Transcriptional and physiological responses to drought stress in Populus nigra L.

Yıldırım, Kubilay
In the current study, we investigated a number of drought related physio-biochemical processes and transcriptional comparisons at different stages of water availability to understand adaptation and response mechanisms of the black poplar (Populus nigra L.). Therefore, a well-watered, successive drought and post drought recovery periods were applied to black poplar clones. According to their drought response, the most sensitive (N.03.368.A) and resistant (N.62.191) black poplar clones were selected for microarray based transcriptional comparisons. The sensitive genotype was characterized with severe defoliation under drought stress. Therefore, the sensitive genotype specific genes were mostly annotated to leaf senescence and cell death. The highest expression of the genes such as NAC (JA), and ap2/erf transcription factors in the sensitive genotype indicated a potential role of Jasmonic Acid and Ethylen hormones controlling the leaf senescence. Expression of the genes involved in proteolysis, cell wall degradation and carbohydrate catabolism in the sensitive genotype were associated with drought induced nutrient and nitrogen mobilization processes. Contrary to the sensitive genotype, the drought resistant black poplar genotypes did not defoliate until severe drought level. The maintenance and recovery of drought traded leaves of the resistant genotype attributed to enhanced synthesis of bark storage proteins during drought stress. These proteins were suggested to be remobilized under drought and re-watering period to be used as an energy source in the drought treated organs. The highest up regulation in chaperons such as Heat Shock Proteins mostly in the resistant genotype were also associated to drought tolerance.
Citation Formats
K. Yıldırım, “Transcriptional and physiological responses to drought stress in Populus nigra L.,” Ph.D. - Doctoral Program, Middle East Technical University, 2013.