Linking changes to breeding objectives and genetic evaluation to genetic gain in New Zealand

This article uses the breeder’s equation, which predicts genetic gain in breeding programs, to frame a general discussion on breeding objectives, new phenotypic techniques for selection criteria and statistical models as applied to short rotation species. Short-rotation breeding programs are increasingly working on wood quality traits; however, we keep on treating them as if they were growth traits. Understanding tree-level patterns of variation can lead to alternative strategies for evaluation, analysis and inclusion in breeding objectives; which I describe in a pilot application in Pinus radiata in New Zealand. Finally I discuss the relationship between the breeder’s equation and formulations of linear mixed models, using genotype by environment interaction as example, to show the interplay between genetic evaluation and breeding strategies. There is tension between increasing complexity (and the implicitly promised flexibility), information recovery (as more parameters are poorly estimated) and computational demands. The latter can be tackled through much more computer power (a never-ending endeavor), exploiting features of the problem or moving back to a lower complexity level.     

Allozyme markers in forest genetic conservation

Genetic diversity is important in tree-breeding, in managing rare and endangered tree species, and in maintaining healthy populations of widespread native tree species. Allozymes are useful in determining genetic relationships among species, where they can be used to assess affiliations of rare taxa and predict relative endangerment among species. Because allozymes sometimes yield different information about genetic variation within species than revealed by other traits, when estimates of total or adaptive genetic variation are important, allozymes are best used in conjunction with other traits. Allozymes are useful for measuring direct allelic diversity when designing ex-situ and in-situ conservation strategies. We demonstrate an application of canonical trend-surface analysis for determining locations of in-situ genetic conservation areas. Allozymes also serve as useful markers in monitoring the effects of forest management and other environmental changes on genetic diversity.This article was written and prepared by U.S. Government employees on official time, and is therefore in the public domain.     

新疆野生山楂资源遗传多样性及亲缘关系的ISSR分析

为给新疆野生山楂资源的保护与利用提供理论依据和技术支持,采取新疆3种野生山楂共计63份材料,利用ISSR标记技术,对其遗传多样性和亲缘关系进行分析。结果表明,12条引物共扩增出233条带,其中多态性条带221条,多态性位点率为94.4%,平均每个引物获得19.42个扩增带。POPGENE1.32分析结果表明:3种野生山楂材料的多态性位点率、观测等位基因数、有效等位基因数、Nei’s基因多样性和Shannon信息指数,均为准噶尔山楂最高,阿尔泰山楂次之,红果山楂最低。3种新疆野生山楂进行两两比较,其Nei’s遗传相似度为0.862 2~0.904 4,平均值为0.890 2;遗传距离为0.100 5~0.148 3,平均值为0.1166。3种野生山楂中,准噶尔山楂存在较为丰富的遗传变异,其次是阿尔泰山楂,红果山楂的遗传变异较小。阿尔泰山楂和红果山楂的亲缘关系较近;准噶尔山楂和红果山楂间亲缘关系较远。     

遗传辩识

本阐述了遗传辩识产生的背景、思想及其应用价值。     

Patterns of genetic diversity in Australian tree species

Australia has a large endemic tree flora with many of the genera largely confined to the southern hemisphere. The two dominant genera are Eucalyptus and Acacia. Isozyme studies of patterns of genetic diversity in populations of these species are reviewed. Generally, Australian tree species have high levels of allozyme variation with most of this variation within rather than between populations. The species with the most genetic differentiation between populations are those with regional distributions but with small disjunct populations. Many of the species show no discernible relationship between current population sizes and genetic diversity. A number of species with widespread distributions exhibit similar clusters of populations both on isozymes and other traits. Such clusters often correspond to large geographic regions. This pattern suggests that preliminary low intensity isozyme surveys could help to define more efficient sampling strategies for intensive seed collections and subsequent field trials of many tree species.     

Managing biological and genetic diversity in tropical agroforestry

Agroforestry Systems - The issues of biological and genetic diversity management in agroforestry are extremely complex. This paper focuses on genetic diversity management and its implications for...     

