Genetic diversity, inter-gene pool introgression and nutritional quality of common beans (Phaseolus vulgaris L.) from Central Africa

Abstract

The Great Lakes region of Central Africa is a major producer of common beans in Africa. The region is known for high population density and small average farm size. The common bean represents the most important legume crop of the region, grown on over a third of the cultivated land area, and the per capita consumption is among the highest in the world for the food crop. The objective of this study was to evaluate the genetic diversity in a collection of 365 genotypes from the Great Lakes region of Central Africa, including a large group of landraces from Rwanda as well as varieties from primary centers of diversity and from neighboring countries of Central Africa, such as the Democratic Republic of Congo and Uganda, using 30 fluorescently labeled microsatellite markers and automated allele detection. In addition, the landraces were evaluated for their seed iron and zinc concentration to determine if genetic diversity influenced nutritional quality. Principal coordinate and neighbor-joining analyses allowed the separation of the landraces into 132 Andean and 195 Mesoamerican (or Middle American) genotypes with 32 landraces and 6 varieties intermediate between the gene pools and representing inter-gene pool introgression in terms of seed characteristics and alleles. Genetic diversity and the number of alleles were high for the collection, reflecting the preference for a wide range of seed types in the region and no strong commercial class preference, although red, red mottled and brown seeded beans were common. Observed heterozygosity was also high and may be explained by the common practice of maintaining seed and plant mixtures, a coping strategy practiced by Central African farmers to reduce the effects of abiotic and biotic stresses. Finally, nutritional quality differed between the gene pools with respect to seed iron and zinc concentration, while genotypes from the intermediate group were notably high in both minerals. In conclusion, this study has shown that Central African varieties of common bean are a source of wide genetic diversity with variable nutritional quality that can be used in crop improvement programs for the region.

Characterization of the common bean host and Pseudocercospora griseola, the causative agent of angular leaf spot disease in Tanzania

“…These results from Tanzania confirm previous findings indicating that both Andean and Mesoamerican beans are grown within some African countries (Wortmann et al, 1998;Mahuku et al, 2002). In Tanzania, it has been found that farmers grow both Andean and Mesoamerican beans and in most cases they mix the two together in the same plot of land as a strategy of risk management since some cultivars fail and others are tolerant to biotic and abiotic factors (Blair et al, 2010).…”

“…In other regions of Tanzania, beans are consumed mostly with rice and maize meal for which the preference is large seeded beans in these dishes. In studies in countries neighboring Tanzania, the proportion of production of Andean and Mesoamerican bean in Uganda (Okii et al, 2014) is similar to that of Tanzania, while in Rwanda, common beans of Mesoamerican origin outnumbered the Andean ones (Blair et al, 2010).…”

Nutritionally Enhanced Staple Food Crops

“…The atomic absorption spectrophotometer (AAS) method has been suggested for routine estimation of Fe and Zn in seeds (Sahrawat et al 2002;Blair et al 2009bBlair et al , 2010aBlair et al ,b,2011). An excellent review on the role of atomic spectrometry in plant science has been published elsewhere, and it is important to recognize recent developments in multielemental and speciation analyses in plants with the resulting functional roles of different elements in plant science ).…”

“…Similarly, the transport of iron in phloem is well studied although the transport mechanism is not well known and may involve citric acid conjugates and/or nicotianamine as a transport system with most of the studies on Fe-transport based on mutants in peas (Grusak 2000(Grusak , 2002 or Arabidopsis (Grotz and Guerinot 2006), or rice (Takahashi et al 2001;Cheng et al 2007;Masuda et al 2009). Iron-uptake through iron reductase activity (IRA) seems to be important for total seed accumulation of this mineral in common bean (Blair et al 2010a).…”

Genetic control of iron concentration in Mesoamerican and Andean common bean seeds

“…Mesoamerican and Andean common bean seeds have a large genetic variability for iron, and values from 29 to 159 mg kg -1 dry matter (DM) have been reported Blair et al, 2010aBlair et al, , 2010bJost et al, 2013;Ribeiro et al, 2014aRibeiro et al, , 2014b, which allows for the selection and use of iron-rich cultivars for human consumption.…”