I. Fawole

ABSTRACT Multivariate analysis is based on a statistical principle involving observation and analysis of more than one statistical variable at a time. The variability of 434 accessions of rice ( Oryza sativa L.) germplasm from Côte d'Ivoire was evaluated for 10 agro‐morphological traits in upland conditions at M'bé, Côte d'Ivoire (7°5′ N, 5°1′ W) in 2002 using augmented experimental design and analyzed with multivariate methods. The unweighted pair group method of the average linkage (UPGMA) cluster analysis, canonical discriminant analysis, and principal component analysis (PCA) were used to analyze the data obtained. This enabled the assessment of the extent and pattern of variation of the germplasm and identification of the major traits contributing to the diversity. Seven cluster groups were obtained from the 10 agro‐botanical traits using the UPGMA. Canonical discriminant analysis showed the contribution of each trait to the classification of the rice accessions into different cluster groups. The first three principal components explained about 72.24% of the total variation among the 10 characters. The results of canonical discriminant analysis and PCA suggested that traits such as plant height, number of days to heading and maturity, tillering ability, and grain size (weight, length, width, and shape) were the principal discriminatory characteristics. It was concluded that variation exists in the germplasm, which provides opportunities for this collection to be useful for genetic improvement.

The impact of cassava transformation technologies for agricultural development in Africa will depend largely on how successfully these capabilities are transferred and adapted to the African environment and local needs. Here we report on the first successful establishment of cassava regeneration and transformation capacity in Africa via organogenesis, somatic embryogenesis and friable embryogenic callus (FEC). As a prerequisite for genetic engineering, we evaluated six African cassava genotypes for the ability of a) induction of FEC b) hygromycin sensitivity and c) T-DNA integration potential by different Agrobacterium strains. FEC was induced in genotypes TMS 60444, TME 1 and TMS 91/02327. Potential tissues for FEC formation were induced in TMS 91/02324, TME 12 and TME 13. Pure and proliferating FEC was obtained and maintained only in TMS 60444. FEC growth and shoot organogenesis were completely suppressed when hygromycin was used at a concentration of 20 mg/l in all tissue types and genotypes. With somatic cotyledons, statistically significant differences (p 0.05) were observed between Agrobacterium strains and genotypes with respect to T-DNA transfer efficiency. Using somatic cotyledons, TME 8 was found to be the most amenable to transformation with maximum blue spots per GUS-positive explants, and Agrobacterium GV3101 proved to be superior to EHA105, LBA4404, and AGl-1 for T-DNA transfer based on transient assays with a reporter gene (GUS). With FEC, Agrobacterium LBA4404 was superior to other strains. This study also identified EHA105 as a new virus helper strain to recover transgenic cassava plants. PCR and Southern hybridization of genomic DNA of the hygromycin-resistant cassava plants to a hpt probe confirmed the integration of hpt with integration events varying between 1 and 2 insertions. The benefit of combining the FEC and shoot organogenesis systems for recovering transgenic cassava plants is described. The contributions of this report to enhancing the development and deployment of genetic engineering of cassava for agricultural biotechnology development in Africa are discussed.

Cowpea is an important legume in sub-Saharan Africa where its protein rich grains are consumed. Insect pests constitute a major constraint to cowpea production. Flower bud thrips (FTh) is the first major pest of cowpea at the reproductive stage and if not controlled with insecticides is capable of reducing grain yield significantly. Information on the inheritance of resistance to FTh is required to facilitate breeding of resistant cultivars. The genetics of resistance was studied in crosses of four cowpea lines. Maternal effect was implicated while frequency distributions of the F2 and backcross generations suggest quantitative inheritance. Additive, dominance and epistatic gene effects made large contributions and since improved inbred lines are the desired product, selection should not be too severe in the early generations to allow for desirable gene recombination. This study suggested that some of the genes involved in the control of resistance to FTh are different in TVu1509 and Sanzi. Broad sense heritability ranged from 56% to 73%. Choice of maternal parent in a cross will be critical to the success of resistance breeding.