| |
A quiver tree in the Northern Cape province from where fungal isolations were made. |
| |
Cross-section of a quiver tree branch, indicating fungal damage to the inside tissue. |
| |
Francois van der Walt standing at a dead camel thorn tree. |
The SERA Centre for Applied Mycological Studies [CAMS] has made significant strides in its objective of documenting South Africa's fungal biodiversity and applying this knowledge to the benefit of the country's economy.
The recent MSc graduation of Mr Francois van der Walt who has described 9 new fungal species and a genus of the Botryosphaeriaceae from indigenous Acacia trees in southern Africa is one example of the progress made in this regard. To the CAMS Team's knowledge, this is the biggest find of this group of fungi in a single study and on a single host.
This study indicated that there is a significantly greater diversity of the Botryosphaeriaceae on native Acacia species in southern Africa than was previously thought. The relevance of these Botryosphaeriaceae as pathogens and their potential risks on native hosts is still unclear and needs further consideration. Together with climate changes on a global scale, plants and their pathogens are also affected. This can cause a shift in the relationships between host-pathogen interactions that could make previous assumptions inaccurate. It is, therefore, important to understand the interactions of the Botryosphaeriaceae and their native hosts so that their ability and threat as pathogens to native and economically important plants can be realized.
Previously, only one member of the Botryosphaeriaceae, Lasiodiplodia theobromae, was known to occur on a native Acacia species in southern Africa. From this study alone, a total of 12 members of the Botryosphaeriaceae were isolated from Acacia, of which nine were identified as new species. Formerly described species included L. pseudotheobromae, Spencermartinsia viticola and Botryosphaeria dothidea, for which a previously unknown Dichomera synanamorph is described in the study for the first time.
Undescribed species included, Diplodia variabilis, Dothiorella oblonga, Fusicoccum avasmontanum, L. pyriformis, S. rosulata, S. capri-amissi and a new genus, Mucodiplodia, represented by two species, M. africana and M. papillata. An unknown Neofusicoccum species was also obtained but not described due to a lack of represented isolates.
While studying the diversity of the Botryosphaeriaceae on native Acacia spp., the question was raised whether these species also occur on non-native trees such as A. mearnsii. Van der Walt was able to demonstrate that only one Botryopshaeriaceae species was found to be associated with this host - described in his study as S. nigra.
While no conclusive evidence could be found that native and non-native Acacia species can share the same species of the Botryosphaeriaceae, this study should only be seen as a pilot study as limited samples were available from the one area studied.
Previous authors estimated that there could be as many as seven new species of fungi per indigenous plant host. Results from the CAMS study, however, may indicate this estimate to be conservative as all the new fungal species described focused only on one fungal family.
This single study has contributed significantly to our understanding of the Botryosphaeriaceae associated with indigenous Acacia species in southern Africa and has resulted in the production of three publications in the scientific press.
|
