Gene Diversity In Populations Research Articles

Flowering variation and its effect on the gene diversity of seed crops in a clonal seed orchard of Pinus koraiensis Siebold et Zucc.

ABSTRACT Pinus koraiensis, an economically and ecologically vital five-needle pine species, was surveyed for female and male strobilus production variation among 52 clones over five years in a seed orchard in Gangwon province of South Korea. We estimated heritability, effective population size and gene diversity, calculated maleness index, and drew parental balance curves for the strobilus production annually. Results demonstrated marked variation in female and male strobilus production among clones and years, particularly in male strobilus production. The maleness indices indicated a considerable deviation from sexual balance. Parental balance curves revealed that the top 20% of the most fertile clones contributed significantly to the total strobilus production. High heritability values underscored the substantial genetic influence on strobilus production. The gene diversity of orchard parents (GDp ) was set as one (GDp = 1) considering panmictic situations, and then loss of gene diversity in the female gametes (GDf ) was relatively estimated to be ranged from 0.096 (loss = 1 − GDf = 1 − 0.904, 9.6% in 2017) to 0.017 ( = 1 − 0.983, 1.7% in 2020). We emphasize the importance of the effective number of parents as a crucial parameter for informing seed orchard management decisions.

Polymorphism and Mutation Rate of 20 Rapidly Mutating Y-Chromosomal Short Tandem Repeats in Chinese Han Population of Sichuan Province

To explore the applicability of 20 rapidly mutating Y-chromosomal short tandem repeats (RM Y-STRs) in Chinese Han population of Sichuan province. Two RM Y-STR multiple amplification systems (RM1, including DYF404S1, DYF399S1, DYS547, DYS526a/b, DYS626, DYF403S1a/b, and DYS612, and RM2, including DYS1003, DYS1007, DYR88, DYS712, DYS711, DYS724, and DYF1002, with 14 RM Y-STR loci in total) and Y41SE-V1.2 (including 6 RM Y-STR loci of DYS627, DYS576, DYF387S1, DYS518, DYS570, and DYS449, 30 ordinary Y-chromosomal short tandem repeats [Y-STR] loci, and 1 Indel locus) were used for the amplification and typing of 200 unrelated males and 260 father-son pairs. The polymorphisms and mutation rates of 20 RM Y-STRs and 30 ordinary Y-STRs in Chinese Han population of Sichuan province were investigated and compared. In the 200 unrelated males, the gene diversity (GD) of 20 RM Y-STR loci ranged from 0.7910 to 0.9975, and there were 200 haplotypes. Haplotype diversity (HD) was 1 and the discriminative capacity (DC) was 1. A total of 198 haplotypes were found in Y41se-v1.2 (the 30 Y-STRs), with 4 cases sharing two haplotypes, the haplotype diversity being 0.9999, and the discriminative capacity being 0.99. A total of 68 mutations were found at the 20 RM Y-STRs loci in the 260 father-son pairs, and there was slightly more increase than decrease of allele repeats (1.19∶1), with the mutation rate ranging from <3.85×10 -3 (95% C I: 0.00-1.41×10 -2) to 2.69×10 -2 (95% CI: 1.09×10 -2-5.47×10 -2), and the average mutation rate being 1.19×10 -2 (95% CI: 9.20×10 -3-1.51×10 -2). The 20 RM Y-STRs and the Y41SE-V1.2 (the 30 Y-STRs) could be used to distinguish 22.3% and 13.8% father-son pairs, respectively. The 20 RM Y-STRs have high gene and haplotype diversity and paternal lineage differentiation rate in Chinese Han population of Sichuan province, showing great potential for application in Chinese Han population of Sichuan province.

