LIPOCHITO-OLIGOSACCHARIDES RE-INITIATE ROOT HAIR TIP GROWTH IN VICIA-SATIVA WITH HIGH-CALCIUM AND SPECTRIN-LIKE ANTIGEN AT THE TIP

Lipochito-oligosaccharides, Nod factors secreted by Rhizobium bacteria , are signal molecules that induce deformation of root hairs of their host plant. A bioassay was used for deformation, and the cytological c hanges induced by specific lipochito-oligosaccharides in root hairs of Vicia sativa L. (vetch), grown between glass slides, were examined. I n the assay, root hairs of a particular developmental stage, those tha t were terminating growth, were susceptible to deformation. These hair s obtained characteristics of tip-growing cells again: (i) a polar cyt oplasmic organization and reverse fountain streaming, (ii) an accumula tion of a spectrin-like antigen at the tip, and (iii) a tip-focused ca lcium gradient. Calcium gradients were visualized in Indo-1 loaded roo t hairs with UV confocal microscopy and ratio-imaging. The results sho w that hairs respond to the bacterial signal by recovering cytoplasmic polarity and exocytosis.