Traditional management of cassava morphological and genetic diversity by the Makushi Amerindians (Guyana, South America): Perspectives for on-farm conservation of crop genetic resources

In this paper we present original data on morphological and genetic diversity of cassava managed by the Makushi Amerindians from Guyana. Although they propagate cassava exclusively vegetatively by means of stem cuttings, many Amerindian farmers also use and multiply volunteer plants grown from seeds produced by sexual reproduction. Morphological characters were recorded for 29 varieties cultivated by the Makushi and two populations of plants originating from volunteer cassava seedlings. Genetic characterisation with AFLP markers was available for 21 of the examined varieties. The morphological and agronomic characters were highly variable among varieties. Every variety could be differentiated from any other one, except for one pair of varieties. However, high intra-varietal variability existed, which might lead to confusions between phenotypically similar varieties by the Makushi. Seedlings were on average different from the pool of the varieties studied, but 67% were found to resemble closely enough one of the varieties to be liable to be assigned to it. Confusion between very similar varieties, as well as assignment of seedlings to a variety, should generate genetic variability within varieties, which was detected with AFLP markers. As in other sites in Amazonia, there was only a weak correlation between inter-varietal distances assessed with molecular and with morphological markers, suggesting that diversification of morphological characters has taken place repeatedly and independently across the Amazonian range of the crop. Diversifying selection, exchanges of varieties between farmers, and incorporation of sexually produced volunteer plants are key mechanisms responsible for the high diversity observed. Strategies of conservation of genetic resources should take these dynamic processes into account. This revised version was published online in July 2006 with corrections to the Cover Date.     

Variation in Rauvolfia serpentina genetic resources in India

Summary Rauvolfia serpentina (L.) Benth. ex Kurtz genetic resources from several regions of India were evaluated at New Delhi in the period 1970–76 to understand the variation pattern for root yield and associated polygenic traits. The Uttar Pradesh populations represented the wides range of diversity for most of the traits; the populations from Assam possessed high root yield potential. In other states, too, variation was evident. On the basis of variation pattern, areas in the Indian subcontinent were identified for collection and conservation of Rauvolfia germplasm.     

Plant genetic resources of Nepal: A guide for plant breeders of agricultural, horticultural and forestry crops

Summary Nepal is rich in indigenous wild and landrace plant genetic resources for agronomic, horticultural, forestry, or medicinal uses, but much of this germplasm remains uncollected and awaits economic development. We list 485 entries (species, or genera for ornamental plants) in 14 categories, and compare these to existing germplasm collections in Nepal and the United States to highlight collection and conservation needs. To help plant plant collecting, we outline the key botanical and logistical data and legal framework for planning field work in Nepal.     

Impact of plant genetic resources on wheat breeding

This article describes the impact of plant genetic resources on wheat breeding. It defines the important contribution of N.I. Vavilov Institute (St. Petersburg, Russia) to broadening the genetic diversity of new wheat cultivars. Special attention is given to conducting a comprehensive evaluation of intraspecific variability for valuable characters, including: 1) formation of special subcollections, consisting of accessions with useful characters and accessions representing intraspecies diversity for a given character; 2) revealing genetic differences among phenotypically superior accessions; 3) determining a genetic system of intraspecific variability for a given character; 4) formation of a genetic collection; 5) revealing and developing the donors of useful characters. An example using plant height shows that the proposed research approach adequately determines the genetic potential of species and reveals the most effective genes for practical uses. It is assumed that the main sources of genes for breeding Triticum aestivum L. in order of importance will remain: 1) intraspecific diversity of T. aestivum itself; 2) other Triticum species; 3) other genera of the Triticeae Dum. tribe (particularly Aegilops L.); 4) more remote genera of the Poaceae Barnh. botanical family. It is stressed that existing diversity of T. aestivum has been poorly investigated genetically and only partially used by breeders. Properly evaluated, it can provide multiple solutions for traditional and new problems of wheat improvement. This revised version was published online in August 2006 with corrections to the Cover Date.     

