Marius R.M. EKUE

Department of Forest Genetics and Forest Tree Breeding
Büsgen Institute
Georg-August University of Göttingen
Büsgenweg 2,
D-37077 Göttingen, Germany

E-mail: mekue@gwdg.de
Blog: http://ekuemr.blogspot.com

Personal Data, Career Path
1994-1998 Studies of Agronomy, University of Abomey-Calavi, Benin
1998-2000 Studies of Natural Resources Management (forest, wildlife, water and fisheries management), University of Abomey-Calavi, Benin
2000 Engineer degree in Natural Resources, Management University of Abomey-Calavi, Benin
2000-2003 Research assistant Laboratory of Applied Ecology, Faculty of Agronomics Sciences, University of Abomey-Calavi, Benin
2003-2005 Studies of Tropical and International Forestry, Georg-August University of Göttingen, Germany
2005 Master of Science in Tropical International Forestry, Georg-August University of Göttingen, Germany
since April 2006 PhD student at Department of Forest Genetics and Forest Tree Breeding, Georg-August University of Göttingen, Germany.

Research Interests
• Forest Genetics Resources Management
• Molecular Genetics of Plants
• Domestication
• Agroforestry Systems
• Non Timber Forest Products
• Biodiversity Indicators

Selected Ongoing or Recently Completed Research Projects
• Ethnobotanical knowledge, morphological variation and genetic diversity assessment of ackee (Blighia sapida) in Benin. PhD thesis in progress
• Population genetics of the cycad Encephalartos barteri ssp. barteri (Zamiaceae) in Benin with notes on leaflet morphology and implications for conservation (DAAD, Germany)
• Exploring the genetic diversity of the endogenous agroforestry species Blighia sapida in Benin (Rothamsted International; African Fellows Programme, UK) http://www.rothamsted-international.org/afp/alumni.shtml

PROJECT

Ethnobotanical knowledge, morphological variation and genetic diversity of ackee (Blighia sapida K.D. Koenig) in Benin

