林木群体交配系统研究进展

本文简要回顾了林木群体交配系统研究的历史,重点阐述了利用同工酶作为遗传标记对该问题的研究进展。目前开展交配系统研究的树种已超过52个,大部分研究集中在针叶树种,研究群体由原来的天然群体为主,到后来的天然群体与人工群体并重,转对人工群体的研究日渐加强。研究结果表明:针叶树种群体的异交率大都在90%左右,阔叶树种则相对较低,异交水平会因个体、冠层、群体密度、花量、花期不同而有所不同。根据上述情况,文章对今后的研究作了讨论,建议国内对同一领域开展研究的重点放在林木种子园中。     

Molecular Markers in Population Genetics of Forest Trees

Rapid progress is being made in many areas of forest population genetics owing to the newly available molecular techniques and the fast growth of genomic and sequence data. This paper reviews the currently available genetic markers and their applications in studies on gene diversity, population structure and differentiation, gene flow, introgression, phylogeny and gene evolution. Various marker-based population analyses have highlighted the evolutionary history of many tree species. However, up to now, genetic markers have not fulfilled the expectations for studies on the adaptive variation and the effects of natural selection on forest tree populations. Studies based on integrated and extensive genome sampling, especially the coding regions of the genome, in combination with adaptive traits can potentially improve this situation. This would provide us with a comprehensive knowledge of the evolutionary mechanisms shaping the population changes, both adaptive and neutral.     

分子标记在林业辅助选择育种中的应用

本文主要阐述分子标记在林木辅助选择育种中的应用。利用多种分子标记(RAPD,RFLP,AFLP,STS,SSR,STR等),可以在林木早期生长阶段对一些性状进行鉴别, 构建单种分子标记遗传连锁图谱或几种分子标记共存的混合连锁图谱和对控制数量性状的基因进行定位, 对林木群体遗传结构、遗传变异、遗传分化和基因流动进行研究, 在基因工程中, 能够追踪目的基因行为和对控制质量性状的基因进行鉴别, 对单株进行指纹图谱, 对种子质量进行监测和对品系、品种和无性系进行鉴定。     

Effect of forest management on gene pools

The influence of current forest management practices on gene pools is discussed. These forest management methods range from natural regeneration to replacing local species with exotics. Genetic changes caused by drift, alterations in the mating system, and directional selection are considered. A baseline is provided by information on genetic variation and demography of natural populations. While biochemical markers are useful for monitoring broad changes in genetic diversity or levels of inbreeding, changes of adaptive characters are likely to go undetected because of the low correlation in level and pattern of variation between biochemical and adaptive characters.     

森林植物分子生态学的研究方法

森林植物分子生态学的核心内容是检测其群落、种群、个体水平上的遗传多样性.较详细地综述了DNA水平上森林植物分子生态学的研究方法:DNA分子标记、DNA测序、基因克隆技术、DNA芯片技术的的原理和方法;简要介绍了蛋白质水平上的研究方法:等位酶分析和蛋白质组学的原理和方法.     

世界林木树种抗逆性育种研究进展

随着世界人口迅猛增长和工业化及大都市化进程的加快, 原有的森林树种将会遇到与自然选择下有重大不同的环境胁迫压力。为保障人类生存环境和生活质量不再劣化, 人类必须学会协助林木去更好更快地适应所遇到的各种随人类社会现代化而加剧和新出现的环境胁迫因素。低质量立地的造林利用技术和抗逆性育种就是摆在当代林学家面前的两大艰巨研究命题。为吸收国际先进经验来推动我国林木抗逆性育种事业, 作者对近些年来国际林学界在这一领域取得的研究进展作了综述。     

江西毛红椿天然群体的遗传多样性分析

以江西境内的5个毛红椿天然群体为研究对象,开展基于ISSR与SSR分子标记的群体遗传多样性研究。结果显示,5个群体总体表现为杂合子过剩,纯合子不足,总的遗传多样性偏低;物种水平的基因多样度（h）为0.2524,各群体基因多样度按大小排序为：九连山>官山>井冈山>马头山>岩泉。毛红椿群体规模小且林龄结构单一,推测这是造成其杂合子过剩但是基因多样性低下的主要原因。遗传分化指标（GST）显示受检测的毛红椿各群体间已发生显著分化,但群体内的遗传变异约占总变异的70%,仍是变异的主要来源;群体间基因流值（Nm）仅为0.596,多世代后的随机遗传漂变会逐渐加剧毛红椿群体遗传分化。为保证遗传完整性及保持群体的多样性水平,在江西境内可仅选择遗传多样性水平较高的九连山与官山两个群体来开展毛红椿的资源保存以及迁地保护。     

