马尾松二代无性系种子园遗传多样性和交配系统分析

运用12对SSR引物,对马尾松二代无性系种子园内61个亲本及其中8个无性系单株的320个子代进行研究。结果显示:子代群体包含亲本群体的所有等位基因,子代与亲本具有同样高的遗传多样性,子代群体的F为0.045,纯合子过剩的现象不明显;树冠北面子代遗传多样性并未因其雌、雄球花量较树冠南面减少而有明显的降低;雌雄均衡和偏雌型植株子代遗传多样性基本一致,以偏雌型植株子代略大,二者F趋于0,子代基本符合哈温平衡。种子园异交率较高,多位点异交率为1.098,子代亲本的近交现象不显著(tm-ts=-0.033);树冠南面多位点与单位点异交率均高于树冠北面;偏雌与雌雄均衡型植株的多位点异交率基本相当,雌雄均衡型植株并未因其雌、雄球花量比例较偏雌型植株减小而呈现异交率明显降低的现象,2种类型植株的近交指数均接近于0。整体而言,马尾松二代种子园子代仍具有丰富的遗传多样性,无性系间基因交流相对充分,子代亲本近交现象不明显。     

Genetic variation, mating patterns and gene flow in a Pinus pinaster Aiton clonal seed orchard

? Relatedness among parents, variation in clonal fertility and background pollination deviate the realized genetic gain and the gene diversity of open pollinated seed orchard from expectation, in particular in wind pollinated species such as Pinus pinaster Aiton.

? This work investigates the genetic variation, the mating system and the pollen contamination in a P. pinaster clonal seed orchard (CSO), by screening the 60 clones from the CSO and the seeds collected from 21 mother-trees with three nuclear microsatellites.

? The expected diversity was similar, but the observed heterozygosity decreased 20% in the progenies compared with the parental trees. The outcrossing rate was 90.1%, the biparental inbreeding 21.7% computed through a multilocus approach, and the observed selfing 3.9%. The observed gene flow from outside the CSO was 52.4%.

? From the results we concluded that the observed gene flow and the biparental inbreeding were high, and care should be taken in the implementation and management of future CSO, in particular clones should be checked for relatedness and the ramet number could be directly proportional to their breeding value.

     

Family Outcrossing Rates of Pinus caribaea Morelet var. caribaea in Seed Orchard and Natural Populations

Family outcrossing rates of Pinus caribaea var. caribaea populations that differed in origin and management were estimated by using isozyme markers. The family outcrossing rates were estimated by (1)fixing the probability of pollen gene frequency (p); (2) allowing pollen gene frequency to vary among families. The estimates of family outcrossing rates for all the populations varied widely among families (clones of the seed orchard), ranging from 0.39 to 2.0. The average family outcrossing rates of both methods were greater than the     

杉木种子发芽率和苗木高生长的近交效应

在杉木种子园中对6个无亲缘关系的无性系进行了双列杂交,包括自交。同时取亲本的自由授扮种子作为对照。在他们的子代林中,取一个全同胞家系和一个自由授粉家系,各选4至6株开花植株连同它们的亲本,分别进行自交、回交、同胞内交配和异交测定。结果表明,杉木近交使得种子发芽率和苗木高生长量大幅度下降。近交衰退随着近交系数(F)的增加而加大。同异交相比,自交、回交和全同胞交配、半同胞交配组合的种子发芽率分别平均降低约88％、42％和20％,苗木平均高度分别下降27％、17％和13％左右。结果也显示,在不同个体之间近交衰退程度存在明显差异。     

Gene dispersion within a population of Pinus sylvestris

Gene dispersion within a population was studied in a 2‐hectare stand of 74 seed trees and 1100 seedlings. Isozyme markers were used to determine the genetic relationships among parental trees, embryos and seedling progenies. Paternity exclusion analyses were used to study multilocus progeny genotypes from certain parents. Results demonstrate large variation between trees in their capacity to contribute their genes through natural regeneration. The proportion of all genes dispersed into a specific distance interval from the source was estimated. The estimation procedure took into account the background of seedlings where parenthood was not excluded, but where the seedlings turned out to be unrelated. We found little evidence for clusters of progeny seedlings surrounding their parental tree. Within 15 m from a tree, approximately 5 % of the genes originated from that tree and 95 % originated from other trees. We found no evidence for an increase in levels of inbreeding, or genetic substructuring in the seedling progeny stand relative to the parental seed trees. A mathematical model for pollen distribution was developed. According to this model, 90% of pollen was distributed more than 15 m from the source. It is concluded that the marker seed trees had a surprisingly low detectable genetic contribution to the regeneration. It seems likely that a considerable part of the new seedlings have parents among felled trees or from surrounding stands.     

