaluation, the genetic structure and diversity were investigated in ten linseed populations collected from five countries belong to two continents (America and Eurasia) to find different genotypes for introducing them for genetic breeding programs. We selected these populations, because they belong to different regions of Holarctic and Paleotropical phytogeographic kingdoms. For this purpose, the nuclear DNA was extracted using the CTAB-modified method and amplified using 32 ISSR primers. Genetic diversity parameters and polymorphism indexes widely varied among the evaluated populations. Moreover, the results of the analysis of variance test proved the significant genetic differences, which its great part belonged to inter-population rather than intra-population. These findings were consistent with the high GST and HT levels and small amounts of HS and populations grouping in MDS plot, which revealed low amount of within population’s diversity, except those for Arak and Masal populations. In addition, low amount of Nm, indicating a flat rate of gene flow and strong population differentiation. According to the STRUCTURE analysis and UPGMA tree of Nei’s genetic distance, six genotypes were recognized among the studied populations. In the detected genotypes, populations with long geographical distances have the same genetic structure. It seems that the populations with the similar genetic structures have been originated from the same genetic diversity center. Hence, we assume that there are at least six centers of genetic diversity for flax in the world; however, evidences of ancestral gene flow were detected in genetic structure. These findings are consistent with the theory that there are several centers for flax genetic diversity around the world. Due to the high intraspecific diversity in Masal and Arak populations, individuals of these populations have great importance for genetic breeding programs of this species.

English

Cape gooseberry (Physalis peruviana L.) is a neglected high potential crop, knowledge of the genetic diversity of the genotypes domesticated in Kenya is limited. To understand the genetic diversity and structure within and between Cape gooseberry germplasm, 70 accessions from six selected counties were analyzed using 15 pairs of highly polymorphic SSR primers. In this study, a total of 61 polymorphic SSR alleles were identified with mean polymorphic information content (PIC) of 0.43. Analysis of Molecular Variance (AMOVA) revealed that 92.8% of the total genetic variation was within accessions whereas variation among accessions accounted for 7.2% of the total genetic variation. Genetic diversity parameters among the 70 accessions revealed that Cape gooseberry was more diverse than previously recorded. Based on the SSR data, the 70 accessions were classified into five main phylogenetic groups, which corresponded to the county of origin through factorial analysis, principal component analysis (PCA), and phylogenetic analysis. Seven core SSR primer pairs, namely SSR1, SSR2, SSR10, SSR11, SSR123, SSR138, and SSR146 were found to have a wide applicability in genotype identification of cape gooseberry, and thus they are recommended for use in genetic characterization of germplasm collected from other counties not covered by the present study. This study demonstrated the existence of considerable genetic diversity in Cape gooseberry accessions growing in selected counties in Kenya and can therefore be used as a basis for future breeding programs in the development of hybrids with desirable traits. This wider genetic diversity is vital for posterity as it will help cope with unpredictable climatic changes and human needs.   Key words: Simple sequence repeats (SSRs), genetic diversity, germplasm, Physalis peruviana L., polymorphic information content (PIC).

Comparative analysis of genetic diversity of rice (Oryza sativa L.) varieties cultivated in different periods in China

Understanding the genetic diversity of various rice (Oryza sativa L.) cultivars cultivated over time in China is of great significance for the selection of parent materials for targeted rice breeding and the cultivation of new desirable varieties. In this study, 36 pairs of SSR markers were used to compare and analyze the genetic diversity of 1610 rice varieties bred in China from the 1980s to the 2010s. A total of 1568 allelic mutations were detected, with each locus varying having from 16 to 115, with an average of 44 per marker. The average gene diversity index and the polymorphism information content (PIC) of each locus were 0.8403 and 0.8243, respectively. The genetic diversity parameter values of japonica (Oryza sativa L. subsp. japonica Kato) rice varieties were higher than those of indica (Oryza sativa L. subsp. indica Kato) varieties. Over time, original unique alleles are lost, and new unique alleles are added. The total number of alleles, the number of unique alleles, and the number of varieties with unique alleles tend to increase over decades of breeding. In all ages, indica rice contained the largest number of unique alleles (19) in the 2000s, and japonica rice contained the largest number of unique alleles (11) in the 2010s. The trends of gene diversity index and PIC values increased first and then decreased. Gene diversity indices and PIC for indica rice reached their maximums (0.698 and 0.664 respectively) in the 1990s and japonica rice reached its highest values for these diversity metrics (0.791 and 0.766 respectively) in the 2000s. Analysis of molecular variance showed that genetic variation was primarily derived from differences of varieties that were bred during a given period. Most of the pair-wise Fst comparisons between different periods were at a statistically significant level. Cluster analysis shows distinctions in the genetic relationship of varieties bred in the twentieth century and the twenty-first century, but the genetic relationship between the varieties is relatively close when comparing within the twentieth or twenty-firs century, respectively. Our study will provide a scientific basis for the effective protection and efficient use of rice germplasm resources.

