木荷种子园的遗传多样性和交配系统

【目的】研究木荷种子园遗传多样性和交配系统,揭示种子园交配机制对后代遗传多样性的影响以及亲、子代遗传多样性变化规律,为木荷种子园遗传管理提供科学依据。【方法】以浙江省兰溪苗圃木荷种子园自由授粉子代为研究对象,运用13对SSR引物,对种子园内44个亲本及11个无性系的328个子代进行分析。【结果】在亲本群体中检测到等位基因数(N_a)5~9个不等,平均为6.286,有效等位基因数(N_e)为3.097;在子代群体中检测到5~11个等位基因(N_a),平均为7.786,较亲本群体高出1.500个等位基因,子代群体的有效等位基因数(N_e)为3.751,较亲本群体高出0.654个有效等位基因。子代群体包含亲本群体所有的等位基因,此外,还检测到1~5个子代特有等位基因。亲本群体遗传多样性水平适中(H_e=0.632),子代群体遗传多样性(H_e=0.600)比亲本略有降低,观测杂合度(Ho)略高于亲本,说明子代群体中实际观察到的杂合单株占全部单株的比例均较亲本有所增加,但差异不大。子代群体Nei’s基因多样度(h)和Shannon’s信息指数(I)分别为0.611和1.152,均与亲本群体基本保持一致。子代群体的F值为-0.143,存在杂合子过剩。多位点交配系统分析(MLTR)结果表明:种子园异交率较高,多位点异交率(t_m)为1.000,单位点异交率(t_s)为0.939,亲本的近交现象不显著(t_m-t_s=0.061),只有较少的双亲近交事件发生;但有效花粉供体数目较少(N_(ep)=2.3),单位点和多位点父本相关性的差值r_p(s)-r_p(m)=0.0120,表明只有小部分花粉供体是近亲关系。参试11个家系间异交率不存在明显差异(t_m为0.992~1.073),少数存在近交现象(31号:t_m-t_s=0.107;9号:t_m-t_s=0.117)。11个家系的父本相关性(r_p)和有效花粉供体数目变化较大,分别为0.210~0.762和1.3~4.8,说明各家系的父本相关性程度不一致,其中31号最高,最低的是48号。【结论】木荷种子园异交率高,近交现象不明显;无性系之间基因交流相对充分,遗传多样性丰富,子代能保持亲本所具有的较高的遗传多样性。     

短枝木麻黄种子散布模式及子代群体的遗传多样性分析

[目的 ]利用短枝木麻黄(Casuarina equisetifolia L.)实生人工林群体及其自由落种长成的天然更新群体,开展短枝木麻黄种子散布规律研究,比较天然更新群体(子代群体)与其母本群体以及30年生实生人工林群体的遗传多样性差异,为人工促进木麻黄天然更新提供理论依据。[方法 ]利用木麻黄11个SSR标记位点的遗传分型数据,通过亲本分析软件Cervus 3.0对天然更新群体植株的母本进行确定,分析短枝木麻黄种子散布的距离和模式,并利用遗传多样性参数对这3个群体的遗传多样性进行比较。[结果 ](1)子代和母本群体共367个个体样本在11个SSR位点共检测出137个等位基因,每个位点的等位基因数为6～24,平均有效等位基因数为4.95,平均期望杂合度、观测杂合度和多态性信息量分别为0.75、0.77和0.72,所有位点均属于中或高度多态性位点。(2)在80%的置信区间下,利用11个标记位点的分型数据,可为148株子代确定它们的母本,占鉴定子代总数的72.20%;种子的有效散布距离为10～130 m,平均散布距离为71 m,属于短距离传播;天然更新群体的母本主要集中在样地的东北和东部,2个方向的母本对子代的贡献率为75.00%。(3)从3个群体中各选择84株个体的DNA样品进行遗传多样性比较,结果显示:天然更新群体在各个遗传多样性参数上均低于母本群体和实生人工林群体,但其参数表明该群体仍具有较高的遗传多样性。[结论 ]短枝木麻黄种子散布属于短距离传播,天然更新群体可以保持较高的遗传多样性,这为人工促进木麻黄实生林的天然更新提供了理论基础。     

