Poster: Plant Pathogen/Symbiont Interactions
Abs #
769: LSD1, a negative regulator of cell death in Arabidopsis, physically interacts with members of the CCAAT binding family of proteins
Plant resistance (R) genes products recognize specific, pathogen derived avirulence (avr) gene products and thus initiate a defense signaling cascade that ultimately leads to resistance. The hypersensitive response (HR) is a type of programmed cell death in plants and is a hallmark response to the R-avr interaction. Genetic regulators of cell death, and possibly the HR, have been identified. LSD1 is a negative regulator of cell death in Arabidopsis and deletion of this gene leads to spontaneous lesion formation and a general failure to prevent lesion spreading, referred to as runaway cell death. We identified numerous LSD1 interacting proteins by yeast two-hybrid analysis and further characterized two CCAAT binding proteins. These CCAAT binding proteins, called LIN1 and LIN2 for LSD1 interacting protein, are homologous to the mammalian CBF-C proteins and are highly related in their putative DNA binding and polymerization motifs. We identified an LSD1 interacting, conserved binding motif by phage display and found that both LIN1 and LIN2 have this motif. We used a semi-in vivo technique to further demonstrate the interaction between LIN1 and LSD1. Additionally, we show that the R-avr specific recognition of Peronospora parasitica isolate Cala2 is impaired in plants strongly reduced for LIN1 mRNA accumulation. We have created a series of putative dominant negative mutations in LIN1 and will discuss the latest progress in testing these constructs in planta.
