Recombinants Rhizobacteria Enhanced Biological Control of Rhizoctonia solani infected Faba Bean

Abstract

This study aimed to test the effect of Rhizobium recombinants on the vegetative growth and yield components of faba bean under biotic stress of Rhizoctonia solani. Tweleve transconjugants resulted from six crosses were evaluated for their antigonism against Rhizoctonia solani. The results showed variations in chitin hydrolysis after genome shortening. At the molecular level, the recipient strains of rhizobia showed more similarity with each other. However, the donar strains of Serratia and pseudomonas showed less similarity. Meanwhile , Rhizobium transconjugants genomes have a similar distribution of bands. Both transconjugants Tr 4 and Tr15 showed more genome size than the other ones due to high level of plasmid transfer. The same transconjugants recorded higher values of chitin hydrolysis zone due to higher expression of chitinase genes. Most transconjugants showed significant increase in nodulation above the uninoculated plants grown in the infected soil. Rhizobium inoculants improved the yield , chlorophyll concentration and NPK content of the plants grown in the soil infected with Rhizoctonia solani compared with uninoculated plants. The results indicated that Rhizobium inoculants improved the growth and yield of plants grown under biotic stress condition. In addition, improved rhizobia with chitinolytic enzymes producing genes could inhibit significantly the growth of pathogenic fungi.