Applications of terpene analysis in forest genetics

Terpenoid substances in forest trees are versatile biochemical systems for use as genetic markers and for studying genetic regulation at the biochemical level. Univariate, multivariate and correlative data analyses from numerous studies on different coniferous species are presented. These data indicate that fitness values for most terpenes examined are probably so low as to be unmeasurable except in long evolutionary time spans. Variation patterns for monoterpenes often closely parallel racial differentiation for morphological traits and reflect the migratory history of species and species-complexes. Random drift and gene flow are likely the major influences on genetic organization of terpene variability. Mutation in regulatory genes may be responsible for quantitative variation within major gene systems for terpenes. The mono-, sesqui- and diterpene systems in conifers offer good opportunities for research on the nature of gene regulation in plants and its evolutionary significance.     

Isozyme variation in tropical trees: patterns of genetic organization

Tropical forests have long been of interest to biologists because of their high species diversity and their complicated patterns of community organization. The traditional notion of the rain forest as an ancient, unvarying archive of species has been challenged by a host of recent ecological studies which have demonstrated that tropical trees are diverse in their reproductive biology and dynamic in their population structure.Data from 97 isozyme studies on the genetics of tropical woody species demonstrate that cultivated taxa maintain higher percentages of polymorphic loci and higher mean heterozygosities than native tropical species. Levels of within-population variation in tropical taxa are as high or higher than in plants in general, previously reviewed by Hamrick and Godt (1989). Levels of genetic variation differ significantly among species with different geographic ranges, life forms, and taxonomic affinities. Levels of population differentiation, measured by Gs, values, are significantly different only between species with different seed dispersal modes. Outcrossing rates in 16 tropical tree species showed a preponderance of highly outcrossed breeding systems. Genetic evidence suggests that gene flow among local populations is high, but geographically separated populations show moderate levels of genetic differentiation.Ecological and historical processes provide the mechanisms influencing the genetic architecture of plant species. Where appropriate, data on isozyme variation in tropical trees are related to breeding systems, seed dispersal mechanisms, demography, and patterns of environmental heterogeneity. Profitable avenues for future research are suggested.     

Genetic diversity and population structure analysis of Pistacia species revealed by phenylalanine ammonia-lyase gene markers and implications for conservation

Information on population genetic structure and crop genetic diversity is important for genetically improving crop species and conserving threatened species.The PAL gene sequence is part of a multigene family that can be utilized to design DNA marker systems for genetic diversity and population structure investigation.In the current study, genetic diversity and population structure of100 accessions of wild Pistacia species were investigated with 78 PAL markers.A protocol for using PAL sequences as DNA markers was developed.A total of 313 PAL loci were recognized, showing 100% polymorphism for PAL markers.The PAL markers produced relatively more observed and effective alleles in Pistacia falcata and Pistacia atlantica, with a higher Shannon's information index and expected heterozygosity in P.atlantica, Pistacia vera and Pistacia mutica.Pairwise assessment of Nei's genetic distance and genetic identity between populations revealed a close association between geographically isolated populations of Pistacia khinjuk and Pistacia chinensis.The accessions of wild Pistacia species had more genetic relationship among studied groups of species.Analysis of molecular variance indicated 19% amongpopulation variation and 81% within-population variation for the PAL gene based DNA marker.Population structure analysis based on PAL revealed four groups with high genetic admixture among populations.The results establish PAL markers as a functional DNA marker system and provide important genetic information about accessions from wild populations of Pistacia species.     

RAPD标记研究马褂木地理种群的遗传分化

利用RAPD标记对马褂木全分布区 15个种群的遗传多样性进行了分析。研究发现 ,马褂木具有丰富的遗传多样性 ,但东部种群因现有种群小 ,其遗传多样性明显地低于西部种群。种群遗传学研究揭示 ,由于小种群效应 ,以及缺乏有效的基因流和特有的致濒机制 ,马褂木种群间的遗传分化巨大 ,30 %以上的遗传变异存在于种群间。但在不同的地理区域 ,种群间的遗传分化程度不同。在西部分布区 ,地域上相距不远的种群其遗传距离较小 ,而在东部即使两个相邻的种群 ,其遗传距离也非常大。使用Nei’s遗传距离进行算术平均数的非加权成组配对法分析 (UPGMA) ,其聚类结果可以很好地将马褂木划分为西部和东部两个种源区 ,而西部种源又可再划分为西南亚区和华中亚区     

A population genetic study in a scattered forest species, wild service tree [Sorbus torminalis (L.) Crantz], using RAPD markers