Genetic Diversity, Conservation and Improvement of Gongronema latifolium Benth., in South-Eastern Nigeria Using the Internal Transcribed Spacer – ITS

Gongronema latifolium Benth., is listed among the important vegetable with medicinal attributes. Its native habitat currently threatened in Nigeria and there is death of molecular genetic information important for breeding and conservation purposes. To study the species genetic diversity, 50 accessions were collected from South Eastern Nigeria where the species is endemic and was subjected to molecular evaluation using the non-coding internal transcribed spacer (ITS 4 and 5) location. Relatively high within population gene diversity and low nucleotide (base) diversity was identified among the fifty (50) accessions. AMOVA analysis highlighted 93% within population diversity (variations). FST = 0.074 genetic differentiation was recorded for genetic diversity. Principle component analysis (PCA) segregated the accessions into four large groups (A-D), along non-geographical lines; with four outliers’ accessions; AwkCH051 (Akwa Ibom), EnuCH014 (Enugu), EboCH036 and EboCH037 (Ebonyi). Expectedly, the species recorded low-moderate genetic diversity common for organisms experiencing decreasing cover range. Enugu recorded the least within population diversity and Ebonyi showed higher diversity than states and might constitute the core of a possible genetic centre for the species. The outlier accessions represent potential parental lines for breeding and improvement programmes. Conservation efforts comprising in situ and ex situ strategies are required to arrest the declining diversity of the species in its native range across Southern Nigeria. Conservation and improvement efforts will sustain the uses of the plants, reduce poverty and improve the livelihood of gatherers, farmers and vendors of the plant, who are particularly women in the region.

Ancient variation of the AvrPm17 gene in powdery mildew limits the effectiveness of the introgressed rye Pm17 resistance gene in wheat

Introgressions of chromosomal segments from related species into wheat are important sources of resistance against fungal diseases. The durability and effectiveness of introgressed resistance genes upon agricultural deployment is highly variable-a phenomenon that remains poorly understood, as the corresponding fungal avirulence genes are largely unknown. Until its breakdown, the Pm17 resistance gene introgressed from rye to wheat provided broad resistance against powdery mildew (Blumeria graminis). Here, we used quantitative trait locus (QTL) mapping to identify the corresponding wheat mildew avirulence effector AvrPm17. It is encoded by two paralogous genes that exhibit signatures of reoccurring gene conversion events and are members of a mildew sublineage specific effector cluster. Extensive haplovariant mining in wheat mildew and related sublineages identified several ancient virulent AvrPm17 variants that were present as standing genetic variation in wheat powdery mildew prior to the Pm17 introgression, thereby paving the way for the rapid breakdown of the Pm17 resistance. QTL mapping in mildew identified a second genetic component likely corresponding to an additional resistance gene present on the 1AL.1RS translocation carrying Pm17. This gene remained previously undetected due to suppressed recombination within the introgressed rye chromosomal segment. We conclude that the initial effectiveness of 1AL.1RS was based on simultaneous introgression of two genetically linked resistance genes. Our results demonstrate the relevance of pathogen-based genetic approaches to disentangling complex resistance loci in wheat. We propose that identification and monitoring of avirulence gene diversity in pathogen populations become an integral part of introgression breeding to ensure effective and durable resistance in wheat.

Genetic Diversity and Population Structure of a Medicinal Herb Houttuynia cordata Thunb. of North-East India.

Intra-species genetic variability assessment is an effective tool in formulating genetic improvement and germplasm conservation strategies. Houttuynia cordata Thunb. is a semidomesticated medicinal herb consumed widely in traditional diet in North-Eastern India. In the present study, an effort has been made to assess the genetic diversity of H. cordata Thunb. from Brahmaputra valley of North-East India. A total of 545 genotypes from 18 populations of H. cordata Thunb. from four different regions, i.e. North-East, North-West, South-East and South-West, with respect to river Brahmaputra were collected and population genetic diversity and structure were analysed using ISSR molecular markers. Population genetic structure analysis using unweighted pair group method with averages (UPGMA)-based hierarchical cluster analysis, principal coordinate analysis (PCoA) and model-based clustering in STRUCTURE program revealed that the population of H. cordata Thunb. grouped according to regional distribution and forms four genetically distinct clusters. The analysis of molecular variance showed that differentiation among regions was significant with 60% genetic variation among region, 3% genetic variation among population within region and 37% genetic variation within population. We found wide variation in Nei’s gene diversity (Hj) ranging from 0.07782 in Margherita population to 0.13634 in Barapani population. Furthermore, Nei’s gene diversity within population (Nei’s Hs) and total gene diversity (Ht) were found to be 0.1081 and 0.1769 respectively. The genetic differentiation among 18 population was high (Fst = 0.3894; p < 0.001) with relatively restricted gene flow (Nm = 0.6564). Based on the result of this study, we suggest ex situ conservation could be an appropriate measure to adequately capture the total genetic diversity of H. cordata Thunb. populations of North-East India by selecting few individuals from different populations.Supplementary InformationThe online version contains supplementary material available at 10.1007/s11105-020-01260-9.