秃杉第1代无性系种子园营建技术研究

总结了德化葛坑国有林场2009年营建的秃杉第1代无性系种子园的营建技术,并于2012年5月对建园效果进行调查分析.结果表明:砧木保存率为89.4％,嫁接保存率为86.9％,嫁接植株的正冠率为82.3％;2010年嫁接的植株平均树高、地径和冠幅分别为1.2m、3.1 cm、0.8m,最优株树高1.8m、胸径1.6 cm、冠幅1.3m.     

中国山杨群体CDS遗传多样性格局与谱系地理分析

目的 基于REF6与BRR2a基因,探讨中国山杨不同群体遗传多样性分布格局、迁移路线,以及群体遗传变异与环境变化的关系。 方法 获取REF6与BRR2a基因的CDS序列,计算不同CDS序列的分子多样性指数,构建单倍型网络图以及系统发育树。 结果 在西南群体中,REF6基因和BRR2a基因3种中性检验的平均值均为负值,核苷酸多态性均低于北方和中部群体。中国山杨群体系统发育树与单倍型网络图结果显示外类群首先与中国山杨北方群体聚集在一起,西南群体往往聚集在末端,且两种基因的单倍型在北方与中部多样性较为丰富,西南群体中单倍型种类相对单一。 结论 中国山杨从北方迁移到南方,为了适应云贵高原独特的气候环境,位于西南地区的群体经历了强烈的自然选择,发生了局部适应。     

Allozyme frequencies,outcrossing rate and pollen contamination in Picea abies seed orchards

Allozymes of Swedish seed orchard clones of Norway spruce (Picea abies Karst.) were studied. There were differences between gene frequencies of origins from different regions. The gene pool of the fertilizating pollen of two different orchards was different. Pollen contamination and outcrossing rates were estimated in two seed orchards. The fraction of paternal gametes which did not originate from any seed orchard clone was 10% and 17%, respectively. Based on simulation it was estimated that only a quarter of the gametes with origin outside the orchard would be detected. Estimation of multilocus outcrossing rates were 0.95 and 0.98.     

墨西哥柏实生种子园营建及其优树子代测定的研究

通过种子园与子代测定相结合的方式,在位于滇中的石林林场建立了含102个优树(家系)的墨西哥柏实生种子园,从中探讨了墨西哥柏实生种子园的营建途径。对该种子园的52个墨西哥柏自由授粉优树子代测定的结果表明,墨西哥柏速生,10年生树高、胸径、材积、冠幅的年均生长量分别为1.04 m、1.43 cm、0.009 6m3和0.22 m。生长性状和结实性状家系间的差异达显著水平。树高、胸径、材积、冠幅、结实量的家系遗传力分别为0.76、0.66、0.68、0.74和0.65,单株遗传力分别为0.27、0.16、0.18、0.23和0.16,其生长性状和结实性状呈显著的负相关。从该种子园中评选出了9个优良家系,22个优良单株,其材积遗传增益平均为13.47%和25.2%。此外,还揭示了墨西哥柏10年生期间的生长规律。     

蓝桉树木园异型杂交及花粉污染的微卫星分子标记研究

本文应用4对微卫星分子多态引物,对利用优株嫁接建立的蓝桉(E.globulus)树木园中的118个自由授粉子代的DNA微卫星指纹进行了分析.结果表明:选用的引物具有高度多态性,各个位点扩增得到的平均等位基因数为14.25,树木园中母株的异型杂交率为15%(95%,整体异型杂交率为47.9%,外源花粉污染率为17.6%.由于该树木园的异型杂交率低,其自由授粉的种子应用价值不高,因此应采用大规模人工授粉来制种或选用树木园中异型杂交率高的母株采种.     

马尾松种子园及其附近人工林的亲子代群体遗传结构分析

利用同工酶标记对广西覃塘林场马尾松无性系种子园及其附近一人工林的亲子代群体遗传结构进行研究。研究结果表明，不论是种子园还是附近人工林均表现为：亲代群体处于遗传平衡状态，杂合体相对过量，但子代已偏离遗传平衡，杂合体相对不足，亲子代的基因频率变化不大。种子园亲代群体的遗传多样性略高于子代，而附近人工林的亲代群体遗传多样性略低于子代。本文研究的种子园具有较宽的遗传基础，该种子园附近人工林的遗传多样性与种子园接近，但不论是人工林本身还是它的子代其多样性平均水平都较种子园的亲代和子代略低。     