林木遗传图谱构建研究概述

林木遗传图谱构建研究是进入90年代以来林木遗传研究领域中进展最快且影响较大的领域之一。构建林木遗传图谱是对林木在分子水平上进行系统研究的基础工作，有重要的理论价值和潜在的应用价值。由于林木复杂的生物学特性，林木的遗传图谱构建一直被视为作图研究的难区，90年代初，由美国北卡州立大学发表的首张林木的遗传图谱曾引起较大的轰动和反响，经过10a来的发展，林木遗传图谱构建研究取得很大的进展。该文就林木遗传图谱构建的基本原理、作图方法和作图过程及近几年来林木作图和图谱应用研究的最新进展进行了综述。     

鹿类微卫星遗传标记的研究现状(英文)

微卫星DNA在染色体上随机即分布，是十分有效的遗传标记。目前，在鹿类发现约有200 多个微卫星位点，除了极少数位点是直接从DNA文库中筛选的以外，绝大多数都是将牛、羊 的微卫星位点“借用”到鹿类。这些位点被广泛应用到父权鉴定、遗传多样性和种群结构分 析、种群基因渗入的检测、孕期长短及越冬存活率等的遗传标记等方面的研究中。然而，微 卫星DNA的数量目前还远不能满足研究需要。将来要在以下方面开展工作：1）分离更多的鹿 类特异的微卫星位点，2）构建微卫星位点的遗传和物理图谱。这样，微卫星DNA才能在鹿类 研究中发挥更大的作用。     

Estimation of genetic gain and diversity under various genetic thinning scenarios in a breeding seed orchard of Quercus acutissima

Genetic gain and diversity were estimated based on three simulated thinning scenarios at various thinning intensities in a breeding seed orchard of Quercus acutissima. The seed orchard was composed of 32 families with 744 individual trees with volume at age 15. The three thinning scenarios were individual thinning (IT) which thinning was based on the individual performance, family thinning (FT) with the removal of inferior families regardless of individual performance, and family + within family thinning (FWF) with family first and then individual from inferior families. The genetic gain was estimated based on stem volume. Expected genetic gain (volume at age 15) under IT was higher than FT and FWF at all thinning intensities. The FWF provided higher genetic gain than FT but lower than IT. The FT gave the lowest genetic gain compared to the other thinning scenarios at all thinning intensities. The loss of gene diversity (GD), estimated by coancestry and family size, was higher under FWF and lower under FT at moderate thinning intensities. The study showed that genetic gain estimation and GD loss were inversely coupled. The IT gave highest genetic gain but lowest GD at the highest thinning intensity.     

利用根癌农杆菌转化木本植物的研究进展

本文着重论述了近年来国内外利用根癌农杆菌介导法转化林木的研究进展。简述了获得转基因林木的应用现状,并将国内外林木转基因工作给以概括,提出了转化过程中存在的问题,并对这一转化方法的应用前景进行了展望。     

锥栗主栽农家品种遗传多样性的SSR分析

为给锥栗杂交育种和遗传作图的亲本选配提供参考,应用SSR分子标记技术,分析了福建省建瓯市17个锥栗主栽农家品种的遗传多样性。结果表明:不同农家品种遗传多样性丰富,利用筛选出的12对引物组合扩增的片段大小主要在50~2 000 bp之间,共扩增出180个位点,多态位点163个,占90.56%;17个锥栗主栽农家品种的遗传相似性系数在0.509 2~0822 1之间,乌壳长芒和牛角仔(晚熟)的相似性系数最大,中尖嘴与白露仔的相似性系数最小,且在相似性系数为0.60处,大尖嘴和中尖嘴单独聚为I类,在相似性系数为0.77处,第II类又被分为A~H共8个组;SSR引物组合Cs CAT33和Cm TCR4共同构建了17个锥栗主栽农家品种的DNA指纹图谱。     

薄壳山核桃果实性状的遗传变异与相关性研究

为了选育适应我国种植的薄壳山核桃优良品种,研究薄壳山核桃实生后代的遗传变异规律,对南京中山植物园周边地区树龄在55～60a的249株薄壳山核桃实生后代果实的9个性状方面的遗传变异情况进行了调查与分析。结果表明:果实质量变异度最大,变异系数为26.67%,其它性状变异度都较小,变异系数在7.12%～12.91%之间;果实性状的变异表现为连续变异,属于数量性状遗传;果实性状的分布表现为正态分布规律,偏倚系数较小;果实性状多数指标的相关性显著,其中果实质量与果壳厚度、果实含油率分别与出仁率和种仁含油率呈极显著正相关性,果实质量和果壳厚度分别与出仁率、果实含油率呈极显著负相关性;根据果实性状间的相关性,建立起相关回归模型,决定系数在0.99以上,回归测验的F值达到了6880,均远高于极显著临界值,模型准确可靠。     

昆虫遗传多样性研究及展望

遗传多样性研究层次主要有细胞、蛋白质和DNA。介绍了遗传多样性的基本含义和现状。从3个层次对昆虫遗传多样性的研究方法和研究内容进行了评述,其中着重讨论遗传多样性的研究进展,并提出了DNA序列变异尺度将成为今后遗传多样性的研究重点。     