GENETIC DIVERSITY OF HONEYBEE (APIS MELLIFERA ADANSONII) IN IJEBU ENVIRONAS REVEALED BY SIMPLE SEQUENCE REPEAT (SSR) MARKERS

Honeybee Apis mellifera adansonii, dominant honey producing species in Nigeria was subjected to genetic variability studies using Simple Sequence Repeat (SSR) in other to provide the baseline data in Nigeria. Nine (9) Simple Sequence Repeats (SSR) primers were used to assess the genetic diversity in Two (2) worker bees each collected from 22 colonies found in the four apiaries in Ijebu environs of Ogun State. Data collected were subjected to analysis and results showed that six (6) out of nine primers produced 80 reproducible, polymorphic bands while the remaining three (3) were monomorphic. Gene diversity (H ) in total population and magnitude of differentiation among T populations (FST) was 0.430 and 0.340, respectively. Analysis of Molecular Variance (AMOVA) partitioned the total genetic variation as 70% within, 30% among populations. The cluster analysis showed that Ipari-Oke 3 and Odo-Epo 1-8 populations diverged from others which showed they are closer in genetic distances while Ipari-Oke 1 and Odo-Epo 2-5 were newly observed subcluster which represents another subspecies. In conclusion, genetic variations existed amongst the honey worker bees populations in Ogun State.

Adult survival in migratory caribou is negatively associated with MHC functional diversity.

Genes of the major histocompatibility complex (MHC) are involved in acquired immunity in vertebrates. Only a few studies have investigated the fitness consequences of MHC gene diversity in wild populations. Here, we looked at the association between annual survival and body mass and MHC-DRB exon 2 (MHC-DRB) genetic diversity, obtained from high-throughput sequencing, in two declining migratory caribou (Rangifer tarandus) herds. To disentangle the potential direct and general effects of MHC-DRB genetic diversity, we compared different indices of diversity that were either based on DNA-sequence variation or on physicochemical divergence of the translated peptides, thereby covering a gradient of allelic-to-functional diversity. We found that (1) body mass was not related to MHC-DRB diversity or genotype, and (2) adult survival probability was negatively associated with point accepted mutation distance, a corrected distance that considers the likelihood of each amino acid substitution to be accepted by natural selection. In addition, we found no evidence of fluctuating selection over time on MHC-DRB diversity. We concluded that direct effects were involved in the negative relationship between MHC functional diversity and survival, although the mechanism underlying this result remains unclear. A possible explanation could be that individuals with higher MHC diversity suffer higher costs of immunity (immunopathology). Our results suggest that genetic diversity is not always beneficial even in genes that are likely to be strongly shaped by balancing selection.

Diverging Genetic Structure of Coexisting Populations of the Black Storm-Petrel and the Least Storm-Petrel in the Gulf of California

