常规林木育种研究现状与发展趋势

常规林木育种最重要的途径是利用树种现有的自然遗传变异以及利用育种手段创造遗传变异,通过选择获得优良品种,使目的性状在遗传上得到改良。把常规育种的分阶段遗传试验如种源试验、子代测定等整合到同一试验,以及对多个性状的综合选择,使传统的田间试验所需时间大大缩短,缩短育种周期,加速育种进程,为育种项目带来巨大的经济效益。另一方面,随着计算机技术的迅速发展,进行复杂模拟和运算的能力不断提高,使育种值估计和预测的精确度越来越高,也使采用复杂的试验设计成为可能。随着许多林木育种项目进入高世代,多世代育种受到日益广泛的重视。在育种群体或种子园内,通过建立优化育种模型对遗传材料进行优化配置。未来林木育种策略和育种目标将会把育种成本等经济因素考虑在内,根据育种项目的经济效果来确定育种方法。育种新技术必须以常规育种项目为依托,才能真正发挥作用。     

Genomic selection in forest tree breeding: the concept and an outlook to the future

Using large numbers of DNA markers to predict genetic merit [genomic selection (GS)] is a new frontier in plant and animal breeding programs. GS is now routinely used to select superior bulls in dairy cattle breeding. In forest trees, a few empirical proof of-concept studies suggest that GS could be successful. However, application of GS in forest tree breeding is still in its infancy. The major hurdle is lack of high throughput genotyping platforms for trees, and the high genotyping costs, though, the cost of genotyping will likely decrease in the future. There has been a growing interest in GS among tree breeders, forest geneticists, and tree improvement managers. A broad overview of pedigree reconstruction and GS is presented. Underlying reasons for failures of marker-assisted selection were summarized and compared with GS. Challenges of GS in forest tree breeding and the outlook for the future are discussed, and a GS plan for a cloned loblolly pine breeding population is presented. This review is intended for tree breeders, forest managers, scientist and students who are not necessarily familiar with genomic or quantitative genetics jargon.     

新西兰辐射松遗传改良研究新进展

新西兰已成为世界上在人工造林事业中取得辉煌成就的少数几个国家之一.新西兰人工造林的成功在很大程度上得益于对辐射松进行的遗传改良研究.本文根据最新资料对新西兰辐射松的遗传改良策略、育种体系、种子园经营技术、无性系林业的发展等方面进行了全面的综迷, 并提出了加快我国林木遗传改良研究进程的对策.     

分子标记技术在林木遗传育种中的应用

分子标记是一种新型的遗传标记,它为包括林木在内的植物遗传育种研究提供了新的手段,在缩短育种周期、提高育种效益等方面展现了广阔的应用前景。本文着重介绍分子标记技术在林木遗传育种中的应用：（１）指纹图谱绘制和基因型鉴定;（２）种质资源和育种群体的遗传结构分析;（３）遗传连锁图谱构建;（４）数量性状定位;（５）分子标记辅助选择;（６）目的基因定位与分离。     

论阔叶树遗传改良策略

就阔叶树的特点和阔叶树改良现状 ,探讨了长短结合、系统改良与局部突破结合、常规与超常规结合的阔叶树遗传改良策略 ,即母树林途径、无性系途径、“有性育种 ,无性快繁推广”的交互发展途径以及现代生物技术育种途径等 ,并提出要加强阔叶树育种群体保护策略     

林木遗传育种基础研究热点述评

林木由于世代周期长、个体高大、遗传负荷高等自身固有的一些特性,一直被认为是一种非常难以操作的遗传学材料,导致林木遗传育种在基础研究方面远远滞后于模式动、植物和其他重要作物,成为限制林木遗传改良进程的主要因素。分子育种是突破林木育种周期长的关键技术,通过基因组学研究,分析和阐明林木基因的功能是进行林木分子育种设计的前提。近年来随着生命科学领域新技术的快速发展,林木遗传育种基础研究也出现一些新的热点。本文主要阐述林木基因组和功能基因组学、连锁与关联分析、木材形成机制及分子育种技术的研究进展,虽然目前相关研究成果实际应用的条件还不成熟,但作为技术储备是急需加强的研究方向。     

Plant regeneration by somatic embryogenesis in Eucalyptus spp.: current status and future perspectives