Genetic structure analysis and genetic finger printing of sweet orange cultivars (Citrus sinensis (L.) Osbeck) by using SCoT molecular markers

Citrus plant species are among the most important and consumed fruit plants throughout the world. In general, genetic diversity investigations in all Citrus species and varieties are in hand in order to add to the knowledge of these important plant species. The sweet orange cultivars (Citrus sinensis), are among the most wanted among Citrus species. Various genetic diversity investigations by using different molecular markers have been performed in different regions of the world. We investigated 23 cultivars of sweet oranges available in Iran and two out-group cultivars produced by crossing Lemon and Kumquat. We used Start Codon Targeted (SCoT) molecular markers for genetic study. The studied cultivars produce 64 SCoT loci or bands. In total each cultivar studied contained 8–29 SCoT bands and six cultivars had 1–2 private/specific bands due to their peculiar genetic structure. Genetic diversity parameters were determined in these cultivars and revealed that the genetic polymorphism varied from 6.15% into 44% in the Studied sweet orange trees. We identified many loci with high discrimination power (> 0.80) in SCoT marker. Analysis of molecular variance (AMOVA) revealed significant genetic difference among these cultivars, and pair-wise AMOVA identified those sweet oranges which differed genetically from each other. Unweighted pair group method with arithmetic mean dendrogram of the studied samples separated most of the cultivars and their replicates in distinct clusters. STRUCTURE analysis revealed genetic structure of sweet oranges, showing their genetic similarities versus genetic uniqueness. We could differentiate some of Thompson cultivars, coming with different origins or locality. It held true for red blood and Jaffa oranges too. We identified few potential hybrids in the country. These findings will be used in future sweet orange conservation and breeding.

Discriminant Canonical Analysis of the Contribution of Spanish and Arabian Purebred Horses to the Genetic Diversity and Population Structure of Hispano-Arabian Horses.

Simple SummaryThe demographic and genetic diversity structure and the contributions of Spanish (PRE) and Arabian Purebred (PRá) horses to the process of conformation of the Hispano-Arabian (Há) horse breed were evaluated. Genetic diversity parameters (inbreeding coefficient, genetic conservation index, coancestry coefficient, non-random mating degree, relatedness coefficient, maximum, complete, and equivalent generations, and number of offspring) were evaluated using a discriminant canonical analysis to determine the partial contributions of each founder breed to the development of Há horse breed. The calculation of Nei genetic distances suggests the overlapping could be estimated in 29.55% of the gene pool of the Há having a PRE origin while 70.45% of the gene pool of the breed may derive from a PRá origin. Although a progressive loss of founder representation may have occurred, breeding strategies implemented considering mating between animals with the highest genetic conservation indices (GCI) may compensate for its effects.Genetic diversity and population structure were analyzed using the historical and current pedigree information of the Arabian (PRá), Spanish Purebred (PRE), and Hispano-Arabian (Há) horse breeds. Genetic diversity parameters were computed and a canonical discriminant analysis was used to determine the contributions of ancestor breeds to the genetic diversity of the Há horse. Pedigree records were available for 207,100 animals born between 1884 and 2019. Nei’s distances and the equivalent subpopulations number indicated the existence of a highly structured, integrated population for the Há breed, which is more closely genetically related to PRá than PRE horses. An increase in the length of the generation interval might be an effective solution to reduce the increase in inbreeding found in the studied breeds (8.44%, 8.50%, and 2.89%, for PRá, PRE, and Há, respectively). Wright’s fixation statistics indicated slight interherd inbreeding. Pedigree completeness suggested genetic parameters were highly reliable. High GCI levels found for number of founders and non-founders and their relationship to the evolution of inbreeding permit controlling potential deleterious negative effects from excessively frequent mating between interrelated individuals. For instance, the use of individuals presenting high GCI may balance founders’ gene contributions and consequently preserve genetic diversity levels (current genetic diversity loss in PRá, PRE, and Há is 6%, 7%, and 4%, respectively).

