Canavalia (Phaseoleae, Fabaceae) species in South Africa: Indigenous and naturalised

Canavalia (Phaseoleae, Fabaceae) species in South Africa: Indigenous and naturalised

Abstracts during pathogen infection and in the study tyloses were predominant in the tolerant genotype compared to the susceptible genotype where bac...

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Abstracts

during pathogen infection and in the study tyloses were predominant in the tolerant genotype compared to the susceptible genotype where bacterial cells occluded most xylem vessels. Thus the ability of Pcb cells to form biofilm aggregates and occlusions in the tolerant genotype was greatly reduced. In addition, vascular system cells in the tolerant genotype had more lignin deposition than the susceptible genotype. The structural modifications observed in the tolerant genotype played a role in limiting tissue maceration that results from the action of plant cell wall degrading enzymes employed by Pcb. In conclusion these results suggest that tolerance in potato stems can be associated with the ability of the host to contain and trap bacterial cells by rapid development of tyloses in the xylem and lignin deposition in cell walls preventing bacterial spread and symptom development. doi:10.1016/j.sajb.2015.03.092

Canavalia (Phaseoleae, Fabaceae) species in South Africa: Indigenous and naturalised A. Moteetee Department of Botany and Plant Biotechnology, University of Johannesburg, PO Box 524, Auckland Park 2006, South Africa Results from a taxonomic study of the genus Canavalia in South Africa are presented. The genus belongs to the subtribe Diocleinae in the legume tribe Phaseoleae. Canavalia is currently divided into four subgenera: Canavalia, Catadonia, Maunaloa and Wenderothia. There are four species of subgenus Canavalia in South Africa namely Canavalia africana, Canavalia ensiformis, Canavalia gladiata and Canavalia rosea. Subgenus Catadonia is a New World subgenus but is represented by one species Catadonia bonariensis, which has a peculiar disjunct distribution occurring in South America, South Africa and Madagascar. Wenderothia is a New World subgenus while Maunaloa is restricted to Hawaii. Canavalia can be distinguished from the related genera mainly by the bilabiate calyx with the upper lip much larger than the lower lip and anatomically by the presence of paired epidermal crystals. doi:10.1016/j.sajb.2015.03.093

Stress tolerance and 16S–23S rRNA-RFLP analysis of Bradyrhizobium population nodulating groundnut (Arachis hypogaea) in South African soil L.A. Msimbiraa, S.K. Jaiswalb, F.D. Dakorab a Department of Crop Sciences, Tshwane University of Technology, Private Bag X680, Pretoria 0001, South Africa b Department of Chemistry, Tshwane University of Technology, Private Bag X680, Pretoria 0001, South Africa Across the globe where groundnut is grown, the crop is of high economic and nutritional value to farmers. Its importance is extended to agricultural systems sustainability, as it fixes atmospheric nitrogen (N2) into plant usable forms through symbiotic association with compatible soil bacteria (rhizobia). The aim of this study was to determine the diversity of stress tolerant groundnut nodulating rhizobia using polyphasic approaches in Mpumalanga Province, South Africa. Root nodules from 16 groundnut genotypes were collected and processed for rhizobial isolation using standard procedures. Salt (NaCl) and pH tolerance of the rhizobial isolates was tested on YMA plates and full length PCR amplification of the IGS (16S–23S rRNA) regions was done. PCR amplified IGS region was

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digested with restriction endonucleases to get IGS-RFLP patterns of the isolates. Except 4 isolates (TUTAHSA56, 58, 65 and 115) all isolates tolerated 2% of NaCl concentration. The majority (85%) of the isolates tolerated the extreme pH 5 and 10. Isolates TUTAHSA30, 45, 57, 80, 87 and 114 were not sensitive to pH stress. There was a positive correlation between salt tolerance and adaptation to alkaline pH 10. A total of fourteen IGS types were found in the rhizobial population studied. The restriction digestion with HindIII and HaeII of IGS region revealed the presence of 22 IGS-RFLP patterns. IGS-RFLP analysis revealed the differentiated isolates into five main clusters, whereas one isolate (TUTAHSA116) stood independently. Groundnut varieties played a major role in trapping diverse group of rhizobia. In conclusion, there was a marked difference in salt and pH tolerance in the isolates which is suitable for location specific selection and PCRRFLP analysis showed the presence of multiple rhizobial genotypes in the rhizosphere of each groundnut variety. doi:10.1016/j.sajb.2015.03.094

Antimicrobial activity and safety evaluation of commonly used South African herbal mixtures R.B. Mulaudzia, E. Tshikalangeb, J.O. Olowoyoc, S.O. Amooa, C.P. Du Plooya a Agricultural Research Council, Roodeplaat-Vegetable and Ornamental Plant Institute, Private Bag X293, Pretoria 0001, South Africa b Department of Plant Science, University of Pretoria, Pretoria, South Africa c Department of Biology, University of Limpopo, Medunsa Campus, South Africa Herbal mixtures are becoming highly used in South Africa to treat several ailments, such as coughs, diarrhoea, fever, sexually transmitted diseases, cancer and diabetes. This study was aimed at evaluating some of the claimed biological activities and safety of commonly used South African herbal mixtures. Two herbal mixtures (Special mixture and Blood mixture) obtained from herbal stores within the Gauteng Province were evaluated for antimicrobial activities using the micro-dilution method against Candida albicans, Neisseria gonorrhoeae, Escherichia coli, Klebsiella pneumoniae and Staphylococcus aureus. Their heavy metal concentrations were analysed using an Inductively Coupled Plasma-Mass Spectrophotometry (ICP-MS). Special mixture exhibited low antifungal and antibacterial activities against C. albicans, N. gonorrhoeae and E. coli with a minimum inhibitory concentration of 6.25 mg/ml. Blood mixture showed no activities against five tested pathogen. Special mixture and Blood mixture contained a high amount of cadmium (0.60 and 0.43 mg/kg, respectively), exceeding the World Health Organization (WHO) safety limit of 0.3 mg/kg. Blood mixture also had a high amount of lead (14.22 mg/kg), which exceeds the WHO safety limit of 10 mg/kg. High concentrations of some heavy metals found in these herbal mixtures raise serious concerns relating to the quality of herbal preparations, source of plant materials used and, most importantly, consumer safety. doi:10.1016/j.sajb.2015.03.095

Phytochemical and pharmacological evaluations of different organs of Scadoxus puniceus: Motivation for plant part substitution D. Naidoo, A.O. Aremu, J. Van Staden, J.F. Finnie Research Centre for Plant Growth and Development, School of Life Sciences, University of KwaZulu-Natal Pietermaritzburg, Private Bag X01, Scottsville 3209, South Africa