Potential of Pseudomonas putida PCI2 for the Protection of Tomato Plants Against Fungal Pathogens.

Tomato is one of the most economically attractive vegetable crops due to its high yields. Diseases cause significant losses in tomato production worldwide. We carried out Polymerase Chain Reaction studies to detect the presence of genes encoding antifungal compounds in the DNA of Pseudomonas putida strain PCI2. We also used liquid chromatography-electrospray tandem mass spectrometry to detect and quantify the production of compounds that increase the resistance of plants to diseases from culture supernatants of PCI2. In addition, we investigated the presence of 1-aminocyclopropane-1-carboxylic acid (ACC) deaminase in PCI2. Finally, PCI2 was used for inoculation of tomato seeds to study its potential biocontrol activity against Fusarium oxysporum MR193. The obtained results showed that no fragments for the encoding genes of hydrogen cyanide, pyoluteorin, 2,4-diacetylphloroglucinol, pyrrolnitrin, or phenazine-1-carboxylic acid were amplified from the DNA of PCI2. On the other hand, PCI2 produced salicylic acid and jasmonic acid in Luria-Bertani medium and grew in a culture medium containing ACC as the sole nitrogen source. We observed a reduction in disease incidence from 53.33 % in the pathogen control to 30 % in tomato plants pre-inoculated with PCI2 as well as increases in shoot and root dry weights in inoculated plants, as compared to the pathogenicity control. This study suggests that inoculation of tomato seeds with P. putida PCI2 increases the resistance of plants to root rot caused by F. oxysporum and that PCI2 produces compounds that may be involved at different levels in increasing such resistance. Thus, PCI2 could represent a non-contaminating management strategy potentially applicable in vegetable crops such as tomato.

4-Phosphopyrazol-2-yl alanine: a non-hydrolysable analogue of phosphohistidine.

We report the synthesis of a stable analogue of τ-phosphohistidine: 4-phosphopyrazol-2-yl alanine (pPza). Polyclonal antibodies generated against the mimic show high reactivity and selectivity for τ-phosphohistidine, with minor or no cross-reactivity towards non-phosphorylated histidine or O-phosphoamino acids, including phosphotyrosine.

Cytotoxic T lymphocyte epitope analogues containing cis- or trans-4-aminocyclohexanecarboxylic acid residues.

In order to improve the immunotherapeutical potential of H-Cys-Leu-Gly-Gly-Leu-Leu-Thr-Met-Val-OH (CLG) peptide, an Epstein-Barr virus (EBV) subdominant epitope derived from the membrane protein LMP2, we have synthesized and tested CLG analogues containing cis- and/or trans-4-aminocyclohexanecarboxylic acid (ACCA) replacing Gly-Gly and/or Thr-Met dipeptide units. All pseudopeptides were tested for metabolic stability and for their capacity to bind HLA-A2 molecules and to sensitize target cells to lysis. All new compounds exhibited higher enzymatic resistance compared to the original CLG and some trans-ACCA-derivatives were able to associate HLA-A2 and to efficiently stimulate CTL responses directed against the CLG natural epitope.