Strategies for conservation of genetic resources in relation with their utilization

The general interest for genetic resources is based on the opportunities offered by their utilization. Genetic resources are a necessary starting point for plant improvement. Up to now, reflection on the management of genetic resources considered a three-step linear model: conservation → evaluation → utilization. In this system, it is expected that genetic resources are kept in a gene bank, in the best possible way, i.e. using methods maintaining over time the initial genetic state of the accessions and conferring them the longest life possible. In this system, important characteristics of conservation of genetic resources are stability and availability. We present a choice of methods of conservation directed to the maintenance of genetic stability of accessions. We also present methods of conservation in relation with the availability of the genetic material for the various utilizations by the plant breeder. Complementary methods are now proposed for the conservation of genetic resources. These methods correspond to a modified version of the linear model, with interactions between conservation, evaluation and utilization. These new methods place less emphasis on the conservation of genetically well defined accessions but promote genetic mechanisms allowing evolution of these accessions. This evolutionary conservation is obtained by management of experimental populations, or by on-farm management of landraces, relying on knowledge and activity of farmers, and on local breeding. For the wild relatives of crops, an in situ management is to be considered. Using some examples, we discuss the constraints of these new modes of genetic resources conservation and utilization. This revised version was published online in July 2006 with corrections to the Cover Date.     

植物杂种优势研究进展

杂种优势是广泛存在的遗传学现象,并在多种动植物中得到成功的利用,但对于杂种优势产生的遗传学机理尚未十分清楚.本文对植物杂种优势机理研究进行了较为详尽地评述,在综述了杂种优势遗传基础经典理论和假说的基础上,概括了利用分子生物学手段解释杂种优势遗传基础的一些新见解.探讨了杂种优势群和分子标记与杂种优势的关系.最后对杂种优势研究的未来发展方向进行了展望.     

黑龙江省大豆遗传结构及遗传多样性分析

利用22个表型性状和60个微卫星(simple sequence repeat, SSR)位点对黑龙江省140份代表性种质(78份地方品种和62份育成品种)进行分析, 根据UPGMA (unweighted pair group method with arithmetic mean)和Model-base对SSR数据进行遗传结构划分。结果表明, 参试品种可分为2大类群, 第II类群的各项多样性指标均高于第I类群, 2个类群遗传距离为0.2427;PCO结果显示这2个类群分布在不同区域, 这与地理来源和育成年代密切有关。依据品种类型分为育成品种和地方品种两组, 后者的各项多样性指标均高于前者, 两组间的遗传距离为0.1131。依据表型数据的PCO分析表明, 分布区域与品种类型有关, 与SSR结构分类的结果吻合度低, 两组品种主要在3个主成分的6个表型性状上有所不同。它们不是2个相对独立的遗传群体, 根据分子标记和表型分类各有特点;建议在种质遗传多样性研究中将分子数据和表型数据结合起来。     

中国普通野生稻遗传多样性研究进展

普通野生稻是亚洲栽培稻的祖先,中国作为亚洲栽培稻的起源地之一,蕴藏着丰富的普通野生稻资源。为了揭示中国普通野生稻的遗传多样性分布状况,探索普通野生稻的遗传变异规律、居群遗传结构以及演化途径等,为亚洲栽培稻的起源进化研究、品种改良和普通野生稻保护提供科学依据,国内外学者对中国普通野生稻开展了大量的遗传多样性研究,获得了丰富的研究结果。本文分别从遗传多样性研究方法、普通野生稻与亚洲栽培稻遗传多样性的比较、普通野生稻遗传多样性与地理分布和生态环境的关系、保护措施和栽培稻基因渗入对遗传多样性的影响等几个方面的研究结果进行了综述,总结了中国普通野生稻遗传多样性的主要特征,提出了未来我国普通野生稻遗传多样性的研究方向。     

