THE USE OF TRANSPOSON-INDUCED NONMOTILE MUTANTS IN ASSESSING THE SIGNIFICANCE OF MOTILITY OF RHIZOBIUM-LEGUMINOSARUM BIOVAR TRIFOLII FOR MOVEMENT IN SOILS

A Tn5+-containing motile strain of Rhizobium trifolii TA I was able to move vertically, or horizontally, through steam-treated yellow sand at field capacity in the presence or absence of clover roots. Under the same conditions, the spread of a Tn5-induced non-motile mutant was markedly reduced. When similar experiments were carried out in untreated soil. no significant difference in movement was seen between the motile and non-motile strains. Active flagellar motility appears not to be a significant factor in the distribution of rhizobia in the soil used in these experiments. Experiments in steam-treated soils may well lead to incorrect conclusions about motilily in relation to dispersal of rhizobia. © 1990.