Grasspea (Lathyrus sativus L.) is an annual, herbaceous, drought-resistant legume and staple crop in Asian and African countries. Little is known about the nature and the amount of genetic diversity present in existing grasspea seed collections, yet this information is pivotal for future breeding programmes, such as those striving to reduce high neurotoxin levels present in seeds. Here we report on the level of genetic diversity within a world-wide collection of L. sativus, determined by isozymatic analysis. Although grasspea is generally considered a predominantly self-pollinating species, we found that the population genetic structure of these accessions showed a considerable outcrossing rate of 36%. The identification of a mixed mating system in L. sativus has significant implications for collecting and multiplying genetic resources for conservation and for future breeding purposes. In addition, we determined the genetic closeness of grasspea accessions from different geographical regions around the world. While we noticed an allelic richness in this species that was conserved across the regions, we did not find any evidence of high genetic identity between accessions, even when originating from the same geographical location. Instead, we found that greater genetic variability existed at the intra-regional level than at the inter-regional level.

Sinapis alba L. is a major specialty crop grown as a condiment in western Canada, but little is known about its genetic diversity. The objective of this study was to assess the level and pattern of genetic diversity in a collection of 127 S. alba accessions held at Plant Gene Resources of Canada using amplified fragment length polymorphism (AFLP) markers. Five AFLP primer pairs were applied, and 134 polymorphic bands were scored for each accession. These scored bands had frequencies of occurrence ranging from 0.02 to 0.99 with an average of 0.69. More AFLP variation was found within single (79.1%) than between (20.9%) S. alba accessions. A small degree of AFLP difference (1.7%) was observed among the accessions of various regions, while relatively large variation (9.2%) existed among the accessions of various countries. A large AFLP difference (15.6%) also existed between the yellow- and brown-seeded accessions, but only 6.2% difference was observed between the cultivar and landrace accessions. Two distinct groups of S. alba germplasm were identified on the basis of the seed colour (yellow or brown), although a few mixtures also existed. No apparent ‘duplicated’ accessions were observed. The most diverse accessions were from Italy, Spain, France and Greece. Among the most genetically distinct accessions were SA97 from Portugal, SA89 and SA88 from France, SA83 from Russia and SA57 from Italy. These findings are significant not only for managing S. alba germplasm, but also for identifying diverse germplasm that can be used by plant breeders to improve S. alba seed yield and quality parameters.

The International Center for Agricultural Research in the Dry Areas (ICARDA) is participating in a large-scale programme, Subprogram 1 of the Consultative Group on International Agricultural Research (CGIAR) Generation Challenge Program, that aims to explore the genetic diversity of the global germplasm collections held by the CGIAR research centres. This project will identify a ‘composite collection’ of germplasm for individual crops, representing the range of diversity of each crop species and its wild relatives, and characterize each composite set using anonymous molecular markers, mainly simple sequence repeats (SSRs). The overall goal of this project is to study diversity across given genera and identify genes for resistance to biotic and abiotic stresses that can be used in crop improvement programmes. ICARDA was responsible for creating the composite collection for lentil. ICARDA has the global mandate for lentil and houses the largest global collection of this crop with 10,509 accessions. From this collection, a global composite collection of 1000 lentil accessions was established with the aim to represent genetic diversity and the agro-climatological range of lentil. Accessions for the composite collection were compiled from landraces, wild relatives, and elite germplasm and cultivars. The methodology presented here combined classical hierarchical cluster analyses using agronomic traits and two-step cluster analyses using agro-climatological data linked to the geographical coordinates of the accessions' collection sites. Genotyping for 30 SSR loci will be carried out for all 1000 accessions. Plants grown for DNA analysis will be harvested and progeny will be evaluated under field conditions at ICARDA.

Kamut wheat, said to have been derived from seed found in the Egyptian pyramids, appeared on the market about 25 years ago. We have investigated its taxonomic placement using microsatellite genotyping. In all, 89 accessions of 13 tetraploid wheat species, along with samples of Kamut wheat, were genotyped using two A and B genome wheat microsatellite markers per chromosome, generating 453 alleles (8–33 alleles per locus), and a mean allelic polymorphic information content (PIC) of 0.80. A diversity analysis showed that nine major accession groups could be defined, and these were inconsistent with formal taxonomic classifications of about 10% of the material. Most of these misclassifications are due to either species introgression or seed admixture. Some accessions appear to be duplicates. The Kamut wheats grouped together in a cluster containing three accessions of Triticum polonicum and three of T. durum, originating from Turkey, Iraq, Iran and Israel. We suggest that Kamut perhaps derived from a natural hybrid between T. durum and T. polonicum, which occurred in the Fertile Crescent.