Wild emmer: genetic resources,gene mapping and potential for wheat improvement

Wild emmer, Triticum dicoccoides, the progenitor of cultivated wheat, harbors rich genetic resources for wheat improvement. They include many agronomic traits such as abiotic stress tolerances (salt, drought and heat), biotic stress tolerances (powdery mildew, rusts, and Fusarium head blight), grain protein quality and quantity, and micronutrient concentrations (Zn, Fe, and Mn). In this review, we summarize (1) traits and controlling genes identified and mapped in T. dicoccoides; and (2) the genes transferred to cultivated wheat from T. dicoccoides. These genes, controlling important agronomic traits such as disease resistance, high protein and micronutrient content, should contribute to wheat production and food nutrition. However, most of the rich genetic reservoir in wild emmer remains untapped, highlighting the need for further exploration and utilization for long-term wheat breeding programs.     

Diversity of potato genetic resources

A considerable number of highly diverse species exist in genus Solanum. Because they can adapt to a broad range of habitats, potato wild relatives are promising sources of desirable agricultural traits. Potato taxonomy is quite complex because of introgression, interspecific hybridization, auto- and allopolyploidy, sexual compatibility among many species, a mixture of sexual and asexual reproduction, possible recent species divergence, phenotypic plasticity, and the consequent high morphological similarity among species. Recent researchers using molecular tools have contributed to the identification of genes controlling several types of resistance as well as to the revision of taxonomical relationships among potato species. Historically, primitive forms of cultivated potato and its wild relatives have been used in breeding programs and there is still an enormous and unimaginable potential for discovering desirable characteristics, particularly in wild species Different methods have been developed to incorporate useful alleles from these wild species into the improved cultivars. Potato germplasm comprising of useful alleles for different breeding objectives is preserved in various gene banks worldwide. These materials, with their invaluable information, are accessible for research and breeding purposes. Precise identification of species base on the new taxonomy is essential for effective use of the germplasm collection.     

植物遗传资源国际交换的新规则

2001年11月3日．联合国粮农组织第31届大会通过了一份重要的国际法律文件,即《粮食和农业植物遗传资源国际条约》。该条约确立了植物遗传资源国际交换的新规则——粮食和农业植物遗传资源的获取和惠益分享多边系统。考虑到未来我国可能在国内落实获取和惠益多边系统的有关要求,本文拟就植物遗传资源国际交换规则的演进、获取和惠益分享多边系统及其实施机制进行较为深入的介绍和分析．以便促使我国相关部门和机构及早加以应对。     

草鱼种质资源研究进展

摘要：草鱼是世界上产量最高的养殖鱼类,也是我国很有特色的养殖对象,已经有1700多年的养殖历史。草鱼自然分布于中国、俄罗斯和保加利亚,但先后被引进到93个国家。在我国主要分布于长江、珠江和黑龙江三大水系。本文简要总结草鱼形态学、细胞遗传学、生化遗传学、分子遗传学及基因组学等方面的主要研究成果,归纳草鱼不同种群在形态、分子等层次上的遗传差异,并从草鱼种质资源研究以及草鱼种质资源的合理利用等角度提出了一些建设性的意见,为草鱼种质资源的保护和合理利用提供参考资料。     

植物核心种质构建方法的研究进展

本文结合国内外最新的研究进展对构建植物遗传资源核心种质的方法进行了综述,针对目前植物核心种质构建方法的研究现状与问题,提出了今后在核心种质构建方法中,应加强对取样策略、核心种质管理与有效性检验等问题的研究。尽快建立一批我国原产的、重要的植物遗传资源的核心种质,提高种质资源利用效率,提升种质创新能力,为我国植物资源的利用奠定基础。     

Collecting and evaluating genetic resources of fodder plants from subalpine and alpine permanent grassland

Summary The permanent grassland in the northern alpine and prealpine regions of Germany, Austria and Switzerland is characterized by a large genetic diversity of commercially important grass and clover species. This gene pool is endangered by the increasing practice of grassland renovation. The collection of genetic resources from that marginal habitat serves two purposes, therefore: Utilization of the gene pool in breeding programmes, and conserving the natural variation of endangered habitats. A considerable number of ecotypes of various species has been collected by several workers over a period of thirty years.Special attention is given to the materials collected and evaluated by Scheller (several species), Tyler (several species), Spatz (perennial ryegrass), Krings & Simon (Italian ryegrass) and Simon (several species). The materials described contain genotypes which appear useful for the improvement of such agronomically important characters as date of heading, plant height, winter hardiness, persistency and rust resistance under marginal conditions. From Simon's collections six cultivars registered or applied for registration in the German List of Cultivars emerged.     