Estimations on the influence of evolutionary and ecological forces as drivers of population gene diversity and genetic structure have been performed on a growing number of colonial seabirds, but many remain poorly studied. In particular, the population genetic structure of storm-petrels (Hydrobatidae) has been evaluated in only a few of the 24 recognized species. We assessed the genetic diversity and population structure of the Black Storm-Petrel ( Hydrobates melania) and the Least Storm-Petrel ( Hydrobates microsoma) in the Gulf of California. The two species were selected because they are pelagic seabirds with comparable ecological traits and breeding grounds. Recent threats such as introduced species of predators and human disturbance have resulted in a decline of many insular vertebrate populations in this region and affected many different aspects of their life histories (ranging from reproductive success to mate selection), with a concomitant loss of genetic diversity. To elucidate to what extent the population genetic structure occurs in H. melania and H. microsoma, we used 719 base pairs from the mitochondrial cytochrome oxidase c subunit I gene. The evaluation of their molecular diversity, genetic structure, and gene flow were performed through diversity indices, analyses of molecular and spatial variance, and isolation by distance (IBD) across sampling sites, respectively. The population genetic structure (via AMOVA and SAMOVA) and isolation by distance (pairwise p-distances and FST/1– FST(using ΦST) were inferred for H. microsoma. However, for H. melania evidence was inconclusive. We discuss explanations leading to divergent population genetic structure signatures in these species, and the consequences for their conservation.

Genetic evidence reveals male‐biased dispersal of the Omei tree frog

AbstractSex‐biased dispersal, which influences species’ social organization, genetic structure and evolution, is an important life‐history event. Although sex‐biased dispersal in mammals and birds has been thoroughly studied, little is known about it in amphibians. In this study, we used eight highly polymorphic microsatellite loci and two mitochondrial DNA (mtDNA) genes to infer patterns of dispersal of the Omei tree frog (Rhacophorus omeimontis). We found that the comparison between two types of markers showed higher FST values in mtDNA compared to microsatellites. Consistently, comparison of pairwise and overall FST values between the sexes revealed higher differentiation in females than in males. Furthermore, the inbreeding coefficient (FIS) and population gene diversity (HS) were lower in females than in males, whereas relatedness (r) was higher in females than in males. Females exhibited relatively higher correlation between genetic distance and geographical distance than males. Additionally, the mean assignment index (mAIC) was lower in males, whereas the variance of assignment index (vAIC) was higher in males. These evidences reflect higher genetic differentiation in females than in males, indicating male‐biased dispersal in the Omei tree frog. Considering the life history reported in this species, we discussed potential mechanisms driving the male‐biased dispersal in the Omei tree frog.

Assessment of genetic structure of the endangered forest species Boswellia serrata population in central India

Boswellia serrata Roxb., a commercially important species for its pulp and pharmaceutical properties was sampled from three locations representing its natural distribution in central India for genetic characterization through 56 RAPD and 42 ISSR loci. The wood fiber dimensions measured for morphometric characterization confirmed 11.36% of the variation in the length and 8.75% of the variation in the width indicating its fitness for local adaptation. Bayesian and non-Bayesian approach based diversity measures resulted moderate within population gene diversity (0.26, SD-0.17), Shannon information index (0.40, SD-0.22) and panmictic heterozygosity (0.28, SD-0.01). A high estimate for genetic differentiation measures i.e. GST (0.31), GST-B (0.33,SD-0.02) and theta-II (0.45) led to the distinct clusters of the sampled genotypes representing their regional variability due to limited gene flow and total absence of natural regeneration. We report the first investigation of the species for its molecular characterization emphasizing the urgent need for the genetic improvement program for the In-situ/Ex-situ conservation and sustainable commercialization.

Human T-cell receptor V gene segment of alpha and beta families: A revised primer design strategy.

The application of human TCR in cancer immunotherapy has gained momentum with developments in tumor killing strategies using endogenous adaptive immune responses. The successful coverage of a diverse TCR repertoire is mainly attributed to the primer design of the human TCR V genes. Here, we present a refined primer design strategy of the human TCR V gene by clustering V gene sequence homolog for degenerate primer design based on the data from IMGT. The primers designed were analyzed and the PCR efficiency of each primer set was optimized. A total of 112 alpha and 160 beta sequences were aligned and clustered using a phylogram yielding 32 and 27 V gene primers for the alpha and beta family. The new primer set was able to provide 93.75% and 95.63% coverage for the alpha and beta family, respectively. A semi-qualitative approach using the designed primer set was able to provide a relative view of the TCR V gene diversity in different populations. Taken together, the new primers provide a more comprehensive coverage of the TCR gene diversity for improved TCR library generation and TCR V gene analysis studies.