Wild service tree [Sorbus torminalis (L.) Crantz] is a forest tree widespread in Europe, characterized by a scattered distribution. Its hermaphroditic flowers are pollinated by insects, and outcrossing is the prominent mating system, also due to the presence of gametophytic self-incompatibility. Genetic diversity and differentiation of 22 populations from northwestern Italy were investigated by means of variation scored at 53 polymorphic RAPD (Random Amplified Polymorphic DNA) loci. Populations differed in genetic variation, with Shannon diversity index ranging from 0.166 to 0.469. According to Analysis of Molecular Variance (AMOVA), most of the genetic variation was found within populations (61.78%) with a significant proportion of variance attributable to genetic differences between regions (23.60%) and between populations (14.62%). Evidence for isolation by distance was found in the set of populations sampled. The effect of habitat fragmentation on genetic variation was also evaluated. The efficacy of RAPD markers in analysing genetic variation, and the contribution of the results in terms of the preservation of biodiversity are discussed.     

红花石蒜遗传多样性的ISSR分析

利用ISSR分子标记技术对14个居群的红花石蒜进行遗传多样性研究,结果表明:POPGEN32分析显示红花石蒜物种的遗传多样性很高,多态位点百分率为92.31%,Shannon指数(H)为0.459 7,Ne i指数(I)为0.302 5;居群水平的遗传多样性较低,多态位点百分率平均为49.65%,Shannon指数(H)平均为0.262 0,Ne i指数(I)平均为0.176 3;居群间的遗传分化系数(Gst)为0.503 5,基因流(Nm)为0.698 3。AMOVA分子变异分析显示:居群间遗传分化程度高,46.12%的变异发生在居群内,53.88%的变异发生于居群间。生境的片段化使居群间的基因流受阻,可能是居群间高遗传分化和居群水平低遗传多样性的主要原因。     

林木重要性状的杂种优势和遗传方式以及杂优预测的可能性

林木杂交育种成功的先决条件, 取决于杂种具有的正向杂种优势是否明显, 因此林木杂种优势的机理研究十分重要。一般来讲, 林木重要性状的杂种优势产生的机理应和该性状的遗传控制方式一致, 但是林木重要性状的遗传控制方式取决于交配群体的遗传结构, 并和多种因素有关, 因而不应随便地根据几个随机亲本的配合力分析结果, 就断然肯定该树种杂交是否有前途。与以往更多地重视种间杂交的观点不同, 文中认为林木的种内杂交在林木多性状改良中也有着巨大的潜力, 并将发挥重要作用。最后根据林木杂种优势与配合力间的联系, 就其对林木杂优预测的影响提出了笔者的认识。     

思茅松天然种群及其种子园的遗传多样性

采用垂直板聚丙烯酰胺凝胶电泳和水平切片淀粉凝胶电泳技术对思茅松 3个天然种群和思茅松种子园的遗传多样性状况进行了研究。 9种同工酶系统 16个基因位点的分析结果表明 :思茅松天然种群具有较高的遗传多样性 ,多态位点比率P =70 1% ,等位基因平均数A =2 2 7,平均预期杂合度He=0 2 91;群体间的遗传分化程度较低 ,基因分化系数GST=0 0 5 2。思茅松种子园的遗传多样性较天然种群丰富 ,以上各遗传参数值依次为P =73 5 % ,A =2 4 2 ,He =0 2 95 ,种子园营建是林木遗传改良的一种有效途径     

雷州半岛白骨壤遗传多样性的ISSR分

利用ISSR标记技术研究表明：雷州半岛5个白骨壤（Avicennia marina）种群具有较高的遗传多样性。种群之间遗传分化很低,遗传分化系数FST=0.081 2,遗传相似系数平均值为0.980 4,种群间具有较强的基因流（Nm=5.654 9）。通过UPGMA聚类将5个白骨壤种群分为三类,特呈岛种群和角尾种群为一类,企水种群和高桥种群为一类,和安种群单独为一类。和安白骨壤种群可能是雷州半岛最古老的白骨壤种群,应予以优先保护。     

Pronounced fluctuations of spruce bark beetle (Scolytinae: Ips typographus) populations do not invoke genetic differentiation

The dynamics of a recent outbreak of the spruce bark beetle (Ips typographus) in Switzerland was ruled by a devastating winter storm in 1999 and the drought and heat of the summer 2003. Starting from a similar level of population sizes, estimated as the rate of infested growing stock, beetle populations increased differently in magnitude and time among different regions in Switzerland. Accordingly, we expected local or regional genetic differentiation as a result of such repeated population expansion/breakdown dynamics. We analyzed 5 nuclear microsatellites of spruce bark beetles sampled from pheromone traps at 30 locations distributed over Switzerland. Our genetic results did not indicate any sign of population differentiation, structure, isolation by distance, or recent bottlenecks. This complete lack of genetic structure suggests that spruce bark beetles are highly mobile, precluding the formation of a spatial structure at neutral molecular markers. Thus, this molecular–genetic approach does not allow us to discriminate among regional gene pools and to identify the origin of expanding beetle populations.     