Out-crossing between genetically modified herbicide-tolerant (GMHT) and non-GM rape cultivars was studied using GMHT source field plots of approximately 0.8 ha. Levels of cross-pollination between adjacent fully fertile rape varieties declined rapidly with increasing distance from the interface between plots. A varietal association with low levels of male sterility showed higher levels of out-crossing than other varieties. Out-crossing data were used to compare negative exponential and inverse power-law models for their fit to describe the observed relationship between cross-pollination and distance from source. Results showed that the inverse power-law model provided a better fit of the data.

Amplified fragment length polymorphism (AFLP) markers were employed to assess intraspecific variability in water yam (Dioscorea alata L.). Fifty-three accessions of diverse geographic origins in West and Central Africa (Benin, Côte d'Ivoire, Ghana, Nigeria and Chad) and Puerto Rico were analysed using three AFLP primer combinations. Of the 342 amplification products generated, a mean of 53.4% were polymorphic. Genetic similarity coefficients ranged from 0.29 to 0.95. The accessions could be clustered into three major genetic groups with one outlier. Each group was a mixture of accessions of different geographical origin indicating that geography has not played a major role in the differentiation of the species. A few accessions clustered very tightly suggesting that there may be duplicate accessions in the collection. The wide genetic variation observed constitutes a good basis for genetic improvement of yam.

Chickpea is one of the most important grain legume crops in the world. Large collections of genetic resources are maintained in the International Crops Research Institute for the Semi-Arid Tropics (ICRISAT) and International Center for Agricultural Research in the Dry Areas (ICARDA) genebanks. Association mapping using neutral markers has been suggested as a means to identify useful alleles in the vast reservoirs of genetic diversity existing in the germplasm collections that could be associated with the phenotypes among the population individuals. ICRISAT in collaboration with ICARDA developed a global composite collection of 3000 accessions that will be profiled using 50 polymorphic simple sequence repeat (SSR) markers. The data generated through this collaborative effort will be used to define the genetic structure of the global composite collection and to select a reference sample of 300 accessions representing the maximum diversity for the isolation of allelic variants of candidate gene associated with beneficial traits. It is then expected that molecular biologists and plant breeders will have opportunities to use diverse lines in functional and comparative genomics, in mapping and cloning gene(s), and in applied plant breeding to diversify the genetic base of the breeding populations which should lead to the development of broad-based elite breeding lines/cultivars with superior yield and enhanced adaptation to diverse environments.

Isozyme data were used to assess genetic diversity within and among a subdivided population of the salt-tolerant Batini barley landrace. Population diversity and its components were estimated on the basis of 12 isozymes scored on 450 single plants representing seven subpopulations. Two principal components, based on mean gene diversity, Shannon's diversity index, percentage polymorphic loci, genetic identity and genetic distance among subpopulations accounted for 91.7% of total variation and separated the subpopulations into four distinct groups. Contributions to total diversity by individual subpopulations were partitioned into intra- and inter-population components. The level of population differentiation indicates that a large percentage of total genetic diversity was apportioned within subpopulations. The presence of valuable genetic diversity in this landrace was confirmed.

Molecular characterization of ex situ plant germplasm, although more attainable than before, has rarely been applied to a whole germplasm collection of 2000 accessions or larger. The benefits of screening large numbers of accessions have not been well recognized for germplasm management and utilization. Challenges also exist in identifying duplicated and genetically related accessions and in validating developed core subsets. Here we show how a new approach using an average marker-based dissimilarity of an accession in a collection can be applied to identify both redundancy and distinctness in a plant germplasm collection. Application of this dissimilarity measure to 2727 flax accessions genotyped by 149 randomly amplified polymorphic DNA (RAPD) markers revealed that up to 22% of accessions could be deemed to be redundant. Up to 500 of the most distinct flax accessions were identified and these can be directly screened for traits of interest to broaden the genetic base in a flax improvement programme. These results demonstrate that molecular screening of a large number of accessions with an informative diversity analysis can facilitate the management and utilization of ex situ plant germplasm.

The improvement of quality and quantitative traits in industrial crops is among the most important goals in plant breeding. Many traits of interest are controlled by multiple genes and improvements have so far only been obtained through conventional breeding. The use of biotechnological tools to modify quantitative traits is highly challenging. CropDesign has developed TraitMill™, an automated plant evaluation platform allowing high-throughput testing of the effect of plant-based transgenes on agronomically valuable traits in crop plants. The focus of the platform is currently on rice, a good model for other important cereals such as maize and wheat. TraitMill™ offers a high-throughput prediction of gene function. Genes of validated function that confer trait improvement can then be transferred to other cereal crop species such as maize, but also to dicots, trees and ornamentals. TraitMill™ involves the following key components: (i) selection of candidate trait improvement genes among genes involved in signal transduction, cell cycle control, transcription, nutrient metabolism, etc.; (ii) a suite of validated constitutive or tissue-specific promoters from rice allowing for the selection of the most appropriate promoter–gene combination in view of the desired trait improvement; (iii) an industrialized plant transformation system generating tens of thousands of transgenic plants annually; and (iv) a robotized trait evaluation set-up for plant evaluation, proprietary image analysis software for measuring plant performance parameters and statistical analysis of results.

