Application of Cry1Ab/Ac Bt strip for screening of resistance for Maruca vitrata in cowpea

Maruca vitrata is a significant constraint to cowpea production in most cowpea growing areas of sub-Saharan Africa. Yield losses caused by M. vitrata in these regions are estimated in millions of tons annually and the prevalence of M. vitrata infestation is steadily increasing. Recombinant DNA technology have led to development of some cowpea lines with Maruca resistance as well as other important agronomic traits but it is time-consuming and difficult to screen for the resistant trait especially in the segregating populations using conventional screening techniques, which will lead to delay in the development of Maruca resistant cowpea varieties. The use of allele-based selection tool will make it easier to select plant traits and reduce the time needed to develop new Maruca resistant cowpea varieties. In this study, the efficacy of using Cry1Ab/Ac Bt strip for detecting Maruca resistant transgene in transgenic cowpea was systematically investigated for the first time through field derived progenies. The results show that the Cry1Ab/Ac Bt strip was effective for detecting the presence of the resistant gene in cowpea genome. Maruca resistant plants were successfully screened from the segregating cowpea plants and the genetics of the gene was monitored. The Cry1Ab/Ac Bt strip was found to be suitable for genetic analysis of the Maruca resistant transgene in cowpea. This study has demonstrated the precision of using Cry1Ab/Ac Bt strips as a screening tool of transgenic lines containing Cry1Ab gene, this has an importance in the hybridization programme where genotypes having cry gene can be distinguished at seedling stage at lesser time, with the potential of putting the breeding process on a fast track and increase the efficiency of breeding activities.Keywords: Bacillus thuriengiensis, Cry1Ab/Ac Bt strips, transgenic cowpea, Maruca vitrata.African Journal of Biotechnology Vol. 12(40), pp. 5869-587

Generation mean analysis of dual purpose traits in cowpea (Vigna unguiculata [L.] walp)

Dual-purpose, the relative ratio of grain to fodder productivity of cowpea (Vigna unguiculata) is one of the major factors affecting the adoption of new varieties in sub-Saharan Africa. Efforts have been made to improve either the fodder or the grain productivity separately. However, there is the need to develop a variety with both good grain and fodder productivity. Gene effects for dual-purpose traits were estimated from the combined analysis of the parental, F1, F2 and backcross populations involving one fodder cowpea and two grain type cowpeas with the aim of understanding the genetic basis of these characteristics. The fodder parent had significantly better performance compared to the grain types for all dual-purpose traits. Transgressive segregates for high and low fodder yield were observed, suggesting that the fodder yielding genes were dispersed among the parents. Frequency analysis showed that all the F2 populations for fodder yield exhibited a continuous distribution, suggesting that inheritance of fodder yield is quantitative in nature and may involve more than two genes. Epistatic effects were found to be important for all dual-purpose traits (days to first flower, plant height, pod weight, leaf weight, branch weight, seed weight, biomass and fodder yield). Fodder yield per plant appeared to be influenced by both additive and non-additive gene effects, whereas grain yield was influenced by complementary gene action. Duplicate gene interaction was predominantly involved in the inheritance of most of the structural traits (plant height, leaf weight and branch weight). For genetic improvement of fodder and grain yield, utilizing non-additive components, intermating among selected segregates in early generation or reciprocal recurrent selection should be effective approaches.Keywords: Gene effects, fodder, Vigna unguiculata, generation mean analysi

Impact of genetic transformation on morphological expression of transgenic cowpea

Two genetically engineered cowpea lines(TCL-709 and TCL-711) were evaluated under field conditions along with the original parental genotype (IT86D-1010) at confined field trial site Samaru Nigeria for expression of morpholgical traits. The present study was designed and conducted in order to understand whether genetic transformation of cowpea with Cry1Ab gene had led to unwanted changes on the morphological features of transgenic cowpea lines, by making comparative assessment between the transgenic lines and untransformed original parental genotype. The result showed that comparison made between transgenic cowpea line TCL-709 and original parental type showed non-significant differences in all the parameters compared. Similarly, comparison made between cowpea transgenic line TCL-711 and IT86D-1010 had significant differences for days to first flowering, days to first pod maturity and plant height while vegetative traits such as number of primary branches, yield attributes like total number of pods per plant at maturity were not significantly different from the original parent. The most important character in a crop-improvement programme is yield, the result indicated that the genotypes (TCL-709, TCL-711 and IT86D-1010) had non-significant differences among themselves regarding total number of pods per plant. It is therefore concluded that the introduction of Cry1Ab gene has not led to harmful changes on the gross morphological characteristics of cowpea plants, besides conferring insect resistance to Maruca pest.Keywords; Cry1Ab-Transgene, Genetic Transformation, Transgenic-Cowpe

