Genotypic variation in tolerance to salinity of common beans cultivated in Western Cameroon as assessed at germination and during early seedling growth

This study was carried out to determine effects of salinity on germination and seedling development of commercially important common bean genotypes in Cameroon. The seeds of eight genotypes were used for both trials. The germination experiments were carried out on petri dishes in the laboratory while early growth trials continued in plastic pots in the screenhouse. Both stages were setup using a randomized complete block design with three replications. Germination and early growth trials of the different genotypes were studied using distilled water as control or osmotic potentials of 50, 100, 150 and 200mM NaCl to study the effects of salinity on germination and seedling growth characteristics. Leaf concentrations of Na+ and K+ were determined. At the germination level, germination percentage, germination index and the coefficient of velocity of germination decreased with increasing salinity while the mean germination time and time to 50% germination increased with increasing level of salt. All the growth variables decreased with increasing salinity with the exception of the root length which was not affected by salinity. It was observed that increasing salinity induced a significant increase in leaf Na+ and substantial reduction in the accumulation of K+ in the leaves. For ions accumulation, germination variables and growth parameters, significant differences at 0.001 probability levels were found among salinity treatments, common bean genotypes and most of their interactions. Significant correlations were found between all germination variables and between most growth parameters. From the effect of salt application, the common bean genotypes namely KEBCB049, KEB-CB053 and Mac-33 were the most tolerant while KEB-CB055 and KEB-CB050 were the most sensitive. The results confirm that there is genotypic variation in salinity tolerance and that the most tolerant genotypes should be further explored in selection programs, with the aim that they should be promoted for cultivation in tropical zones affected by salinity

Agro-ecological distribution of the phenotypic diversity of aerial yam (Dioscorea bulbifera L.) in Cameroon using multivariate analysis: prospect for germplasm conservation and improvement

Aerial yam (Dioscorea bulbifera L.) is a crop of great economic importance and an excellent candidate for improving food security in developing countries. Understanding the genetic variability of any crop species is a decisive step for its improvement and requires characterization and evaluation of available germplasm. The objectives of this study were to determine the extent of genetic variability, estimate the association between agromorphological traits and clustering among 57 genotypes of aerial yam from three distinct agro-ecological zones in Cameroon using multivariate analysis. Thirty nine characters (23 qualitative and 16 quantitative) were used for the study. Significant differences in genetic diversity indices were found. Accessions from the bimodal humid forest zone (Na = 2.08, He = 0.27) showed significantly lower diversity compared to both western highland (Na = 2.30, He = 0.34) and humid monomodal forest zones (Na = 2.57, He = 0.32). Means values of most quantitative traits also showed significant differences between agro-ecological zones. Batingla-3 and Bawouwoua-1 had important bulbil yield, reaching 3500 g / plant. Significant associations were found between many traits. The use of the Unweighted Pair Group Method with Arithmetic Mean allowed the distribution of the 57 genotypes into six distinct clusters with the clustering pattern not showing any parallelism with location sites or agro-ecological zones. Mahalanobis D2 statistics revealed the highest inter-cluster distance between cluster II and VI. Accessions of these clusters are potential parents for future breeding programs. This study showed that aerial yam from Cameroon has an enormous wealth of traits variation, indicating huge potential for its genetic improvement through selection and hybridization

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

Abstract 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.</p

Crystal structure, spectroscopic analysis, electronic properties and molecular docking study of costunolide for inhibitor capacity against Onchocerca volvulus main protease

Mountessou BYG, Mbobda ASW, Stammler H-G, et al. Crystal structure, spectroscopic analysis, electronic properties and molecular docking study of costunolide for inhibitor capacity against Onchocerca volvulus main protease. Journal of Molecular Structure. 2023;1282: 135185.Costunolide, a naturally occurring sesquiterpene lactone, was investigated experimentally and theoret-ically to determine the structural, electronic, spectroscopic, and chemical reactivity properties. As de-duced from a single crystal X-ray diffraction (XRD) analysis, the absolute configurations of the two chiral centres were assigned as (6R,7S). Vibrational frequencies (IR, UV and NMR), electronic properties (HOMO and LUMO), and the molecular structure of costunolide were investigated by DFT calculations using Gaus-sian 09 molecular package at the B3LYP/6-311 ++ G(d,p) level of theory. NMR chemical shifts were calcu-lated from the magnetic shielding tensors obtained through the gauge-independent atomic orbital (GIAO) method, while the UV-vis spectrum was simulated by time dependent-DFT (TD-DFT) calculations. All cal-culations showed correlations to experimental data. The 6-311 + G(2d,p) basis set was additionally used for better correlation in NMR studies. The first order hyperpolarizability value indicated that costunolide has nonlinear optical (NLO) properties. Costunolide stability arising from hyperconjugative interactions and charge delocalisation was analysed using natural bond orbital (NBO). Thermodynamic parameters also correlated in the temperature range 10 0-70 0 K. The molecular docking results showed that costuno-lide binds strongly to the Onchocerca volvulus main protease with a relative binding affinity of -5.94 kcal mol-1 and an inhibition constant of 44.61 mu M.(c) 2023 Elsevier B.V. All rights reserved