Temporal stability of genetic diversity revealed by microsatellite markers in restocked populations of Caspian roach, Rutilus caspicus (Yakovlev, 1870)

Abstract Rutilus caspicus is considered one of the most important bony fish with high economic value in the Caspian Sea. Since the population size of Caspian roach has decreased during recent decades, restocking of the populations is done through releasing hatchery-produced larvae into the wild. In the present study, the genetic diversity of wild and hatchery populations of R. caspicus was investigated using ten microsatellite loci. Also, microsatellite analysis was performed to compare the population structure of Caspian roach over a time frame of about 11 years. Although the allelic and gene diversity of hatchery populations tended to be lower than those of the wild populations, no significant differences in genetic diversity parameters were observed among the wild and hatchery populations. Similar variation levels were noticed among temporal samples of the same population, suggesting temporal stability in the genetic diversity of the wild populations. In most cases, significant departure from the Hardy-Weinberg equilibrium was observed after sequential Bonferroni correction. Results from analysis showed that a captive hatchery population was the most differentiated group. Also, the UPGMA dendrogram showed that the captive population was the most distant group. The stability of genetic composition between the two periods was noticed by the low and non-significant and estimates. The results from this study are anticipated to provide important information for setting up more efficient strategies for the conservation and restocking of R. caspicus.

Genetic variability in wild and hatchery populations of commercially important fish: The common carp (Cyprinus carpio)

Ahmadi M, Kashiri H, Shabani A, Moghadam AA. 2018. Genetic variability in wild and hatchery populations of commercially important fish: The common carp (Cyprinus carpio). Biodiversitas 19: 1468-1474. Common carp, Cyprinus carpio, is considered as one of the most important bony fish with high economic value in the Caspian sea. Since the population size of common carp has decreased during recent decades, restocking of the populations is done through releasing the hatchery-produced larvae into the Caspian Sea. In the present study, the genetic diversity of hatchery and wild populations of C. carpio was investigated using eight microsatellite loci (MFW7, MFW9, MFW13, MFW16, MFW17, MFW20, MFW26 and MFW28). A total of 145 different alleles were observed across all loci, with some of them being unique to each population. Although the allelic and gene diversity of hatchery populations tended to be lower compared to the wild populations, no significant differences (P&gt;0.05) in genetic diversity parameters were observed among the wild and hatchery populations. In most cases, significant departure from Hardy-Weinberg equilibrium was observed, mainly because of the heterozygosity deficiency. Results from FST, RST and UPGMA analysis showed that the hatchery-reared population was the most differentiated and distant group. The results from this study are anticipated to provide important information for setting up more efficient strategies in conservation and restocking of C. carpio.

Genetic diversity of Thymus sibthorpii Bentham in mountainous natural grasslands of Northern Greece as related to local factors and plant community structure

The local scale genetic diversity of Thymus sibthorbii, an aromatic species of the Greek flora, was studied both in relation to its habitat characteristics. The study was conducted in Cholomontas mountain, northern Greece at altitudes of 760–870m. Genetic material from Southern and Northwestern exposures and from different grazing intensities within each exposure, was studied using ISSR molecular markers. The plant cover at each study site was measured and the floristic composition of the site was calculated. The grazing intensity affected the species composition and reduced the abundance of T. sibthorpii. The floristic diversity in terms of species richness, evenness and Shannon index (IF) was higher at the southern sites. Within population gene diversity (HE) ranged from 0.203 to 0.245 and Shannon index (IG) from 0.311 to 0.377. Most of the genetic diversity resided within populations (88%). Significant genetic differentiation was detected among the populations from the southern and northwestern sites, as well as among populations of each exposure. Genetic diversity of T. sibthorpii was not correlated to species diversity (richness and evenness), either within or between populations. Instead, genetic diversity was found to be positively correlated with environmental factors, such as N soil content and soil moisture.

