Rhizobium meliloti produces lipochitooligosaccharide nodulation NodRm factors that are required for nodulation of legume hosts. NodRm factors are O-acetylated and N-acylated by specific Cl6-unsaturated fatty acids. nodL mutants produce non-O-acetylated factors, and nodFE mutants produce factors with modified acyl substituents. Both mutants exhlbited a significantly reduced capacity to elicit infection thread (IT) formation ln alfalfa. However, once initiated, ITs developed and allowed the formation of nitrogen-fixing nodules. In contrast, double nodFlnodL mutants were unable to penetrate into legume hosts and to form ITs. Nevertheless, these mutants induced widespread cell wall tip growth in trichoblasts and other epidermal cells and were also able to elicit cortical cell activation at a distance. NodRm factor structural requirements are thus clearly more stringent for bacterial entry than for the elicitation of developmental plant responses.

Rhizobium meliloti produces lipochitooligosaccharide nodulation NodRm factors that are required for nodulation of legume hosts. NodRm factors are O-acetylated and N-acylated by specific C16-unsaturated fatty acids. nodL mutants produce non-O-acetylated factors, and nodFE mutants produce factors with modified acyl substituents. Both mutants exhibited a significantly reduced capacity to elicit infection thread (IT) formation in alfalfa. However, once initiated, ITs developed and allowed the formation of nitrogen-fixing nodules. In contrast, double nodF/nodL mutants were unable to penetrate into legume hosts and to form ITs. Nevertheless, these mutants induced widespread cell wall tip growth in trichoblasts and other epidermal cells and were also able to elicit cortical cell activation at a distance. NodRm factor structural requirements are thus clearly more stringent for bacterial entry than for the elicitation of developmental plant responses.

No abstract

The results obtained in the present study demonstrate the NF kappaB-mediated nuclear delivery of 3NF-plasmids. Due to its high affinity for fixing several NF kappaB, the 3NF sequence is a very promising helper for a nonviral gene delivery system.