华山松种子园无性系开花习性研究

云南楚雄华山松种子园的无性系,其雌球花着生在树冠外围枝条,而雄球花主要着生在树冠的内膛枝条。在水平方向上,雌球花多着生在树冠南部,雄球花的分布比较均衡;在垂直方向上,雄球花基本分布在树冠的中下部,雌球花则分布在树冠的中上部。大多数无性系的雄球花散粉期比雌花可授期早2~4 d;不同无性系间的雌雄花期具有一定的同步性。各无性系间雌、雄球花数量存在极显著差异,且有明显的偏雌或偏雄特性。雄球花量与无性系生长性状间存在显著正相关,雌球花量与树体生长相关性不显著。     

A robust set of black walnut microsatellites for parentage and clonal identification

We describe the development of a robust and powerful suite of 12 microsatellite marker loci for use in genetic investigations of black walnut and related species. These 12 loci were chosen from a set of 17 candidate loci used to genotype 222 trees sampled from a 38-year-old black walnut progeny test. The 222 genotypes represent a sampling from the broad geographic distribution of the species. Analysis of the samples using the 12 loci revealed an average expected heterozygosity of 0.83, a combined probability of identity of 3×10⁻¹⁹, and a combined probability of exclusion for paternity analysis of >0.999. The 222 genotyped trees from the progeny test comprised 39 open-pollinated families, 29 of which (having at least five sampled progeny) were used to estimate the outcrossing rate for the progeny trial. The same 29 families were used to construct a Neighbor-Joining dendrogram based upon allele sharing between individuals. The multilocus estimate of the outcrossing rate was 100% (standard error of zero), higher than the 90% level found in previous studies at the embryo stage, suggesting that both artificial and natural selection against selfs may have occurred over the 38-year lifespan of the progeny trial. In the Neighbor-Joining dendrogram, the majority of the putative siblings grouped together in 21 out of the 29 families, showing that the microsatellites were able to discern most of the family structure in the dataset. Our results indicate that errors were sometimes committed during the establishment of the progeny test. This set of microsatellite loci clearly provides a powerful tool for future applications in black walnut.     

Pollen dispersal,mating patterns and pollen contamination in an insect-pollinated seed orchard of <Emphasis Type="Italic">Schima superba</Emphasis> Gardn. et Champ.

Pollen flow and mating patterns are the most important factors influencing the genetic structure of insect-pollinated forest trees and are essential parts of genetic management in seed orchards. We investigated pollen flow, the mating system and the level of pollen contamination in a clonal seed orchard of Schima superba Gardn. et Champ. In total, 328 open-pollination progenies coming from 11 mother trees were identified using 13 polymorphic microsatellite loci. A total of 203 full-sib families were identified and were nested among the 11 studied seed donors. The male reproductive success rate from 0.49 to 7.77% for most male parents, with an average of 2.44%. More than 80% of the crosses were found within a distance of 60 m, and the most frequent pollination distance between female parent and male parents was approximately 20 m. Mating system analysis showed that the outcrossing level was very high (t _m  = 1.000, outcrossing rate = 98.5%) in the seed orchard and that there was an average of 2.3 effective pollen donors (N _ep ) per female parent. In addition, the mating success of individual males within neighborhoods was moderately influenced by their fecundity and the direction of their location relative to mother trees. The pollen contamination from outside the seed orchard was high (7.01%). Our findings are valuable for the assessment of seed orchards, and it may be worthwhile to use pollen management strategies to decrease pollen contamination and increase the genetic quality of the seeds produced.     

Population management: potential impacts of advances in genomics

Even with advanced gene technologies continued population improvement remains a key foundation for future genetic gain in forest trees. Currently, this is served by maintaining genetic diversity while capturing genetic improvement, often through structuring populations into a genetic hierarchy, setting population sizes, and managing pedigrees and inbreeding. In the future, information from genomic technologies will complement classical approaches, such as common-garden field experiments, for characterizing the genetic base and measuring and monitoring genetic diversity. This will entail directly measuring DNA sequence diversity of both selectively neutral markers and functional genes. Calibrating neutral marker diversity against functional diversity will become easier with functional genomics. For maintaining pedigree and managing inbreeding, genomic information can be used to relax some traditional tenets of population management. With future knowledge of functional polymorphisms, the better understanding of the nature and origins of genetic variation should enhance management of populations to both conserve genetic diversity and exploit it by more efficient selection. Where fungal diseases threaten biotic crises, very large populations may be needed, the requisite sizes often being very uncertain. Gene discovery holds enormous promise, but depends heavily on comparative genomics, capitalizing on genomic information from Arabidopsis, Populus and Eucalyptus, and the increasing numbers of accessible ESTs. Much greater insights into non-codon mutational processes and rates should also guide population management. A key challenge, however, will be to utilize information and apply tools cost-effectively. Also, very detailed genomic information, exemplified by the poplar-genome sequencing, may allow earlier adaptation of technology and development of new information in angiosperms than in gymnosperms.     

