Features of proline degradation in plant-pathogen interactions".

CECCHINI NM; ÁLVAREZ ME

Congreso; SAIB XLI Annual Meeting; 2005

Incompatible plant-pathogen interactions trigger a known type ofprogrammed cell death (PCD), the Hypersensitive Response (HR),at the infection sites. The biochemical signals promoting PCD inHR remains to be investigated. We recently described net alterationsof the L-Proline (Pro) metabolism in HR. In addition, accumulationof Δ1-Pyrroline-5-carboxilate (P5C), an intermediate of Prodegradation, was proposed to induce PCD. Hence, we analyzed theputative effects of P5C along HR development. We usedArabidopsis thaliana cell suspension cultures infected withPseudomonas syringae strains to produce or not HR (incompatibleand compatible interactions, respectively). We evaluated by RTPCRthe transcriptional regulation of the genes implicated in Procatabolism, Pro-dehydrogenase (ProDH) and P5C-dehydrogenase(P5CDH), along infection. Rapid induction of ProDH and arepression of P5CDH were only observed in incompatibleinteractions. The uncoupled expression of these genes is suspectedto cause P5C accumulation. We found that these transcriptionalchanges parallel the second phase of the oxidative burst and thealkaline pH shift, and they precede cell death. Interestingly, pretreatmentof cells with a specific ProDH inhibitor abolishespathogen-induced cell death. Taking together these results suggestthat P5C is a key component of HR during plant-pathogenincompatible interactions.