Southern Sudan has a rich tree flora. Trees are important in the livelihoods of the numerous tribes of the region, who use them for shelter, fuel, food, fodder, medicine and income generation. The gallery and depression forests contain valuable timber trees. Other species provide non-timber forest products that are potentially tradable outside Sudan, particularly in African countries that have over-exploited their own forest resources. As the carrying capacity of the western and central areas of Sudan decreases, the pressure on the natural resources of the higher rainfall southern areas will increase. This in itself might initiate conflict, as various tribes compete over a relatively rich resource base. The recent peace established between the north and south could result in depletion of the forest resources of the south through commercial exploitation. This paper details and discusses the wild tree resources of southern Sudan, including many already threatened species.

Conservation of crop germplasm diversity involves the establishment of in situ and ex situ genebanks. The major activities for ex situ genebanks include assembling, conserving, characterizing and providing easy access to germplasm for scientists. More than six million accessions are currently assembled in over 1300 genebanks worldwide. ICRISAT is one of the 15 CGIAR centres, with headquarters at Patancheru, India, and conserves genetic resources of sorghum, pearl millet, chickpea, pigeonpea, groundnut, and six small millets. The ICRISAT genebank holds 114,870 accessions from 130 countries, including both archival materials from various organizations throughout the world, and from fresh collections resulting from 213 missions in 62 countries. The ICRISAT genebank supplies annually over 40,000 germplasm samples to scientists worldwide. Sixty-six varieties selected from the basic germplasm have been released for cultivation in 44 countries, and ICRISAT has restored/repatriated crop germplasm to eight countries. The research focus is on germplasm diversity assessment, developing core and mini-core collections, and using a molecular characterization approach to both enhance the utilization of germplasm in research and improve the efficiency of germplasm management. Following these approaches, we have been able to identify a significant number of accessions with traits potentially relevant for crop improvement.

A chickpea collection of 1600 desi and 1400 kabuli were evaluated for yield losses arising from pod borer (Helicoverpa armigera) infestation under rainfed conditions by spraying half the plots to prevent pod borer infestation and allowing the other half to be infested. From these lines, 82 were selected for further detailed evaluation of Helicoverpa resistance and drought resistance under irrigated and rainfed conditions. The yield losses from Helicoverpa damage varied from 10 to 33% depending on the chickpea type and the growing environment. Spreading types were more susceptible to Helicoverpa damage than erect types, as were kabuli types compared to desi types. Yield losses due to Helicoverpa infestation were always greater in the irrigated than in the rainfed materials. Terminal drought reduced yields by 13–37% depending on plant type. The yields in the kabuli c“hickpea lines were more severely reduced than were the desi types, due to a greater reduction in the number of branches and pods per plant in the kabuli compared to the desi lines. It appears that the extent of pod borer damage varies between the chickpea types, and that desi types have greater drought resistance than kabuli ones. These characteristics should be informative for the population improvement of chickpea for environments in which terminal drought and Helicoverpa damage occur frequently.

Molecular investigations of qualitative and quantitative changes in the genetic diversity of cultivated crops are useful for plant breeding and the management of crop genetic resources. A genotyping study, based on 28 genomic (g-SSR) and 13 expressed sequence tag-derived (e-SSR) microsatellite markers uniformly distributed across the barley genome, was conducted on samples of cultivated barley (Hordeum vulgare L.) collected at intervals of 40–50 years in three comparable geographical regions in Austria, Albania and India. The analysis indicated an absence of any significant differences either in the total number of alleles per locus or in g-SSR and e-SSR polymorphic information content (PIC) values from the Indian and Austrian materials. However, a slight reduction in genetic diversity was noted among the materials collected in Albania. The trend in numbers of collection mission-specific SSR alleles suggests significant allele flow over the time interval sampled. The g-SSRs yielded a higher mean number of alleles per locus and a superior PIC than the e-SSR markers. We conclude that a qualitative, rather than a quantitative shift in diversity has taken place over time, and that g-SSR markers detect more diversity than do e-SSR markers.