Current distribution and characterization of the wild grapevine populations in Andalusia (Spain)

For decades, human activities have gradually destroyed the natural habitats of wild grapevine, Vitis vinifera L. subsp. sylvestris (Gmelin) Hegi, and nowadays this species is endangered in southern Europe. In this paper, 94 populations of this species have been localized and characterized in the Andalusian region in the Iberian Peninsula between 1989 and 2013. Location, ecological aspects, and sanitary characteristics are described. Must properties and in vitro tolerance to calcareous conditions were also checked. The paper also contains a global description of female and male individuals. Two hundred individuals from six river basin populations have been sampled, and their genetic structure analyzed by using 25 nuclear microsatellites loci to investigate the gene diversity of wild grape populations in Andalusia at two levels: total individuals and at river basin populations. Also, the genetic relationship of wild and cultivated accessions has been tested. Wild grapevine is considered the ancestor of the cultivated varieties and should be preserved as this material could be used to start breeding programs of cultivated varieties and also to restore riverbank forests, which constitute one of the worst preserved ecosystems in the area.

Ameliorating the loss of genetic diversity in captive wildlife populations

Ameliorating the loss of genetic diversity in captive wildlife populations

DIVERSITY OF DROUGHT-RESPONSIVE GENES IN CENTRAL AND PERIPHERAL POPULATIONS OF Trifolium purpureum Loisel

Drought-responsive genes may differ in structure and complexity in native populations of a species established in different ecosystems. Peripheral populations may be a source of genetic variability for breeding cultivated plants for abiotic stresses tolerance and the target for core collections in germplasm preservation programs. Genetic studies including both peripheral and central populations are still limited. This research evaluated genetic diversity of drought-responsive genes in peripheral and central populations of Trifolium purpureum Loisel. Genomic DNA isolated from leaves of three northern and three southern populations of Israel was digested with restriction enzymes and hybridized with four drought-induced and four drought-repressed gene fragments. RFLPs were analyzed for gene diversity, molecular variation and fixation indexes (FST). Gene diversity of drought-induced genes ranged from 0.1 to 0.42 but differences of individual or pooled genes between central and peripheral populations were nonsignificant. Gene diversity for drought-repressed genes ranged from 0.08 to 0.348. Even though there were no differences for individual genes, a joint analysis showed a significantly larger (P ≤ 0.05) gene diversity in peripheral populations of T. Purpureum than in central ones. Variation within populations for both drought-induced and drought-repressed genes was the main component of molecular variance. Fixation index (FST) for drought-induced genes was between 0.029 and 0.214 while for drought repressed genes it was between 0.04 and 0.33. Results of this study show that peripheral population might be a reservoir for drought-responsive genes.

