Economically, legumes (Fabaceae) represent the second most important family of crop plants after the grass family, Poaceae. Grain legumes account for 27% of world crop production and provide 33% of the dietary protein consumed by humans, while pasture and forage legumes provide vital part of animal feed. Fabaceae, the third largest family of flowering plants, has traditionally been divided into the following three subfamilies: Caesalpinioideae, Mimosoideae, and Papilionoideae, all together with 800 genera and 20,000 species. The latter subfamily contains most of the major cultivated food and feed crops. Among the grain legumes are some of mankind's earliest crop plants, whose domestication parallelled that of cereals: Soybean in China; faba bean, lentil, chickpea and pea in the Fertile Crescent of the Near East; cowpeas and bambara groundnut in Africa; soybean and mungbeans in East Asia; pigeonpea and the grams in South Asia; and common bean, lima bean, scarlet runner bean, tepary bean and lupin in Central and South America. The importance of legumes is evidenced by their high representation in ex situ germplasm collections, with more than 1,000,000 accessions worldwide. A detailed knowledge of the phylogenetic relationships of the Fabaceae is essential for understanding the origin and diversification of this economically and ecologically important family of angiosperms. This review aims to combine the phylogenetic and genetic diversity approaches to better illustrate the origin, domestication history and preserved germplasm of major legume crops from 13 genera of six tribes and to indicate further potential both for science and agriculture.

The use of crop wild relatives (CWRs) in breeding is likely to continue to intensify as utilization techniques improve and crop adaptation to climate change becomes more pressing. Significant gaps remain in the conservation of these genetic resources. As a first step toward a national strategy for the conservation of CWRs, we present an inventory of taxa occurring in the United States, with suggested prioritization of species based on potential value in crop improvement. We listed 4600 taxa from 985 genera and 194 plant families, including CWRs of potential value via breeding as well as wild species of direct use for food, forage, medicine, herb, ornamental, and/or environmental restoration purposes. United States CWRs are related to a broad range of important food, forage and feed, medicinal, ornamental, and industrial crops. Some potentially valuable species are threatened in the wild, including relatives of sunflower (Helianthus annuus L.), walnut (Juglans regia L.), pepo squash (Cucurbita pepo L.), wild rice (Zizania L.), raspberry (Rubus idaeus L.), and plum (Prunus salicina Lindl.), and few accessions of such taxa are currently conserved ex situ. We prioritize 821 taxa from 69 genera primarily related to major food crops, particularly the approximately 285 native taxa from 30 genera that are most closely related to such crops. Both the urgent collection for ex situ conservation and the management of such taxa in protected areas are warranted, necessitating partnerships between concerned organizations, aligned with regional and global initiatives to conserve and provide access to CWR diversity.

Significance: This study provides conservation assessments for 600 US native plants that are wild relatives of important agricultural crops. We found that more than one-half of the species may be endangered in their natural habitats, and that the great majority require further conservation action, both ex situ (in gene banks and botanical gardens) and in situ (in protected areas). Diversity hotspots across the nation represent focal regions for further collecting for ex situ conservation as well as for enhanced habitat protection. Wider collaborations, as well as greater awareness, access to, and information about these resources are needed to bolster their conservation and use.

Drought resistance is an important breeding target for enhancing alfalfa productivity in arid and semi-arid regions. Identification of genes involved in drought tolerance will facilitate breeding for improving drought resistance and water use efficiency in alfalfa. Our objective was to use a diversity panel of alfalfa accessions comprised of 198 cultivars and landraces to identify genes involved in drought tolerance. The panel was selected from the USDA-ARS National Plant Germplasm System alfalfa collection and genotyped using genotyping by sequencing. A greenhouse procedure was used for phenotyping two important traits associated with drought tolerance: drought resistance index (DRI) and relative leaf water content (RWC). Marker-trait association identified nineteen and fifteen loci associated with DRI and RWC, respectively. Alignments of target sequences flanking to the resistance loci against the reference genome of M. truncatula revealed multiple chromosomal locations. Markers associated with DRI are located on all chromosomes while markers associated with RWC are located on chromosomes 1, 2, 3, 4, 5, 6 and 7. Co-localizations of significant markers between DRI and RWC were found on chromosomes 3, 5 and 7. Most loci associated with DRI in this work overlap with the reported QTLs associated with biomass under drought in alfalfa. Additional significant markers were targeted to several contigs with unknown chromosomal locations. BLAST search using their flanking sequences revealed homology to several annotated genes with functions in stress tolerance. With further validation, these markers may be used for marker-assisted breeding new alfalfa varieties with drought resistance and enhanced water use efficiency.

Aim: To fill critical knowledge gaps with regard to the distributions and conservation status of the wild relatives of chile peppers (CapsicumL.).Location: The study covered the potential native ranges of currently recognized wildCapsicumtaxa, throughout the Americas.Methods: We modelled the potential distributions of 37 wild taxa in the genus, characterized their ecogeographic niches, assessed their ex situ and in situ conservation status, and performed preliminary threat assessments.Results: We categorize 18 of the taxa as “high priority” for further conservation action as a consequence of a combination of their ex situ and in situ assessments, 17 as “medium priority,” and two as “low priority.” Priorities for resolving gaps in ex situ conservation were determined to be high for 94.6%, and medium or high with regard to increased habitat protection for 64.9% of the taxa. The preliminary threat assessment indicated that six taxa may be critically endangered, three endangered, ten vulnerable, six near threatened and 12 least concern.Main conclusions: Taxonomic richness hot spots, especially along the Atlantic coast of Brazil, in Bolivia and Paraguay, and in the highlands of Colombia, Ecuador, Peru and Venezuela, represent particularly high priority regions for further collecting for ex situ conservation as well as for enhanced habitat conservation.