Abstract
Bromegrass is an extremely cold hardy perrenial grass and its suspension culture provides a unique system where freezing tolerance can be induced by two different stimuli, cold and ABA. The latter process has an optimum temperature at 25C or over. The objective is to characterize each process and find common phenomena. We analyzed gene expression profiles during these two freezing tolerance induction processes (4C vs. ABA at 25C) using rice micro-arrays. We focused on genes expressed after 7 days of treatment. Cold induced many genes involved in protein synthesis, RNA functioning and protein degradation while ABA induced many stress-related genes and genes involved in storage compounds. These processes involve expression of fairly different sets of genes but have some common processes such as induction of anti-oxidating enzymes and cell wall alterations. Plasma membrane ATPase was up-regulated by cold (in agreement of physiological studies) and ABA.
