The pressure collar (PC) technique was applied to shoots of the isohydric cultivar Grenache, to induce cycles of embolism formation - by PC pressurization - and recovery - by PC depressurization - in xylem vessels without metabolic interference, as it happens on the contrary during water stress/rehydration (WS) conditions. The PC was applied on a branch of the irrigated plant, whereas another branch was used as irrigated (IRR) control. We measured leaf gas exchange by Infra Red Gas Analyzing to assess stomatal conductance (gs), leaf water potential (Ψleaf) by pressure chamber technique, and hydraulic resistance by High Pressure Flow Metering (HPFM) to assess the percent loss of conductivity (PLC) caused by embolism. Five hours of the PC treatment increased PLC and reduced Ψleaf and gs to values similar to WS plants. Thereafter, we depressurized PC branches and irrigated WS plants. In PC branches, Ψleaf, gs and PLC recovered four hours later, whereas WS plants recovered after rehydration more slowly (two days after) according to a gradual, ABA-affected recovery of gs. WS and PC leaf petioles were sampled at end treatment (maximum stress conditions) contemporarily with petioles of IRR controls. In addition, PC and WS leaf petioles were sampled when PLC was recovered. The sampled petioles were processed in order to isolate Vessels Associated Cells (VACs) with Laser Micro Dissection (LMD) technique after paraffin embedding. To comprehend VACs activity during the cycles of formation and recovery of embolism, transcripts of sugar transporters, genes related to ABA metabolism, aquaporins and stress-related transcription factors were detected by RT-PCR assays. VACs metabolic involvement during embolism recovery was elucidated.
Induction and recovery of embolism generated by water stress or pressure collar technique in grapevine
PERRONE, Irene;PAGLIARANI, CHIARA;SCHUBERT, Andrea;LOVISOLO, Claudio
2010-01-01
Abstract
The pressure collar (PC) technique was applied to shoots of the isohydric cultivar Grenache, to induce cycles of embolism formation - by PC pressurization - and recovery - by PC depressurization - in xylem vessels without metabolic interference, as it happens on the contrary during water stress/rehydration (WS) conditions. The PC was applied on a branch of the irrigated plant, whereas another branch was used as irrigated (IRR) control. We measured leaf gas exchange by Infra Red Gas Analyzing to assess stomatal conductance (gs), leaf water potential (Ψleaf) by pressure chamber technique, and hydraulic resistance by High Pressure Flow Metering (HPFM) to assess the percent loss of conductivity (PLC) caused by embolism. Five hours of the PC treatment increased PLC and reduced Ψleaf and gs to values similar to WS plants. Thereafter, we depressurized PC branches and irrigated WS plants. In PC branches, Ψleaf, gs and PLC recovered four hours later, whereas WS plants recovered after rehydration more slowly (two days after) according to a gradual, ABA-affected recovery of gs. WS and PC leaf petioles were sampled at end treatment (maximum stress conditions) contemporarily with petioles of IRR controls. In addition, PC and WS leaf petioles were sampled when PLC was recovered. The sampled petioles were processed in order to isolate Vessels Associated Cells (VACs) with Laser Micro Dissection (LMD) technique after paraffin embedding. To comprehend VACs activity during the cycles of formation and recovery of embolism, transcripts of sugar transporters, genes related to ABA metabolism, aquaporins and stress-related transcription factors were detected by RT-PCR assays. VACs metabolic involvement during embolism recovery was elucidated.
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