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Crop landraces have unique local agroecological and societal functions and offer important genetic resources for plant breeding. Recognition of the value of landrace diversity and concern about its erosion on farms have led to sustained efforts to establish ex situ collections worldwide. The degree to which these efforts have succeeded in conserving landraces has not been comprehensively assessed. Here we modelled the potential distributions of eco-geographically distinguishable groups of landraces of 25 cereal, pulse and starchy root/tuber/fruit crops within their geographic regions of diversity. We then analysed the extent to which these landrace groups are represented in genebank collections, using geographic and ecological coverage metrics as a proxy for genetic diversity. We find that ex situ conservation of landrace groups is currently moderately comprehensive on average, with substantial variation among crops; a mean of 63% ± 12.6% of distributions is currently represented in genebanks. Breadfruit, bananas and plantains, lentils, common beans, chickpeas, barley and bread wheat landrace groups are among the most fully represented, whereas the largest conservation gaps persist for pearl millet, yams, finger millet, groundnut, potatoes and peas. Geographic regions prioritized for further collection of landrace groups for ex situ conservation include South Asia, the Mediterranean and West Asia, Mesoamerica, sub-Saharan Africa, the Andean mountains of South America and Central to East Asia. With further progress to fill these gaps, a high degree of representation of landrace group diversity in genebanks is feasible globally, thus fulfilling international targets for their ex situ conservation.

The history of CGIAR and the development and implementation of the International Treaty on Plant Genetic Resources for Food and Agriculture (“Plant Treaty”) are closely intertwined. In accordance with the agreements that 11 CGIAR centers signed with the Plant Treaty's Governing Body under Article 15 of the treaty, >730,000 accessions of crop, tree, and forage germplasm conserved in CGIAR genebanks are made available under the terms and conditions of the multilateral system of access and benefit sharing, and the CGIAR centers have transferred almost 4 million samples of plant genetic resources under the system. Many activities of CGIAR centers and their genebanks (e.g., crop enhancement, improved agronomic methods, seed system strengthening, and capacity building) are influenced by, and promote, the Plant Treaty's objectives. The continued existence and optimal functioning of the Plant Treaty's multilateral system of access and benefit sharing is critically important to CGIAR in the pursuit of its mission. However, the multilateral system has encountered some challenges since the Plant Treaty came into force. The successful conclusion of the ongoing process for enhancing the functioning of the multilateral system could increase monetary benefit sharing and incentives for exchanging more germplasm. In the meantime, increased efforts are necessary to promote nonmonetary benefit sharing through partnerships, technology transfer, information exchange, and capacity building. These efforts should be integrated into countries’ and organizations’ work to implement the Plant Treaty's provisions on conservation and sustainable use of plant genetic resources, and farmers’ rights.

Landraces (traditional varieties) of domesticated species preserve useful genetic variation, yet they remain untapped due to the genetic linkage between the few useful alleles and hundreds of undesirable alleles. We integrated two approaches to characterize the diversity of 4,471 maize landraces. First, we mapped genomic regions controlling latitudinal and altitudinal adaptation and identified 1,498 genes. Second, we used F-one association mapping (FOAM) to map the genes that control flowering time, across 22 environments, and identified 1,005 genes. In total, we found that 61.4% of the single-nucleotide polymorphisms (SNPs) associated with altitude were also associated with flowering time. More than half of the SNPs associated with altitude were within large structural variants (inversions, centromeres and pericentromeric regions). The combined mapping results indicate that although floral regulatory network genes contribute substantially to field variation, over 90% of the contributing genes probably have indirect effects. Our dual strategy can be used to harness the landrace diversity of plants and animals.