贵州省马尾松主要群体的遗传多样性分析

利用ISSR分子标记技术对贵州省马尾松主要分布区天然林群体、贵州省都匀马尾松种子园基因收集区、种子园建园亲本及子代进行了遗传多样性分析,结果表明:贵州省马尾松天然林群体保持较高的遗传多样性;由于种源间基因交流频繁,贵州省马尾松变异主要存在于种源内;都匀马尾松种子园和子代仍然存在较高的遗传多样性水平,人工选育过程中并没有导致遗传范围变窄,种子园还有进一步选择的潜力;种子园收集区遗传多样性较低,需要进一步收集种质资源加以补充。该研究结果可以为贵州省马尾松种质资源的收集与保存、种子园遗传管理以及贵州省马尾松多世代育种策略的制定提供参考依据。     

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。     

红豆树优树子代遗传多样性及与生长相关性分析

[目的]研究红豆树优树自由授粉子代遗传多样性及其对生长的影响,比较天然居群子代和孤立木子代遗传多样性差异,揭示子代遗传多样性的变化规律及天然居群在子代遗传多样性维持中的作用,为红豆树遗传保育和优异种质挖掘提供科学依据。[方法]以来自浙、闽、赣、川等26个红豆树优树自由授粉家系为研究对象,利用11对SSR引物对765个子代群体进行遗传多样性评价,同时分析子代遗传多样性参数与种子、生长性状的相关性。[结果](1)红豆树优树子代群体具有较高的遗传多样性,有效等位基因数为7.766个,观测杂合度(H_O)和期望杂合度(H_E)分别为0.469和0.865。(2)除SSR8外,其余位点的观测杂合度均小于期望杂合度,表明子代群体绝大多数位点处于杂合子缺失状态。(3)红豆树不同家系的遗传多样性存在明显差异,12号家系的遗传多样性水平最高,8号家系则最低。(4)比较发现,天然居群子代的遗传多样性显著或极显著地高于孤立木子代。(5)F统计量和分子方差分析(AMOVA)均表明,红豆树优树子代群体的遗传变异主要存在于家系内,家系间的遗传分化相对较小。(6)相关性分析发现,子代遗传多样性参数与种子性状、子代年高生长量呈显著正相关(r=0.378~0.527)。[结论]较大的红豆树天然居群在维持其子代较高遗传多样性中发挥了重要作用,子代遗传多样性显著影响苗木生长,这为红豆树遗传保育和优良家系选择提供了理论依据。     

陈山红心杉母树林与种子园遗传多样性分析

掌握陈山红心杉母树林和种子园的遗传背景信息,为陈山红心杉种子园的生产经营和有效利用提供依据。本研究利用SSR标记分析陈山红心杉母树林、1代和1.5代种子园的遗传多样性。结果表明,陈山红心杉（母树林+种子园）平均等位基因数4.8,有效等位基因数1.826,观测和期望杂合度分别为0.408和0.398,Shannon′s信息指数0.747。与母树林相比,1代和1.5代种子园的等位基因数等遗传多样性参数发生变化,但没有显著差异。遗传结构和PCoA分析显示陈山红心杉遗传聚类不明显,遗传背景较为一致。     

林木群体中的交配系统

从交配系统、人工林中的交配系统、交配系统与群体的遗传多样性3个方面对交配系统的重要性进行了论述。认为交配系统是群体遗传学中的—个重要因素，它的变化会引起群体遗传参数的变化，影响林木群体的多样性，进而影响自然资源保护的策略。在诸如种子园等人工林中，交配方式的不同对种子的产量及质量均有影响。对交配系统进行研究可为人工林的建立提供理论依据。     

长白落叶松第二代种子园子代测定技术

子代测定是种子园核心技术,以汪清林业局长白落叶松第二代种子园为试验基地,探索实践了子代测定技术.结果表明,子代测定可以为生产群体提供优良的、具有广泛变异、配合力高的材料,提高生产群体的遗传改良水平.     

