[44]

Plant Adaptation To Abiotic Stress – From Physiology To Genomics.  Hans J. Bohnert,  Department of Plant Biology & Department of Crop Sciences, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA

   Physiological balance in plants is often challenged by abiotic factors, such as temperature extremes, osmotic and ionic imbalances, light quantity or quality, or nutrient deficit.  Several decades of studies have resulted in a body of knowledge that described stress-dependent changes in overall plant development, and the physiology and biochemistry of photosynthetic tissues, organs and cells.  Genetic and molecular studies provided information on individual components of the plant stress response but genomics-type studies have truly revolutionized our approach to understanding what constitutes stress and stress tolerance or sensitivity.

Based on established physiological protocols, experiments can now be designed and the results correlated with gene complement, transcript profiles, protein amount and dynamics, and metabolite changes.  A common set of close to 30,000 genes in all angiosperms has evolved through genome and gene duplications and changes in the control of gene and protein expression.  Thus, stress-adaptive evolutionary diversity in species, and in ecotypes and lines of one species, appears to be based mainly on how (fast) any stress is perceived and signaled to a common set of downstream genes and the modification of constitutively expressed proteins.  Examples will highlight hormonal abiotic stress responses that, transmitted through reactive oxygen species and calcium-dependent signaling, determine plant tolerance capacity (supported by NSF, DOE, USDA and institutional funds).