Application of fast technology for analysis (FTA) for sampling and recovery of deoxyribonucleic acid (DNA) for molecular characterization of cowpea breeding lines for Striga resistance

Article purchasedStriga gesnerioides (Willd) Vatke is a significant constraint to cowpea production in the dry savannas of sub-Saharan Africa. Yield losses caused by S. gesnerioides in these regions are estimated in millions of tons annually and the prevalence of Striga soil infestation is steadily increasing. Conventional breeding efforts have developed some cowpea lines with Striga resistance as well as other important agronomic traits but it is time-consuming and difficult to pyramid favorable traits. The use of marker-assisted selection (MAS) makes it easier to select plant traits and reduce the time needed to develop new varieties. The potential of Fast Technology for Analysis (FTA) as an effective technology for sampling and retrieval of DNA from plant tissue and their subsequent molecular analysis was assessed in the laboratory. DNA was successfully recovered from the leaf tissues of cowpea pressed into the FTA® Classic card and the DNA obtained from the FTA papers was found to be suitable for molecular analysis by PCR-based techniques. The marker efficiency of Sequence Characterized Amplified Region (SCAR) marker MahSe2 and C42B was 93% in detecting SG3 resistance. This study demonstrated that the application of MAS using FTA technology has the potential to put the breeding process on a fast track and increase the efficiency of breeding activities

Phenotyping cowpea for seedling root architecture reveals root phenes important for breeding phosphorus efficient varieties

Open Access Article; Published online: 15 Sep 2021Cowpea (Vigna unguiculata L. Walp.) is a key climate-resilient legume for food security, especially in sub-Saharan Africa. Cowpea yields are limited by edaphic stresses including drought and low phosphorus (P) availability. Identifying genotypes with advantageous root phenotypes can facilitate breeding for improved yield in marginal environments. We evaluated 50 elite genotypes from African and U.S. sources for seedling root architecture and root hair length and density. Significant genotypic variation was detected for all phenes, and high heritability was observed for architectural phenotypes including primary root length (77%), basal root number (72%), and taproot branching density (67%). Moderate heritability was detected for root hair length and density among different root classes (34 to 63%), which were positively associated with each other. Principal component analysis identified three clusters, primarily defined by seed dimension and seedling root architecture. Genotypes were identified with longer root hairs (TVu-7778, Vita7, and Sanzi) and longer taproots (IT96D-610, IT98K-111-1, and IT97K-499-35), as potential parents. Root phenotypes, grain, and fodder yield were assessed on a subset of 20 genotypes under contrasting P availability in the field. Some seedling root phenotypes were significantly related to mature plant dry fodder weight (taproot hair density) and to grain yield (lateral root hair density) under low P. Root hairs are positively related to plant productivity under low P. We suggest selection for longer primary roots, as more basal and lateral root roots may be beneficial for cowpea in drought and low P environments. These findings suggest seedling root phenotypes can support cowpea breeding for suboptimal environments

Genetic analysis of male sterility genes in different A and B sorghum lines

Hybrid seed production requires use of cytoplasmic male sterility (CMS). Without this system, hybrid seed production would not be economically feasible. There is, therefore, need for developing A and B sorghum lines, as an essential step for development of hybrid sorghum industry. A genetic study of male sterility in different A and B sorghum ( Sorghum bicolor (L.) Moench) lines was conducted at the research farm Institute for Agriculture Research in Samaru and Kadawa. Chi-square test revealed goodness-of-fit to single gene of observed proportion of sterile and fertile plants to the expected ratio in all the backcross generations, thereby upholding the assumption of single gene inheritance for the traits studied. Stability of male sterile genes across generations of backcrosses indicated that sterility was inherited 68 to 95% among the different genotypes. Based on high number of sterile plants, crosses 159 x 160 and 421 x 422 are the best in terms of breeding potential for male sterility.La production des semences hybrides n\ue9cessite l\u2019utilisation de la st\ue9rilit\ue9 m\ue2le cytoplasmique (CMS). Sans ce syst\ue8me, la production des semences hybrides ne serait pas \ue9conomiquement faisable. Il y a donc, un besoin pour d\ue9velopper des lign\ue9es A et B du sorgho, comme une \ue9tape essentielle dans le d\ue9veloppement d\u2019industrie de sorgho hybride. Une \ue9tude g\ue9n\ue9tique de la st\ue9rilit\ue9 m\ue2le dans diff\ue9rentes lign\ue9es A et B du sorgho ( Sorghum bicolor (L.) Moench) a \ue9t\ue9 conduite \ue0 la ferme d\u2019exp\ue9rimentation de l\u2019Institut des Recherches Agricoles de Samaru et Kadawa. Le test de Chi-carr\ue9 a r\ue9v\ue9l\ue9 la qualit\ue9 d\u2019association d\u2019un seul g\ue8ne de la proportion observ\ue9e de plants st\ue9riles et fertiles au ratio observ\ue9 dans les g\ue9n\ue9rations de r\ue9trocroisement, ainsi soutenant l\u2019hypoth\ue8se de l\u2019h\ue9ritage d\u2019un g\ue8ne pour les traits \ue9tudi\ue9s. La stabilit\ue9 de g\ue8nes de la st\ue9rilit\ue9 m\ue2le \ue0 travers les g\ue9n\ue9rations du r\ue9trocroisement a indiqu\ue9 que la st\ue9rilit\ue9 \ue9tait h\ue9rit\ue9e entre 68 \ue0 95% entre les diff\ue9rents g\ue9notypes. Sur la base du nombre \ue9lev\ue9 de plantes st\ue9riles, les croisements 159 x 160 et 421 x 422 sont les meilleurs en termes du potentiel d\u2019am\ue9lioration g\ue9n\ue9tique pour la st\ue9rilit\ue9 m\ue2le