贵州省湄潭地区杀虫杀菌植物资源调查研究

通过对湄潭地区杀虫、杀菌植物资源调查发现,植物对病虫害的作用不同,本文将植物分为8大类：杀虫、杀菌、驱虫、抑菌、抗菌、杀虫杀菌、驱虫杀菌、抑菌驱虫植物。8类植物分布于59科116个种内     

基于SSR标记的雪茄烟种质资源指纹图谱库的构建及遗传多样性分析

为从分子水平研究我国雪茄烟种质资源的遗传多样性差异并建立雪茄烟品种的DNA指纹图谱数据库,本研究利用43对多态性好的SSR引物对220份雪茄烟种质进行遗传多样性分析,筛选出14对核心引物对雪茄烟种质进行指纹图谱的构建。结果表明,43对SSR引物在220份雪茄烟种质材料中共扩增出243个等位基因,平均每个标记5.65个,变幅为2～13,每个位点的多态性信息量(polymorphism information content,PIC)变化为0.2078～0.9087,平均为0.6360。有效等位基因数(number of effective alleles, Ne)范围为1.3081～11.7876,平均有效等位基因数为3.9077;观测杂合度(observed heterozygosity, H_o)变化范围为0.0828～0.7639,平均为0.3191;预期杂合度(expected heterozygosity,He)的变化范围为0.2361～0.9172,平均为0.6809;种群平均Shannon遗传多样性指数(Shannon genetic diversity...     

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.     

A diversity analysis of genetic resources in rice

Summary A total of 1407 japonica and 488 indica accessions representing nine countries were randomly drawn from the International Rice Research Institute catalog of germ plasm resources for an analysis of diversity. The qualitative gene frequencies as well as means and coefficients of variation for quantitative traits for each race and country in general confirmed the widely recognized pattern of indica-japonica differentiation but suggested more overlap than often realized. Use of a diversity index showed indica to be more variable than japonica, but with different countries having similar levels of diversity. A multivariate analysis based on 39 characters showed divergence among countries within each race but with a great amount of overlap in the scatter of individual entries. This study was carried out simply to illustrate some genetic resource analyses and it is therefore discussed in relation to the documentation aspects.     

水源涵养区水土资源合理利用与管理研究综述

对国内外水源涵养区内水污染及水土流失防治、生态补偿、水土资源合理利用与管理模式及规划与管理模型等方面研究进行了回顾,并对其有关的理论和实践方面以及研究特点进行了概括与分析,同时指出了当前我国研究中存在的问题,最后对有待于进一步研究的问题进行了展望。     

Genome-wide genetic dissection of germplasm resources and implications for breeding by design in soybean

