Expression of Caenorhabditis elegans PCS in the AtPCS1‐deficient Arabidopsis thaliana cad1‐3 mutant separates the metal tolerance and non‐host resistance functions of phytochelatin synthases. (19th May 2015)

• Record Type: Journal Article
• Authors: Kühnlenz, Tanja; Westphal, Lore; Schmidt, Holger; Scheel, Dierk; Clemens, Stephan
• Is Part Of: Plant, cell and environment. Volume 38:Number 11(2015:Nov.)
• Page Start: 2239
• Page End: 2247
• Publication Date: 2015-05-19
• Subjects: cadmium -- metal homeostasis -- phytochelatins -- plant defence -- innate immunity -- non‐host resistance; Plant physiology -- Periodicals; Plant cells and tissues -- Periodicals; Plant communities -- Periodicals; 581.105
• DOI: 10.1111/pce.12534
• Languages: English
• ISSNs: 0140-7791

Abstract

Abstract: Phytochelatin synthases (PCS) play key roles in plant metal tolerance. They synthesize small metal‐binding peptides, phytochelatins, under conditions of metal excess. Respective mutants are strongly cadmium and arsenic hypersensitive. However, their ubiquitous presence and constitutive expression had long suggested a more general function of PCS besides metal detoxification. Indeed, phytochelatin synthase1 from A rabidopsis thaliana (AtPCS1) was later implicated in non‐host resistance. The two different physiological functions may be attributable to the two distinct catalytic activities demonstrated for AtPCS1, that is the dipeptidyl transfer onto an acceptor molecule in phytochelatin synthesis, and the proteolytic deglycylation of glutathione conjugates. In order to test this hypothesis and to possibly separate the two biological roles, we expressed a phylogenetically distant PCS from C aenorhabditis elegans in an AtPCS 1 mutant. We confirmed the involvement of AtPCS1 in non‐host resistance by showing that plants lacking the functional gene develop a strong cell death phenotype when inoculated with the potato pathogen P hytophthora infestans . Furthermore, we found that the C . elegans gene rescues phytochelatin synthesis and cadmium tolerance, but not the defect in non‐host resistance. This strongly suggests that the second enzymatic function of AtPCS1, which remains to be defined in detail, is underlying the plant immunity function. Abstract : Phytochelatin synthases have been implicated in two seemingly unrelated biological functions, toxic metal tolerance and innate immunity. We tested whether the two functions can be separated by expressing a non‐plant phytochelatin synthase in a respective Arabidopsis thaliana mutant. Our results demonstrate a role of phytochelatin synthases in resistance against the nonhost pathogen Phytophthora infestans and show that this function is apparently unrelated to phytochelatin synthesis.