GENES-CONTROLLING NODULATION COMPETITIVEN ESS OF NODULE BACTERIA

It was shown that genes determining motility (mot), chemotaxis (che), bacteriocin synthesis (tfx), polysaccharide synthesis (eps, lps, exo), and virulence (nod, cnb, nfe), as well as some other genes, participa te in control of nodulation competitiveness of nodule bacteria. In fas t-growing Rhizobium species (R. meliloti, R. fredii, R. loti, R. legum inosarum bv. trifolii, bv. viceae, and bv. phaseoli), it was shown tha t these genes are localized both on the chromosome and on different ty pes of plasmids (symbiotic and nonsymbiotic); in slow-growing species (Bradyzhizobium japonicum), these genes are located only on the chromo some. Ways of genetic construction of highly efficient and competitive rhizobia strains are discussed.