Forest tree improvement programs benefit from the emergence of new biotechnological strategies that complement plant developmental biology and discovery of genes associated with complex multigenic traits. Recently, significant progress has been made in the area of plant regeneration via somatic embryogenesis (SE) for economically important tree species (e.g. pines). These advances have opened up new scenarios for deployment of new high-performance clonally replicated planting stock to forest plantations and may also be a valuable tool for the development of efficient gene transfer techniques. Although high rates of plant propagation from axillary shoot proliferation can be achieved easily in many Eucalyptus species, even higher multiplication rates through SE have been recorded in other tree species. If the clonal propagation of Eucalyptus through SE proves to be an effective propagation method, it has the potential to meet the increasing industrial demands for high-quality uniform materials and to rapidly capture the benefits of breeding programs. Since 2002 a reproducible protocol for SE induction from mature zygotic embryos of E. globulus has been available. However, for SE to be useful in E. globulus improvement programs, the frequency of SE initiation, maturation, germination and acclimatisation needs to be improved and controlled. If this technology could be extended to elite germplasm, it would become an economically feasible tool for large-scale production and delivery of improved planting stock. This is one of the greatest current challenges in Eucalyptus tissue culture. In this review we update the most important aspects of SE in Eucalyptus with particular emphasis on E. globulus. We highlight both genetic control and the influence of different environmental factors in the SE process (e.g. medium composition, antioxidants, light and plant growth regulators), from induction to plant acclimatisation in both primary and secondary SE.     

林木全基因组选择研究现状和应用

全基因组选择（GS）是利用覆盖全基因组的高密度遗传标记对复杂数量性状进行预测的育种方法。在林木种苗阶段根据基因组估计育种值（GEBV）可以利用GS进行个体选择,相比常规育种能增强遗传增益、加快选育进程。该方法无需定位与性状相关的数量性状位点（QTL）,相比分子标记辅助育种能极大地提高对微效位点的捕获功效,是具有巨大潜力的林木育种策略。文中系统介绍了GS的概念和优势,及其在林木中的研究现状和应用。我国林木GS研究处于初期阶段,可优先在常规育种较成熟的树种中开展研究,建立林木GS程序为其他树种提供范式。该综述有助于系统了解全基因组选择育种策略和研究进展,并为全基因组选择在林木育种中的应用提供理论和技术信息。     

菊花营养性状杂种优势表现与主基因+多基因混合遗传分析

以匍匐性地被菊'雨花落英'为母本,直立型盆栽菊'奥运含笑'为父本杂交获得F<,1>杂种,调查该F<,1>群体的株高、冠幅和叶片等8个营养性状在2008-2009年2个年度的表型资料,运用单个分离世代的主基因+多基因混合遗传分析方法,对这8个营养性状分别进行遗传分析.结果表明:8个营养性状在F<,1>群体广泛分离,变异系数为11.54%～41.89%;杂种优势和超亲分离现象普遍存在,除叶宽外,其他7个性状的中亲优势值均达极显著水平.混合遗传分析表明:菊花株高、叶长和叶宽3个性状符合A-O模型,无主基因控制;冠幅符合A-2模型,主基因表现为加性,主基因遗传率为78.61%;株高/冠幅比、叶长/宽比和花颈长度3个性状表现为有2对主基因控制的B-2模型,主基因表现为加性-显性,其遗传率分别为40.33%,45.19%和99.56%;节间长度符合A-4模型,主基因表现为负向完全显性,主基因遗传率为51.46%.这些主基因的存在将为菊花优良营养性状QTL定位和分子标记辅助育种的深入研究奠定理论基础.     

世界加速林木育种轮回研究的现状

林木育种事业向多世代发展, 通过缩短每一育种轮长度追求单位时间平均最大育种效益并降低育种作业成本, 已成为林木育种先进国家广为探讨的一个研究领域。决定缩短育种轮回的因素是如何克服林木始花龄晚和能否有效进行早期测验和选择。近20多年来欧洲和北美等国学者在上述两方面的研究中均取得了突破性进展, 使松科一些树种的育种轮比常规方法缩短1/2的时间。我国针叶树育种事业虽有近40年历史, 但这一领域的研究却几近空白, 与国际先进水平存在着质和量双重性差距, 严重限制着多世代育种的进展。本文在概述国外在这一领域的技术成就的基础上, 讨论了我国应采取的对策。     

Socio-economic factors affecting smallholder tree planting and management intentions in Leyte Province,Philippines

