Year: 2018
Type: article
Abstract: Vachellia karroo (formerly Acacia karroo) is distributed widely in southern Africa.It is a common pioneer species that grows in varied soil types and occurs in diverse habitats.One of the factors contributing to this ecological diversity could be its symbiotic association with a specific group of soil bacteria.These are collectively termed rhizobia and are capable of fixing atmospheric nitrogen when they occur in nodules on the roots of the plant.During this interaction, the plant obtains nitrogenous compounds from the bacterium, while providing it with carbohydrates and protection from external stresses.Rhizobia have so far only been found in the classes Alpha-and Betaproteobacteria, where they are respectively referred to as alpha-and beta-rhizobia.Although rhizobia might be important for the adaptability of V. karroo, very little is known about its nitrogen-fixing symbionts.Our aim was therefore to investigate the rhizobial diversity associated with this legume in South Africa.Rhizosphere soil collected from V. karroo in 28 locations (spanning six provinces, seven biomes) were used in 'trapping' experiments to isolate rhizobia from root nodules that developed on the roots of the respective plants.Among the 88 rhizobia recovered, our DNA-based analyses revealed 67 alpharhizobia (representing five genera).The remaining 21 isolates were beta-rhizobia and represented members of the genus Paraburkholderia, which predominantly originated from plants grown in Fynbos soils.This was expected as the Western Cape is regarded as one of two global hotspots for this bacterial genus.No other significant pattern could be observed regarding the distribution of the different bacterial species found, which indicates that V. karroo is a promiscuous host able to interact with diverse rhizobia.Our future research will seek to determine whether this apparent diversity in symbiont associations is linked to the abundance of the specific rhizobial taxa in the various geographic regions.
Source: South African Journal of Botany
Authors: M.A. Bonta, S.O. Bamigboye
Institutions: Pennsylvania State University, University of Venda
Language: English
Subfield: Plant Science
Domain: Life Sciences
SDG: Life on land
Open Access status: hybrid
Estimated APC paid: $2,750
OpenAlex ID: W2797525329