Micro propagation of wormwood ( Artemisia annua l.) using leaf primordia

A study was carried out to determine the effect of varying concentrations of some plant growth hormones on the in vitro propagation of Artemisiaannua from leaf primordial in the Biotechnology Laboratory of Plant Science Department of Ahmadu Bello University, Zaria. Leaf primordial from aChinyong variety were sterilized, excised and inoculated on a full and half strengths Murashige & Skoog basal media supplemented with differentconcentrations of GA3, BAP and NAA. Highest regeneration percent was observed using full strength MS media supplemented with a combination of 1.5µm/l GA3 and 0.5µm/l BAP. However, a combination of 0.5µm/l GA3  and 0.5µm/l NAA had the fewer days to regeneration. Highest height wasobserved at 1.0µm/l GA3 and 0.5µm/l BAP. Similarly, 2.0µm/l GA3 and 0.5µm/l BAP followed by 0.5µm/l GA3 and 0.1µm/l BAP produced the best vigor with no response from half strength MS media. Results of Analysis of Variance indicated significant difference among the treatments compared  with the control which did not respond (P.0.05). Regeneration of Artemisia through leaf primordial provides a biomass of leaf material needed for Artemisinin production. Therefore, this is a viable approach to the supply ofthe raw materials needed for the production of anti malaria drugs for the fight against malaria fever.Key Words: Artemisia annua, Plant growth hormones, in vitro propagation, leaf primordia

Genetic variability and heritability studies of some reproductive traits in cowpea (Vigna unguiculate (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

Suitability and use of two molecular markers to track race-specific resistance striga gesnerioides in cowpea (Vigna unguiculata (L.) Walp.)

The obligate root parasitic weed Striga gesnerioides poses a severe constraint to cowpea productivity in the dry savannahs of West and Central Africa, where cowpea is a major crop. At least seven races of S.gesnerioides have been identified within the cowpea-growing regions of West and Central Africa, based onhost differential response and genetic diversity analysis. Molecular markers linked to resistance to  different races of S. gesneriodes have been identified. It was desirable to demonstrate the applicability and efficiency for use in marker-assisted selection (MAS) to fast-track the development of cowpea for resistance to S. gesnerioides. The objective of the study was to determine the suitability of two molecular markers in tracking race-specific S. gesnerioides resistance in cowpea (SG3), the predominant race found in Nigeria. F2 mapping populations and recombinant inbred lines (RILs) derived from the cross involving IT97K-499-35 and a susceptible local landrace (Borno Brown), and another resistant parent B301 with the same susceptible land race (Borno Brown) were assayed using two linked markers. Genetic analysis showed that resistance to S. gesnerioides in cowpea is qualitatively inherited with single dominant gene action. Two SCAR markers, 61RM2 and C42-2B were validated in the same F2 populations and subsequent recombinant inbred lines (RILs). The two markers were able to discriminate between resistance and susceptibility and the genotypic score was quite similar to the phenotypic score with the markers score showing greater efficiency in selection than phenotypic score. The 61RM2 had two bands in resistant cultivars and amplified a ~450 bp fragment with marker efficiency of 98% while C42-2B amplified a single ~250 bp fragment with marker efficiency of 96% in resistant cultivars and absent in susceptible cultivars. The genetic distance between 61RM2 and phenotypic score was 3.5 cM while that of C42-2B and phenotypic score was 8.5 cM. The two marker data set were significantly correlated with the phenotypic data (r=0.95). Based on the tight linkage with the resistant locus, 61RM2 was found to be a utility marker to initiate MAS in cowpea breeding for resistance to S. gesnerioides.Key words: Cowpea, Striga, molecular marker, genetic distance, race-specific, obligate parasitic weed, Vigna unguiculata

Evidence of heterosis in Okra (Abelmoschus esculentus) landraces from Burkina Faso

