LIPOCHITOOLIGOSACCHARIDE-INDUCED TOBACCO CELLS RELEASE A PEPTIDE AS MEDIATOR OF THE GLYCOLIPID SIGNAL

Lipochitooligosaccharides (LCOs) are plant growth regulators that prom ote at subfemtomolar concentrations cell division in tobacco protoplas ts. In response to LCO treatment, tobacco cells release a second growt h factor that fully mediates the growth-promoting activities of the in itial extracellular LCO stimulus. This diffusible growth factor was is olated from the protoplasts' culture filtrate and shown to be a peptid e. We report that the LCO-induced mitogen released by tobacco cells an d a synthetic heptadecapeptide derived from region 2 of the tobacco ho molog of the early nodulin gene ENOD40 are antigenically related and q ualitatively indistinguishable in their ability to stimulate cell divi sion.