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Despite an increasing awareness of the potential of “orphan” or unimproved crops to contribute to food security and enhanced livelihoods for farmers, coordinated research agendas to facilitate production and use of orphan crops by local communities are generally lacking. We provide an overview of the current knowledge on leafy vegetables with a focus on Gynandropsis gynandra, a highly nutritious species used in Africa and Asia, and highlight general and species-specific guidelines for participatory, genomics-assisted breeding of orphan crops. Key steps in genome-enabled orphan leafy vegetables improvement are identified and discussed in the context of Gynandropsis gynandra breeding, including: (1) germplasm collection and management; (2) product target definition and refinement; (3) characterization of the genetic control of key traits; (4) design of the ‘process’ for cultivar development; (5) integration of genomic data to optimize that ‘process’; (6) multi-environmental participatory testing and end-user evaluation; and (7) crop value chain development. The review discusses each step in detail, with emphasis on improving leaf yield, phytonutrient content, organoleptic quality, resistance to biotic and abiotic stresses and post-harvest management.

28Engineering C 4 photosynthesis into C 3 crops could substantially increase their yield by alleviating 29 photorespiratory losses. This objective is challenging because the C 4 pathway involves complex 30 modifications to the biochemistry, cell biology and anatomy of leaves. Forward genetics has 31 provided limited insight into the mechanistic basis of these properties, and there have been no 32 reports of significant quantitative intra-specific variation of C 4 attributes that would allow trait 33 mapping. Here, we show that accessions of the C 4 species Gynandropsis gynandra collected from 34 locations across Africa and Asia exhibit natural variation in key characteristics of C 4 photosynthesis. 35Variable traits include bundle sheath size and vein density, gas exchange parameters, and carbon-36 isotope discrimination associated with the C 4 state. Abundance of transcripts encoding core 37 enzymes of the C 4 cycle also showed significant variation. Traits relating to water use showed 38 more quantitative variation than those associated with carbon assimilation. We propose that 39 variation in these traits likely adapted the hydraulic system for increased water use efficiency 40 rather than improving carbon fixation, indicating that selection pressure may drive C 4 diversity in G. 41 gynandra by modifying water use rather than photosynthesis. The accessions analyzed can be 42 easily crossed and produce fertile offspring. Our findings therefore indicate that natural variation 43 within this C 4 species is sufficiently large to allow genetic mapping of key C 4 traits and regulators. 44www.plantphysiol.org on April 27, 2019 -Published by Downloaded from

Main conclusion The variability in nutrient content and morphology in Gynandropsis gynandra is associated with the geographic origin of the accessions and provides a basis for breeding for higher levels of vitamin C, carotenoids or tocopherols in higher-yielding cultivars. We examined the variation in carotenoids, tocopherols and ascorbic acid as well as morphological traits in a worldwide germplasm of 76 accessions of the orphan leafy vegetable Gynandropsis gynandra (Cleomaceae) using greenhouse experiments and high-performance liquid chromatography analysis. The levels of carotenoids and tocopherols accumulating in the leaves varied significantly across accessions and were linked with the geographical origin and morphological variation. The main carotenoids included lutein, β-carotene, α-carotene and violaxanthin. A twofold to threefold variation was observed for these compounds. The main tocopherols detected were α-tocopherol and γ-tocopherol with a 20-fold variation. A ninefold variation in vitamin C concentration and independent of geographical origin was observed. Overall, the accessions were grouped into three clusters based on variation in nutrient content and morphology. West African accessions were short plants with small leaves and with high tocopherol contents and relatively low carotenoid contents, Asian accessions were short plants with broad leaves and with relatively low carotenoid and high tocopherol contents, while East-Southern African plants were tall with high contents of both carotenoids and chlorophylls and low tocopherol contents. Carotenoids were positively correlated with plant height as well as foliar and floral traits but negatively correlated with tocopherols. The absence of a significant correlation between vitamin C and other traits indicated that breeding for high carotenoids or tocopherols content may be coupled with improved leaf yield and vitamin C content. Our study provides baseline information on the natural variation available for traits of interest for breeding for enhanced crop yield and nutrient content in Gynandropsis gynandra.