Marker ordering during linkage map construction is a critical component of QTL mapping research. In recent years, high-throughput genotyping methods have become widely used, and these methods may generate hundreds of markers for a single mapping population. This poses problems for linkage analysis software because the number of possible marker orders increases exponentially as the number of markers increases. In this paper, we tested the accuracy of linkage analyses on simulated recombinant inbred line data using the commonly used Map Manager QTX (Manly et al. 2001: Mammalian Genome12, 930–932) software and RECORD (Van Os et al. 2005: Theoretical and Applied Genetics112, 30–40). Accuracy was measured by calculating two scores: % correct marker positions, and a novel, weighted rank-based score derived from the sum of absolute values of true minus observed marker ranks divided by the total number of markers. The accuracy of maps generated using Map Manager QTX was considerably lower than those generated using RECORD. Differences in linkage maps were often observed when marker ordering was performed several times using the identical dataset. In order to test the effect of reducing marker numbers on the stability of marker order, we pruned marker datasets focusing on regions consisting of tightly linked clusters of markers, which included redundant markers. Marker pruning improved the accuracy and stability of linkage maps because a single unambiguous marker order was produced that was consistent across replications of analysis. Marker pruning was also applied to a real barley mapping population and QTL analysis was performed using different map versions produced by the different programs. While some QTLs were identified with both map versions, there were large differences in QTL mapping results. Differences included maximum LOD and R2values at QTL peaks and map positions, thus highlighting the importance of marker order for QTL mapping.

Brachiariaspecies are widely sown on the infertile and Al‐toxic soils of neotropical savannas. Breeding programs seek to combine edaphic adaptation with other traits in interspecific hybrids. Edaphic adaptation is difficult to assess because it is only manifest in pasture persistence across several growing seasons. We developed and validated a solution‐culture technique that uses rooted vegetative propagules from mature plants to assess two key components of edaphic adaptation: root vigor and Al resistance. Root vigor was assessed by measuring growth of adventitious root systems in 200 μMCaCl2(pH 4.2). Aluminum resistance was assessed by comparing root growth in this solution vs. root growth in an identical solution that also contained 200 μMAlCl3The well‐adapted parent (Brachiaria decumbensStapf cv. Basilisk) was superior to the less‐adapted parent (B. ruziziensisGermain & Evrad clone 44‐02), and both traits segregated as expected in a set of 44‐02 × Basilisk hybrids. A simplified version of this technique, which exclusively relies on visual inspection, has been implemented in our breeding program to facilitate progress toward edaphic adaptation.

Several peralkylated polyaminophosphazenium cations were evaluated for the generation of novel anhydrous F−salts. Two of them have been characterized by X‐ray analysis and are particularly soluble, even in apolar aprotic solvents like benzene or THF, one of them even at −30 °C. Such solutions probably represent the most basic metal‐free and stable media known to date. Comparison of these fluorides with known F−sources demonstrates that they are of unprecedented reactivity and selectivity in E2 elimination reactions.

A series of peralkylated polyaminophosphazenium cations exhibiting extraordinary base resistance under phase‐transfer conditions were efficiently synthesized from readily available starting materials. Their half lives under these conditions exceed those of the most stable conventional organic cations by factors of up to 3000.

We previously developed a new simple technique of methylene blue (MB) staining for the discrimination of aluminum (Al)-tolerant protoplasts from 4 plant species (rice, oats, maize and pea). The objectives of the present study were to confirm the applicability of this technique to a wider range of plant species, cultivars and lines, and to identify a common strategy for the early stage of Al tolerance. A total of 10 plant species, two Brachiaria spp., two Oryza spp., buckwheat, maize, pea, triticale, wheat and barley, corresponding to 18 different plant samples (species, cultivars, and lines), were used. Al tolerance (relative net root elongation of the longest root), which was screened at 20 μM AICI3 in 0.2 mM CaCl2 (pH 4.9) for 24 h, ranged widely from 10 to 88. Among cultivars and lines within the same species, Al accumulation in the root tip portion was higher in Al-sensitive plants, corresponding to more severe permeabilization of the plasma membranes (PM). Protoplasts isolated mainly from the epidermis, and outer and central parts of the cortex were stained to different degrees by MB, and the blue color was observed both on the surface and inside the protoplasts. Color pictures obtained after staining for 3 min with 0.1% MB were analyzed by Image Hyper II. The ratio of the heavily stained area at threshold 95 to the entire area stained with MB at threshold 125 was defined as MB stainability. MB stainability was negatively correlated with Al tolerance (y= 48.6e-0.02x, R2= 0.676**) suggesting the common importance of permeation characteristics of PM, in addition to PM negativity for Al tolerance in a wide range of plant species, cultivars and lines. Analysis of the PM lipid composition was proposed as an important topic for future studies on the negativity and permeation of PM.