广宁红花油茶果实性状的遗传变异规律

为了选育适合我国种植的广宁红花油茶优良品种,对广东省广宁县及周边地区树龄在40～55 a的99株广宁红花油茶实生后代果实的9个性状方面的遗传变异情况进行了调查与分析。结果表明:干籽质量变异度最大,变异系数为32.24%,其它性状的变异系数在8.51%～30.14%之间;各产地按照不同性状变异系数的大小主要可以分为5部分,干籽质量、鲜籽质量的变异系数较大,其次为单果籽数、果实质量、果皮厚,再次为纵径和横径,果形指数的变异系数较小,变异系数最小的是种仁含油率。含油率的变异系数的波动性较大。     

Estimates of genetic parameters and genetic gains for growth traits of two Eucalyptus urophylla populations in Zululand,South Africa

In South Africa, Eucalyptus urophylla is an important species due to its disease tolerance to fungal diseases such as Crysoporthe austroafricana and the Coniothyrium sp. cankers. It is mainly planted as a parental species in a hybrid combination with E. grandis. Generally, the E. grandis × E. urophylla hybrid has better disease tolerance and higher wood density than pure E. grandis. The current strategy is to maintain large breeding populations of both parental species in order to provide improved elite selections for hybrid crosses on a regular basis. With this in mind, two E. urophylla populations, consisting of five provenance/progeny trials, were established in the subtropical region of Zululand. The aims of this study were, firstly, to determine the magnitude of genotype × environment interaction of E. urophylla in Zululand; secondly, to estimate genetic parameters and correlations for diameter at breast height (DBH), height and volume; and thirdly, to identify selections to advance the current breeding population as well as to hybridise with E. grandis. Results indicated that genotype × environment interaction effects would be practically negligible for growth in Zululand and therefore a single breeding population will be appropriate. In general, all growth traits were under low to moderate genetic control, with narrow-sense heritabilities ranging between 0.14 and 0.48 for volume. The genetic correlations between growth traits were high (0.98 and 0.99 for DBH– volume). This is an indication that DBH is a sufficient growth measure to use in E. urophylla breeding programmes. Best linear unbiased prediction estimates indicated that aa selection scenario of 200 individuals will generate genetic gains of 44.7% over the population mean. The estimated gains for the top 50 individuals that could potentially be used as hybrid parents to cross with E. grandis was 59.8% over the population mean.     

黧蒴栲半同胞家系生长性状变异规律及遗传参数估算

为探讨黧蒴栲半同胞家系生长性状遗传变异规律和估测其遗传参数,采用完全随机区组设计,对52个6年生黧蒴栲半同胞家系进行生长测定分析。结果表明：黧蒴栲家系间胸径、树高和材积生长均存在极显著差异。52个黧蒴栲半同胞家系平均胸径为8.53em,变异幅度为6.31～10.85am;平均树高为8.23m,变异幅度为5.08～10.14m;平均材积为0.02828 m^3,变异幅度为0.01099～0.05407 m^3。黧蒴栲半同胞家系胸径遗传变异系数为13.74％、广义遗传力为0.7404;树高遗传变异系数为13.74％,广义遗传力为0.7150;材积遗传变异系数为35.36％,广义遗传力为0.7539。表明黧蒴栲半同胞家系胸径、树高变异较小,受较强遗传控制,材积变异较大,也受较强遗传控制,通过一定强度的选择,能获得较高的遗传增益。     

Patterns of genetic diversity that result from bottlenecks in Scots Pine and the implications for local genetic conservation and management practices in Bulgaria

As one of the principal coniferous species of commercial importance in Bulgaria, Scots Pine has been subjected to strict management, which has posed a challenge for the conservation and management of its gene pool. In this study, we measured genetic diversity and population structure using 6 microsatellite loci in 12 populations from Bulgarian mountain ranges. Our analysis showed good intrapopulation divergence (18.22%; AMOVA) and genetic evidence of bottlenecks. “NJ-IAM” and “non-admixing” clusters divided the populations into 3 large groups. Our microsatellite analysis was consistent with the documented “mountain effect” influence on genetic diversity. Two methods—the Coalescent Bayesian model and M-stat analysis—implicated recent bottlenecks for all populations, suggesting that the genetic structure of Bulgarian Scots Pine was shaped over a long period (one thousand generations; i.e. 20,000 years) by the interaction of genetic and autoecological processes. Our results suggest that conservation and management practices should strive to maintain this genetic differentiation, specifically by emphasizing reforestation efforts with stocks from local provenances to avoid nonlocal introductions.