Effects of soybean genotype on the glyceollin elicitation competency of cotyledon tissues to Phytophthora sojae glucan elicitors

In some soybean cultivars, wounding or hypersensitive (HR) cell death is required for the activation of the competency of immediately surrounding (proximal) cells to deploy defense responses to the cell wall glucan elicitor from the pathogen Phytophythora sojae. These proximal defense responses include Phenolic polymer deposition and accumulation of the glyceollin phytoalexins. In Williams soybeans, elicitation competency is an induced and transient state and is triggered by two endogenous competency factors Which are associated with wounded or HR dying cells. In this paper it is reported for the first time that certain cultivars. including Harosoy and Bragg, are at least partially inherently competent. That is, they do not require wound- or HR-associated factors for the glyceollin response to occur. The effects oil competency of several Rps genes for resistance to P. sojae are examined in near isolines of both Williams (incompetent) and Harosoy (competent) and genes controlling nodulation by Bradyrhizobium. Preliminary results suggest that genes that are linked to the Rp 1,3 and 7 loci may modulate the signaling events required for the establishment of the competent state. (C) 2001 Academic Press.