Monitoring of the environmental influence on stress regulated genes in oak
The objectives of this study were to characterize the response of Quercus robur to long-term drought stress and rewatering on the whole plant level. Based on these results easily applicable functional markers for the selection of trees with increased drought resistance level will be developed. In a three-year glasshouse experiment five year old clonally propagated oak plants from tissue culture were subjected to controlled drought stress and subsequent rewatering. Phenotypic parameters were
... tored and leaf material was sampled in regular intervals for analyses of the transcriptome (cDNA-microarray), proteome and physiological parameters (carbohydrates, polyols, proline). The experiment comprised three treatments: 1) control, 2) one year drought followed by one year rewatering, 3) two years drought followed by one year rewatering. The application of drought stress led to growth reduction and change in flushing time, osmotic adjustment and starch degradation, reinforcement of the cuticula, repression of photosynthesis, and induction of genes with protective function and senescence associated genes. Rewatering resulted in the (early) recovery of photosynthesis, down-regulation of genes with protective function and senescence-associated genes, slow but strong induction of growth processes, and up-regulation of "rehydration-specific" genes. In conclusion, Q. robur displayed a very specific response depending on intensity and duration of the stress combining both drought avoidance and tolerance strategies. As a result plants were able to fully recover upon rewatering. Candidate genes for further selection of drought resistant oak trees are suggested.