Aldehyde dehydrogenase plays crucial roles in response to lower temperature stress in Solanum tuberosum and Nicotiana benthamiana

•Intragenic DNA methylation of StALDH2B7a is modulated by cold stress in potato.•StALDH2B7a expression is correlated to intragenic DNA methylation status.•NbALDH2C4, StALDH2B7a’s homolog, scavenges toxic MDA originated from ROS. The aim of this study is to elucidate the role of ALDH2B7a during the response to lower temperature in Solanum tuberosum. This gene was found to have altered intragenic DNA methylation status in our previous reports. A total of 18 orthologs of StALDH2B7a were identified in the S. tuberosum genome, which were then divided into 8 aldehyde dehydrogenase (ALDH) subfamilies. The methylation statuses of four intragenic cytosine sites in intron 5 and exon 6 of genomic StALDH2B7a were altered by lower temperature stress, resulting in changes in the expression of StALDH2B7a. Silencing of NbALDH2C4, a homolog of StALDH2B7a in Nicotiana benthamiana, resulted in plants which were sensitive to lower temperature and accumulation of reactive oxygen species (ROS) and malondialdehyde (MDA). These data suggested that the expression of StALDH2B7a was upregulated by alteration of its intragenic cytosine methylation status during lower temperature stress, and additional StALDH2B7a enzymes scavenged excess aldehydes resulting from ROS in a response to cold stress in potato. Our study expands the understanding of the mechanisms involved in plant responses to lower temperature, and provides a new gene source to improve potato tolerance to cold stress in northern China, where lower temperature is one of the key limiting factors for crop production.