Diversity of sporadic symbionts and nonsymbiotic endophytic bacteria isolated from nodules of woody, shrub, and food legumes in Ethiopia.

Fifty-five bacterial isolates were obtained from surface-sterilized nodules of woody and shrub legumes growing in Ethiopia: Crotalaria spp., Indigofera spp., and Erythrina brucei, and the food legumes soybean and common bean. Based on partial 16S rRNA gene sequence analysis, the majority of the isolates were identified as Gram-negative bacteria belonging to the genera Achromobacter, Agrobacterium, Burkholderia, Cronobacter, Enterobacter, Mesorhizobium, Novosphingobium, Pantoea, Pseudomonas, Rahnella, Rhizobium, Serratia, and Variovorax. Seven isolates were Gram-positive bacteria belonging to the genera Bacillus, Paenibacillus, Planomicrobium, and Rhodococcus. Amplified fragment length polymorphism (AFLP) fingerprinting showed that each strain was genetically distinct. According to phylogenetic analysis of recA, glnII, rpoB, and 16S rRNA gene sequences, Rhizobium, Mesorhizobium, and Agrobacterium were further classified into six different genospecies: Agrobacterium spp., Agrobacterium radiobacter, Rhizobium sp., Rhizobium phaseoli, Mesorhizobium sp., and putative new Rhizobium species. The strains from R. phaseoli, Rhizobium sp. IAR30, and Mesorhizobium sp. ERR6 induced nodules on their host plants. The other strains did not form nodules on their original host. Nine endophytic bacterial strains representing seven genera, Agrobacterium, Burkholderia, Paenibacillus, Pantoea, Pseudomonas, Rhizobium, and Serratia, were found to colonize nodules of Crotalaria incana and common bean on co-inoculation with symbiotic rhizobia. Four endophytic Rhizobium and two Agrobacterium strains had identical nifH gene sequences with symbiotic Rhizobium strains, suggesting horizontal gene transfer. Most symbiotic and nonsymbiotic endophytic bacteria showed plant growth-promoting properties in vitro, which indicate their potential role in the promotion of plant growth when colonizing plant roots and the rhizosphere.

Phylogenetically diverse groups of Bradyrhizobium isolated from nodules of Crotalaria spp., Indigofera spp., Erythrina brucei and Glycine max growing in Ethiopia.

Ethiopian Bradyrhizobium strains isolated from root nodules of Crotalaria spp., Indigofera spp., Erythina brucei and soybean (Glycine max) represented genetically diverse phylogenetic groups of the genus Bradyrhizobium. Strains were characterized using the amplified fragment length polymorphism fingerprinting technique (AFLP) and multilocus sequence analysis (MLSA) of core and symbiotic genes. Based on phylogenetic analyses of concatenated recA-glnII-rpoB-16S rRNA genes sequences, Bradyrhizobium strains were distributed into fifteen phylogenetic groups under B. japonicum and B. elkanii super clades. Some of the isolates belonged to the species B. yuanmingense, B. elkanii and B. japonicum type I. However, the majority of the isolates represented unnamed Bradyrhizobium genospecies and of these, two unique lineages that most likely represent novel Bradyrhizobium species were identified among Ethiopian strains. The nodulation nodA gene sequence analysis revealed that all Ethiopian Bradyrhizobium isolates belonged to nodA sub-clade III.3. Strains were further classified into 14 groups together with strains from Africa, as well as some originating from the other tropical and subtropics regions. Strains were also clustered into 14 groups in nodY/K phylogeny similarly to the nodA tree. The nifH phylogenies of the Ethiopian Bradyrhizobium were generally also congruent with the nodA gene phylogeny, supporting the monophyletic origin of the symbiotic genes in Bradyrhizobium. The phylogenies of nodA and nifH genes were also partially congruent with that inferred from the concatenated core genes sequences, reflecting that the strains obtained their symbiotic genes vertically from their ancestor as well as horizontally from more distantly related Bradyrhizobium species.

Biocontrol competence of Beauveria bassiana, Metarhizium anisopliae and Bacillus thuringiensis against tomato leaf miner, Tuta absoluta Meyrick 1917 under greenhouse and field conditions.

Tomato is one of the most important crops grown under both greenhouse and field conditions throughout the world. Its production is highly challenged by infestation of leaf miner insect, Tuta absoluta Meyrick regardless of excessive insecticide application. The chemical insecticides results insect resistance, environmental pollution, and health problems and there is urgent need for management options such as integrated pest management (IPM) to obviate these problems. Thus, the present study aims to evaluate the effectiveness of single and combination treatments of entomopathogens; Beauveria bassiana, Metarhizium anisopliae, Bacillus thuringeinsis, and an insecticide against T. absoluta under greenhouse and field conditions. Two varieties (Awash and Venes) of tomato for greenhouse experiment and one (Gellila) variety for field experiment were used with Tutan36%SC (insecticide with active ingredient of Chlorphenapyr 36%SC) and untreated plots as positive and negative controls, respectively. The results showed significant leaf and fruit damage reduction in all the treatments. B. bassiana-AAUB03, M. anisopliae-AAUM78, and B. thuringiensis-AAUF6 showed the highest (93.4%, 89.7% and 90.1%) leaf and (93.5%, 94.4% and 95%) fruit protection under greenhouse condition. The combined treatments improved leaf protection efficacy up to 95.3% under field condition. When the entomopathogens were combined with half or quarter reduced concentrations of Tutan36% SC, it showed 94.4% of pest protection. In all the treatments, 72-96% of marketable fruit was obtained as par insecticide treatment scored 85-93%. All the entomopathogens did not cause any adverse effect on the growth of tomato rather improved shoot length, shoot branching, leaf and fruit numbers. Therefore, application of entomopathogens in single, consortium or in combination reduced the recommended concentration of Tutan36%SC to control T. absoluta.