In situ localization and penetration route of an endophytic bacteria into roots of wheat and the common bean

We examined the structural interaction of the green fluorescent protein−labeled bacterium Herbaspirillum lusitanum, strain P6-12, with Triticum aestivum L. and Phaseolus vulgaris L. The interaction was examined by fluorescence and confocal microscopy for 21 days after inoculation. As early as 0.5 h after inoculation, H. lusitanum P6-12 was observed between the loose peripheral cells of the root cap. This suggests that the bacterium entered the plants through the loose parenchyma of the root cap. One h after inoculation, H. lusitanum P6-12 was detected in the root division zone, and after one and a half h, it reached the elongation and maturation zones.