Genetic diversity in Egyptian bottle gourd genotypes based on ISSR markers

Genetic diversity among 12 Egyptian bottle gourd genotypes was assessed using 11 ISSR molecular markers. The ISSR analysis generated 76 amplicons in a size range of 170–1600 bp with maximum (9) polymorphic amplicons by UBC 811. The high degree of polymorphism and PIC values greater than 0.50 indicate that 844-B, HB 10, UBC 807 and UBC 825 markers could be useful for rapid fingerprinting of many bottle gourd genotypes. Parameters of genetic diversity and its partitioning were estimated among genotypes. Various parameters namely, observed heterozygosity, effective number of alleles per locus, Shannon's index, expected heterozygosity, and represents percentage of polymorphic band were estimated. The genetic analysis demonstrated that Egyptian bottle gourd genotypes keep relatively high genetic diversity. Cluster analysis (UPGMA) clustered all genotypes into three main clusters based on the ISSR data. Overall, the results indicated that fingerprinting using ISSR markers might be an efficient tool in future breeding programs for varietal identification and assessing genetic diversity within the Egyptian bottle gourd genotypes. The high genetic variability among studied genotypes would be beneficial for breeding and conservation programs.

Genetic variation among Iranian Medicago polymorpha L. populations based on SSR markers

Burr medic (Medicago polymorpha L.), a native of the Mediterranean Basin, has become a worldwide weed. Pasture cultivars have been selected, especially in Australia. The species is extremely variable, and there is little agreement on its infraspecific classification. Towards a better understanding of its variation pattern, present study examined population genetic structure and genetic diversity in Iran, employing co-dominant SSR markers. Seventy-one randomly collected plants from 14 geographical populations were sampled. Six primer pairs generated 21 polymorphic bands. The average polymorphic information content was high (0.923). Genetic diversity parameters were determined in these populations. STRUCTURE analysis and K-Means clustering identified two and three gene pools in the country. Mantel test results revealed isolation by distance among the studied populations. The cluster analysis showed correlation between genetic and geographical distance. AMOVA revealed a significant genetic difference among populations and showed that 46% of total genetic variation was due to among population diversity. These data may be useful for future breeding and conservation of this important and potentially agricultural plant.

Limited effect of a highway barrier on the genetic structure of a gypsum soil specialist.

BackgroundGypsum ecosystems are edaphic islands surrounded by a matrix that is inhospitable to gypsum soil plant specialists. These naturally fragmented landscapes are currently exacerbated due to man-made disturbances, jeopardising their valuable biodiversity. Concomitant action of other fragmentation drivers such as linear infrastructures may increase the already high threat to these specialists. Although some evidence suggest that gypsophytes are not evolutionary dead-ends and can respond to fragmentation by means of phenotypic plasticity, the simultaneous action of barriers to genetic flow can pose a severe hazard to their viability. Here, we evaluated the effect of a highway with heavy traffic on the genetic flow and diversity in the species Lepidium subulatum, a dominant Iberian shrubby gypsophyte.MethodsWe tested the possible existence of bottlenecks, and estimated the genetic diversity, gene flow and genetic structure in the remnant populations, exploring in detail the effect of a highway as a possible barrier.ResultsResults showed variability in genetic diversity, migrants and structure. The highway had a low impact on the species since populations can retain high levels of genetic diversity and genetic parameter, like FST and FIS, did not seem to be affected. The presence of some level of genetic flow in both sides along the highway could explain the relatively high genetic diversity in the habitat remnants.DiscussionNatural fragmentation and their exacerbation by agriculture and linear infrastructures seem to be negligible for this species and do not limit its viability. The biological features, demographic dynamics and population structures of gypsum species seem to be a valuable, adaptive pre-requisite to be a soil specialist and to maintain its competitiveness with other species in such adverse stressful conditions.