Monitoring gene expression in response to short- and long- term water stress in potato

Understanding the molecular mechanisms regulating plant response to environment is of fundamental interest to plant biology as abiotic stresses are major limiting factors of plant growth and productivity. Plant respond to stress signals by altering the expression of many genes, whose products have important reparative and protective functions, allowing cellular adptation to stress conditions. We previously reported that gradual acclimation of potato cells to PEG-mediated water stress induces a set of metabolic changes, not observed in cells exposed abruply to stress (Leone et al., 1994 Plant Physiol 106: 703). To identify genes involved in these processes and crucial for the acquisition of long term tolerance a potato trascriptome analysis using TIGR 10k cDNA arrays challenged with RNA from untreated, PEG-shocked and -acclimated cells, was performed. Microarray data revealed that more than 300 genes belonging to different functional categories were up-regulated in response to drought, and that only few genes were common to both cell populations, thus confirming that different gene networks mediate short and long- term response to water deficit. Some of the identified genes, e.g. hsp80, sato and gtp-binding genes, whose expression have been further characterized by qRT-PCR, showed to be stress -inducibile also in potato vegetative tissues. A functional analysis using arabidopsis is in progress to define the biological role of these genes in stress response mechanisms.