Changes in gene expression in wild potato (Solanum sogarandinum) during cold acclimation

Abstract

The expression of genes corresponding to twenty eight cDNA clones (Ssci), representing cold induced mRNAs was analyzed by Northern blot hybridization in potato plantlets treated with cold, NaCl, sorbitol, water and ABA. The response of the genes to cold was examined in two genetically related potato species, a freezing tolerant and able to acclimate Solanum sogarandinum and a freezing sensitive cultivated Solanum tuberosum, cv. Cisa. The results of Northern blots revealed that the majority of the cold responsive genes showed similar levels of accumulation of the corresponding transcripts under cold treatment in both potato types. Only genes corresponding to six of the analyzed clones (Ssci1, Ssci12, Ssci16, Ssci17, Ssci18 and Ssci20), encoding S-adenosyl-methionine decarboxylase, a homolog of TAS14 dehydrin, kinase 3-phosphate glycerate, glucosyl transferase, a homolog of CAS15 hydrophylic protein and PSBS protein of PSII, respectively, showed higher levels of the corresponding transcripts during cold treatment in the cold resistant potato as compared with the cold sensitive one. With the exception of the Ssci7 and Ssci12 genes encoding myo-inosytol-1-phosphate synthase and a homolog of dehydrin TAS14, respectively, the transcripts were not induced by ABA, NaCl, sorbitol or water treatments. The expression of most of the clones was not regulated by the day/night cycle, however, accumulation of the transcripts corresponding to the Ssci1, Ssci2 and Ssci20 clones was light dependent. Higher activity of the genes corresponding to the Ssci1, Ssci12, Ssci16, Ssci17, Ssci18 and Ssci20 clones during cold treatment in the freezing tolerant potato correalates positively with the increase in freezing resistance during cold treatment. Potential contribution of these six Ssci genes in the acclimation processes in potato is discussed.