Center Of Genetic Diversity Research Articles

Phylogeography of Morella nana: The Wumeng Mountains as a natural geographical isolation boundary on the Yunnan-Guizhou Plateau.

The Yunnan-Guizhou Plateau (YGP) is characterized by the distinctive isolated habitat of the limestone Karst Islands and features the Wumeng Mountains, which divide the YGP into the two Plateaus of Yunnan and Guizhou. This study aimed to assess the effects of geographic isolation and past climate fluctuation on the distribution of flora in the YGP. To achieve this, we carried out the phylogeographical pattern and genetic structure based on chloroplast and nuclear ribosomal DNA sequence in relation to past (Last Glacial Maximum) and present distributions based on ecological niche modeling for Morella nana, an important wild plant resource and endemic to the YGP once considered a vulnerable species. The results suggest that the genetic and chlorotype network structures of M. nana are divided into at least two groups: cpDNA chlorotype H2 (or dominant nrDNA haplotypes h1 and h2), distributed primarily to the east of the Wumeng Mountains, and cpDNA chlorotypes H1 and H3-H10 (or dominant nrDNA haplotype h2 and h3), distributed to the west of the Wumeng Mountains. A deep genetic split was noted within the two groups to reach 25 steps, especially for the cpDNA fragment variation. This east-west divergence reveals the existence of a natural geographical isolation boundary in the form of the Wumeng Mountains, and supports the existence of at least two glacial refuges during the Quaternary glacial period, along with two genetic diversity center, and at least two large geographic protection units for the important species of M. nana. This study indicates that the phylogeographical pattern of M. nana can be attributed to geographic/environmental isolation caused by the Wumeng Mountains and climate fluctuation during the last glacial maximum, and proposes an effective strategy to protecting this important plant resource.

Genetic diversity and geographic distribution patterns of Malus landraces from 5 cultivated species under climate change in China

China is the largest center of genetic diversity of apple (Malus Mill.), with rich germplasm resources. In the process of evolution and domestication, a large number of apple landraces appeared, and they played a very important role before the introduction of modern cultivated apple varieties to China. However, the habitat of Malus landraces is under serious threat. In this study, 19 pairs of polymorphic simple sequence repeat primers were used to analyze the genetic structure and genetic relationships of Malus landraces and the potential distribution was predicted according to eight environmental variables using MaxEnt modeling. The results showed that the genetic variation of Malus landraces was high (Ho = 0.728 and He = 0.884), and the genetic differentiation was mainly distributed within respective populations and with almost no differentiation among populations. The five population groups were ranked, from highest genetic diversity level to lowest, as follows: Malus domestica subsp. chinensis > Malus prunifolia > Malus robusta > Malus asiatica > Malus micromalus. The 216 germplasms were divided into five groups based on Nei's genetic distance, whereas the Bayesian structure analysis categorized them into two groups. Population structure and principal coordinate analyses showed that Malus domestica subsp. chinensis, Malus asiatica and Malus prunifolia may be derived from similar genetic sources. In the modeling analysis, the cumulative contribution of temperature to the distribution of Malus landraces in suitable growth areas reached 66.1 %, and BIO4 (temperature seasonality) was identified as the major factor influencing the distribution of Malus landraces. Under four future emission scenarios, the potential distribution range of Malus landraces basically unchanged, but the total potential distribution area is projected to grow greatly over time and will tend to shift to higher latitudes.

Phylogeographic Substructuring in the Southernmost Refugium of the European Common Frog Rana temporaria.

Rana temporaria is one of the most widespread Palearctic brown frogs. We aimed to clarify distribution pattern of two main genetic clades in the understudied Balkan peninsula by using 16SrRNA and MT-CYTB sequences, already widely applied in analyses of populations from other parts of Europe, while focusing on the broad area along the Morava river (central Balkans) as a known gap in the species distribution. Additionally, we were interested in revealing the extent of haplotype diversity within the main genetic clades in the Balkans, particularly around the supposed suture zone. The results revealed a suture zone between the Western and Eastern Clades in the central part of the Balkan Peninsula. This indicated the existence of a historical barrier between the Balkan Mountain Belt and geographically close mountains surrounding the Vlasina Plateau (Rhodope/Serbian-Macedonian Massif). The overall observed haplotype diversity in populations of R. temporaria from the Balkan Peninsula seems high. Harboring both main genetic clades of R. temporaria qualifies the Balkan Peninsula as another important center of species' genetic diversity, as well as rich in unique haplotypes. This points out the necessity of applying conservation measures focused on the common European frog populations and habitats in this part of the species' distribution area.