Survey data have been collected from four rural communities in Leyte Province, the Philippines, on household tree planting and management intentions, as well as the socio-economic characteristics, attitudes to tree planting and management, farming practices and the number of trees planted. In relation to intended tree planting and management activities, respondents were asked a series of structured questions as to what tree species they intend to plant, how many individual trees of each of those species they plan to plant, and for what purpose they propose to plant each of the tree species. This paper reports the results of analyses of the stated tree management intentions of households in the four communities and identifies the socioeconomic factors that influence householders’ tree management intentions. Respondents were generally enthusiastic about the possibility for further tree planting on their land, 75% indicating they would undertake planting. About 60% indicated an interest in commercial tree farming, with no significant differences in this level of interest between communities. It was found that a number of socio-economic variables indicating higher levels of land ownership and previous experience in the forestry industry are related to the intention to plant trees to produce timber for sale. These include the use of materials from public lands, participation in community organisations and community forestry programs, and the present management of trees to produce timber for sale.     

Breeding for value in a changing world: past achievements and future prospects

Large-scale tree improvement programs began in the 1950s. Tree improvement is now part of operational silviculture programs in many companies and countries around the world and tree breeding programs have produced very impressive results: (1) realized gains in plantations being established today of some 40–50 % in volume yield above unimproved material for many programs; (2) increased efficiencies in all aspects of breeding, selection, testing and deployment; and (3) a shortening of the generation interval by a factor of two from approximately 30 years in the first generation to less than 15 years today for pine programs. What about the future? What should tree breeders be thinking, planning and doing to ensure that results 60 years from now are even more impressive than those from the previous 60 years? Tree breeders today live in a rapidly changing world faced with: increasing demands for food, energy and water; globalization leading to an interconnectedness of markets and rapid spread of exotic organisms; climate change and its implications for genetic deployment; burgeoning technology in robotics, communications and molecular tools; shifting ownership patterns of forest land; and the real possibility of completely new forest products and markets in the future. Three ideas for “Breeding for Value in a Changing World” are: (1) adopt a robust philosophy that aims to ensure maximum value produced per ha even in a future world that will be quite different; (2) embrace technology at every phase in the tree improvement process; and (3) encourage interdisciplinary teams of scientists to solve complex problems that require expertise ranging from molecular to landscape scales.     

分子标记辅助选择在林木育种中的应用

历史上,数量遗传学被认为是指导林木育种的唯一有效工具,这有两个方面的原因：第一,在林木上具有重要经济价值的性状,如树干材积生长、木材纤维长度及适应性等,均是以数量方式遗传的性状,并且控制这些性状的每一个过程是假设受微效多基因所控制的;第二,林木具有很长的世代间隔,很高的遗传杂合性和很高的遗传负荷,这些特性限制了一些经典的遗传材料,如近交系,突变体及特异类型的产生。然而,传统的数量遗传学方法用于指导林木育种的实践并不是完美无缺的。林木个体高大,占地面积大,且大多栽植在非农用耕地上,这样的环境异质性在很大程度上影响性状遗传力的提高,有些林木树种人工杂交比较困难,很难获得足够大的家系,从而产生不平衡的交配设计。Ｎａｍｋｏｏｎｇ 和Ｒｏｂｅｒｄｓ（１９７６） 认为,不平衡的交配设计很难获得准确的遗传参数估计。到目前为止,大多数成功的林木育种方案往往都是基于对表型的简单选择。这种表型选择不能利用林木固有的非加性效应,以及对异质环境的反应潜能,因而育种效果是极为有限的。分子标记技术为现代数量遗传学的发展提供了新的方向。通过利用中性标记与影响数量性状的位点（ＱＴＬ） 之间的连锁关系,人们已经提出了一套统计方法用来鉴定重要的Ｑ     

A comparison of deterministically predicted genetic gains with those realised in a South African Eucalyptus grandis breeding program

