DspE of Erwinia amylovora interacts with receptor kinases of apple

Erwinia amylovora causes fire blight of apple, pear, and other rosaceous plants and elicits plant defense responses in nonhost plants. Previous research indicated that a disease specific gene, dspE, from E. amylovora is essential for pathogenicity. DspE is a homolog of AvrE of Pseudomonas syringae. The LexA yeast-two-hybrid system was used to seek DspE-interacting proteins from apple to further explore its role in pathogenicity. Bait constructs consisting of several portions of the dspE gene were made in the expression vector pGlida. A representative cDNA library of apple (Malus x domestica cv. 'Royal Gala') was constructed in the vector pB42AD. 198 putative interacting clones were selected and re-screened to yield four unique, positive clones. A Blast search of cDNA sequences of the four clones indicated that all had protein kinase domains and belonged to LRR receptor-like kinases. The full-length sequences of the four clones were identified. Further characterization of the cDNAs and the encoded kinases are underway. Studies of the gene function are in progress.