Spatial genetic structure in European marbled newts revealed with target enrichment by sequence capture

European marbled newts come in two species that have abutting ranges. The northern species, Triturus marmoratus, is found in France and the northern part of the Iberian Peninsula, whereas the southern species, T. pygmaeus, is found in the southwestern corner of the Iberian Peninsula. We study the intraspecific genetic differentiation of the group because morphological data show geographical variation and because the Iberian Peninsula is a recognized center of speciation and intraspecific genetic diversity for all kinds of organisms, amphibians included. We use target enrichment by sequence capture to generate c. 7 k nuclear DNA markers. We observe limited genetic exchange between the species, which confirms their distinctiveness. Both species show substantial genetic structuring that is only in part mirrored by morphological variation. Genetically differentiated groups are found in the south (T. marmoratus) and west (T. pygmaeus) of the species ranges. Our observations highlight the position of the Iberian Peninsula as a hotspot for genetic differentiation.

GENETIC VARIATION AND HERITABILITY ESTIMATES IN CHICKPEA SEEDLING TRAITS: IMPLICATIONS FOR BREEDING PROGRAMS

Chickpea, also known as Bengal gram, Channa, or garbanzo bean, is a vital pulse crop that offers wholesome food to the growing population. Originating from modern-day southeast Turkey and Syria, chickpea germplasm is abundant in Ethiopia, serving as a secondary centre of genetic diversity for various dietary legumes. Two main varieties are desi and Kabuli. A study at the University of Punjab Lahore found significant genetic variations in chickpea seedlings, with high genetic components and a broad-sense heritability of 87.04%. Root length showed a significant genotypic effect, with a PCV of 16.39% and a larger GCV than SL. The root-to-seedling length ratio showed a significant genotypic variance, with a heritability estimate of 69.98% and a genetic advance of 5.740%. Seedling biomass did not show significant genotypic variation. Leaf characteristics showed substantial genotypic differences, indicating extensive genetic heterogeneity. The correlation matrix showed substantial correlations between seven qualities in chickpea seedlings, suggesting genetic and physiological links between the qualities. These findings can inform breeding efforts, improve breeding programs, and generate new varieties with improved features.

Multilocus phylogeography of Italian Moorish geckos adds insights into the evolutionary history of European populations

AbstractGeckos of clade III of the Tarentola mauritanica species complex are widespread throughout southern Europe and northern Africa. We investigated the genetic variability of the Italian populations by performing a widespread sampling throughout the mainland and the two main islands of Sicily and Sardinia. We analysed 199 newly generated sequences of the mitochondrial 16S rRNA gene and 269 nuclear genotypes inferred from nine microsatellite loci from 307 individuals. We found 13 new mitochondrial haplotypes in Italy, whereas previous findings reported a single haplotype widespread throughout the country and in the rest of Europe, which currently make Italy the centre of genetic diversity of this taxon. There was no evidence of mitochondrial DNA structuring with geographic correlation. At the population genetic level, our multilocus approach based on nuclear markers returned a shallow genetic structure. Nonetheless, we disclosed the presence of at least four distinct genetic clusters (namely the Adriatic, two Tyrrhenian and the Calabrian clusters). Our findings do not support the two hypotheses proposed to explain the low level of mitochondrial polymorphism in this taxon, namely the genetic hitch‐hiking due to selective sweep and the historical human‐mediated colonization hypotheses. Based on the fossil record, the presence in Italy of this taxon since the Pleistocene Epoch is plausible. Given the discordance in genetic structure between mitochondrial and nuclear DNA, the exact role of the Italian Peninsula in shaping the observed patterns of genetic diversity during the Pleistocenic climatic oscillations needs further investigation.

Populus cathayana genome and population resequencing provide insights into its evolution and adaptation.