Loss of seed viability, poor and delayed germination, and inaccessibility to high-quality seeds are key bottlenecks limiting all-year-round production of African traditional leafy vegetables (TLVs). Poor quality seeds are the result of several factors including harvest time, storage, and conservation conditions, and seed dormancy. While other factors can be easily controlled, breaking seed dormancy requires thorough knowledge of the seed intrinsic nature and physiology. Here, we synthesized the scattered knowledge on seed dormancy constraints in TLVs, highlighted seed dormancy regulation factors, and developed a conceptual approach for molecular genetic analysis of seed dormancy in TLVs. Several hormones, proteins, changes in chromatin structures, ribosomes, and quantitative trait loci (QTL) are involved in seed dormancy regulation. However, the bulk of knowledge was based on cereals and Arabidopsis and there is little awareness about seed dormancy facts and mechanisms in TLVs. To successfully decipher seed dormancy in TLVs, we used Gynandropsis gynandra to illustrate possible research avenues and highlighted the potential of this species as a model plant for seed dormancy analysis. This will serve as a guideline to provide prospective producers with high-quality seeds.

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We investigated the relationships between the cultural importance of spider plant (Gynandropsis gynandra), a neglected leafy vegetable in West Africa, and the different management regimes of the species among six socio-linguistic groups in Benin and one in Togo. Semi-structured interviews were conducted with 428 respondents. Cultural significance and management indices were used to quantify the importance of the species for each respondent. In addition to food uses, G. gynandra was used to cure 42 different diseases. A regression tree analysis revealed that the cultural importance and level of management of the species were strongly associated with ethnicity, gender, and to a lesser extent to age, education, income, and land tenure. Socio-linguistic groups with similar cultural background had convergent perceptions of the cultural importance of the species and described similar management practices. An analysis of farmers' willingness to change their current management practices revealed that migration, market opportunities, and external intervention might significantly affect future management decision-making processes. We discuss community-oriented approaches to upscale the species cultivation in the region. Our study highlights how cultural importance influences current and future management intensity and illustrates how ethnobotanical research can guide research for development strategies to enact positive changes in communities' management of traditional leafy vegetables.Nous avons étudié les relations entre l'importance culturelle du Caya blanc (Gynandropsis gynandra), un légume-feuille négligé en Afrique de l'Ouest, et les différents régimes de gestion de l'espèce au sein de six groupes socio-linguistiques au Bénin et un au Togo. Des entretiens semi-structurés ont été menés auprès de 428 informants. Des indices d'importance culturelle et de gestion ont été utilisés pour quantifier l'importance de l'espèce pour chaque informant. En plus des utilisations alimentaires, G. gynandra a été utilisé pour soigner 42 maladies différentes. Une analyse par arbre de régression a révélé que l'importance culturelle de l'espèce était fortement associée à l'ethnicité et au genre, et dans une moindre mesure à l'âge, l'instruction, le niveau de revenu et le mode de faire-valoir de la terre. Les groupes sociolinguistiques culturellement proches ont eu des perceptions convergentes de l'importance culturelle de l'espèce et décrit des pratiques de gestion similaires. Une analyse de la volonté des agriculteurs de modifier leurs pratiques de gestion actuelles a montré que la migration, les opportunités de marché et l'intervention extérieure pourraient affecter les futurs processus décisionnels de gestion. Nous avons discuté des approches axées sur la communauté pour améliorer la production de l'espèce dans la région. La présente étude souligne comment l'importance culturelle influence l'intensité de la gestion actuelle et future et illustre comment la recherche ethnobotanique peut guider les stratégies de recherche pour le dévelo...

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