Suppression of Defense Response Related to Plant Cell Wall

In plant–parasite interactions, “effectors” are thought to play an important role in suppressing the innate immune response, but the vast majority of effector functions and host target molecules remain unclear, except for several combinations. A pea pathogenic fungus, Mycosphaerella pinodes, secretes compounds that block defense responses of the host plants only and also induce local susceptibility (“accessibility”), even to avirulent pathogens. These compounds have been called “suppressors” or “suppressors of defense.” The M. pinodes-suppressors, which are low-molecular weight mucin-type glycopeptides, were named supprescins and their presence markedly blocked elicior-induced resistance, such as the generation of superoxide, formation of infection-inhibitors, production of phytoalexin and so on, in host plants. For three decades from 1977, it was found that supprescins disturb the fundamental functions of the host cells, particularly apyrase and redox enzymes in the host cell wall in a speciesspecific manner. In this review, the role of supprescins with the plant cell wall in determining specificity was introduced. Discipline: Plant disease/Plant protection Additional key words: effector, elicitor, MAMPs (microbe-associated molecular pattern), plant-pathogen specificity, suppressor * Corresponding author: e-mail [email protected] Received 26 March, 2012; accepted 1 June, 2012. 21 JARQ 47 (1), 21 – 27 (2013) http://www.jircas.affrc.go.jp