Populus cathayana Rehder, an indigenous poplar species of ecological and economic importance, is widely distributed in a high-elevation range from southwest to northeast China. Further development of this species as a sustainable poplar resource has been hindered by a lack of genome information the at the population level. Here, we produced a chromosome-level genome assembly of P. cathayana, covering 406.55Mb (scaffold N50 = 20.86Mb) and consisting of 19 chromosomes, with 35 977 protein-coding genes. Subsequently, we made a genomic variation atlas of 438 wild individuals covering 36 representative geographic areas of P. cathayana, which were divided into four geographic groups. It was inferred that the Northwest China regions served as the genetic diversity centers and a population bottleneck happened during the history of P. cathayana. By genotype-environment association analysis, 947 environment-association loci were significantly associated with temperature, solar radiation, precipitation, and altitude variables. We identified local adaptation genes involved in DNA repair and UV radiation response, among which UVR8, HY5, and CUL4 had key roles in high-altitude adaptation of P. cathayana. Predictions of adaptive potential under future climate conditions showed that P. cathayana populations in areas with drastic climate change were anticipated to have greater maladaptation risk. These results provide comprehensive insights for understanding wild poplar evolution and optimizing adaptive potential in molecular breeding.

Potential impacts of climate change on wild relatives of lentil (Lens spp.): An ecological niche model approach

Ecological niche models play a pivotal role in assessing the impacts of climatic changes on species, and in the development of conservation strategies. This study aimed to evaluate the potential impact of different climatic factors using ecological niche modeling. These models were constructed using occurrence data and bioclimatic variables with the MaxEnt (Maximum Entropy Algorithm) modeling algorithm. The analysis covers three timeframes: the current and two future periods (2060 to 2080 and 2080 to 2100). Our findings indicate that the suitable habitats of wild lentils will be impacted to varying degrees under all future climate scenarios, with the most significant impact projected in the worst-case scenario, which predicts a temperature increase of 5°C by 2100. It is recommended to consider habitat reduction or shift in four taxa while developing conservation strategies. Comparing habitat suitability across timeframes, some species such as L. nigricans (M. Bieb.) Godron exhibited no drastic changes. On the other hand, the models predict slight reductions, shifts, or fragmentations in the potential habitats of L. culinaris subsp. odemensis (Ladiz.) M.E. Ferguson & al., L. lammotei Czefr., and L. ervoides (Brign.) Grande, in future periods. Particularly, a significant reduction and shift in the projected potential habitats of L. culinaris subsp. orientalis (Boiss.) Ponert, accepted as the progenitor of the lentil, means that conservation measures should be taken. In conclusion, this study emphasizes the significance of the protection of habitats for lentil wild relatives in specific regions, even when species are not currently under threat. It is recommended to develop ex situ and in situ conservation strategies that consider potential impacts of climate changes, especially in the centers of genetic diversity.

Resequencing of global Lotus corniculatus accessions reveals population distribution and genetic loci, associated with cyanogenic glycosides accumulation and growth traits

BackgroundLotus corniculatus is a widely distributed perennial legume whose great adaptability to different environments and resistance to barrenness make it an excellent forage and ecological restoration plant. However, its molecular genetics and genomic relationships among populations are yet to be uncovered.ResultHere we report on a genomic variation map from worldwide 272 L. corniculatus accessions by genome resequencing. Our analysis suggests that L. corniculatus accessions have high genetic diversity and could be further divided into three subgroups, with the genetic diversity centers were located in Transcaucasia. Several candidate genes and SNP site associated with CNglcs content and growth traits were identified by genome-wide associated study (GWAS). A non-synonymous in LjMTR was responsible for the decreased expression of CNglcs synthesis genes and LjZCD was verified to positively regulate CNglcs synthesis gene CYP79D3. The LjZCB and an SNP in LjZCA promoter were confirmed to be involved in plant growth.ConclusionThis study provided a large number of genomic resources and described genetic relationship and population structure among different accessions. Moreover, we attempt to provide insights into the molecular studies and breeding of CNglcs and growth traits in L. corniculatus.

