ISHS Acta Horticulturae 689: VII International Symposium on Grapevine Physiology and Biotechnology
MONITORING THE RESPONSE OF GRAPEVINE PLANTLETS TO EXCESS LIGHT BY REAL-TIME PCR |
| Authors: | L.C. Carvalho, P. Vidigal, B. Vilela, P. Mullineaux, S. Amâncio |
| Keywords: | ascorbate-glutathione cycle, ex vitro growth, in vitro plantlets, light stress, gene expression, Vitis vinifera |
| Abstract:
Environmental stresses, such as excess light, exert at least part of their effect by producing reactive oxygen species (ROS). Understanding the functioning of the antioxidant defense system in plants is attracting considerable interest. Micro-propagated plantlets transferred to ex vitro have proven to be a good model system to study physiological responses to excess light. In the present work we show the response of in vitro propagated grapevine plantlets during the first seven days after transfer to ex vitro under an irradiance four times greater than that of the in vitro conditions. We monitored the activities of enzymes associated with ROS detoxification, mRNA levels for their isozymes by real-time PCR and the contents of GSH and GSSG. We present evidence that excess light triggers the expression of the genes, particularly the SOD gene family and SOD activity matching the expression patterns. GSH synthesis was stimulated by light and maintained at steady state levels until day 6 when a sharp decrease was observed. The percentage of reduced GSH was above 95% except on days 2 and 4. The responses measured at day 2 were triggered by photo-oxidative stress while those at day 6 indicated the effect of active growth associated with the formation of new structures. | |
Download Adobe Acrobat Reader (free software to read PDF files) | |
