The continuous improvement of crop plants is essential for agriculture in the coming decades and relies on the use of genetic variability through breeding. However, domestication and modern breeding have reduced diversity in the crop germplasm. Global gene banks conserve diversity, but these resources remain underexplored owing to a lack of efficient strategies to isolate important alleles. Here we describe a large-scale allele-mining project at the molecular level. We first selected a set of 1,320 bread wheat landraces from a database of 16,089 accessions, using the focused identification of germplasm strategy. On the basis of a hierarchical selection procedure on this set, we then isolated 7 resistance alleles of the powdery mildew resistance gene Pm3, doubling the known functional allelic diversity at this locus. This targeted approach for molecular utilization of gene bank accessions reveals landraces as a rich resource of new functional alleles. This strategy can be implemented for other studies on the molecular diversity of agriculturally important genes, as well as for molecular breeding.allele mining ͉ powdery mildew ͉ gene banks ͉ wheat landraces

Efficient methods to explore plant agro-biodiversity for climate change adaptive traits are urgently required. The focused identification of germplasm strategy (FIGS) is one such approach. FIGS works on the premise that germplasm is likely to reflect the selection pressures of the environment in which it developed. Environmental parameters describing plant germplasm collection sites are used as selection criteria to improve the probability of uncovering useful variation. This study was designed to test the effectiveness of FIGS to search a large faba bean (Vicia faba L.) collection for traits related to drought adaptation. Two sets of faba bean accessions were created, one from moisture-limited environments, and the other from wetter sites. The two sets were grown under well watered conditions and leaf morpho-physiological traits related to plant water use were measured. Machine-learning algorithms split the accessions into two groups based on the evaluation data and the groups created by this process were compared to the original climate-based FIGS sets. The sets defined by trait data were in almost perfect agreement to the FIGS sets, demonstrating that ecotypic differentiation driven by moisture availability has occurred within the faba bean genepool. Leaflet and canopy temperature as well as relative water content contributed more than other traits to the discrimination between sets, indicating that their utility as drought-tolerance selection criteria for faba bean germplasm. This study supports the assertion that FIGS could be an effective tool to enhance the discovery of new genes for abiotic stress adaptation.

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Collections of crop genetic resources are a valuable source of new genetic variation for economically important traits, including resistance to crop diseases. New sources of useful crop traits are often identified through evaluation in field trials. The number of relevant accessions in genebank collections available to be evaluated is often substantially larger than the capacity of the evaluation project. The focused identification of germplasm strategy (FIGS) is an approach used to select subsets of germplasm from genetic resource collections in such a way as to maximize the likelihood of capturing a specific trait. This strategy uses a range of methods to link the expression of a specific trait (of a target crop) with the eco-geographic parameters of the original collection site. This study contributes to the development of the approach by which a FIGS subset could be assembled for biotic traits. We have evaluated trait-specific subset selection methods for two fungal crop diseases, namely stem rust {Puccinia graminis Pers.) in wheat {Triticum aestivum L. and Triticum turgidum L.) and net blotch {Pyrenophora teres Drechs.) in barley {Hordeum vulgäre L.). The results indicate that the climate layers from freely available eco-geographic databases are well suited to model and predict the reaction in these crops to biotic stress traits. This result has the potential to improve the efficiency of field screening trials to find novel sources of economically valuable crop traits.

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Russian wheat aphid, Diuraphis noxia (Kurdjumov), is an important pest of wheat and barley in North America, Africa and the Middle East. Host plant resistance is the most economical and practical means of controlling this insect. Field and greenhouse screening in Syria of bread wheat lines from the International Center for Agricultural Research in the Dry AreasÕ (ICARDA) gene bank, using the Focused Identification of Germplasm Strategy (FIGS), identified 12 lines resistant to D. noxia. These sources of resistance will be used to develop germplasm resistant to D. noxia for the highland areas of North Africa, and West and Central Asia, where this insect causes economic damage. This study also showed the relevance of the FIGS approach in better targeting accessions held in gene banks for valuable traits.

Sunn pest, Eurygaster integriceps Puton, is the most damaging insect pest of wheat in West and Central Asia and East Europe. Host plant resistance has been investigated as one component of a total integrated pest management program for the control of this pest. In Syria, field screening of artificially infested wheat accessions from the International Center for Agricultural Research in the Dry Areas (ICARDA) gene bank, selected using the Focused Identification of Germplasm Strategy (FIGS), identified one durum wheat and eight bread wheat accessions with good levels of resistance at the vegetative stage to overwintered Sunn pest adults. ICARDA is using these sources of resistance in wheat breeding programs to develop cultivars resistant to overwintered Sunn pest adults, which damage wheat at the vegetative stage (shoots and leaves). This study also demonstrated that the FIGS approach was effective in mining genetic resource collections for useful traits.

Drought is a major constraint to faba bean (Vicia faba L.) production, and there are many mechanisms by which leaves can regulate water loss. Our primary objective was to test if the origin of the faba bean accessions, from drought-prone and non-drought-prone environments, was associated with differences in measurable aspects of stomatal morphology and physiology related to water use. Two sets, each consisting of 201 faba bean accessions, were chosen from environments with contrasting seasonal moisture profiles following the Focused Identification of Germplasm Strategy, and then screened under well watered conditions. From these, two subsets of 10 accessions each were chosen to test for differences in response to drought. Parameters related to stomatal function and water status were measured. The dry-adapted set had bigger stomata, higher leaf relative water content (LRWC) and cooler leaves under well watered conditions. Stomatal density and stomatal area per unit area of leaflet were negatively correlated with gas exchange parameters and positively correlated with intrinsic water use efficiency. Drought caused stomatal densities to increase in the dry set while stomatal length decreased in both sets. The moisture deficit was sufficient to decrease gas exchange in both sets to similar levels, but the dry-adapted set maintained warmer leaves and a higher LRWC that showed no significant correlations with leaf morphology or gas exchange, demonstrating more effective stomatal regulation. The results also support that collection site data from the environment where genetic resources are collected can be used as indicators of adaptive traits in an herbaceous annual species.