A collection of 120 Ethiopian tetraploid wheat accessions was analysed for high-molecular weight (HMW) glutenin subunit, low-molecular weight (LMW) glutenin subunit and omega gliadin composition by SDS–PAGE. For the HMW glutenin subunits, a new allelic variant, 2****, was detected which has not been previously described at the Glu-A1 locus. A high proportion of Glu-A1x banding pattern was observed in durum wheat. For the Glu-B1 locus four different banding patterns were detected. Among those HMW glutenin subunits, 7+8 were the most common, while subunits 14+15 and 6+8 were found to be rare. A high degree of variation was evident for the LMW glutenin subunits and D-zone omega gliadins. The association of the composition of the gluten with quality has been discussed. This wide variation can be used in improving the quality of wheat and to widen its genetic base.

Genomic and proteomic diversity provide the basis of evolutionary change by natural selection under abiotic and biotic stresses, and the human-driven evolutionary process of domestication by artificial selection. Described here are some of the regional and local genomic and proteomic long-term multidisciplinary studies conducted at the Institute of Evolution, University of Haifa, Israel, during 1975–2005 (see publications at http://evolution.haifa.ac.il), involving both wild barley, Hordeum spontaneum, the progenitor of cultivated barley and wild emmer sheat, Triticum dicoccoides, the progenitor of modern tetraploid and hexaploid cultivated wheat. Wild cereals harbour large amounts of as yet untapped adaptive genetic resources for crop improvement (resistances against abiotic and biotic stresses, micronutrient metal deficiencies, storage proteins, amylases and photosynthetic yield, among others). The adaptive genomic diversity of wild cereals, including cryptic beneficial alleles at specific quantitative trait loci of T. dicoccoides and H. spontaneum is the best genomic resource to be conserved in situ and ex situ for utilization by classical and modern biotechnologies, to enrich the genetically impoverished and stress-vulnerable food cultivars, advance crop improvement, and thereby increase and optimize world food production in a second genetic green revolution.

The cryopreservation of embryonic axes of two wild and endangered species, Citrusmacroptera Mont. and C. latipes Tanaka, was attempted using air desiccation–freezing, vitrification and encapsulation–dehydration. Successful cryopreservation was achieved in both the species using these three methods. However, the two species responded differently to: the rate of drying and the degree of tolerance to desiccation following air desiccation–freezing; the response to loading duration following vitrification; and to the sucrose concentration during pre-culture following encapsulation–dehydration. C. macroptera was more tolerant to desiccation and freezing than C. latipes with recovery rates of, respectively, 87% and 64%. Recovery from encapsulation–dehydration was 62% for C. macroptera and 45% for C. latipes. In both species, the vitrification protocol gave a significant improvement in recovery rates: 92% and 77% for C. macroptera and C. latipes, respectively. The air desiccation–freezing protocol being a simple and practical technique is recommended for the cryopreservation of these two species.

A regional (Oceania) core collection for taro germplasm has been developed based on phenotypic and molecular characterization. In total, 2199 accessions of taro germplasm have been collected by TaroGen (Taro Genetic Resources: Conservation and Utilisation) from 10 countries in Oceania: Papua New Guinea, Solomon Islands, Vanuatu, New Caledonia, Fiji, Palau, Niue, Tonga, Cook Islands and Samoa. Our objective was to select 10% from each country to contribute to a regional core. The larger collections from Papua New Guinea, Vanuatu and New Caledonia were analysed based on phenotypic characters, and a diverse subset representing 20% of these collections was fingerprinted. A diverse 20% subsample was also taken from the Solomon Islands. All accessions from the other six countries were fingerprinted. In total, 515 accessions were genotyped (23.4% overall) using taro specific simple sequence repeat (SSR) markers. DNA fingerprint data showed that great allelic diversity existed in Papua New Guinea and the Solomon Islands. Interestingly, rare alleles were identified in taros from the Solomon Islands province of Choiseul which were not observed in any of the other collections. Overall, 211 accessions were recommended for inclusion in the final regional core collection based on the phenotypic and molecular characterization.

Drought tolerance (DT) is a very complex trait. For the purpose of developing DT rice cultivars, a research programme was initiated in 1997 in China, consisting of four coherent parts: the development of a DT field screen facility and evaluation standard; the collection, evaluation and enhancement of DT rice resources; DT gene/quantitative trait locus (QTL) discovery; and DT rice breeding. More than 2000 rice accessions, mostly from China, were collected and evaluated in a new DT screening facility with a powerful water management system. Eighty-six entries were selected to serve as a core DT collection. A set of 187 recombinant inbred lines was developed for the genetic mapping of DT and high yield-related QTL under drought conditions. Several DT rice cultivars adapted to southern and central China were released. DT rice CMS lines were developed and distributed to most parts of China to encourage the development of DT or water-saving hybrid rice.