Monosaccharide transporter OsMST6 is activated by transcription factor OsERF120 to enhance chilling tolerance in rice seedlings

Abstract Chilling stress caused by extreme weather is threatening global rice (Oryza sativa L.) production. Identifying components of the signal transduction pathways underlying chilling tolerance in rice would advance molecular breeding. Here, we report that OsMST6, which encodes a monosaccharide transporter, positively regulates the chilling tolerance of rice seedlings. The mst6 mutants showed hypersensitivity to chilling, while the OsMST6 overexpression lines were tolerant. During chilling stress, OsMST6 transported more glucose into cells to modulate sugar and ABA signal pathways. We showed that the transcription factor OsERF120 could bind to the DRE/CRT element of the OsMST6 promoter and activate the expression of OsMST6 to positively regulate chilling tolerance. Genetically, OsERF120 was functionally dependent on OsMST6 when promoting chilling tolerance. In summary, OsERF120 and OsMST6 form a new downstream chilling regulatory pathway in rice in response to chilling stress, providing valuable findings for molecular breeding aimed at achieving global food security.