利用2个F_2群体整合中国豌豆高密度SSR遗传连锁图谱

豌豆(Pisum sativum L.)是一种重要的食用豆类作物,在全世界范围内广泛种植,既可作为人类食物,也可作为牲畜饲料。用SSR标记构建的遗传连锁图谱在豌豆和其他作物的标记辅助育种中发挥着重要的作用。尽管对豌豆遗传连锁作图的研究已有悠久历史,但公众可获得且可转移的SSR标记以及基于遗传独特的中国豌豆种质的高密度遗传连锁图谱仍然有限。为了获得更多可转移的SSR标记和中国豌豆的高密度遗传连锁图谱,本研究首先从自主开发和文献获取的12,491个全基因组SSR标记中筛选了617个多态性SSR标记,并用于G0003973×G0005527 F_2群体遗传连锁图谱的加密。加密后的图谱全长扩展到5330.6 cM,包含603个SSR标记,标记平均间距离8.8 cM,相比之前的图谱有明显改善。基于上述结果,我们又筛选了119个具有多态性的SSR标记,用于构建大样本W6-22600×W6-15174 F_2群体的遗传连锁图谱,新图谱累积长度为1127.1 cM,包含118个SSR标记,装配在7条连锁群上。最后,将来自以上2个遗传图谱的数据进行整合,得到了一张覆盖范围6592.6 cM的整合图谱,包含668个SSR标记,由509个基因组SSR、134个EST-SSR和25个锚定标记组成,分布在7条连锁群上。这些SSR标记和遗传连锁图谱将为豌豆的遗传研究和标记辅助育种提供有力工具。     

Estimating genetic effects in maternal and paternal half-sibs from tetraploid-diploid crosses in <Emphasis Type="Italic">Musa</Emphasis> spp.

Ploidy manipulations and interspecific crosses have allowed considerable genetic progress in Musa breeding, but estimation of genetic parameters for parental selection remains a major challenge. This study aimed to determine the components of genetic variance and the relative contribution of genetic effects to phenotypic variation of yield and phenological traits in secondary triploid hybrids from tetraploid–diploid crosses. The hybrids were evaluated in two consecutive growth cycles on a tropical forest site. Non-genetic effects accounted for a large fraction of the variation observed for most traits, except bunch weight. Partitioning of genetic variance into additive and dominance components confirmed the predominant role of additive genetic effects on the expression of bunch weight, fruit filling time, fruit length, plant height, and number of leaves while primarily non-additive effects accounted for suckering behavior and fruit circumference. Maternal general combining ability (GCA) effects accounted for the additive genetic variation in plant height and number of leaves, suggesting that selection for these traits should be carried out in tetraploid clones. Conversely, paternal GCA effects were the primary causes of genetic variation for fruit filling time, bunch weight, and fruit length, suggesting that these characters should be selected for in diploid clones. Specific combining ability (SCA) effects were observed for all traits, except fruit filling time, suggesting that additional genetic gain could be achieved through recombinative heterosis for these traits.     

河南夏大豆区近30年主要大豆品种产量改良的遗传进展

提高产量是大豆育种的主要目标。研究大豆产量及其相关性状的遗传进展,对于今后制定高产育种策略有重要参考意义。本研究随机选择近30年河南主要育成品种中的18个大豆品种,进行两年产量评价试验的研究。结果表明,产量随育种年份增加总体呈递增趋势,遗传进展为17.39kghm^-2,年递增率是0.7%;有效分枝、主茎节数、百粒重、株高有弱的正向遗传进展,而单株荚数和每荚粒数表现弱的负向遗传进展,但均不显著。百粒重、主茎节数和株高与产量有显著的遗传相关与表型相关,环境相关均不显著,表明这3个性状具有较大的遗传力,随产量性状的遗传改良,这3个性状均协同提高,且不易受环境条件的影响;而有效分枝、单株荚数、每荚粒数与产量的遗传相关和表型相关均没达到显著水平,这是它们与百粒重、主茎节数、株高有极显著负遗传相关所致。     

