Lebot V.,CIRAD BIOS |
Lawac F.,VARTC |
Michalet S.,University Claude Bernard Lyon 1 |
Legendre L.,University Claude Bernard Lyon 1
Plant Genetic Resources: Characterisation and Utilisation | Year: 2015
The starchy corms of taro (Colocasia esculenta) are consumed throughout the tropics and are essential for food security in many developing countries. Taro corms are increasingly processed into fries, chips, flours or flakes in urban areas, and varieties with attractive corm flesh colours are now needed. The identification of flavonoids in taro corms would add value to this crop. The present study developed a high-performance thin layer chromatography (HPTLC) protocol for the high-throughput screening of flavonoids in taro germplasm. Overall, 350 different accessions were analysed including 259 varieties from Vanuatu, one from Vietnam, eight from Thailand, eight from the Philippines, six from Malaysia, two from Japan and 18 from Indonesia. Forty-eight breeding lines (hybrids) including 21 from Vanuatu, 21 from Samoa, four from Hawaii and two from Papua New Guinea were also analysed. Ten flavones, namely luteolin-6-C-hexoside-8-C-pentoside, schaftoside, luteolin-3′,7-di-O-glucoside, homoorientin, isovitexin, orientin, luteolin-4′-O-glucoside, luteolin-7-O-glucoside, vitexin and apigenin-7-O-glucoside, were successfully detected in the corm and are responsible for the attractive yellow colour of the flesh and fibres. Quantitatively, luteolin-6-C-hexoside-8-C-pentoside and schaftoside were the most important of all the detected flavonoids. However, only 18% of the varieties analysed presented these two compounds and 80% presented poor flavonoid composition. No geographical structure of the variation was detected and the most flavone-rich varieties originated from Vanuatu, Thailand, the Philippines, Malaysia and Indonesia. The compounds detected in the present study were significantly and positively correlated, suggesting that there is potential for fast improvement through controlled crosses, subsequent evaluation of full-sib progenies and cloning of elite individuals. Copyright © NIAB 2015
Somarriba E.,Tropical Agriculture Research and Higher Education Center |
Lachenaud P.,CIRAD BIOS
Forests Trees and Livelihoods | Year: 2013
Cocoa was used as a fruit in its native range. Cocoa fruits were harvested from "wild" cocoa stands embedded into the forests growing on the high terraces of the Amazon and Orinoco river systems and in the Guiana shield. "Wild" cocoa stands resulting from human intervention and disturbance of the local forest ecosystem are called subspontaneous cocoa stands. We propose that these sub-spontaneous cocoa forests are a new type of cocoa production system that we propose to call "successional cocoa agroforest." This article (1) describes the history of extractive cocoa in the Amazon basin, (2) outlines the possible historic path of domestication and use of cocoa subspontaneous stands, (3) specifies the biophysical and cultural processes that determine the creation-destruction-regeneration of the successional cocoa agroforest, (4) proposes a model for the functioning of this cocoa production system, and (5) documents the scarce information available on the changes in both the forest vegetation and biomass, and cocoa population numbers along the course of forest succession. This study shows the need to broaden the popular five classes classification of coffee and cocoa production systems (open sun cultivation, specialized shade, commercial shade, mixed shade, and rustic systems) to include a sixth type, the "successional cocoa agroforest." © 2013 Taylor &Francis.
Chapuis M.-P.,CIRAD BIOS |
Plantamp C.,CNRS Biometry and Evolutionary Biology Laboratory |
Blondin L.,CIRAD - Agricultural Research for Development |
Pages C.,CIRAD - Agricultural Research for Development |
And 2 more authors.
Molecular Ecology | Year: 2014
Between plagues, the solitarious desert locust (Schistocerca gregaria) is generally thought to exist as small populations, which are particularly prone to extinction events in arid regions of Africa and Asia. Given the high genetic structuring observed in one geographical area (the Eritrean coast) by former authors, a metapopulation dynamics model involving repeated extinction and colonization events was favoured. In this study, we assessed the validity of a demographic scenario involving temporary populations of the solitarious phase of the desert locust by analysing large-scale population genetic data. We scored 24 microsatellites in 23 solitarious population samples collected over most of the species range during remission. We found very little genetic structuring and little evidence of declining genetic diversity. A Bayesian clustering method distinguished four genetically differentiated units. Three groups were largely consistent with three population samples which had undergone recent bottleneck events. Nevertheless, the last genetically homogeneous unit included all individuals from the remaining 18 population samples and did not show evidence of demographic disequilibrium. An approximate Bayesian computation treatment indicated a large population size for this main genetic group, moderately reduced between plague and remission but still containing tens of thousands of individuals. Our results diverge from the hypothesis of a classical metapopulation dynamics model. They instead support the scenario in which large populations persist in the solitarious phase of the desert locust. © 2014 John Wiley & Sons Ltd.
