Co-infection of Tylosema esculentum (Marama bean) seed pods by Alternaria tenuissima and a Phoma spp.

Marama bean, Tylosema esculentum, is an endemic, perennial wild tuberous Fabaceae, widely distributed in the Southern Kalahari (Namibia, Botswana and to a lesser extends in South Africa). It is well adapted to the deep sandy soils of the Kalahari. It is drought avoiding. It has been valued by the indigenous people of the semi arid land of the Kalahari for its nutritional and medicinal qualities. The aim of the study was to determine the identity of fungal pathogens that occur on marama bean. Diseased pods presenting necrotic spots with dense sporulation in the centre were collected. They were subjected to fungal isolation using potato dextrose agar (PDA) at room temperature under fluorescent light for five days. Two fungi with different cultural conidial morphology were isolated. Single spores from the two cultures were separately inoculated on PDA to obtain a pure culture. Genomic fungal DNA was extracted from fresh mycelium using the cetyl trimethylammonium bromide (CTAB) method and was used as a template in internal transcribed spacer (ITS) PCR amplification. Based on the sequence analysis of the 5.8S ribosomal DNA and the ITS, the two isolates associated with necrotic Marama pods were identified as Alternaria tenuissima and Phoma spp. Isolate Po72 due to the high sequence homology, which was 99% in both cases. To our knowledge, this is the first report describing the presence of these two fungi on Marama bean.Key words: Marama, ITS, fungal pathogen, Tylosema esculentum

Molecular identification of a fungus associated with the holoparasitic angiosperm ydnora abyssinica in Namibia

In the present study, we have consistently observed a fungus that is in association with the fruits of the holoparasitic angiosperm Hydnora abyssinica. This holoparasite spends a large portion of its life cycle underground attached to the roots of its host (various Acacia species). This fungal-holoparasite association is intriguing in the sense that the fungus does not cause any reduction in seed viability of the holoparasite. In this study, the objective was to determine the identity of the fungus. Pure single spore cultures of the fungus were obtained and DNA was isolated from fungal mycelium to be used as templates in an internal transcribed spacer (ITS)-PCR amplification. The ITS products were electrophoresced on agarose gels and sequenced in an automated sequencer. Basic Local Alignment Search Tool (BLAST) searches revealed the identity of the fungus to be Aspergillus niger. We endeavour to determine the nature of the fungus-holoparasite interaction. We propose that the fungus helps in digesting the fruits to facilitate easy seed dispersal

Biocontrol Potential of Forest Tree Endophytes

Peer reviewe

Molecular identification of a fungus associated with the holoparasitic angiosperm ydnora abyssinica in Namibia

In the present study, we have consistently observed a fungus that is in association with the fruits of the holoparasitic angiosperm Hydnora abyssinica. This holoparasite spends a large portion of its life cycle underground attached to the roots of its host (various Acacia species). This fungal-holoparasite association is intriguing in the sense that the fungus does not cause any reduction in seed viability of the holoparasite. In this study, the objective was to determine the identity of the fungus. Pure single spore cultures of the fungus were obtained and DNA was isolated from fungal mycelium to be used as templates in an internal transcribed spacer (ITS)-PCR amplification. The ITS products were electrophoresced on agarose gels and sequenced in an automated sequencer. Basic Local Alignment Search Tool (BLAST) searches revealed the identity of the fungus to be Aspergillus niger. We endeavour to determine the nature of the fungus-holoparasite interaction. We propose that the fungus helps in digesting the fruits to facilitate easy seed dispersal

Molecular identification of a fungus associated with the holoparasitic angiosperm ydnora abyssinica in Namibia

In the present study, we have consistently observed a fungus that is in association with the fruits of the holoparasitic angiosperm Hydnora abyssinica. This holoparasite spends a large portion of its life cycle underground attached to the roots of its host (various Acacia species). This fungal-holoparasite association is intriguing in the sense that the fungus does not cause any reduction in seed viability of the holoparasite. In this study, the objective was to determine the identity of the fungus. Pure single spore cultures of the fungus were obtained and DNA was isolated from fungal mycelium to be used as templates in an internal transcribed spacer (ITS)-PCR amplification. The ITS products were electrophoresced on agarose gels and sequenced in an automated sequencer. Basic Local Alignment Search Tool (BLAST) searches revealed the identity of the fungus to be Aspergillus niger. We endeavour to determine the nature of the fungus-holoparasite interaction. We propose that the fungus helps in digesting the fruits to facilitate easy seed dispersal