Summary
Native to West Africa, ackee (Blighia sapida K.D. Koenig) is a multipurpose species important for the livelihoods of rural populations and is managed by farmers in different traditional agroforestry systems. Ackee has emerged recently as a candidate species for domestication in Benin, but knowledge needed to elaborate a clear domestication strategy is still very sketchy in West Africa in general because the species has received very little attention from the research communities so far. The present work aimed at providing detailed first hand data enabling to elaborate a sustainable participatory domestication of this important neglected and underutilized species (NUS) in West Africa. The main objectives were (1) to collect farmer’s indigenous knowledge and perception of variation of ackee taking into account the variation among ethnic groups and gender, (2) to measure the morphological variability in tree and fruit traits in relation to environment and to establish a predictive model for production of the different useful part of the fruit, and (3) to characterize the genetic variability within and among populations, to assess the impact of human management practices on the genetic structure, and to evaluate the consequences for domestication and conservation of ackee by using different molecular markers systems.
Farmers’ knowledge on uses, management and perception of intraspecific variation among different ethnic groups was addressed by semi-structured interviews with 240 randomly selected persons (50% women) belonging to five different ethnic groups in Benin, with an additional 5 women active in the processing of ackee fruits and 6 traditional healers. For morphology and genetic analyses, fourteen stands (6 forest stands and 8 field/fallow stands) covering the range of the species in Benin, and situated in three different climatic zones were sampled. Overall, 279 trees were measured among which 71 are from the Guinean zone, 124 from the Guineo-Sudanian zone and 84 from the Sudanian zone. Also, up to 30 mature fruits were randomly collected from each of 27 trees (9 in the Guinean zone, 11 in the Guineo-Sudanian zone and 7 in the Sudanian). A total of 810 fruits were sampled.
People have different interests in using ackee, variable knowledge on uses and management practices, and have reported 9 differentiation criteria mainly related to the fruits. Ackee phenotypes with preferred fruit traits (size, color, aril taste and oil content) are perceived by local people to be more abundant in managed in situ and cultivated stands (field/fallow stands) than in unmanaged wild stands (forest stands) suggesting that traditional management has initiated a domestication process. Indigenous knowledge varied significantly among ethnic groups and gender.
Tree diameter at breast height, tree height and number of branches varied significantly among climatic zones and stand types. The mean annual rainfall, the potential evapotranspiration, the relative humidity, the temperature and the number of days of rain are the climatic variables explaining the variation observed. Fruits variables (fruit weight, aril weight, capsule weight, seed weight and number of seeds per fruit) did not vary significantly among climatic zones but the Sudanian zones exhibited the highest values. Field/fallow stands had the highest values for all fruits parameters. Fruit and capsules weight variation was significant. Climatic factors were not responsible for the variation observed in ackee fruits. Only capsule and seed weights could be predicted accurately from the fruit weight and number of seeds. Farmer indigenous selection practices and management of the species over generations are probably playing a role in the variation observed.
A set of 12 primer pairs for simple sequence repeats (SSRs) previously developed for lychee (Litchi chinensis) has been evaluated for polymorphism in ackee. The two species belong to the Sapindaceae family suggesting the transferability of the markers. Seven primer pairs were found to be transferable, among which four were polymorphic. The average number of alleles per locus dropped from 4.9 for lychee to 3.7 for ackee. Characterization of the four polymorphic markers revealed that the numbers of alleles per locus range from 2 to 14 with a mean number of 5.8. The observed and expected heterozygosities range between 0.020 to 0.359 and 0.020 to 0.396, respectively, for ackee.
Genetic variation at AFLP markers, the 4 polymorphic nuclear microsatellite (nSSR) loci transferred to ackee and one chloroplast microsatellite (cpSSR) marker was examined in all 279 individuals sampled. AFLP revealed that ackee has moderate levels of diversity in Benin (mean and total genetic diversity values are PPL=52.8%, Hj=0.157 respectively for 375 AFLP fragments). nSSR mean diversity values are HE = 0.286 (range 0.156 - 0.419) AR = 2.77 (range 1.88 – 3.67). To test for concerns of genetic erosion, the comparison of genetic variation of forest and field/fallow stands did not differ markedly suggesting that to date local farmer-led domestication activities have had little effect on diversity levels in the species. The analysis of molecular variance revealed that only 7.3% and 5.2% of the variation was partitioned among populations respectively for nSSR and AFLP. For AFLP and nSSR, a Mantel test revealed significant correlation between population pairwise geographic ln (distance) and FST/(1−FST) for all stands. Mantel test performed on forest stands alone was not significant. The only identified polymorphic chloroplast microsatellite marker (ccmp7) had three haplotypes (121, 135 and 145 bp). Haplotypes 121 and 135 bp were distributed across the country while one allele is restricted to the Northeastern part of Benin.
The results of this study show that traditional agroforestry systems of ackee in Benin are fulfilling their role in the circa situ conservation of this genetic resource. Thus, the strategy of participatory domestication of ackee should capitalize on that and make sure that actual and future planted stands keep the diversity of the species circa situ. The best way to guaranty the conservation circa situ function of ackee in agroforestry systems is to collect germplasm from trees meeting various market-oriented ideotypes ensuring thus that cultivars will be highly variable in many other desirable traits. In addition to forest stands, a representative unit for in situ conservation should also be defined in the North East. For an eventual establishment of provenance trials, seeds must also be collected from 3 additional representative units: one from the South in the Guinean zone, one from the Centre in the Guineo-Sudanian zone and the last one in the Sudanian zone but in the Western part near the border with Togo.
Based on the results obtained in this study and taking also into account the various ethnic groups using the species, 7 zones can be considered for germplasm collection: 2 zones in the Guinean zone, 3 in the transition Guineo-Sudanian zone and 2 in the Sudanian zone. Within each zone, two villages could be chosen for an initial collection. In each of the 14 villages, fruits should be collected from 15 to 20 fruiting trees with the helps of farmers based on traits important to them. Fruits and especially its arils are the most important part of ackee tree. Therefore, fruit size is probably the first criterion to select elite tree for germplasm collection, but other traits such as aril taste and aril color are very important for long-term storage. Seasonality of fruiting should also be taken into account.
The development of vegetative propagation techniques should be done in 7 pilot nurseries established each between the two villages selected in each zone and farmers should be involved in the management of the nursery. Exchange of germplasm should be limited to each zone to avoid any negative impact of mal-adaptation and outbreeding depression that can occur. Women, men and young farmers should be all involved in the identification, collection and multiplication activities of the germplasm
The market study remained to be done for the whole country. The distribution channel of products, the processing, storage, transformation and packaging should also be examined and improved. Those elements are as essential as the ability to deliver improved domesticated germplasm for planting, if one wants to insure any successful domestication of ackee. Socio-economic studies should also look at the regional trade of the fruits involved in transboundary exchange of non-timber forest products and/or agroforestry tree products with Benin’s immediate neighboring countries.