Accessions of Solanum tuberosum ssp. andigena show differences in photosynthetic recovery after drought stress as reflected in gene expression profiles

A drought screen is described that identifies accessions of Solanum tuberosum ssp . andigena that show varying degrees of physiological acclimation or adaptation to repeated drought stress. VTSA01 shows adaptation, recovering photosynthesis after a first cycle and maintaining this ability upon subsequent stress exposure. VTSA03 shows acclimation, recovering photosynthesis only after a second cycle of stress. VTSA02 shows an intermediate phenotype with partial recovery after one cycle and, later, improved recovery. Using statistical methods, we correlated changes in expression, of specific pathways and genes with the adaptive and acclimation-related phenotypes exhibited by the three accessions. These pathways and genes include transcripts in anti-oxidant defense, metallothioneins, flavonoid biosynthesis, and cytochrome P450. Genes involved in chromatin remodeling and transcriptional control of gene expression were also up-regulated. In the latter group, two types of zinc finger transcription factors, and several Myb and bZIP factors stand out, not previously associated with stress responses. Distinct and diverse responses to drought exist and attest to germplasm complexity within these potato land races.