The major leaf ferredoxin Fd2 regulates plant innate immunity in Arabidopsis.

Ferredoxins, the major distributors for electrons to various acceptor systems in plastids, contribute to redox regulation and antioxidant defence in plants. However, their function in plant immunity is not fully understood. In this study, we show that the expression of the major leaf ferredoxin gene Fd2 is suppressed by Pseudomonas syringae pv.

Separable roles of the Pseudomonas syringae pv. phaseolicola accessory protein HrpZ1 in ion-conducting pore formation and activation of plant immunity.

The HrpZ1 gene product from phytopathogenic Pseudomonas syringae is secreted in a type-III secretion system-dependent manner during plant infection. The ability of HrpZ1 to form ion-conducting pores is proposed to contribute to bacterial effector delivery into host cells, or may facilitate the nutrition of bacteria in the apoplast. Furthermore, HrpZ1 is reminiscent of a pathogen-associated molecular pattern (PAMP) that triggers immunity-associated responses in a variety of plants.