References

w w w . a g r a r . u n i – k a s s e l . d e

1Organic Plant Production and Agroecosystems Research in the Tropics and Subtropics (OPATS), University of Kassel, Germany 2Forest Genetics and Forest Tree Breeding, Georg-August-University Göttingen, Germany 3Tree Genetic Resources and Domestication, World Agroforestry Centre (ICRAF), Nairobi, Kenya 4Department of Horticulture, University of Khartoum, Sudan 5Sustainable Agricultural Production Systems with Special Focus on Horticulture, Rhine-Waal University of Applied Sciences, Germany

Martin Wiehle1, Kathleen Prinz2, Katja Kehlenbeck3, Sven Goenster1,

Seifeldin Ali Mohamed4, Reiner Finkeldey2, Andreas Buerkert1 and Jens Gebauer5

Baobab (Adansonia digitata L.) –

Morphological and genetic diversity of a neglected

population in the Nuba Mountains, Sudan

Diversity: Tree height and diameter at breast height differed significantly

among locations, whereas fruit morphology exhibited low differences.

However, tree-to-tree variation within locations was high. Samples from the

southwest showed slightly higher genetic diversity indices (Table). High

diversity in all locations.

Genetic structure: A Bayesian clustering approach structured the samples

into two genetically different groups (Fig. 3): cluster 1, mainly trees from the

southwest (SW) and cluster 2, mainly trees from other locations. Urgent

need to implement conservation strategies in both genetically distinct

units.

Human impact: Baobabs sampled in or close to homesteads showed

slightly higher genetic diversity compared to trees far from homesteads

(‘wild’). First indication that human-mediated seed admixture from

various origins have possibly enriched the genetic base in the

homestead stands.

Introduction & Methods

Results & Discussion

Adansonia digitata L. is an important fruit tree of semi-arid sub-Saharan

Africa (Fig. 1). Baobab’s fruit pulp provides local nutrition and supports

national economies and even export markets. Despite its importance,

information of the tree’s ecology and distribution as well as morphological

and genetic diversity is lacking, particularly for the East African range. Within

that region, Sudan harbors the northernmost populations with potential

adaptations to dry conditions (Fig. 1). However, these populations are

threatened by lack of rejuvenation as well as habitat loss due to climate

change and human impact. A strong human association to baobabs leads to

the question if humans altered the species’ variation.

Therefore, morphological (dendrometric and fruit traits) and genetic data

(microsatellite markers) of 306 trees from Sudan were assessed that can be

used to develop suitable ex and/or in situ conservation strategies for this

important tree species. Figure 1. Natural distribution map (Wickens, 1979) and

sampling locations in the Nuba Mountains, Sudan.

Study area

The surprisingly high morphological variability and genetic diversity of

baobab highlights the potential for domestication of this neglected wild tree

in Sudan. The development of region-specific and sustainable management

strategies as part of circa situm conservation approaches will contribute to

maintain the genetic resources of this important, but threatened species in

the Nuba Mountains.

tropcrops@uni-kassel.de

Figure 3. Bayesian

cluster plots obtained

with the STRUCTURE

software package

2.3.1 (Pritchard et al.

2000) for two

clusters, the most

plausible grouping of

all investigated

genotypes. Each

vertical bar

partitioned into two

colored segments

refers to a particular

tree and illustrates

the assignment

likelihood of the

respective genotype

to one of the two

clusters. Table. Morphological and genetic indices assessed for 306 A. digitata trees in the Nuba Mountains, 2010. ns=non-significant

according to Kruskal-Wallis for locations and Mann-Whitney test for ‘Homestead’ and ‘Wild’.

Homestead

trees

Microsatellite

application

DNA extraction

Wickens, G. E. (1979), Chapter 15: The uses of the baobab

(Adansonia digitata L.) in Africa. In: Taxonomic aspects of

African economic botany, Kunkel, G. (ed.).

Pritchard, J. K., M. Stephens, et al. (2000). Inference of

population structure using multilocus genotype data. Genetics

155: 945–959.

Financially supported by

Figure 2. Baobab

leaf and section of

DNA double helix.

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Conclusions