Chloroplast microsatellite diversity of Pinus brutia Ten. and Pinus halepensis Mill. populations across the Mediterranean basin: Inferences of their distributions

Aim of study: To characterize and compare the genetic resources and gain some insights into the evolutionary history of Aleppo pine (Pinus halepensis Mill.) and Brutia pine (Pinus brutia Ten.) species which are both distributed across more than 8 million hectares of area in the Mediterranean Basin.
 Study area: Fifty-six populations from eight Mediterranean basin countries where P. halepensis and P. brutia species are located.
 Materials and methods: We analyzed 1344 seeds belonging to 56 populations using five cpSSR primers (Pt15169, Pt30204, Pt41093, Pt87268, and Pt110048).
 Main results: The analysis of molecular variance (AMOVA) revealed that the genetic diversity among the Brutia pine populations was slightly higher than that of Aleppo pine (27.06% and 24.27%, respectively). The Aleppo pine populations separately displayed a clear east-west differentiation across the Mediterranean Basin, confirming previous results using other markers. Although the Brutia pine populations showed no spatial genetic pattern, geographically close populations and/or populations from their continual distribution range were genetically closer than the fragmented and/or ecologically marginal populations.
 Research highlights: The seven Aleppo pine populations from the eastern range (Türkiye, Greece, and Italy) were more than two-fold diverse than the 13 populations from the western range (Spain and Morocco). The eastern range of Aleppo pine and Brutia pine populations had similar levels of genetic diversity parameters. These results suggested that the Eastern Mediterranean Basin is a possible genetic diversity center for the two pine species.

Keragaman Genetik Varietas Kelapa Sawit (Elaeis guineensis Jacq.)

Oil palm (Elaeis guineensis Jacq.) is one of the leading national commodities because of its large contribution to the Indonesian national economy. In the plantation industry, palm oil is known as a commodity that has high value because it is an ingredient for producing palm oil. The genetic diversity of Indonesian oil palm accessions is currently very low. In an effort to increase genetic diversity, germplasm exploration has been carried out at the genetic diversity center of oil palm. In addition to exploration, other efforts have been made to increase genetic variation by introduction. Oil palm is a type of plant that comes from the Arecaceae family. Oil palm plants usually grow on peat soil types spread across the islands of Sumatra, Kalimantan and Sulawesi. This is a type of plant that has a fairly high level of risk of being attacked by pests. In its distribution, there are two types of oil palm that are usually cultivated by farmers, namely Elaeis guineensis Jacq., and Elaeis oleifera. Differences in properties can be seen from the morphology of the oil palm fruit endocarp ehich has different levels of thickness as a form of genetic diversity. Oil palm varieties are distinguished by the thickness of the endocarp, and also by the color of the fruit. Based on the thickness of the endocrap, oil palm is divided into three types, namely Pisifera, Dura, and Tenera. If based on the color of the fruit, there are Nigrescens, Virescens, and Albescens. One of the methods that can be used for genetic analysis is Random Amplified Polymorphic DNA (RAPD).Keywords: diversity, accession, endocarp, palm oil

Morphological variability of wild-growing crown imperial (Fritillaria imperialis L.) germplasm in central region of Iran—implications for in-situ conservation initiatives

BackgroundCrown imperial (Fritillaria imperialis L.) is a threatened bulbous plant which has great ornamental and medicinal values and importance. In the present study, a total of 100 specimens of wild-growing F. imperialis from 10 natural areas of Markazi province, Iran, representing one of the main centers of genetic diversity of this species, were evaluated using 37 phenotypic attributes during April 2021.ResultsHigh level of genetic variation within populations (75%) and low levels of genetic variation among populations (25%) was revealed. The highest coefficient of variation (CV) was found in leaf trichome (82.00%) and then margin of crown leaves (80.44%). In addition, flower color (CV = 50.86%), flower number (CV = 44.61%), peduncle diameter (CV = 33.44%), and plant length (CV = 32.55%)—all important from an ornamental point of view- showed relatively high CV values. The CV was the lowest for flower shape, filament color, bulb shape, bulblet number, and floral scent. Ward cluster analysis identified two main clusters, containing 14 and 86 specimens, respectively. The first group consisted mainly of specimens from the adjacent Shahbaz and Rasvand populations. According to the principal component analysis (PCA), the first six components of data accounted for 88.36% of total variance. The Shahbaz-1, Shahbaz-2, Shahbaz-6, Shahbaz-7, Shahbaz-9, and Bolagh-8 specimens showed the highest variation and were separated from others, which they can be used further in breeding programs, while Sarchal-2, Bolagh-3, and Chepeqli-4 specimens showed the lowest variability. Moreover, the studied populations were clustered into four distinct groups, each including populations that were geographically close to one another.ConclusionsAlthough the examined specimens revealed high genetic diversity herein, the results indicated that wild-growing populations of F. imperialis are still at risk suffering from overcollection in the most of studied areas, especially in Deh-Sad and Tureh.