苜蓿生物技术研究进展

苜蓿是世界上重要的豆科牧草,它具有品质优良、易于栽培等特点,在生态环境保护方面也发挥着积极作用。随着分子生物学和植物基因工程的发展,在分子水平上对苜蓿进行遗传改良的研究已取得了部分成果。本文简单介绍了苜蓿组织培养的种类及影响因素,综述了近年来遗传转化和分子标记等生物技术在苜蓿研究领域的应用,并展望了苜蓿基因工程在今后研究工作中的重要地位和前景。     

新疆自育陆地棉品种SSR遗传多样性分析

利用SSR标记对94份新疆自育陆地棉品种的基因组进行分析,研究新疆陆地棉品种的遗传多样性。结果: 从分布于棉花全基因组的206对SSR标记中筛选出54对具有稳定多态性的引物, 共检测出153个多态性位点, 每对引物的等位变异为2~6个,平均为2.93个;基因型多样性(H′)变幅为0.0439–0.7149,平均为0.4491;引物多态信息含量(PIC)为0.0430–0.6640,平均为0.3831。表明SSR标记在品种间可以反映较丰富的遗传多样性信息。94份品种间成对遗传相似系数变幅为0.3846~0.9835, 71.9%的品种相似系数在0.601~0.800内,反映出新疆陆地棉品种间的遗传相似性相对较高。根据UPGMA 聚类分析,在阈值为0.63时,将94份品种划分为2个类群,说明新疆陆地棉品种间遗传关系相对简单,品种的遗传基础相对狭窄,品种遗传组分差异较小,总体上遗传多样性不够丰富;分子聚类结果与品种本身遗传系谱背景和演变趋势吻合度较高,符合品种的真实特性。研究证明,自育品种在分子水平上差异不大,需要努力拓宽品种选育的遗传基础。     

籼型杂交早稻稻米品质性状的种子、细胞质和母体遗传效应分析

研究早籼杂交稻稻米品质性状的种子、细胞质和母体遗传效应,能为品质遗传改良提供理论依据.本研究以6个籼型不同胞质类型的三系不育系为母本,5个旱籼恢复系为父本,按不完全双列杂交设计,采用禾谷类作物种子数量性状平均数遗传模型,分析了旱籼杂交稻品质性状的遗传效应.结果表明糙米率、精米率、粒长、垩白粒率、直链淀粉含量、碱消值、整...     

Analysis of Global Stability of Soil Nailing Bracing Structures in Non-homogeneous Soil

Based on Swedish slices limited equilibrium method, a new computation formula of stability safety factor is presented for interior stability analysis of soil nailing wall in non-homogeneous soil. A new genetic algorithm is put forward by adopting dynamic self-adaptive technology and nonstandard genetic operators. Applying the dynamic self-adaptive technology and nonstandard genetic operators into the field of soil-nailing wall interior stability analysis, the dynamic adaptive genetic algorithm for searching the arbitrary critical slip surface is established. It is shown that the dynamic adaptive genetic algorithm has better performance in finding optimal solution, quicker convergence than traditional algorithm as well as more reasonable results.     

大豆籽粒异黄酮含量的遗传效应研究

大豆异黄酮含量差异较大的6个大豆品种为亲本，通过双列杂交配置杂交组合，测定了两个环境条件下亲本、F₁和F₂种子的异黄酮含量。采用双子叶植物种子数量性状遗传模型和统计分析方法, 分析了胚、细胞质和母体植株等不同遗传体系的基因效应以及环境互作效应。结果发现大豆籽粒异黄酮含量的表现主要受制于母体遗传效应, 其次为胚(子叶)基因效应,细胞质效应影响较小。不同遗传体系的基因主效应明显大于环境互作效应。异黄酮含量的机误方差较大,说明异黄酮含量更易受到环境条件变化影响。亲本遗传效应分析表明, 选用豫豆29或郑90007亲本有利于增加杂种后代大豆籽粒异黄酮含量,提高品质改良的效果。胚显性方差和母体显性方差均极显著，表明种子杂种优势和母体杂种优势会同时存在，而且是不受环境影响的主效应基因。     