浙江低山地区多用途植物无患子的开花物候特征

PDF HTML阅读 XML下载 导出引用 引用提醒 浙江低山地区多用途植物无患子的开花物候特征 DOI: 10.5846/stxb201501130107 作者: 作者单位: 作者简介: 通讯作者: 中图分类号: 基金项目: 林业公益性行业科研专项（201404104，200804032）；浙江省-中国林科院省院合作项目（2013SY01）；浙江省重大科技专项重点农业项目（2011C12015） Flowering phenology of the multipurpose tree species Sapindus mukorossi Gaertn. in low mountain areas of Zhejiang Province Author: Affiliation: Fund Project: 摘要 | 图/表 | 访问统计 | 参考文献 | 相似文献 | 引证文献 | 资源附件 | 文章评论 摘要:无患子（Sapindus mukorossi Gaertn.）是我国长江以南地区传统的重要绿化树种，其果皮富含皂苷，种仁富含油脂，是国家林业局审定的新型木本油料树种之一。为研究多用途树种无患子在浙江低山地区的开花特征，2012年和2013年连续两年对位于浙江省天台县9年生无患子人工林在群体、个体、花序和单花水平进行开花物候观测和比较，并运用开花日期、相对开花强度和同步性等指数研究了无患子开花物候特征。观察结果显示：无患子花呈浅黄白色，花的类型有雄花和两性花，没有发现雌花。雄花较两性花大（花径分别为5.09 mm和3.72 mm），雄蕊多为8枚，个别7或9、10枚；雌蕊退化仅留下浅绿色凸起。两性花花萼稍抱拢，花药藏于花被片下，雄蕊大多8枚，极少数7枚或9枚，柱头高于花药并伸出花苞，子房一般具3室，极少数4室或仅2室。无患子2012年的开花进程略早于2013年，其花期集中在在5月中旬至6月上旬，单花从花蕾膨大到花朵凋谢一般为8-9 d。在2012年和2013年，无患子在群体、个体和花序水平的花期约为30 d、20 d、11 d和28 d、19 d、13 d。个体水平的开花振幅均呈单峰曲线，年际间相似性较高；开花同步性在个体水平同步性较高（同步指数为0.868），表现出一种大量、集中的开花式样；相对开花强度在单株间分布范围相对宽泛，但主要分布在30%-40%，在年际间和年际内均呈现极显著差异。花期同步指数在两年的变异范围分别是0.81-0.97和0.70-0.98，不同单株开花同步性在年际内差异极显著，但在年际间差异性则不显著。由此可见，无患子的生殖资源分配存在明显的时空差异，较长的花期可以减少非法花粉的干扰、保持其种群基因多样性，遗传因子是决定无患子开花物候的主要因素，生态环境对无患子开花物候的影响还需进一步研究，本研究以期为探索无患子开花的主要限制因子奠定基础。 Abstract:Sapindus mukorossi Gaertn. is a traditional and important virescent tree species in southern China with peel and seed oil rich in saponins. This tree species is one of the newly developed woody-oil species approved by the State Forestry Administration of China. To investigate the flowering phenology and characteristics of this multipurpose tree species, we observed and compared 9-yr-old plantations of S. mukorossi at population, individual, inflorescence, and single-flower levels in Zhejiang Province, Tiantai County, from 2012 to 2013, based on the first flowering date, relative flowering intensity, flowering synchrony, and so on. The results showed that the flower color of S. mukorossi was yellowish white and the flowers were either male or bisexual. The male flower (5.09 mm in diameter) was larger than the bisexual flower (3.72 mm in diameter). There were usually eight stamens in the male flower; however, a few flowers had seven, nine, or ten. The pistil of the male flower was degenerated and only a slight, light-green protuberance was preserved. The calyx of the bisexual flower folded together lightly and the anthers were under the perianthes. There were generally eight stamens in the bisexual flower, but some also had seven or nine. The chapiter was higher than the anther and was outside the bud. Generally, the ovary had three chambers, but had two or four in rare cases. S. mukorossi flowered earlier in 2012 than in 2013, and the flowering period of the test populations was from the middle of May to late June. The development of the single flower was 8-9 d long from the flower bud to wilting stages. In 2012 and 2013, the florescences of the population, individuals, and inflorescences were approximately 30, 20, and 11 d, and 28, 19, and 13 d, respectively. The flowering amplitude of individuals and inflorescences showed a single peak, sharing a high similarity from year to year. The temporal patterns of flowering of S. mukorossi were very similar at the population level, with a well-defined peak and marked synchrony. The index of synchronicity was about 0.868. The relative flowering intensity was distributed over a wide range, but was concentrated between 30% and 40%. The flowering intensity showed an extremely significant (P=0.01) correlation annually and over different years. The range of variation of flowering synchrony was 0.81-0.97 and 0.70-0.98 in 2012 and 2013, respectively. The flowering synchrony correlation was extremely significant (P=0.01) annually, but not in different years. This suggested that there were temporal and spatial differences in the allocation of S. mukorossi reproductive resources, with longer flowering periods and higher flowering synchronization. Long flowering periods can alleviate the interference of illegal pollen and maintain population gene diversity. Heredity is the main factor affecting flowering phenology in S. mukorossi populations. The effects of ecological and environmental factors on flowering phenology need to be researched further. 参考文献 相似文献 引证文献

Comparison of Genetic Structure of Epixylic Liverwort Crossocalyx hellerianus between Central European and Fennoscandian Populations.