苏南杉木当地单株选优与种源选择的效果比较

杉木的遗传改良应以种源选择为主。先选择适宜的优良种源组成育种原始群体，再从优良种源群体中选出优良单株，建立嫁接种源种子园。然后，根据后代表现挑选最优亲本建立第一代生产性种子园，或直接引进优良种源经鉴定的优良单株无性系，建立一代性种子园．这样优树子代才能有效地提高选种的效益，而从当地种源杉木中选优，建立种子园意义不大，优树子代多表现不良。     

杉木人工林干扰和自然条件下的遗传多样性研究

采用垂直板型聚丙烯酰胺凝胶电泳,测定了杉木人工林的遗传多样性及受间伐和天然更新影响产生的变化.结果显示被选用的0.35hm2(230株)的小面积杉木人工林仍具有很高的遗传多样性,观察杂合度为0.357,期望杂合度为0.300.间伐后的林分几乎保留了原先林分全部的遗传多样性,天然实生更新子代保留了原先林分的约91%的遗传多样性.     

Genetic Diversity and Mating System Analysis of Pinus massoniana in Second-Generation Clonal Seed Orchard

A total 61 clone parents and 320 open-pollination progenies from 8 clone individuals were identified by 12 polymorphic SSR loci.The result showed that the level of genetic diversity in progeny population was the same as in maternal population, progeny population had all alleles detected in maternal population,and there were not obvious surplus phenomenon of homozygotes in progeny population (F= 0.046).The south crown had more strobili than the north crown,however the genetic diversity of the north crown strobili was not substantially reduced.The progeny of neutral trees had the same level of genetic diversity as in the progeny of partial female trees,with the fixation index tended to be zero,which was accorded with Hardy-Weinberg equilibrium.The multilocus outcrossing rate in the seed orchard was 1.097,and there was no significant inbreeding between parents(t_m-t_s= - 0.031).The multilocus outcrossing rate and singlelocus outcrossing rate in the south crown were higher than that in the north crown.The multilocus outcrossing rate of partial female trees was the same as in neutral trees,and the neutral tree had no obvious declining outcrossing rate with reduced proportion of female and male strobilus compared with partial female tree, with the fixation index tended to be zero.The progeny of the second generation clonal seed orchard still had rich genetic diversity,gene exchange among clones was relatively sufficient,and biparental inbreeding was not significant.     

杉杂交组配与两系种子园建立技术研究揪

通过初级种子园双列交配设计控制授粉，进行全同胞子代测定，评选出花期相近、自交系不育、正反交子代均生长突出(材积增益30％以上)的组合建立杂交种子园。我省从457个组合的全同胞子代测定林中，评选出杂交种子因亲本9组，并在靖州、会同、江华、资兴建成种子园共200亩。杂交种子因子代14a生单株材积0．1866—0．2274m^3，大于生产种对照30．0％-58．4％，建园效益十分显著。     

Estimates of pollen contamination and selfing in a coastal Douglas-fir seed orchard

Seed orchards are the link from tree breeding to reforestation programs and are theoretically expected to function as closed, perfect populations, ensuring gain and diversity are consistently and predictively delivered as improved seed and seedlings. Seed orchard populations often deviate from panmixia due to fertility variation, reproductive asynchrony, and gene flow, leading to reduced seed crops genetic quality. Here, as a part of multiyear monitoring study, we used DNA fingerprinting (simple sequence repeat markers) to assess a Douglas-fir (Pseudotsuga menziesii) seed orchard's seed crop genetic quality (2009 seed crop). The studied seed crop was produced under ambient temperature (i.e. no reproductive phenology manipulation) and pollination was augmented by pollen from within orchard's pollen donors. DNA fingerprinting of the parental population (66 parents) along with 207 gametophyte (1n) – embryo (2n) pairs of random bulk sample of seed allowed parentage (maternal and paternal) assignment and the direct assessment of pollen contamination (0.18 ± 0.027) and selfing (0.17 ± 0.025) rates as well as parental (pollen, ovule and individual parent) gametic contribution was compared to a previous year's crop (2005). The extended reproductive phenology coupled with variable within-orchard pollen availability has created opportunities for both self and foreign pollen to be successful at various times resulting in the seemingly paradoxical scenario of high selfing and gene flow. These results (2005 and 2009) allowed comparison of seed orchard's crop management practices and are expected to provide scientific foundations to effective seed crops genetic quality improvement.     