石榴遗传标记研究进展

石榴属石榴科石榴属植物,是我国古老的栽培果树之一,具有较高的营养、药用、观赏价值。本文分别对形态学标记、细胞学标记、生物化学标记、和分子标记在石榴上的应用进展进行了综述,并对当前石榴遗传标记研究存在的问题及对策进行了分析和探讨。     

AFLP分析小豆种(Vigna angularis)内遗传多样性

利用12对AFLP引物,对来自于世界6个国家的146份小豆(Vigna angularis)栽培变种(var. angularis)和野生变种(var. nipponensis)种质的基因组DNA进行扩增,得到580条清晰的显带,其中313(53.93%)条呈多态性,平均每对AFLP引物得到26.08条多态性带;平均遗传距离0.35,变异幅度为0.00～0.87.利用AFLP多态性数据进行的Jaccard''s遗传距     

山核桃子代甲基化分析及其与薄壳山核桃甲基化的比较

为了研究山核桃的遗传,本研究采用MSAP (Methylation sensitive amplification polymorphism)标记分析了山核桃30个半同胞子代群体及薄壳山核桃29个无性系,并在山核桃亲子代间及山核桃与薄壳山核桃间比较了遗传及甲基化水平。研究发现,山核桃半同胞子代群体非甲基化遗传位点(Non-methylation loci,NML)的比例较高,占33.69%,随后依次是内部胞嘧啶甲基化位点(15.18%)、半甲基化位点(9.25%);其遗传多样性(0.110 3±0.028 4)极显著地小于表观遗传多样性(0.568 5±0.112 3)(p<0.000 1);半同胞子代群体间存在显著的遗传与表观遗传分化,且大部分遗传变异和表观遗传变异存在于群体内,说明亲本间存在遗传差异。甲基化水平在山核桃亲子代间无显著差异(p>0.05),说明甲基化存在代际遗传。山核桃中NML的比例远大于薄壳山核桃,两物种表观遗传多样性相当,但薄壳山核桃的遗传多样性要高于山核桃;两物种遗传和表观遗传差异极显著(p<0.000 1),供试个体基于物种的遗传位点可以分别聚类,说明两物种各自个体间有遗传差异。甲基化敏感位点(Methylation-sensitive loci, MSL)及NML在两物种间存在极显著差异,且变异主要存在于物种内,两物种有明显的分化,但从各遗传参数值来讲,两物种又十分相像,正反交基于亲缘关系可行。不同于山核桃,薄壳山核桃遗传位点对甲基化位点影响极显著。     

基因多态性与牛疾病相关性的研究进展

基因多态性是指基因组序列上的变异,它是决定家畜对疾病易感性与抵抗力、疾病临床表现多样性以及不同个体对药物反应性的重要因素。研究基因多态性有利于鉴定和定位致病基因和疾病易感基因,使得从遗传学的角度控制疾病成为可能,从而达到减少家畜疾病防治的成本,改良家畜品种,为人类提供健康的动物产品的目的。本文主要从抗病育种的角度综述了近年来基因多态性与牛疾病易感性和抗性的相关研究,并结合遗传信息学和表观遗传学,阐述家畜疾病控制的新进展。     

农杆菌介导遗传转化在水稻基因工程育种中的应用

随着生物技术的发展，水稻基因工程育种在水稻育种中发挥着越来越重要的作用。在诸多的转基因方法中，农杆菌作为一种天然的植物基因转化系统，以其独特优点而倍受重视。本文概述了农杆菌介导转化水稻的原理，农杆菌介导转化水稻的优点并且介绍了农杆菌菌株、受体材料和培养基成分的不同对农杆菌介导转化水稻的影响。另外对农杆菌介导遗传转化在水稻抗虫基因工程育种、抗病基因工程育种、抗逆基因工程育种、优质基因工程育种、耐除草剂基因工程育种及提高水稻光合效率和延缓衰老方面的研究进展进行了综述。最后对农杆菌介导遗传转化在水稻基因工程育种中存在的问题和发展前景做了简要说明。     