Genetic variation and divergence in Scots pine (Pinus sylvestris L.) within its natural range in Italy

Twenty-one populations of Scots pine sampled over the entire Italian range of the species were analysed for genetic variation scored at nine nuclear SSR markers. The main aim of the work was to find genetic features useful for conservation management, namely allelic composition, gene diversity and differentiation. High levels of intra-population variability were scored. The only population sampled in the Apennines gave the lowest values, confirming the genetic erosion undergone in the Scots pine remnants in this area. A low level of genetic variability was also scored for populations from the Po valley and hills of Piedmont. Most genetic diversity was found within populations, while only a small amount occurred among them (F _ST?=?0.058). Both Bayesian clustering and sPCA analysis showed a East–West subdivision, notwithstanding the unclear position of populations from the Po valley. The population from the Apennines was always clearly separated from the others. The results are discussed in terms of post-glacial recolonisation, as well as for defining genetically homogeneous regions for Scots pine in Italy. The management of genetic resources could benefit from the identification of such ‘gene zones’, thereby avoiding the use of non-local reproductive material for plantations, which can represent one of the most important reasons for failure of reforestation. In addition, the assessment of the biogeographic genetic structure by neutral markers is a prerequisite for disentangling the influence of selectively neutral and non-neutral processes on the distribution of adaptive genetic variability.     

Gene flow pattern and mating system in a small population of Quercus semiserrata Roxb. (Fagaceae)

Pollen flow from external sources is important for the conservation of tree species in fragmented forests or small populations, because it can be sufficient to prevent differentiation among them, and appears to be able to prevent the loss of their genetic diversity through genetic drift. In this study, we examined the genetic heterogeneity of pollen pools accepted by each Quercus semiserrata seed parent at the Khun Wang Royal Agriculture Research Center, Thailand, both within and among two mast fruiting years (2005 and 2007), using paternity analysis and analysis of molecular variance (AMOVA). The mating systems of the trees were also examined using the multilocus mating system model (MLTR), after determining the genotypes at eight microsatellite loci of 26 seed-trees and 435 seeds from 8 seed-trees in the 2 mast fruiting years. The average distance of effective pollen flow within the plot was estimated to be 52.4 m, and 95% of effective pollen was dispersed within 200 m, indicating that effective pollen flow is highly localized and that most effective pollen is contributed by near-neighbor trees. The proportion of effective pollen that immigrated from external sources was estimated to be 26.2%. The AMOVA analysis based on the pollen haplotypes showed that the pollen pools, both total and for each reproductive year, significantly genetically differed among the seed parents. Using a mixed mating model, the estimate of biparental inbreeding for the total population (t_m − t_s) was 0.013, indicating that a low proportion of mating occurred among close relatives. The effective number of pollen donors (N_ep) was estimated to be 9.987 using the TwoGener model, or 10.989 using the mixed mating model. The effective number of pollen donors of seeds was higher in the mast fruiting year 2005 than in the other examined year, 2007. Consequently the allelic richness and genetic diversity of seeds produced in 2005 were higher than those produced in 2007. Overall, the results show that high outcrossing rates, high levels of gene flow from other populations and heterogeneity in the pollen received by an individual may enhance the ability of populations to maintain effective population sizes. Therefore, these processes may be sufficient to prevent loss of genetic diversity through genetic drift of Q. semiserrata at this study site.     

Local population structure of Hymenoscyphus fraxineus surveyed by an enlarged set of microsatellite markers

The population structure of Hymenoscyphus fraxineus, the causal agent of ash dieback, was assessed at four closely located sites in the Czech Republic. To analyse the genetic variation, one Swiss and one Norwegian population with known population structures were selected as reference points. The analysis was performed using 16 previously published and five newly developed microsatellite markers. The quality of the new markers was assessed by sequencing the flanking region, identifying the type of the mutation and analysing the inheritance and linkage between all pairs of loci. In addition, markers were tested on 45 Japanese strains to confirm their usability on native H. fraxineus populations in Asia. One of the new markers was monomorphic in all European populations and one marker exhibited a high percentage of null alleles in the Japanese samples. Twenty markers in the four Czech populations showed lower average gene diversity than in the other two European populations. One Czech population significantly differed from all the others, with a pairwise G_ST of approximately 0.2, the lowest allelic richness and very low average gene diversity, likely resulting from a founder effect. The amount of genetic differentiation between the four neighbouring Czech populations exceeds the expected value from previous Europe‐wide population studies and suggests that local population dynamics can affect the population structure of H. fraxineus.