1. Biosciences Department Seminar

    "The Ammonium/Nitrate Ratio Acts as an Input Signal in the Plant Immune Response through Modulation of Nitric Oxide Production"

    Presented by Yiji Xia, Department of Biology, Hong Kong Baptist University, Hong Kong

    Friday, July 19, 2013, 11 am
    John Dunn Seminar Room, Bldg. 463

    Hosted by: Chang-Jun Liu

    Plants use complex mechanisms to fine-tune their immune responses. The Arabidopsis AtNUDT7 and AtNUDT6, two members of the Nudix hydrolase superfamily that are found in all classes of organism and hydrolyze a wide range of organic pyrophosphates, were identified as negative regulators of the defense pathway. The nudt6 nudt7 double mutant exhibits autoimmune phenotypes that are modulated by temperature. The nudt6 nudt7 mutation leads to increased production of nitric oxide (NO) and promotes nuclear accumulation of EDS1 which is a key positive regulator of the immune response. We found that a low ammonium/nitrate ratio in growth media enhances autoimmunity in nudt6 nudt7 and many other autoimmune mutants in Arabidopsis. The ammonium/nitrate ratio apparently acts as an input signal to determine the amplitude of the EDS1-mediated defense response likely through modulation of NO production.