Recurrent selection of cocoa populations in Côte d'Ivoire: comparative genetic diversity between the first and second cycles

In Côte d'Ivoire, the cocoa breeding programme has been based on the creation of hybrids between different genetic groups. From 1990 onward, a reciprocal recurrent selection programme has been set up with the purpose of improving simultaneously the characteristics of the two main genetic groups: Upper Amazon Forastero (UA) and a mixture of Lower Amazon Forastero (LA) and Trinitario (T). Based on data obtained from 12 microsatellite primers, the genetic diversity and genetic distances of the parental populations used in the first and second selection cycles are presented. The results revealed that the diversity of populations UA0 and UA1 on the one hand and (LA+T)0 and (LA+T)1 on the other is similar. The genetic distances were small between the parental populations used for the first and second cycles. Genetic diversity was greater in the UA group than in the LA+T group. The number of rare and of private alleles was reduced for both genetic groups, as well as the number of the frequent alleles in the LA+T group.     

Molecular assessment of genetic diversity in winter barley and its use in breeding

Summary During the last decades extensive progress has been achieved in winter barley breeding with respect to both, yield and resistance to fungal and viral diseases. This progress is mainly due to the efficient use of the genetic diversity present within high yielding adapted cultivars and – with respect to resistance – to the extensive evaluation of genetic resources followed by genetic analyses and introgression of respective genes by sexual recombination. Detailed knowledge on genetic diversity present on the molecular level regarding specific traits as well as on the whole genome level may enhance barley breeding today by facilitating efficient selection of parental lines and marker assisted selection procedures. In the present paper the state of the art with respect to virus diseases, i.e. Barley mild mosaic virus, Barley yellow mosaic virus, and Barley yellow dwarf virus is briefly reviewed and first results on a project aiming on a genome wide estimation of genetic diversity which in combination with data on yield and additional agronomic traits may facilitate the detection of marker trait associations and a more efficient selection of parental genotypes are presented. By field tests of 49 two-rowed and 64 six-rowed winter barley cultivars the genetic gain in yield for the period 1970–2003 was estimated at 54.6 kg ha⁻¹ year⁻¹ (r² = 0.567) for the six-rowed cultivars and at 37.5 kg ha⁻¹ year⁻¹ (r² = 0.621) for the two-rowed cultivars. Analysis of 30 SSRs revealed a non-homogenous allele distribution between two and six-rowed cultivars and changes of allele frequencies in relation to the time of release. By PCoA a separation between two and six-rowed cultivars was observed but no clear cut differentiation in relation to the time of release. In the two-rowed cultivars an increase in genetic diversity (DI) from older to newly released cultivars was detected.     

茶树遗传演化研究进展及SSR在茶树遗传演化研究中的应用前景

茶树[Camellia sinensis (L.) O. Kuntze]起源于我国的西南地区,在由起源地向我国其他地区和世界其他地区传播的过程中,发生了从形态学水平到细胞水平再到分子水平的一系列演化。对茶树遗传演化的研究,是茶树基础生物学的一个基本问题,也是茶树种质资源研究的重要方面。近年来,各种新技术、新方法被广泛应用于研究茶树遗传演化关系,取得了一定的进展。本文从形态学、细胞学、生物化学、分子生物学方面对茶树遗传演化研究取得的进展进行了综述,分析了SSR标记在植物遗传演化中的应用,探讨了SSR标记在茶树遗传演化研究中的应用前景,旨为进一步深入研究我国茶树遗传多样性、亲缘关系及演化路径分析提供参考。