“Breeding by Design” as a concept described by Peleman and van der Voort aims to bring together superior alleles for all genes of agronomic importance from potential genetic resources. This might be achievable through high-resolution allele detection based on precise QTL (quantitative trait locus/loci) mapping of potential parental resources. The present paper reviews the works at the Chinese National Center for Soybean Improvement (NCSI) on exploration of QTL and their superior alleles of agronomic traits for genetic dissection of germplasm resources in soybeans towards practicing “Breeding by Design”. Among the major germplasm resources, i.e. released commercial cultivar (RC), farmers’ landrace (LR) and annual wild soybean accession (WS), the RC was recognized as the primary potential adapted parental sources, with a great number of new alleles (45.9%) having emerged and accumulated during the 90 years’ scientific breeding processes. A mapping strategy, i.e. a full model procedure (including additive (A), epistasis (AA), A × environment (E) and AA × E effects), scanning with QTLNetwork2.0 and followed by verification with other procedures, was suggested and used for the experimental data when the underlying genetic model was usually unknown. In total, 110 data sets of 81 agronomically important traits were analyzed for their QTL, with 14.5% of the data sets showing major QTL (contribution rate more than 10.0% for each QTL), 55.5% showing a few major QTL but more small QTL, and 30.0% having only small QTL. In addition to the detected QTL, the collective unmapped minor QTL sometimes accounted for more than 50% of the genetic variation in a number of traits. Integrated with linkage mapping, association mappings were conducted on germplasm populations and validated to be able to provide complete information on multiple QTL and their multiple alleles. Accordingly, the QTL and their alleles of agronomic traits for large samples of RC, LR and WS were identified and then the QTL-allele matrices were established. Based on which the parental materials can be chosen for complementary recombination among loci and alleles to make the crossing plans genetically optimized. This approach has provided a way towards breeding by design, but the accuracy will depend on the precision of the loci and allele matrices.     

Legume genetic resources: management, diversity assessment, and utilization in crop improvement

Grain legumes contribute significantly to total world food production. Legumes are the primary source of dietary proteins in many developing countries, where protein hunger and malnutrition are widespread. Grain legumes germplasm constitute ~15% of the 7.4 M accessions preserved globally. Nearly, 78% of the CGIAR??s, 0.217 M accessions, have been characterized, compared to 34% of national genebank collections. Interestingly, limited data on grain quality are available as the primary focus has been on morpho-agronomic traits. Clearly, more resources should be targeted on biochemical evaluation to identify nutritionally rich and genetically diverse germplasm. The formation of core and mini core collections has provided crop breeders with a systematic yet manageable entry point into global germplasm resources. These subsets have been reported for most legumes and have proved useful in identifying new sources of variation. They may however not eliminate the need to evaluate entire collections, particularly for very rare traits. Molecular characterization and association mapping will further aid to insights into the structure of legume diversity and facilitate greater use of collections. The use of high resolution elevational climate models has greatly improved our capacity to characterize plant habitats and species?? adaptive responses to stresses. Evidence suggests that there has been increased use of wild relatives as well as new resources resulting from mutagenesis to enhance the genetic base of legume cultigens.     

Organic varieties for cauliflowers and cabbages in Brittany: from genetic resources to participatory plant breeding

Plant breeding for organic agriculture (OA) was stimulated when it came under the European Organic Agriculture Regulation (2092/91) in 2004. In Brittany, the need for specific varieties for organic farming arose early for the Brassica species because of the unsuitability of most of the modern varieties to the principles of OA. Moreover, the private sector of plant breeding finds it economically difficult to satisfy the demands of OA. The aim of the present study is to provide varieties and seed for organic farmers for two vegetable Brassica crops, and to show how genetic resources can contribute to this purpose in the framework of a Participatory Plant Breeding (PPB) programme. The emergence of PPB in Brittany is the result of several concomitant and favourable circumstances: the will of the professionals (represented by IBB, Inter Bio Bretagne), their organization (an experimental station, the PAIS, Plateforme Agrobiologique d’IBB à Suscinio), the research initiative in INRA and the availability of genetic resources. From genetic resource observations, our experience showed several breeding situations: reviving a traditional activity (Roscoff cauliflower and local cabbages), extending tradition (autumn cauliflower), diversifying production by new introductions (coloured cauliflowers), and creating new forms of population varieties (broccoli and coloured cauliflowers). Farmers have taken charge of population breeding by mass selection and the PAIS, with INRA scientific support, has taken up innovative selection and the improvement of varieties completing the farmers’ initiatives. The PAIS remained the central point for information and for providing the seed for trials. Seed production will be managed in a collective way. Until now, the exchange of seed remained an experimental dimension of PPB. French seed legislation represents a limitation on the development of seed exchange by PPB.     

A pricing method of depletable nonrecyclable resources

A pricing method of depletable nonrecyclable resources has been advanced in this paper. Prices of resources, made with the method, can meet the needs of depletable nonrecycclable resources optimum allocation.