ABSCISIC ACID IS INVOLVED IN THE RESPONSE OF GRAPE (VITIS VINIFERA L.) CV. MALBEC LEAF TISSUES TO UV-B RADIATION BY ENHANCING UV-ABSORBING COMPOUNDS, ANTIOXIDANT ENZIMES AND MEMBRANE STEROLS

BERLI F.; MORENO D.; PICCOLI P.; HESPANHOL-VIANA L.; SILVA M.F.; BRESSAN-SMITH R.; CAVAGNARO J.B.; BOTTINI R.

PLANT CELL AND ENVIRONMENT

BLACKWELL PUBLISHING LTD

Año: 2010 vol. 33 p. 1 - 10

1365-3040

We investigated the interactions of abscisic acid (ABA) in the responses of grape leaf tissues to contrasting ultraviolet (UV)-B treatments. One-year-old field-grown plants of Vitis vinifera L. were exposed to photosynthetically active radiation (PAR) where solar UV-B was eliminated by using polyester filters, or where PAR was supplemented with UV-B irradiation. Treatments combinations included weekly foliar sprays of ABA or a water control. The levels of UV-B absorbing flavonols,  quercetin and kaempferol were significantly decreased by filtering out UV-B, while applied ABA increased their content. Concentration of two hydroxycinnamic acids, caffeic and ferulic acids, were also increased by ABA, but not affected by plus UV-B (+UV-B) treatments. Levels of carotenoids and activities of the antioxidant enzymes, catalase, ascorbate peroxidase and peroxidase were elevated by +ABA treatments, but only if +UV-B was given. Cell membrane beta-sitosterol was enhanced by ABA independently of +UV-B. Changes in photoprotective compounds, antioxidant enzymatic activities and sterols were correlated with lessened membrane harm by UV-B, as assessed by ion leakage. Oxidative damage expressed as malondialdehyde content was increased under +UV-B treatments. Our results suggest that the defence system of grape leaf tissues against UV-B is activated by UV-B irradiation with ABA acting downstream in the signalling pathway.