The spatial genetic differentiation of the legume pod borer, Maruca vitrata F. (Lepidoptera: Crambidae) populations in West Africa

The legume pod borer, Maruca vitrata, is an endemic insect pest that causes significant yield loss to the cowpea crop in West Africa. The application of population genetic tools is important in the management of insect pests but such data on M. vitrata is lacking. We applied a set of six microsatellite markers to assess the population structure of M. vitrata collected at five sites from Burkina Faso, Niger and Nigeria. Observed polymorphisms ranged from one (marker 3393) to eight (marker 32008) alleles per locus. Observed and expected heterozygosities ranged from 0.0 to 0.8 and 0.0 to 0.6, respectively. Three of the loci in samples from Nigeria and Burkina Faso deviated significantly from Hardy-Weinberg Equilibrium (HWE), whereas no loci deviated significantly in samples from Niger. Analysis of molecular variance (AMOVA) indicated that 67.3% level of the genetic variation was within individuals compared to 17.3% among populations. A global estimate of FST=0.1 (ENA corrected FST=0.1) was significant (P≤0.05) and corroborated by pairwise FST values that were significant among all possible comparisons. A significant correlation was predicted between genetic divergence and geographic distance between subpopulations (R2=0.6, P=0.04), and cluster analysis by the program STRUCTURE predicted that co-ancestry of genotypes were indicative of three distinct populations. The spatial genetic variance among M. vitrata in West Africa may be due to limited gene flow, south-north seasonal movement pattern or other reproductive barriers. This information is important for the cultural, chemical and biological control strategies for managing M. vitrata

Inheritance of time to flowering in cowpea [Vigna unguiculata (L.) Walp]

SIGLEAvailable from British Library Document Supply Centre-DSC:DXN011466 / BLDSC - British Library Document Supply CentreGBUnited Kingdo

Optimization of protocol for multiple shoots regeneration from apical meristem of embryonic axes in cowpea (Vigna unguiculata L. Walp)

No AbstractKeywords: Cowpea, Embryonic axes, Regeneration, Multiple shoots, N6-benzylaminopurin

Genetic variability and heritability studies of some reproductive traits in cowpea (Vigna unguiculata (L.) Walp.)

The success of most crop improvement programs largely depends upon the genetic variability and the heritability of desirable traits. The magnitude and type of genetic variability help the breeder to determine the selection criteria and breeding schemes to be used for improvement purposes. A screen house experiment was carried out at Samaru, Nigeria in 1999 and 2000 dry seasons to estimate the genotypic variability of some reproductive traits and their heritability in some selected cowpea varieties. Results of the study showed that there was considerable variation among cultivars for duration of reproductive phase and rate of photosynthate partitioning. Genotypic coefficients of variation were also high for days to first flower, 100-seed weight, plant height, and harvest index. Broad-sense heritability estimate (h2) was 98.9% for 100-seed weight, 94% for duration of reproductive phase, 84.5% for days to first flower, 83.9% for days to maturity, and 77.3% for harvest index. This information showed that there is sufficient genetic variance to warrant selection for improvement in the cowpea genotypes studied. We concluded that considerable progress in cowpea breeding could be achieved by exploiting these traits

Evaluation of cowpea genotypes for their reactions to Striga gesnerioides in the dry savanna of northeast Nigeria

The parasitic weed Striga gesnerioides (Willd) Vatke is one of the most important constraints to cowpea production in the dry savanna. Yield losses due to S. gesnerioides range from 83 to 100%. No single method however seems to be fully adequate in the control of this parasite. One practice, host plant resistance, appears to have merit in effectively and economically controlling the parasite in that it is affordable to farmers. A total of 30 breeding lines including some varieties were evaluated in a field trial at Damboa and Tilla in 2005 and 2006 to identify resistant parents that could be used in breeding programme. Results showed varietal difference with respect to Striga infection in the genotypes studied. Location and cultivars were found to be associated with yield losses in soils infested by Striga. The location effect was probably due to lower soil fertility and severity of Striga damage. Cultivars effect was evident at both locations. The cowpea varieties B301, IT00K-1217, IT97K-205-8, IT03K-338-1 and IT97K-499-35 showed complete resistance to Striga while cowpea varieties IT81D-994, 1T98K-503-1, IT99K-7-21-2-2 and IT98K-216-44 earlier reported to be resistant supported many emerged Striga shoot, thus, suggesting the presence of different strains of Striga in the region. On the other hand, the varieties like Borno local, IT84S-2246-4, IT98D-1399, TVU-7778 and TVX-3236 have low yield potential as well as susceptible to Striga. Average yield loss in susceptible variety (Borno local) relative to the mean yield of resistant cultivars was 44%. There was a strong negative correlation (r = - 0.537) between grain yield and emerged Striga shoot. A significant negative (r = - 0.391, r = - 0.188) correlation was also obtained between grain yield, pods per plant and Striga height. This information showed that there is sufficient genetic variability in the cowpea genotypes studied, which can be exploited in breeding cowpea varieties for resistance to S. gesnerioides. A great progress toward developing improved cowpea germplasm that has local phenotypes with durable resistance to S. gesnerioides can be achieved if the genes from the resistance cultivars identified could be introgressed into the adapted susceptible local varieties in the area. This will further increase the potential impact of adoption of resistant cowpea varieties in the zone