Nod-Factor Signaling in Legume-Rhizobial Symbiosis

Abstract

Leguminous plants (or Legumes, family Fabaceae) are known to form symbioses with extremely broad range of beneficial soil microorganisms (BSM), representing examples of almost all plant-microbe mutualistic systems. One of the most ecologi‐ cally important and well-studied legume beneficial symbioses is root nodule (RN) symbiosis (symbiotic association with nitrogen-fixing bacteria). Compared with other interactions of legumes with BSM, RN symbioses demonstrate high level of genetic and metabolic integrity, which implies, inter alia, highly specific mutual recognition of partners. In this chapter, we describe the mechanisms of plant-microbe recognition during initial steps of RN symbiosis using the interaction of model legumes - pea (Pisum sativum L.), barrel medic (Medicago truncatula Gaertn.) and Lotus japonicus (Regel.) K. Larsen - with rhizobia as an example. We paid particular attention to symbiotic system of P. sativum since pea, besides its importance as a model object of genetics, is also a valuable crop plant. Hence, in conclusion, we discuss the potential to use obtained knowledge for optimizing the broad spectrum of plant adaptive functions and to improve the sustainability of legume crop production. Keywords: legume-rhizobial symbiosis, Nod factor, plant signaling, genetic control 1.