Molecular identification of a fungus associated with the holoparasitic angiosperm ydnora abyssinica in Namibia

In the present study, we have consistently observed a fungus that is in association with the fruits of the holoparasitic angiosperm Hydnora abyssinica. This holoparasite spends a large portion of its life cycle underground attached to the roots of its host (various Acacia species). This fungal-holoparasite association is intriguing in the sense that the fungus does not cause any reduction in seed viability of the holoparasite. In this study, the objective was to determine the identity of the fungus. Pure single spore cultures of the fungus were obtained and DNA was isolated from fungal mycelium to be used as templates in an internal transcribed spacer (ITS)-PCR amplification. The ITS products were electrophoresced on agarose gels and sequenced in an automated sequencer. Basic Local Alignment Search Tool (BLAST) searches revealed the identity of the fungus to be Aspergillus niger. We endeavour to determine the nature of the fungus-holoparasite interaction. We propose that the fungus helps in digesting the fruits to facilitate easy seed dispersal

Isolation and Identification of Culturable Fungal Species Associated with Disease in Vachellia tortilis in Namibia

Vachellia tortilis is a tree belonging to the family Fabaceae that inhabits high temperature and dry environments of the world. It is ecologically and economically significant amongst others of the genera Vachellia and Senegalia. It is native to Namibia and several other countries. Various parts of the V. tortilis plant are used for different therapeutic purposes both in the traditional and pharmacological settings. However, V. tortilis is vulnerable to pathogenic infection to which they lack natural resistance and little is known regarding the pathogens responsible for such infections. The aim of the study was to isolate and identify the fungal species associated with twig dieback disease in V. tortilis. Pure cultures from diseased V. tortilis were grown using potato dextrose agar (PDA) and DNA was subsequently isolated and later amplified in a PCR reaction using ITS1 and ITS4 primers. Sequencing and BLAST search revealed the identity of the isolates as; Penicillium rubefaciens, Penicillium herbarum, Trichoderma longibrachiatum and Trichoderma harzianum. Results indicated that P. herbarum was associated with disease symptoms in A. tortilis, T. longibrachiatum and T. harzianum were antagonistic fungi while the effect of P. rubefaciens on V. tortilis remained unknown. It is recommended that further investigations using Koch’s postulates should be performed on V. tortilis using the isolates

Prevalence and antimicrobial resistance pattern of Salmonella in animal feed produced in Namibia

The occurrence of Salmonella is a global challenge in the public health and food production sectors. Our study investigated the prevalence, serovar and antimicrobial susceptibility of strains of Salmonella serovars isolated from animal feed (meat-and-bone and blood meal) samples from two commercial abattoirs in Namibia. A total of 650 samples (n = 650) were examined for the presence of Salmonella. Results showed that 10.9% (n = 71) were positive for Salmonella. Of the Salmonella serovars isolated, S. Chester was the most commonly isolated serovar (19.7%), followed by S. Schwarzengrund at 12.7%. From the Salmonella isolates, 19.7% (n = 14) were resistant to one or more of the antimicrobials (nalidixic acid, trimethoprim-sulfamethoxazole, sulfisoxa-zole, streptomycin and/or tetracycline), whereas 80.3% (n = 57) were susceptible to all 16 antimicrobials tested. Resistance to sulfisoxazole and the trimethroprim-suflamethoxazole combination were the most common. The resistant isolates belonged to ten different Salmonella serovars. The susceptibility of most of the Salmonella isolated to the antimicrobials tested indicates that anti-microbial resistance is not as common and extensive in Namibia as has been reported in many other countries. It also appears that there is a range of antimicrobials available that are effective in managing Salmonella infections in Namibia. However, there is some evidence that resistance is developing and this will need further monitoring to ensure it does not become a problem