Nitric oxide is critical for inducing phosphatidic acid accumulation in xylanase-elicited tomato cells.

LAXALT, AM, RAHO, N, TEN HAVE, A, AND LAMATTINA, L.

JOURNAL OF BIOLOGICAL CHEMISTRY

Año: 2007 vol. 282 p. 21160 - 21168

0021-9258

   Nitric Oxide (NO) is a second messenger related to developmentand (a)biotic stress responses in plants. We have studied the role ofNO in signaling during plant defense responses upon xylanase elic-itation. Treatment of tomato cell cultures with the fungal elicitorxylanase resulted in a rapid and dose-dependent NO accumula-tion. We have demonstrated that NO is required for the produc-tion of the lipid second messenger phosphatidic acid (PA) viathe activation of the phospholipase C (PLC) and diacylglycerolkinase (DGK) pathway. Defense-related responses downstreamof PA were studied. PA and, correspondingly, xylanase wereshown to induce reactive oxygen species production. Scaveng-ing of NO or inhibition of either the PLC or the DGK enzymediminished xylanase-induced reactive oxygen species produc-tion. Xylanase-induced PLD 1 and PR1 mRNA levels decreasedwhen NO or PA production were compromised. Finally, we haveshown that NO and PA are involved in the induction of celldeath by xylanase. Treatment with NO scavenger cPTIO, PLCinhibitor U73122, or DGK inhibitor R59022 diminished xyla-nase-induced cell death. On the basis of biochemical and phar-macological experimental results, we have shown that PLC/DGK-derived PA represents a novel downstream component ofNO signaling cascade during plant defense.