Micro-organisms associated with endangered Cordeauxia edulis affect its growth and inhibit pathogens

Cordeauxia edulis is an endangered leguminous shrub native to semi-arid border between Ethiopia and Somalia. To enable its successful cultivation in new environment, we investigated the effect of its microbial residents on establishment and growth. Plant growth-affecting bacteria and arbuscular mycorrhizal fungi (AMF) were the focus of this study. Bacteria were isolated from rhizosphere soil and pre-germinated seeds of C. edulis and tested for in vitro inhibition of Aspergillus niger, A. biciliate and A. versicolor. The three aspergilli were found as frequent colonizers of seeds with deteriorating effect on emergence. Six bacteria were further evaluated in greenhouse experiments for their effect on plant growth. The isolates with beneficial effects seemed to belong to Pseudomonas sp., Klebsiella sp. And Pantoea sp. Occurrence and abundance of AMF was determined as spore density and % root colonization in the field samples. Effect of AMF on plant growth was also studied in greenhouse, on seedlings inoculated with its native population and the results compared with those inoculated with a commercial mix, Vaminoc or in vitro cultured Glomus intraradices. Our results show that, C. edulis harbours both AMF and bacteria with plant growth affecting potential and that it responds positively to microbial inoculations in foreign environments.