Molecular Plant-Microbe Interactions (2002) 15, 281-291

Jeff H. Chang, Yin-Shan Tai, Adriana J. Bernal, Daniel T. Lavelle, Brian J. Staskawicz and Richard W. Michelmore (2002)
Functional analyses of the Pto resistance gene family in tomato and the identification of a minor resistance determinant in a susceptible haplotype
Molecular Plant-Microbe Interactions 15 (3), 281-291
Abstract: Pto is a member of a multigene family and encodes a serine/threonine kinase that mediates gene-for-gene resistance to strains of Pseudomonas syringae pv. tomato expressing avrPto. The inferred amino acid sequence of the Pto homologs from both resistant (LpimPth2 to LpimPth4,) and susceptible (LescFen, LescPth2 to LescPth5) haplotypes suggested that most could encode functional serine/threonine kinases. In addition, the activation segments of the homologs are similar in sequence to that of Pto, and some have residues previously identified as required for binding of AvrPto by Pto in the yeast two-hybrid system. The Pto homologs were therefore characterized for transcription, for the ability of their products to interact with AvrPto in the yeast two-hybrid system, for their autophosphorylation activity, and for their potential to elicit cell death in the presence of and absence of a ligand, as well as their dependence on Prf. LpimPth5, LpimPth4, and LescPth4 were not transcribed at levels detectable by reverse transcription-polymerase chain reaction. The interaction with AvrPto was unique to Pto in the yeast two-hybrid system. LescPth2 autophosphorylated in vitro as a fusion protein. LpimPth2, LpimPth3, LpimPth4, LescPth3, and LescPth4 did not autophosphorylate in vitro. Transient expression of wild-type Fen and wild-type LpimPth3, as well as LescFen, LescPth3, and LescPth5 with perturbations in their P+1 loop caused cell death in Nicotiana benthamiana. LpimPth3 and LescPth3 with amino acid substitutions in the P+1 loop also elicited cell death in tomato; this was dependent on the presence of wild-type Prf. Consequently, some homologs could potentially encode functional resistance proteins. LescPth5 induced cell death specifically in response to expression of AvrPto in tobacco in a Prf-dependent manner; this is consistent with a homolog from a 'susceptible' haplotype encoding a minor recognition determinant.
(The abstract is excluded from the Creative Commons licence and has been copied with permission by the publisher.)
Link to article at publishers website
Database assignments for author(s): Richard W. Michelmore

Research topic(s) for pests/diseases/weeds:
resistance/tolerance/defence of host

---

Pest and/or beneficial records:

Beneficial	Pest/Disease/Weed	Crop/Product	Country	Quarant.
	Pseudomonas syringae pv. tomato	Tomato (Solanum lycopersicum)
	Pseudomonas syringae