Genetic diversity in early maturity Chinese and European elite soybeans: A comparative analysis

Soybean (Glycine max [L.] Merr.) is a legume crop important for global food security due to supplying high-quality vegetable protein and oil. China is the origin and rich center of soybean genetic diversity represented by numerous landraces and other genetic resources. During the nineteenth and twentieth centuries, world-wide dissemination of plant introductions laid the foundation of modern soybean production. Due to selection for regional adaptation, present-day elite soybean cultivars do have a comparatively narrow genetic base. However, as genetic variation is the major component of future breeding progress, diversity of early maturity Chinese and European elite soybeans was comparatively analyzed using a high-throughput functional SNP array and an SSR marker set. Results revealed a clear differentiation between Chinese and European elite cultivars, and the level of genetic diversity was similar between the two populations. Both in Chinese and European cultivars, unique SSR alleles were found which indicates that selection for specific adaptation can preserve genetic variation. The European population was markedly structured by maturity groups which was less clear in the Chinese population. Structure analysis indicated that European cultivars are based on two major ancestral lines, whereas Chinese elite soybean cultivars trace back to more ancestral lines pointing to the rich natural soybean diversity of China. The results confirm that long-term selection under divergent environmental and agronomic conditions can produce specific diversity which could potentially be utilized for future enhancing both Chinese and European soybean breeding.

Geography, ecology, and history synergistically shape across-range genetic variation in a calanoid copepod endemic to the north-eastern Oriental.

The center-periphery hypothesis (CPH) predicts that peripheral populations will have lower genetic variation than those at the center of a species' distribution. However, ecological margins do not always coincide with geographical edges when topographies are diverse. Historical climate changes can also strongly affect genetic variation. Here, we examined genetic variation in Phyllodiaptomus tunguidus, a calanoid copepod endemic to the north-eastern Oriental. This species was predicted to exhibit a complex pattern of genetic variation across its range due to the diverse topographies and stable climate history of the north-eastern Oriental. To test this, we used geographic distance to the center of the distribution, current ecological suitability, and climate during the last glacial maximum as geographical, ecological, and historical factors, respectively, in our analyses. We measured genetic diversity and population differentiation using mitochondrial and nuclear markers. This showed that P. tunguidus had 3 refugia during the last glacial maximum (LGM). Such a pattern of multiple refugia complicates the determination of the center and periphery of spatial genetic diversity. Both regression models and redundancy analyses failed to support the CPH. Instead, they showed that geographical, ecological, and historical factors together shaped population genetic structure in this species. Ecological factors explained significantly more genetic variation than did geographical and historical factors-however, all three factors interacted significantly to affect the pattern of genetic variation. The results extend our understanding of the CPH and the extent to which it can explain genetic variation across populations.

Effects of Traditional Ethnic Minority Food Culture on Genetic Diversity in Rice Landraces in Guizhou Province, China

