Background

​

Common bean (Phaseolus vulgaris L.) is an important crop that offers plenty of protein, dietary fibres, vitamins and micronutrients such as iron (Fe) and zinc compared to other staple food crops grown in Tanzania. It is the most cultivated and consumed grain legume in the country, and particularly bean varieties with a yellow seed coat are favoured. Common bean is produced for home consumption and a source of income to the farmers, bean traders, and the country at large. While beans are known for their relatively high seed iron content, the yellow bean varieties in Tanzania are relatively low in seed Fe content. Moreover, the bioavailability and absorption of minerals from food is negatively affected by phytic acid (PA), which is relatively high in two Tanzanian widely cultivated yellow bean varieties.

 

Therefore, this project is aimed at improving seed Fe content of the two widely grown yellow bean varieties and at the same time reduce their PA content through traditional breeding for increased bioavailability of Fe. The project will be implemented in Tanzania, using exotic light to dark yellow bean genotypes previously identified to contain high seed Fe bioavailability and some with relatively low PA as donor parents. The widely consumed yellow bean varieties (Selian 13 and Njano Uyole) will be crossed with high seed Fe, high Fe bioavailability and low PA bean genotypes. The presence of high seed Fe, high Fe bioavailability and low PA contents in the landraces will also be validated through planting the genotypes in different locations and determining their Fe and PA contents, and Fe bioavailability. F2 lines (second filial generation lines) will be made available for further improvement and advancement using marker assisted selection (MAS) aimed in a couple of years to release a yellow bean variety high in seed Fe, and high Fe bioavailability with increased seed yield.

 

Objectives:​

​

1. To increase the seed amount of the exotic yellow bean varieties imported from other bean growing countries.

2. To screen the widely consumed yellow bean varieties and other popular bean market class types in Tanzania for the presence/absence of the molecular marker (Phvul.010G130600 STS marker) associated with non-darkening (ND) of the seed coat of bean genotypes.

3. To determine the levels of seed Fe, PA, and Fe bioavailability among common bean parents grown in three different agro-ecological zones used for common bean cultivation in Tanzania.

4. To develop F2 populations of common bean lines by crossing widely consumed yellow bean varieties (Selian 13 and Njano Uyole) with high and stable seed Fe, low PA, and high Fe bioavailability genotypes, reported and selected in objective (ii).