Differential Expression of Drought Related Genes in Populus nigra Clones

The completion of whole genome sequencing in Populus trichocarpa offers ample opportunities to interrogate the impact of environmental stress factors on trees. With the current study, the genetic nature of tree adaptation to drought stress was examined by utilizing two Populus nigra clones ('N.62/191' and 'N.03.368.A') which  exhibit contrasting tolerance to drought in field and green house experiments, 'N.62/191'  productivity being less hampered by drought than that of 'N.03.368.A'. During the experiment one year old trees were submitted to a moderate and severe water deficit by withholding irrigation and ended with re-watering of the drought treated trees. Microarray experiments conducted with the GeneChip® Poplar Genome Array containing over 56 000 transcripts and gene predictions using leaves collected at these different water deficit levels and compared with the control plants for both genotypes. Our analysis detected several candidate genes and processes that are differentially regulated in leaf for different drought level.  Total of 256, 428 and 312 different sets of genes were expressed in control, drought and re-watering regimes of two clones, respectively. These candidate genes could be responsible for explaining the genomic basis of variation among clones in drought response.