Ethnic minorities living in Guizhou Province, China, have produced numerous rice landraces that are rich in genetic variations. Studying the genetic diversity and population structure of rice landraces in Guizhou has therefore become a topic of great research interest. However, the influence of ethnic minorities and their traditional food cultures on rice landraces remains unclear. We analyzed the genetic diversity of 598 rice landraces using simple sequence repeat (SSR) markers. Furthermore, we analyzed the nucleotide variations between two similar populations collected during two different time periods using a single-nucleotide polymorphism (SNP) haplotype analysis of six unlinked nuclear loci. The three major results were as follows: (1) The genetic diversity index of rice landraces in six ecologically distinct rice farming zones of Guizhou Province was high (He = 0.7721), and Southwest Guizhou, which has a large population of ethnic minorities, is the center of genetic diversity of rice landraces in the province; this region had the highest He at 0.7823 and the highest polymorphic information content (PIC) at 0.7562. (2) A neighbor-joining (NJ) phylogenetic tree and a model of the population structure showed that the rice landraces from the southwest, south, and southeast of Guizhou had unique genetic structures and genetic backgrounds, which are closely related to the traditional diet cultures of the local ethnic minorities. (3) A nucleotide variation analysis of similar rice landraces collected in 1980 and 2015 revealed that, after 35 years of domestication by ethnic minorities, the original dominant haplotypes were well-preserved; the frequency of the most favorable haplotypes gradually increased to adapt to the traditional food culture. This study is expected to promote the protection and sustainable utilization of rice landraces from this unique region and to provide valuable germplasm materials and information for future rice breeding and basic research efforts.

Exploring genetic diversity of wild and related tetraploid wheat species Triticum turgidum and Triticum timopheevii

IntroductionThe domestication bottleneck has reduced genetic diversity inwheat, necessitating the use of wild relatives in breeding programs. Wild tetraploid wheat are widely used in the breeding programs but with morphological characters, it is difficult to distinguish these, resulting in misclassification/mislabeling or duplication of accessions in the Gene bank. ObjectivesThe study aims to exploreGenotyping by sequencing (GBS) to characterize wild and domesticated tetraploid wheat accessions to generate a core set of accessions to be used in the breeding program. MethodsTASSEL-GBS pipeline was used for SNP discovery, fastStructure was used to determine the population structure and PowerCore was used to generate a core sets. Nucleotide diversity matrices of Nie’s and F-statistics (FST) index were used to determine the center of genetic diversity. ResultsWe found 65 % and 47 % duplicated accessions in Triticum timopheevii and T. turgidum respectively. Genome-wide nucleotide diversity and FST scan uncovered a lower intra and higher inter-species differentiation. Distinct FST regions were identified in genomic regions belonging to domestication genes: non-brittle rachis (Btr1) and vernalization (VRN-1).Our results suggest that Israel, Jordan, Syria, and Lebanonas the hub of genetic diversity of wild emmer;Turkey, and Georgia for T. durum; and Iraq, Azerbaijan, and Armenia for theT. timopheevii. Identified core set accessions preserved more than 93 % of the available genetic diversity. Genome wide association study (GWAS) indicated the potential chromosomal segment for resistance to leaf rust in T. timopheevii. ConclusionThe present study explored the potential of GBS technology in data reduction while maintaining the significant genetic diversity of the species. Wild germplasm showed more differentiation than domesticated accessions, indicating the availability of sufficient diversity for crop improvement. With reduced complexity, the core set preserves the genetic diversity of the gene bank collections and will aid in a more robust characterization of wild germplasm.

Phylogeographical Pattern and Population Evolution History of Indigenous Elymus sibiricus L. on Qinghai-Tibetan Plateau.

Elymus sibiricus L. is a perennial allotetraploid belonging to Triticeae of Poaceae, Elymus L., as the type species of genus Elymus L. The existing geographical distribution pattern and genetic spatial structure of E. sibiricus on Qinghai–Tibetan Plateau (QTP) are not yet clear. In this study, population genetic structure and demography history of 216 individuals from 44 E. sibiricus populations on QTP were studied used specific-locus amplified fragment sequencing (SLAF-seq). The result of genetic diversity showed that there was no single genetic diversity center was observed across all E. sibiricus populations. The results of genetic variation showed that 44 populations were clearly divided into the following three groups: Qinghai Plateau (Group I), South Tibet (Group II), and Hengduan Mountains (Group III). From the three analyses of AMOVA, Mantel test and Treemix, strong genetic differentiation across all populations and low genetic differentiation among populations within three groups. Molecular dating indicated that E. sibiricus diverged at 16.08 Ma (during the early Miocene) can be linked to the Himalayan Motion stage of QTP uplift. It is speculated that the reasons affecting the current phylogeographical pattern are as follows: (1) The environmental changes due to the uplift of the QTP; (2) The geographic distance between the populations (Groups I and III are close in geographic distance, and gene flow are frequent); (3) Geographical barriers (the Tanggula and Bayangela Mountains between Groups I and II). This study provides new evidence and historical perspective to the future exploration of the evolution and geographic distribution pattern of Elymus L.

