Chapter 8 - Vertical pathosystem: Resistance genes and their products. Signal transduction

Abstract

The chapter discusses resistance genes and susceptibility genes and their products in detail with examples. Attempts have been made to describe the investigation of genes by the methods of classical genetics. Illustrations explain the different methods and their combinations to isolate the resistance genes from different plants. The process of recognition of extracellular substances is carried out using the “signaling systems” that determine the cellular response to various chemical and physical exposures. This chapter explains signal transduction and the various signaling systems present. An essential role in this signaling system is played by salicylic acid with its concentration growing not only in infection sites but also in the tissues far from the infection site. A signaling transcription of a plant defense response involves more than 1500 transcript factors. This chapter also describes the interactions of the signaling systems induced by nonspecific and specific elicitors. Signaling systems can be activated or inactivated by the secondary messengers of the other signaling systems. Plant cells possess a coordinated signaling network where some signaling systems can activate or, alternately, inactivate the other systems. One of the features of the signaling systems is not only signal transfer to the genetic system but also its considerable amplification. Interaction of one signaling molecule with a receptor can lead to a million molecules governing the cell response. All the signaling systems known to date can be classified into evolutionarily earlier and later ones. It is very likely that efforts of the researchers studying plant signal transduction will lead to the discovery of both the new signaling systems and their interactions.