Lebot V.,CIRAD BIOS |
Michalet S.,CNRS Microbial Ecology |
Legendre L.,CNRS Microbial Ecology
Journal of Food Composition and Analysis | Year: 2016
The objectives of the present study were to develop a simple high performance thin layer chromatography (HPTLC)-based protocol: (i) to allow high-throughput profiling of phenolic compounds of microwaved roots from 295 sweet potato varieties and breeding lines, (ii) to quantify the content of anthocyanins and caffeoylquinic acid (CQA) derivatives, and (iii) to determine their respective contributions to the antioxidant activity of sweet potato methanolic extracts using the DPPH test. Analysed accessions were separated into three groups: white-fleshed (n = 100), orange-fleshed (n = 64) and purple-fleshed (n = 131). Purple-fleshed accessions presented the highest mean CQA content. After DPPH treatment and transmittance scanning of the plate at 517 nm, the most active free radical scavengers were found to be the four CQAs (CGA, 3,4-, 4,5- and 3,5-diCQA) while the anthocyanins were found to be less active. The total antioxidant capacity of the sweet potato methanolic extracts was mostly linked to total CQAs content. This method can now be used for fast routine analysis and selection of sweet potato breeding clones. © 2016 .
Lebot V.,CIRAD BIOS
Environment, Development and Sustainability | Year: 2013
The capability of Pacific Island countries' agriculture to adapt to climatic and environmental changes is analysed. After presenting key features of the region's food cropping systems, findings of genetic diversity studies for the most important food crops are reviewed and their implications for adaptation are discussed. Biophysical and economic vulnerabilities of the food system are identified. For the major food crops, the needs for genetic improvement are detailed, and practical solutions for broadening genetic bases are suggested. The paper concludes by identifying areas for additional research on crops and agro-ecosystems adaptation aiming at increasing the flexibility of agriculture in the Pacific. In this region, plant breeding has to cope with the insularity constraints of the small island states. The new varieties need to satisfy farmers' agronomic requirements in very diverse environments. However, because of genotype-by-environment interactions (G × E), it is difficult to identify a variety that would be accepted by most farmers on different islands. A new type of breeding programme with a pragmatic approach is therefore necessary. The geographical distribution of allelic diversity appears as a practical and cost-efficient solution. © 2013 Springer Science+Business Media Dordrecht.
Lebot V.,CIRAD BIOS |
Simeoni P.,Geoconsulte Ltd.
Human Ecology | Year: 2015
To study food production systems of six communities located on six different islands of Vanuatu we selected villages in zones of low and high population pressures. We measured land availability, soil fertility, genetic resources, average yields of food gardens, their plant densities, traditional knowledge richness (TKR), and household incomes and expenses. We analyzed a total of 224 plots belonging to 30 farmers and identified 13 root crop species with the total number of cultivars in communities ranging from 74 to 261. Surprisingly, villages under high population pressure have shorter fallow periods but higher yields. In both zones, women have higher TKR. In high population pressure villages there are signs of soil fertility reduction and mineral depletion but no signs of significant decrease in soil fertility after the first year of cultivation, indicating that root crop species remove limited amounts of total N and minerals per year. The purchase of imported foods is associated with a sociocultural change in diets rather than pressures on land or soils. Our quantitative and integrative methodology allows clear differentiation between villages under different pressures and can be used to assess levels of resilience and vulnerability. © 2015 Springer Science+Business Media New York.
PubMed | CIRAD BIOS
Type: | Journal: Journal of insect science (Online) | Year: 2016
Miridae (Hemiptera: Heteroptera: Cimicomorpha), or plant bugs, are one of the most diverse and species-rich families of insects. Most of them are phytophagous, but some are insect predators and used for biocontrol. Among this family, the mango bug, Orthops palus (Taylor 1947), is one of the most important pest of mango in Reunion Island. We developed 11 polymorphic microsatellite loci to study the population genetics of this pest species. The microsatellite markers were characterized by genotyping 78 field-collected insects sampled at different localities in Reunion Island. The number of alleles per locus ranged from 1 to 13 and heterozygosity levels ranged between 0.40 and 0.94. Several loci were not at Hardy-Weinberg equilibrium for the tested populations. These markers are the first to be developed for a species of the genus Orthops.