Aluminum toxicity limits plant growth in acid soils. Because of their advanced state of weathering, acid soils of the tropics also tend to be deficient in nutrients. A realistic assessment of plant adaptation to these soils would therefore require Al‐toxic conditions under which growth is simultaneously limited by nutrient deficiency. We developed and tested a nutrient solution for this purpose. We analyzed soil solutions of two Oxisols from the Colombian savannas. Nutrient concentrations were extremely low (ionic strength <1.7 mM). Nitrification during incubation of soil samples acidified soil solutions, resulting in a release of cations from the exchange phase, an increase in the activity of Al3+, and a decrease in that of H2PO−4Predicted ion activities were taken as guidelines for designing a nutrient solution that simulates these soil solutions. Growth of well‐adapted signalgrass (Brachiaria decumbenscv. Basilisk) and less‐adapted ruzigrass (Brachiaria ruziziensiscv. Common) in this solution mirrored the interspecific difference in forage yield that had previously been observed in a field close to where one of the soils originated. This suggests that the designed solution may be a realistic approximation to chemical soil properties that limit forage productivity. The different growth response of the two grasses was apparently due to increased Al sensitivity of less‐adapted ruzigrass under low nutrient supply; neither Al toxicity nor nutrient deficiency alone resulted in a comparable growth difference between the grasses. These data highlight the importance of taking into account interactions among stress factors that occur in parallel in infertile acid soils.

Aluminum-resistant Brachiaria decumbens Stapf cv. Basilisk (signalgrass) and closely related, but less resistant Brachiaria ruziziensis Germain & Evrard cv. Common (ruzigrass) both accumulated high concentrations of aluminum (Al) in roots. Approximately two thirds of the total Al was complexed by soluble low-molecular-weight ligands, suggesting that it had been taken up into the symplasm. We therefore investigated whether these species might employ Al-chelating organic acids for internal detoxification of Al taken up by root apices, the primary site of Al injury. Unlike root apices of other Al-resistant plant genotypes, which secrete organic-acid anions to detoxify Al externally, apices of Brachiaria species accumulated organic acids within the tissue. A comparison with whole roots showed that this preference for accumulation (as opposed to secretion) was restricted to apices. Citric acid, and to a lesser extent trans-aconitic acid, accumulated in a uniform dose-dependent manner in root apices of both species as their Al content increased under Al-toxic growth conditions. Their accumulation was accompanied by a stimulation of malate synthesis in Al-resistant B. decumbens, while it occurred at the expense of malate in Al-sensitive B. ruziziensis. These data suggest a role of organic acids in the internal detoxification of Al in root apices of both Brachiaria species, presumably contributing to their comparatively high basal level of Al resistance. Yet internal detoxification of Al by organic acids does not appear to be the principal mechanism responsible for the superior resistance of B. decumbens.

Genebanks underpin global food security, conserving and distributing agrobiodiversity for use in research and breeding. The CGIAR collections include >700,000 seed accessions, held in trust as global public goods. However, the role of genebanks in contributing to global food security can only be realized if collections are effectively managed. Examination of the historical viability monitoring data from seven CGIAR genebanks confirmed that high seed viability was maintained for many decades for the various crops and forage species. However, departures from optimum management procedures were revealed, and there were insufficient data gathered to derive reliable estimates of longevity needed to better forecast regeneration requirements, estimate the size of seed lots that should be stored, and optimize accession monitoring intervals.