AQUAPORIN INTERACTING PROTEIN (AQI), a new regulator of cell death in plants
A. PFITZNER (1), E. Glink (1), K. Fischer (1), B. Neuhäuser (1), U. Ludwig (1) (1) Universitaet Hohenheim, Germany

Programmed cell death (PCD) is an important defense mechanism of animal and plant cells against pathogens. In plants, this defense response leads to a localized necrotic reaction, the hypersensitive response (HR), which depends on recognition of the pathogen by plant resistance genes. The developing local lesions act as barriers between uninfected host tissue and the pathogen, thus avoiding systemic expansion of the pathogen within the whole plant. In addition, HR leads to induction of systemic acquired resistance (SAR), a transient immunity against secondary pathogen attacks. In previous experiments, we identified two members of Nicotiana tabacum aquaporins, NtTIP1.1 and NtPIP2.2, as H2O2 channels involved in the signaling pathway leading to PCD. To identify regulators of NtTIP1.1 and NtPIP2.2, a yeast-2-hybrid screen for interacting proteins was performed. A cDNA clone coding for a new protein with sequence homology to M20 peptidases was isolated from an Arabidopsis library and named AQUAPORIN INTERACTING PROTEIN (AQI). Coexpression of NtAQI with NtTIP1.1-GFP in N. benthamiana plants prevents NtTIP1.1-GFP mediated induction of necrosis indicating a functional relevance for the NtAQI–NtTIP1.1 interaction. In conclusion, our results show that induction of cell death in plants is dependent not on generation of the cell death elicitor H2O2, but also on control of its influx via the AQI barrier. 

Abstract Number: P18-688
Session Type: Poster