Antioxidant and Phytochemical Studies of 31 Cowpeas (Vigna unguiculata (Walp L)) Genotypes from Burkina.

Antioxidant compounds of dietary plants have been widely studied because of their bioactive properties. The objective of this research study was to analyse the health enhancing attributes of 31 cowpeas varieties from Burkina Faso. Significant variations were observed in the phenolic content as well as the antioxidant and anti-lipid peroxidation activities amongst the cowpea varieties. Pearson correlation coefficient analysis showed that the ferric reducing ability (r = 0.954) and anti-lipid peroxidation (r = 0.616) were positively correlated with the total phenolic content. A significant relationship between cowpea ferric reducing ability and anti-lipid peroxidation (r = 0.64) was also revealed. However, nitric oxide scavenging potential was found not to be related to its total phenolic and total flavonoid content. 2,2-diphenyl-1-picrylhydrazyl (DPPH) and hydroxyl radicals scavenging potentials were not correlated with the total flavonoid content. The pigmented seeds of cowpea varieties possess higher total phenolic, total flavonoid content, ferric reduction ability, and anti-lipid peroxidation activities than the colourless ones. The results obtained from this study suggest that Burkina Faso cowpea cultivars are rich in phenolic compounds and have significant antioxidant and anti-lipid peroxidation activities. Consumption of the cowpea, particularly of coloured cowpea seed varieties, should be beneficial for chronic human diseases prevention.

Genetic structure and mating system of wild cowpea populations in West Africa.

BACKGROUND: Cowpea is a highly inbred crop. It is part of a crop-weed complex, whose origin and dynamics is unknown, which is distributed across the African continent. This study examined outcrossing rates and genetic structures in 35 wild cowpea (Vigna unguiculata ssp. unguiculata var. spontanea) populations from West Africa, using 21 isozyme loci, 9 of them showing polymorphism. RESULTS: Outcrossing rates ranged from 1% to 9.5% (mean 3.4%), which classifies the wild cowpea breeding system as primarily selfing, though rare outcrossing events were detected in each population studied. Furthermore, the analyses of both the genetic structure of populations and the relationships between the wild and domesticated groups suggest possibilities of gene flow that are corroborated by field observations. CONCLUSIONS: As expected in a predominantly inbred breeding system, wild cowpea shows high levels of genetic differentiation and low levels of genetic diversity within populations. Gene flow from domesticated to wild cowpea does occur, although the lack of strong genetic swamping and modified seed morphology in the wild populations suggest that these introgressions should be rare.

AFLP markers linked to resistance against Striga gesnerioides race 1 in cowpea (Vigna unguiculata).

Amplified fragment length polymorphism (AFLP) analysis was used in combination with bulked segregant analysis (BSA) to identify molecular markers linked to two cowpea (Vigna unguiculata (L.) Walp.) genes conferring resistance to Striga gesnerioides race 1. After AFLP analysis of an F2 population derived from a cross between the resistant cultivar Gorom and the susceptible cultivar Tvx 3236, seven AFLP markers were identified that are linked to Rsg3, the gene conferring race I resistance in 'Gorom'. The distances between these markers and Rsg3 ranged from 9.9 to 2.5 cM, with two markers, E-AGA/M-CTA460 and E-AGA/M-CAG300, flanking Rsg3 at 2.5 and 2.6 cM, respectively. Analysis of a second F2 population derived from the cross between 'Tvx 3236' and the resistant cultivar IT81D-994 identified five AFLP markers linked to the race 1 resistance gene 994-Rsg present in 'IT81D-994'. The two markers showing the tightest linkage to the 994-Rsg locus were E-AAG/M-AAC450 and E-AAG/M-AAC150 at 2.1 and 2.0 cM, respectively. Two of the markers linked to 994-Rsg, E-AGA/M-CAG300 and E-AGA/M-CAG450, were also linked to Rsg3. The identification of molecular markers in common between the two sources of race 1 resistance suggests that either Striga resistance genes are clustered in these plants or that these loci are allelic. Mapping of the resistance loci within the cowpea genome revealed that three markers linked to Rsg3 and (or) 994-Rsg are located on linkage group 6.