Tree breeders attempt to predict the genetic gains that are likely to be achieved through selection and breeding of new generations, using stochastic or deterministic modelling. There are many factors that may cause a discrepancy between the predicted and realised genetic gains. Often the predictions for genetic gains are based on single trait selection, whereas in reality the breeding tends to be multitrait in nature. The violation of Hardy-Weinberg conditions, assumptions regarding outcrossing and relatedness, assumptions regarding the effect of the interaction between the environment and the genotype, and numerous possible errors in the process of breeding, all could result in unexpected discrepancies between the realised and predicted genetic gains. A series of genetic gains trials containing representatives of three generations of Eucalyptus grandis selections were compared with the view to verifying the effectiveness of the E. grandis breeding program. Genetic gains of the F₃ (third generation of pedigreed progeny) over the F₂ generation (second generation of pedigreed progeny) were 15% for tree growth (volume). A comparison between F₂ and P₀ revealed an improvement of between 20% and 33% for growth. This exercise highlighted complexities of modelling the predicted genetic gains of assimilated genetic breeding trials. The predictions of genetic gains did deviate (in both directions) from those realised, although these deviations may be explained as functions of imperfect modelling. On average, however, the predicted genetic gains for tree volume over three generations was 13% between generations, whereas the average realised genetic gain in the genetic gains trial was 14%. It is therefore assumed that the E. grandis breeding population is indeed performing as expected, following classical tree breeding assumptions.     

巨桉遗传改良研究进展

进行巨桉种源试验和地理变异研究时, 应重视从树种的生物学特性出发, 考虑试材的取样标准、群体的生殖和生态特性, 采用现代生物气候方法综合分析。巨桉有些群体存在着复杂的多型性, 采用复合轮回选择能明显提高自由授粉家系后代的遗传增益, 并提高种子园改良的质量。应用入选家系或个体的无性繁殖材料进行改良, 可获得更大的遗传增益。巨桉遗传改良应把有性和无性两条途径结合起来, 遵循简便、实用和高效的原则;基于这个原则, 本文提出了巨桉目前可能的最佳改良程序。     

Growth characteristics, stress-wave velocity, and Pilodyn penetration of 15 clones of 12-year-old Tectona grandis trees planted at two different sites in Indonesia

Tree improvement programs for teak (Tectona grandis) have mainly focused on breeding of trees with superior growth characteristics. However, improvement in wood quality should be included in breeding programs for high yield and high quality timber. In the present study, growth characteristics [stem diameter (D), tree height (H), and bole volume (V)], stress-wave velocity (SWV), and Pilodyn penetration (Py) were measured for 15 clones of 12-year-old teak trees planted at two different sites in Indonesia to clarify the variations in tree growth characteristics, SWV, and Py among clones, their repeatability, interaction between genotype and environment, and correlations between measured characteristics. Significant differences of all measured characteristics were found among 15 clones at both sites. Their repeatability showed relatively moderate to high values in both sites. These results indicate that these characteristics are closely related to genetic factors. Significant interaction between genotype and environment was found in all measured characteristics. In addition, SWV and Py showed lower interaction between genotype and environment than growth characteristics. No significant correlation was found between growth characteristics and SWV. These results suggest that wood properties and growth characteristics of teak trees can be improved by application of an appropriate tree breeding program.     

Tree domestication for agroforestry: present status and future directions

Seven different activities constitute tree domestication: (1) manipulation of tree populations by silvicultural practices; (2) enhancement of site productivity; (3) control of destructive agents; (4) evolution of trees under natural selection; (5) semi-natural selection for survival in the socio-agricultural circumstances in which trees are grown; (6) conscious human selection for desired characteristics; and (7) correlated response to selection (which usually involves reduction of those plant parts that are not desired). Each of these activities is discussed, and its contribution to the present makeup of tree populations used for agroforestry is considered.Although tree domestication has been practiced by farmers for many centuries, selection and breeding programs for multipurpose agroforestry trees have existed for only the past thirty years. Some of the problems faced by existing tree improvement programs are discussed; these include: multiplicity of usable species, great demand for multipurpose trees (MPTs), existence of improvement programs with few species, difficulty of combining desired traits in a multipurpose ideotype, high cost and slow progress with present methods, and the fate of improved material introduced on farms. Among the solutions considered is more involvement of farmers in the process of selection, testing, and propagation of MPTs. The possible use of species mixtures also holds promise.     

林木营养遗传和改良研究进展

就林木营养遗传研究进行综合评述,包括林木基因型对施肥反应的遗传差异、林木性状的遗传表达与营养环境、林木营养的遗传控制和变异机制等.鉴于我国现有林地和潜在造林地肥力普遍偏低,土壤缺氮少磷严重,在我国主要用材树种的现有育种程序中必须考虑营养性状的遗传改良.