Patterns of genetic variation and spatial genetic structure (SGS) were investigated in Crossocalyx hellerianus, a strictly epixylic dioicous liverwort (Scapaniaceae s.l., Marchantiophyta). Studied populations were located in Fennoscandia and Central Europe, with localities differing in availability of substrate and the population connectivity, and their populations consequently different in size, density, and prevailing reproductive mode. A set of nine polymorphic microsatellites was successfully developed and used. Identical individuals were only found within populations. Especially in large populations, the majority of the individuals were genetically unique. Resampled number of genotypes, mean number of observed alleles per locus after rarefaction, and Nei’s gene diversity in large populations reached high values and ranged between 4.41–4.97, 3.13–4.45, and 0.94–0.99, respectively. On the contrary, the values in small populations were lower and ranged between 1.00–4.42, 1.00–2.73, and 0.00–0.95, respectively. As expected, large populations were found to be more genetically diverse than small populations but relatively big diversity of genotypes was also found in small populations. This indicated that even small populations are important sources of genetic variation in bryophytes and processes causing loss of genetic variation might be compensated by other sources of variability, of which somatic mutations might play an important role. The presence of SGS was discovered in all populations. Large populations possessed less SGS, with individuals showing a pronounced decrease in kinship over 50 cm of distance. Apparent SGS of small populations even at distances up to 16 meters suggests the aggregation of similar genotypes, caused predominantly by the deposition of asexually formed gemmae. Although no strong kinship was detectable at the distances over 16 meters in both small and large populations, identical genotypes were occasionally detected at longer distances (20–80 m), suggesting effective dispersal of asexual propagules.

Evaluation of genetic diversity in barley (Hordeum vulgare L.) from Wollo high land areas using agro-morphological traits and hordein

This study aimed to determine the genetic diversity and relationships among barley varieties (Hordeum vulgare L.) growing at Wollo Highland areas by using hordein and agro-morphological traits. Twenty (20) varieties were laid down in randomized complete block design (RCBD) design with three replications; they were planted by irrigation at Wollo University, Dessie Campus from January to May 2014. The genetic analysis using hordein was done in the laboratory of Ethiopian Biodiversity Institute (EBI) in July 2014. Ten (10) competitive random plants from the rows of the experimental plots were taken for recording their agro-morphological characters. Electrophoretic separation of barley storage proteins or hordeins was done using acid polyacrylamide gel electrophoresis (A-PAGE). The traits: day of heading, day of maturity, grain yield (kg/ha), plant height, spike length, number of spiklet per spike, kernel number per spike, weight of seed per spike and biomass yield (g/plot) were highly significant for the diversity of barely, whereas thousand seed weight was less significant. The results reveal positive correlation between spike length and number of spiklet per spike (the highest correlations from the agro morphological traits); the next highly correlated traits were kernel weight per spike and thousand seed weight. The A-PAGE analysis showed limited variation among the analysed accessions. The Nei’s genetic distance for all varieties of barely varied from 0.0000 to 1.6094. It is found that the 20 genotypes of barely investigated in this research were having a gene diversity (h) of overall populations (0.138) using hordein. The cluster analysis grouped the 20 barely genotypes into three different clusters using agro-morphological traits and into four clusters using hordein. This indicates the presence of wide diversity among the tested genotypes. From cluster mean values of agro-morphological traits, genotypes in cluster III deserve consideration for directly developing high yielding barely varieties. The result of the principal components analysis revealed that the first three principal components having greater than 1 eigenvalue contributed 84.22% of the total variation. From this study, it can be concluded that the presence of high morphological variation indicated the potential of Wollo Highland areas in contributing to barley improvement and conservation activities of land areas. Key words: Acid polyacrylamide gel electrophoresis, agro-morphological traits, hordein, genetic distance, hordeum vulgare, variability.