AvrPto Enhances Growth and Necrosis Caused by Pseudomonas syringae pv. tomato in Tomato Lines Lacking Either Pto or Prf

Jeff H. Chang^1,2, John P. Rathjen¹, Adriana J. Bernal¹, Brian J. Staskawicz^1,3, and Richard W. Michelmore^1,4,*

¹ NSF Center for Engineering Plants for Resistance Against Pathogens (CEPRAP), University of California, Davis, One Shields Avenue, Davis, CA 95616.

² Current Address: Department of Biology CB#3280, 108 Coker Hall, Chapel Hill, NC 27599.

³ Department of Plant and Microbial Biology, University of California, Berkeley, CA 94720.

⁴ Department of Vegetable Crops, University of California, Davis, CA 95616.

Abstract

AvrPto was introduced into three tomato genotypes using two biotic agents to study its role in compatible interactions. avrPto enhanced the capacity of Pseudomonas syringae pv tomato strain T1 to induce necrotic symptoms on tomato plants that lacked either Pto or Prf genes. The enhanced necrosis correlated with a small increase in bacterial growth. In planta expression of avrPto in isolation did not elicit necrosis in the absence of a functional Prf gene.