Abstract

The potato is susceptible to water stress at all stages of development. We examined four clones of tetraploid potato, Cardinal, Desirée, Clone 37 FB and Mije, from the germplasm bank of the National Institute of Agricultural Research (INIA) in Chile. Water stress was applied by suspending irrigation at the beginning of tuberization. Stomatal conductance, tuber and plant fresh and dry weight was used to categorize water stress tolerance. Cardinal had high and Desirée moderate susceptibility to water stress. Mije had moderate and Clon 37 FB high tolerance. Differential gene expression with control and water stress was examined using transcriptome sequencing. Water stress tolerant Clon 37 FB had the largest number of differentially expressed genes and susceptible Cardinial the fewest. The water stress tolerant was associated with up-regulation of abscisic acid (ABA) responsive transcription factor genes and increased expression of genes involved in osmolyte biosynthesis. The results also suggest that increased tolerance for water stress was associated with reduced biotic responses. Heat shock protein genes were differentially expression in all clones except for highly susceptible Cardinal. Together the gene expression study demonstrates variation in the molecular pathways and biological processes in response to water stress contribute to tolerance and susceptibility.