Overexpression of SlMYB1R1 improves chilling stress tolerance in tomato

Low temperatures can affect plant growth and geographical distribution. This study identified an MYB transcription factor, which is a positive regulator of chilling tolerance in tomato (Solanum lycopersicum), designated SlMYB1R1. The germination vigor and radicle lengths of overexpression SlMYB1R1 (SlMYB1R1OE) lines were significantly higher than those of the wild-type (Micro-Tom; MT) lines during germination. The leaf angle and leaf length of SlMYB1R1OE plants were significantly greater than those of MT plants. Furthermore, the expression of SlMYB1R1 was induced by cold stress. The degree of wilting was lower in SlMYB1R1OE plants than in MT plants under chilling stress. Overexpression of SlMYB1R1 in tomatoes resulted in low relative electrolyte leakage, malondialdehyde content, and reactive oxygen levels. The activities of peroxidase and catalase in SlMYB1R1OE plants were higher than those in MT plants after chilling stress. During cold stress, the transcriptional levels of the four cold-related genes were higher in SlMYB1R1OE lines than in MT plants. These results show that SlMYB1R1 plays key roles in tolerance to chilling stress in tomato.