Intragenic cytosine methylation modification regulates the response of SUCLα1 to lower temperature in Solanaceae

The tricarboxylic acid cycle (TCAC) is a fundamental metabolic process governing matter and energy in plant cells, playing an indispensable role. However, its involvement in responding to low temperature stress in potato remains poorly understood. Previous studies have identified succinyl-CoA ligase (SUCL), which catalyzes the phosphorylation of TCAC substrates, as a gene associated with lower temperatures. Nevertheless, its function in potato's response to lower temperatures remains unclear. Phylogenetic analysis has revealed that Solanum tuberosum possesses α and β subunits of SUCL, which cluster with those of Solanum lycopersicum, Nicotiana tabacum and Nicotiana benthamiana. Further investigation has shown that StSUCLα1 is predominantly located within mitochondria. Low temperatures induce methylation modification alterations at 11 intragenic cytosine sites and lead to changes in StSUCLα1 expression levels. Correlation analysis suggests that alterations in intragenic cytosine methylation sites of SUCLα1 may be associated with MET1. Knocking down NbSUCLα1, the homologous gene of StSUCLα1 in N. benthamiana, results in increased susceptibility to low temperature stress in plants. In summary, we have confirmed that SUCLα1 is a key gene modulated by intragenic cytosine methylation in response to lower temperatures, providing a novel target for genetic breeding aimed at enhancing potato tolerance to low temperature stress.