Heat shock triggers H2O2 production and extends postharvest life of spinach leaves

GÓMEZ FACUNDO; FERNÁNDEZ LAURA; GUIAMET JUAN JOSÉ; CHAVES ALICIA; BARTOLI CARLOS GUILLERMO

Bristol, Inglaterra

Congreso; Oxygen metabolism, ROS and redox signalling in plants; 2005

Association of Applied Biologists and The Society for Free Radical Research

            The aim of our work was to extend the post-harvest life of spinach by the application of moderate heat shock treatments. The rationale of the experiments is that a moderate stress would trigger plant responses leading to a delay of leaf senescence.             Detached spinach leaves were immersed in water baths at 37, 40 , 43ºC or ambient temperature (AT) for 3.5 min. Then leaves were carefully dried with a paper towel and stored in polyethylene bags in darkness at 23ºC. Physiological parameters were determined on the harvest day and after 3 and 7 days.             The effect of heat shock treatments was monitored by determining the accumulation of small heat shock proteins (sHSP) 4 and 24 hs after the treatments were applied. sHSP content increased proportionally to temperature, with undetectable levels in control leaves (AT). Senescence was delayed in leaves treated with 37 and 40ºC, as visualised by higher chlorophyll content after storage for 7 days. Solute leakage was decreased by all treatments, indicating preservation of membrane integrity. Preliminary experiments showed that temperatures higher than 43ºC were deleterious and accelerated senescence. A higher in vivo production of H2O2 was observed as temperature increased, although leaf respiration was unaltered by the treatments. We are currently measuring the effect of heat shock treatments on leaf antioxidant contents and subcellular production of H2O2.             These results suggest that H2O2 might function as a signal triggering protective mechanisms leading to the extension of post-harvest leaf life. Uncovering the processes triggered by heat treatments would allow a better post-harvest manipulation of plant tissues.