In our study, 24 hybrids obtained by diallel cross between ecotypes of okra were subjected to analysis of their combining ability effects and hybrid vigor for different important traits for producers and consumers. Parents and hybrids differed significantly for gca effect. UAE 3 and UAE 20 were found to be the best general combiners for 50% day of flowering and number of fruits per plant. While UAE 25, UAE 3 and UAE 5 were best for seeds weight per fruit and yield per plant; between tester lines, UAE 19 shown good gca effect of number of seeds per fruit and fruit yield per plant, when UAE 22 is good for number of seeds per fruit. The most heterotic combinations for number of fruits per plant were those including UAE 22 in their combination.The same hybrids have shown medium heterobeltiosis effect for fruit  length and in some of them (H22-20 and H22-5) was observed highest heterobeltiosis of yield per plant, varied from 59.90 to 77.57 respectively. The highest depression (non heterobeltiosis) was observed in hybrids with combination including H19 for number of seeds per fruit. Overall, the results discussed above indicated the fact that okra hybrid with UAE 22 hasgreat potentialities of maximizing fruit yield while hybrid H3-19 and H22-3 have the smallest days of flowering. Similarly, the heterosis effect  appeared in F1 in these hybrids with UAE22 as a mother form keeps up to the third generation. Key words: hybrid vigor, combining ability, okra, Burkina Faso

Screening Arachis hypogaea genotypes for resistance to Cercospora leaf spots in North Cameroon

Early and late leaf spots caused by Cercospora arachidicola Hori and Cercosporidium personatum (Berk. & Curt.) Deighton are among the major biotic constraints to groundnut production in Sub-Saharan Africa. A two-year field screening experiment was conducted in 2001 and 2002 at the Institute of Agricultural Research for Development (IRAD) farm, Maroua to identify resistant genotypes for the groundnut breeding programme. The International Crops Research Institute for the Semi-Arid Tropics (ICRISAT) nine-point scale was used for Cercospora severity rating. Groundnut genotypes were grouped into various classes of resistance to leaf spots using the method suggested by the West and Central African Council for Agricultural Research and Development (WECARD). The results indicate that no genotype was immune to both leaf spots or resistant to late leaf spot. The genotype ICGV 91225 was found to be resistant to early leaf spot and could be used as donor parent for early leaf spot resistance breeding. The genotypes ICG 6902, #3-94, SAMNUT 22 and SAMNUT 21, which performed better than the resistant check GP-NC 343 in terms of disease severity at harvest, could be sources of resistance for late leaf spot resistance breeding. Keywords: Groundnut, breeding, immune, resistance , donor parent Cameroon Journal of Experimental Microbiology Vol. 4 (2) 2008: pp. 67-7

Nutrient and Anti-nutrient Compositions of New Crop Varieties of Cowpea (Vigna unguiculata L.) and Maize (Zea mays L.)

Objective: To determine the proximate composition and anti-nutrient content of new varieties of cowpea and maize released by the Institute for Agricultural Research [IAR], Ahmadu Bello University [ABU] – Zaria. Materials and Methods: Samples of eleven varieties each of cowpea and maize were collected from their respective breeders in the Department of Plant Science, IAR, ABU, Zaria. Carbohydrate, crude protein, ash, moisture, crude lipid and crude fiber contents were determined using standard methods. Determination of phytate, tannin, cyanide, saponin and oxalate were conducted on the cowpea varieties while for the maize varieties, all the above listed anti-nutrients were determined except oxalate. The various analyses were expressed as mean + standard deviation and analyzed using one-way analysis of variance [ANOVA]. Results: Crude protein content in the cowpea varieties ranged from 22.66 to 24.10% and for maize 9.62 to 10.16%, carbohydrate ranged between 56.48 and 59.70% in cowpea and 72.88 to 74.35% in maize, lipid from 2.16 to 3.14% in cowpea and 0.23 to 1.80% in maize, ash from 2.68 to 3.40% in cowpea and 2.84 to 3.66% in maize, moisture from 8.12 to 9.46% in cowpea and 9.66 to 10.16% in maize and crude fibre from 3.30 to 4.42% in cowpea and 1.42 to 2.12% in maize. Phytate content varied from 1.04 to 1.88% in cowpea and 0.16 to 0.26% in maize, tannin from 0.18 to 0.48% in cowpea and 0.02 to 0.18% in maize, cyanide from 0.04 to 0.16% in cowpea and 0.10 to 0.16% in maize and saponin from 0.02 to 0.08% in cowpea and 0.0002 to 0.0004% in maize. Oxalate ranged from 0.00 to 0.004% in cowpea. Conclusion: The study showed that the IAR released cowpea and maize varieties were nutritionally rich, low in anti-nutrients and suitable for local consumption and industrial utilization. Key Words:Nutrients, Anti-nutrients, Cowpea, Maize, New varietie