浙江长乐杉木种子园营建技术和改良效果的研究

浙江长乐杉木种子园，始建于1976年，目前已建成初级种子园514亩，一代种子园136亩，本文对该种子园的建园技术路线，主要经营技术和改良效果作了较系统深入的研究，资料分析表明，杉木资源较少的浙江地区，大量收集杉木中心产区的优树材料建立种子园，其后代增益十分明显，7．5年生子代林平均材积比当地对照增长30％以上，研究还表明，气象因子特别是2－3月份的降水量和日照时数，以及亲本来源，土壤状况和坡向等是影响种子园种子产量和质量的重要原因。     

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。     

杉木第二代种子园子代遗传变异及优良家系选择研究

来自广东省龙山林场杉木第二代种子园的39个自由授粉家系参加了1998年多点子代测定和2001年单点子代测定试验,结果表明：11年生子代测定林的树高、胸径、单株材积在家系和地点间差异达到极显著水平（P〈0．01）,8年生子代测定林生长性状的差异较小;家系平均树高、胸径、材积遗传力分别为0．24、0．26、0．30,主要生长性状受中等偏下的遗传力控制;第二代种子园材积遗传增益在1．88％～5．85％．其遗传增益和现实增产效果高于1．5代种子园,也高于初级种子园。对11年生多点子代测定林家系进行了丰产稳定性分析,选择出广谱丰产稳定家系5、8、17、19、23、26、28号,平均单株材积比群体均值提高3．39％;丰产家系3、7、15、21号和家系20、22、25号,分别适合龙山林场和曲江林场及相似立地条件地区限制性推广利用,平均单株材积比群体均值分别提高9．91％和4．89％;8年生单点子代测定林,以单株材积高于群体均值作为入选标准,有1、2、4、6、7、8、10、11、12、14、15、19等12个家系入选,平均单株材积比群体均值提高6．76％。     

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.     

湿地松改良种子园无性系的遗传评价及新一轮育种亲本选择*

台山湿地松（Pinus elliottii）改良种子园营建于1988—1997 年,为评价该种子园无性系的遗传品质,项目组在种子园内采集无性系的自由授粉种子并营建子代测定林。文章根据1 块营建在台山市红岭种子园的湿地松子代测定林4、13、18 a 的生长性状数据,分析了改良种子园的现实增益,评价建园无性系的选择效果,选择新一轮的育种亲本,结果如下：3 个年份数据分析结果均显示,在生长量方面,改良种子园子代显著甚至极显著大于湿地松一代种子园子代,18 a 生时,树高、胸径、单株材积的平均现实增益分别为3.09%、4.70%、15.08%;根据单株材积育种值选择出优良亲本无性系6 个,其育种值介于0.050 5~0.186 1 m3,其中有5 个亲本无性系的遗传品质已得到多次验证,可以作为新一轮的育种亲本甚至是核心育种亲本;新选优树15 株,其单株材积育种值介于0.114 9~0.276 9 m3,可充实到新一轮的育种群体中。     

Genetic variation in fruitfulness in a hinoki (Chamaecyparis obtusa Endl.) seed orchard and its impact on the maintenance of genetic diversity in seedlots

Genetic variation in seed/cone production among clones was studied in a hinoki (Chamaecyparis obtusa Endl.) seed orchard containing 25 plus-trees by analyzing the number of cones, the yield of cones and seeds of individual ramets for 5 successive years (1982 to 1986). There was significant variation among clones each year and parental contribution in the seed orchard. Specifically, in the years 1982, 1983, 1984, 1985, and 1986, 20% of the clones produced 37.2, 60.6, 36.0, 44.3, and 44.8% of the total cones, respectively. The size of the crop greatly influenced the parental balance in the resulting seed/cone crops. The product moment correlation coefficients and Spearman’s coefficients of rank correlation were small and insignificant between consecutive years, but large and highly significant between alternate years, suggesting the presence of carry-over effects in seed/cone production. The broad-sense heritability on a clone mean basis was 0.74 ± 0.15 for the number of cones, 0.72 ± 0.14 for the yield of cones, and 0.68 ± 0.13 for the yield of seeds. The corresponding heritabilities from analyses combined over all years were 0.24, 0.558, and 0.724, respectively. These results indicate that seed/cone production in hinoki is under strong genetic control. Several managerial measures are discussed that maintain the genetic diversity in seedlots used for reforestation, by reducing the variation in seed/cone production among clones and producing seed crops with equal contributions from all parents.