Unequal deployment of clones to seed orchards by considering genetic gain, relatedness and gene diversity

Related clones in seed orchards lead to inbreeding depressionand reduced genetic value of the seeds. This study aims to developthe methodology for deployment of related clones to seed orchardswhen the breeding value and the pedigree are available for eachcandidate. The following goals were considered: high geneticgain, high genetic gain adjusted for predicted inbreeding depression(net gain), high gene diversity, and high effective clone number.The selection strategies included truncation selection withor without relatedness restrictions, maximizing genetic gain(linear deployment) with or without restrictions on relatednessand maximizing net gain. The selection strategies were appliedto Norway spruce seed orchard candidates evaluated in clonaltests. The material comprised full-sib and half-sib relationships.Comparisons were made both at the same gene diversity and atthe effective clone number. Maximizing net gain by unequal rametnumber deployment resulted in considerable higher net gain anda considerable reduction of related ramets in many comparisons.Linear deployment restricted against related clones comparedat the same status number resulted in almost as high net gain.Reduction in gene diversity may be a more important reason toavoid relatives in seed orchards than the subsequent inbreedingfor achieving a high net gain.     

Tolerance of broadleaved tree and shrub seedlings to preemergence herbicides

Isoenzymes were used to study the genetic variation of 121 mature trees of Sorbus torminalis in a natural stand and a subset of 21 high yielding seed trees in the same stand used for a commercial harvest. Eight enzyme systems were studied. The genetic variation of the mature stand was higher than that of other stands reported in the literature. However, this level of genetic variation was not represented to the same extent by the seeds of the commercial harvest. Differences between the bud sample taken from the mature stand and the seed sample taken from the commercial subset were particularly obvious with respect to diversity measures and heterozygosities. The hypothetical gametic multilocus diversity (HGMD) of a bud sample of the mature Sorbus torminalis trees was more than 70% higher (94.1) than the value of the seed harvest sample (55.1). Deviations between the genetic structures of both samples were statistically significant. There is no indication that inbreeding is an essential component of the mating system of Sorbus torminalis. The potential causes for the lack of Sorbus torminalis seedlings and saplings originated from seeds and their consequences for regenerating this species are discussed. This research underscores that sampling a forest tree population for commercial harvest can result in a statistically significant reduction in the genetic diversity of the sampled group relative to the overall population.     

马尾松人工群体交配系统研究

借助水平淀粉凝胶电泳同工酶分析方法，研究了马尾松一无性系种子园，该种子园附近一人工林，马尾松－优树收集区的交配系统。研究结果表明，该种子园的多位点异交率为：０．７９２（ＳＥ＝０．０６２），种子园中心区与边缘区的多位点异交率分别为：０．８０１（ＳＥ＝０．０７５），０．８００（ＳＥ＝０．０６７）；种子园附近人工林的多位点异交率为：０．８２１（ＳＥ＝０．１８８），优树收集区的多位点异交率为：０．４３１（ＳＥ＝０．１３１）。说明该马尾松种子园的异交率较低，这可能成为影响种子园种子产量和种子质量的一个制约性因子。文章讨论了影响群体交配系统的主要因子，分析了马尾松异交率较低的可能原因，并对这一方面的进一步研究提出了一些建议。     

直干桉生长性状的遗传效应分析

对直干桉的树高，胸径，材积，冠幅，枝下高，弯曲度和枝径比等7个性状的一般配合力（GCA），特殊配合力（SCA），母本效应（FEM），父本效应（MAL）和特殊正反交效应（SRE）进行了分析。重点讨论了树高，胸径和材积3个性状的遗传效应。这些性状主要受SRE和MAL的控制，GCA仅对树高和枝下高有较澌上的影响。有两个亲本数量性状的GCA值高，可用于建立种子园，直干桉自交衰退非常严重，有8个组合的数量性状显著高于平均值。对直干桉进行遗传改良的最好途径是，通过杂交育种，从中再选出优异个体进行无性繁殖。培养出优良无性系后应用于生产。若要以建立种子园来改良直干桉，必须引进或引变新的育种材料才有效果。     

思茅松优树半同胞子代测定结果分析

在思茅松种子园建设中, 分别采集不同产地的９０ 株优树种子培育子代林, 在普文林场进行了半同胞子代测定。各性状相关分析结果表明树高、胸径、冠幅与材积生长相关密切。通过主要性状方差分析显示差异显著,进而对主要性状的遗传参数进行了评估, 并根据检验ｔ 值的显著性, 进行了优良家系选择。对各家系的主要性状所作的遗传相关分析结果表明树高早晚期遗传稳定, 为思茅松早期选择提供了依据。