A gene cluster were proven to be required for phenotypic expresion of P. syringae avr genes in E. coli . Research of the interaction between tomato and the bacterial pathogen Pseudomonas syringae pv. When expressed in corresponding systems, results in resistance to bacterial speck disease. Sequence analysis of avr Pto and Pto was conducted in an attempt to determine the functions of both genes. Pto did not reveal its function, but the Pto gene was discovered to encode a serine-threonine kinase.
Fen confers sensitivity to the insecticide fenthion.
Other components of the signaling pathway in tomato include the Prf and Pti 1 genes. Pti 1 is also a serine-threonine kinase and is thought to be acting downstream of Pto in the signaling pathway. Using an Agrobacterium -mediated transient gene expression assay, it was tested to see if Avr Pto protein could elicit a HR when expressed inside plant cells. A yeast two-hybrid system was used to test if whether Pto and Avr Pto physically interact during recognition specificity. And finally, if there is physical interactions between Pto and Avr Pto, a series of chimeric proteins were constructed to test if particular regions are necessary for interaction between the two proteins.