Common Bean Case Study
. Introduction
The common bean (Phaseolus vulgaris L.) is the most important food legume crop grown worldwide (Wortmann and Allen, 1994; Wortmann et al., 1998; Buruchara, 2006). Beans are considered by many to be the perfect food as they are nutrient dense with high contents of protein, micronutrients especially iron and zinc, vitamins, and dietary fibre (Wortmann and Allen, 1994; Bennink, 2005; Widers, 2006). The crop is currently the second most important source of human dietary protein (Buruchara, 2006). East Africa accounts for over 75% of the total bean production in Africa, with Kenya being the leading producer in East Africa( FAOSTAT, 2007).Despite the importance of common bean in Kenya and other developing countries, its production …show more content…
vulgarius) possesses by far the widest adaptation of all Phaseolus spp. with over 85% of the cultivated species falling under this species worldwide (Singh, 2001). Common beans are classified in the sub-phylum Dicotyledons, division Magnoliophyta, class Magnoliopsida, family
Leguminosae, sub-family Papilionoideae/Fabaceae/Lotoideae and order Leguminales(Rutger and Beckham, 1970; Stoetzer, 1984). Common beans are a diploid and are a self-pollinated crop (Rutger and Beckham, 1970; Stoetzer, 1984) possessing complete,papilionaceous flowers with 10 stamens, and an ovary with a long, coiled style and a hairy introrse stigma; the stigma is situated laterally along the inner arc of the curved style, where it intercepts pollen dehiscing from its own anthers. The crop is highly polymorphic, showing considerable variation in growth habit, vegetative characters, flower colour and size, shape and colour of pods and seeds (Purseglove, 1968).
Genetic Diversity
According to Evans (1973; 1980), genetic diversity in common bean may be organised into three general classes according to seed size namely, the large-seeded (>40g 100 seed weight-1) Andean genepool and the medium (25-40g 100 seed weight-1) and small (<25g 100 seed weight-1) seeded Middle American genepool. The presence of two genepools …show more content…
and Ndjiondjop, M.N. 2006). The gain from selection using such index is expected to be higher than phenotypic selection used in conventional recurrent methods (Semagn, K., Bjornstad, A. and Ndjiondjop, M.N.2006). Significant progress has been made through phenotypic selections for agronomic traits. For example; significant progress has been achieved in selecting BCMV and BCMNV resistant lines (Kelly, J. D. and Miklas, P. N. 1998).
MAS is an approach designed to avert problems encountered with conventional/classical plant breeding by increased precision of selection, selecting phenotypes through the selection of genes that control the traits of interest (Collards, B.C.Y, Jahufer, M.Z.Z., Brouwer, J.B., Pang, E.C. K.2005). This is because molecular markers are clearly not influenced by environment and are detectable at all stages of plant growth (Babu, R., Nair, S.K., Prasanna, B.M and Gupta H.S.
The common bean (Phaseolus vulgaris L.) is the most important food legume crop grown worldwide (Wortmann and Allen, 1994; Wortmann et al., 1998; Buruchara, 2006). Beans are considered by many to be the perfect food as they are nutrient dense with high contents of protein, micronutrients especially iron and zinc, vitamins, and dietary fibre (Wortmann and Allen, 1994; Bennink, 2005; Widers, 2006). The crop is currently the second most important source of human dietary protein (Buruchara, 2006). East Africa accounts for over 75% of the total bean production in Africa, with Kenya being the leading producer in East Africa( FAOSTAT, 2007).Despite the importance of common bean in Kenya and other developing countries, its production …show more content…
vulgarius) possesses by far the widest adaptation of all Phaseolus spp. with over 85% of the cultivated species falling under this species worldwide (Singh, 2001). Common beans are classified in the sub-phylum Dicotyledons, division Magnoliophyta, class Magnoliopsida, family
Leguminosae, sub-family Papilionoideae/Fabaceae/Lotoideae and order Leguminales(Rutger and Beckham, 1970; Stoetzer, 1984). Common beans are a diploid and are a self-pollinated crop (Rutger and Beckham, 1970; Stoetzer, 1984) possessing complete,papilionaceous flowers with 10 stamens, and an ovary with a long, coiled style and a hairy introrse stigma; the stigma is situated laterally along the inner arc of the curved style, where it intercepts pollen dehiscing from its own anthers. The crop is highly polymorphic, showing considerable variation in growth habit, vegetative characters, flower colour and size, shape and colour of pods and seeds (Purseglove, 1968).
Genetic Diversity
According to Evans (1973; 1980), genetic diversity in common bean may be organised into three general classes according to seed size namely, the large-seeded (>40g 100 seed weight-1) Andean genepool and the medium (25-40g 100 seed weight-1) and small (<25g 100 seed weight-1) seeded Middle American genepool. The presence of two genepools …show more content…
and Ndjiondjop, M.N. 2006). The gain from selection using such index is expected to be higher than phenotypic selection used in conventional recurrent methods (Semagn, K., Bjornstad, A. and Ndjiondjop, M.N.2006). Significant progress has been made through phenotypic selections for agronomic traits. For example; significant progress has been achieved in selecting BCMV and BCMNV resistant lines (Kelly, J. D. and Miklas, P. N. 1998).
MAS is an approach designed to avert problems encountered with conventional/classical plant breeding by increased precision of selection, selecting phenotypes through the selection of genes that control the traits of interest (Collards, B.C.Y, Jahufer, M.Z.Z., Brouwer, J.B., Pang, E.C. K.2005). This is because molecular markers are clearly not influenced by environment and are detectable at all stages of plant growth (Babu, R., Nair, S.K., Prasanna, B.M and Gupta H.S.