Figure 7.

Model of TIP4;3‐mediated cold tolerance in maize. Under cold stress conditions, TIP4;3, a tonoplast aquaporin, suppresses stomatal closure and facilitates reactive oxygen species (ROS) accumulation, as well as downregulates the expression of cold‐responsive genes, thereby negatively regulating maize cold tolerance. Hap2 maize inbred lines harbour a 328‐bp transposon insertion in the TIP4;3 ^Hap2 promoter. This insertion increases the level of histone modifications H3K9me2 and H3K27me3, contributing to the repression of TIP4;3 expression. Thus, TIP4;3 ^Hap2 inbred lines show lower TIP4;3 expression and better cold tolerance than TIP4;3 ^Hap1 inbred lines.