Genomic Analysis Provides Insights Into the Plant Architecture Variations in in situ Conserved Chinese Wild Rice (Oryza rufipogon Griff.).

In situ conserved wild rice (Oryza rufipogon Griff.) is a promising source of alleles for improving rice production worldwide. In this study, we conducted a genomic analysis of an in situ conserved wild rice population (Guiping wild rice) growing at the center of wild rice genetic diversity in South China. Differences in the plant architecture in this population were investigated. An analysis using molecular markers revealed the substantial genetic diversity in this population, which was divided into subgroups according to the plant architecture. After resequencing representative individuals, the Guiping wild rice population was compared with other O. rufipogon and Oryza sativa populations. The results indicated that this in situ conserved wild rice population has a unique genetic structure, with genes that were introgressed from aromatic and O. sativa ssp. indica and japonica populations. The QTLs associated with plant architecture in this population were detected via a pair-wise comparison analysis of the sequencing data for multiple DNA pools. The results suggested that a heading date-related gene (DHD1) might be associated with variations in plant architecture and may have originated in cultivated rice. Our findings provide researchers with useful insights for future genomic analyses of in situ conserved wild rice populations.

Postglacial Expansion Routes and Mitochondrial Genetic Diversification of the Freshwater Pearl Mussel in Europe and North America

The freshwater pearl mussel Margaritifera margaritifera is a unionid species distributed across Northwestern Russia, Fennoscandia, Western and Southwestern Europe, and the Atlantic Coast of North America. In this study, we reconstructed the post-glacial expansion routes of this species based on FST genetic distances and the fact that M. margaritifera distribution is directly connected with salmonid expansion. The freshwater-pearl-mussel populations from North America and Northeastern Europe were the closest groups, judging by FST distances, supporting the concept of the North Atlantic Salmo salar colonization of the Barents and White Sea basins. We also documented that unique haplotypes in the populations of the Baltic and White Sea basins may have originated in isolated glacial refugia in Eastern and Northeastern Europe. The Iberian clade was the most distant group of populations, which is consistent with the previously observed role of the Iberian Peninsula as a glacial refugium. The high genetic diversity in the populations of Northern and Eastern Karelia was facilitated by migrants utilizing complex periglacial hydrological networks and by admixture in the contact zone where the migration flows met. We confirm that this region should be considered as a major center of genetic diversity within the European part of the species’ range.

Waxy allele diversity in waxy maize landraces of Yunnan Province, China

Waxy maize is one of the main fresh-eating maize types, and a mutation of the waxy gene causes the waxy character of maize grains. China is rich in waxy maize landraces, and Yunnan and its surrounding areas, are the place of origin and genetic diversity center of Chinese waxy maize. The six known waxy alleles of Chinese waxy maize are wx-D7, wx-D10, wx-Cin4, wx-124, wx-Reina, and wx-Xuanwei. The mutation sites of these alleles all occur in the coding region of the waxy gene, however, the mechanism by which the waxy characteristic is caused by the mutation in the regulatory region has only been reported rarely in maize. In this study, 405 waxy maize landraces from Yunnan were used as materials to identify the insertion and deletion of a large sequence fragment in the upstream ∼3.5 kb regulatory region of the waxy gene by molecular marker detection. Three different waxy alleles were identifed in this study: wx-PIF/Harbinger, wx-hAT and wxElote2. These three types of mutations all represented transposons inserted into the regulatory region of the waxy gene. Wx-PIF/Harbinger was a 304-bp MITE class transposon insertion belonging to the PIF/Harbinger family, while wx-hAT was a 560-bp MITE class transposon insertion belonging to the hAT family, and wx-Elote2 was a 6 560-bp LTR-like transposon insertion. In this study, the alleles were identifed for more than 70% of the waxy maize landraces in Yunnan, which provids a basis for the utilization of these waxy maize landraces.