The SOD gene family in potato and effects of elevated temperature and salicylic acid on gene expression

Abstract

Potato, Solanum tuberosum L., is the world's most important non-grain food crop, which is highly heat-susceptible. Even moderately elevated temperatures have a significant impact on potato growth and tuberization, limiting productivity. High-temperature stress is accompanied by secondary oxidative stress due to elevation of reactive oxygen species (ROS) levels. Superoxide dismutases (SODs) are metalloenzymes that play an important role of primary ROS scavengers. So far, the SOD gene family was not systematically described in potato, and the data regarding the expression of potato SOD genes under elevated temperature are scarce. We performed an in silico study of potato SODs and analyzed the transcriptional expression in response to moderately elevated (26 °C) and high (29 °C) temperature. The potato genome contains seven SOD genes, including three Cu/ZnSODs, one MnSOD and three FeSODs, unevenly distributed on five chromosomes. Phylogenetic analysis revealed that potato SOD protein sequences share the most similarity to S. lycopersicum SODs and can be separated into two groups: Cu/ZnSOD and FeSOD-MnSOD. Cis-elements related to different signals, including high temperature, plant hormones, and light, were found in promoters of potato SOD genes. Gene expression analysis at different temperature treatments revealed heat-responsive SOD genes. Salicylic acid (SA) is a plant growth regulator and signaling molecule involved in plants' defense responses to abiotic stresses. Application of SA promoted expression of most SODs, especially at moderately elevated (26 °C) temperature. The results of our study revealed heat-inducible SOD genes that might be important for potato antioxidant defense under heat stress.