Role of the Arabidopsis peptide transporter AtOPT6 in heavy metal detoxification and plant-pathogen interaction

Abstract

AtOPT6, is a member of oligopeptide transport (OPT) gene family. In Arabidopsis thaliana, there are nine members in the OPT gene family that are thought to be involved in peptide transport. Spacial and temporal expression of AtOPT6 correlates with transport of peptides in the major sink tissues indicating that this transporter may be involved in long distance transport of peptides to provide organic nitrogen to the developing plant organs. Over-expression of AtOPT6 leads to cadmium hyper-sensitivity and higher accumulation of cadmium and phytochelatins in root tissues. opt6 mutant plants exhibited less sensitivity to virulent pathogen Psuedomonas syringae pv tomato DC3000 and showed minimal chlorosis in leaves. The differential in bacterial growth in opt6 mutant and wild-type plants was abolished when infected with Pst DC3000 COR- strain, indicating a possible role of AtOPT6 in transport of bacterial phytotoxin coronatine. In addition, opt6 mutant plants showed less susceptibility when infected with both cyst and root-knot nematode. Expression of AtOPT6 increased during early stages of both cyst and root-knot nematode infection in and around the developing feeding sites. AtOPT6 mediated transport of various Arabidopsis CLAVATA3/ESR-like (CLE-like) and nematode secreted peptides when expressed in Xenopus. Collectively, these data suggest that AtOPT6 may transport nutrients into the feeding site or AtOPT6 transports plant CLEs or nematode secreted peptides into the infected root cells to induce root differentiation.