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.

Applied genetics combined with practical plant breeding is a powerful tool in agricultural development and for food security. The Green Revolution spurred the world's potential to meet its food, feed and fibre needs at a time when vast regions were notoriously food-insecure. Subsequent adaptations of such strategies, from the late 1980s onwards, in order to develop new plant varieties in a more participatory way, have strengthened the focus on applying technology to farmers' diverse needs, feeding research results into a variety of seed systems. During these developments, there were no major legal impediments to the acquisition of either local or formal knowledge or of the building blocks of plant breeding: genetic resources. The emergence of molecular biology in plant science is creating a wealth of opportunities, both to understand better the limitations of crop production and to use a much wider array of genetic diversity in crop improvement. This ‘Gene Revolution’ needs to incorporate the lessons from the Green Revolution in order to reach its target groups. However, the policy environment has changed. Access to technologies is complicated by the spread of private rights (intellectual property rights), and access to genetic resources by new national access laws. Policies on access to genetic resources have changed from the concept of the ‘Heritage of Mankind’ for use for the benefit of all mankind to ‘National Sovereignty’, based on the Convention on Biological Diversity, for negotiated benefit-sharing between a provider and a user. The Generation Challenge Programme intends to use genomic techniques to identify and use characteristics that are of value to the resource-poor, and is looking for ways to promote freedom-to-operate for plant breeding technologies and materials. Biodiversity provides the basis for the effective use of these genomic techniques. National access regulations usually apply to all biodiversity indiscriminately and may cause obstacles or delays in the use of genetic resources in agriculture. Different policies are being developed in different regions. Some emphasize benefit-sharing, and limit access in order to implement this (the ‘African Model Law’), while others, in recognition of countries' interdependence, provide for facilitated access to all genetic resources under the jurisdiction of countries in the region (the Nordic Region). There are good reasons why the use of agricultural biodiversity needs to be regulated differently from industrial uses of biodiversity. The International Treaty on Plant Genetic Resources for Food and Agriculture, which entered into force in 2004, provides for facilitated access to agricultural genetic resources, at least for the crops that are included in the Treaty's ‘Multilateral System of Access and Benefit-sharing’. Ratification of the Treaty is proceeding apace, and negotiations have entered a critical stage in the development of practical instruments for its implementation. Although the scope of the Treaty is all plant genetic resources for food and agriculture, there are important crops that are not covered by its Multilateral System. Humanitarian licences are being used to provide access for the poor to protected technologies: countries may need to create such a general humanitarian access regime, to ensure the poor have the access they need to agricultural genetic resources.

Advances in genomics have provided technologies for high throughput analysis of plant genomes with potential for use in gene discovery in germplasm collections. The establishment of DNA banks facilitates this screening by making DNA from large numbers of plant accessions widely available. DNA banks require the development of appropriate policies for access and benefit sharing. Tools for automating sample and data handling are essential. Standard molecular methods for fingerprinting DNA accessions for international comparisons need to be determined. New screening technologies are required to take advantage of the emerging availability of large DNA collections. The Australian Plant DNA Bank aims to collect DNA from all Australian plant species and to sample the diversity within each species. DNA from all individuals of the species is being stored for rare species. Domesticated or economically important species from all countries are also being collected and stored. International networking of DNA banks will be a key step in linking genomics tools to global plant diversity.

There is a long-standing concern that modern plant breeding reduces crop genetic diversity, which may have consequences for the vulnerability of crops to changes in pests, diseases, climate and agricultural practices. Recent molecular assessments of genetic diversity changes in existing genepools of major agricultural crops may shed some light on the impact of plant breeding on crop genetic diversity. Reviewing published assessments revealed different impacts of plant breeding on improved genepools, not only narrowing or widening their genetic base, but also shifting their genetic background. In general, the genome-wide reduction of crop genetic diversity accompanying genetic improvement over time is minor, but allelic reduction at individual chromosomal segments is substantial. More efforts are needed to assess what proportion of lost alleles is associated with undesirable traits.

The effectiveness of association mapping (AM) based on linkage disequilibrium (LD) is currently being tested in a number of crops. An important prerequisite for the application of AM is the availability of collections of accessions with a suitable level of genetic variation for target traits and with limited spurious LD due to the presence of population structure. Herein, the results of a genome-wide molecular characterization of a collection of elite durum wheat accessions well-adapted to Mediterranean environments are presented. Ninety-seven highly polymorphic simple sequence repeats and 166 amplified fragment length polymorphism markers were used to characterize 189 durum accessions, mainly cultivars and advanced breeding lines. Genome-wide significant and sizeable LD indices at a centimorgan scale were observed, while LD mainly decayed within 10 cM. On the other hand, effects due to spurious LD were notably lower than those previously observed in a durum wheat collection sampling durum gene pools of more diverse origin. These results, coupled with the high level of genetic variability detected for a number of important morpho-physiological traits and their high heritability, indicate the suitability of this collection for AM studies targeting agronomically important traits.