Coordination between bZIP28 and HSFA2 in the regulation of heat response signals in Arabidopsis.

Heat stress can have detrimental effects on yield production worldwide. Although bZIP28 and HSFA2 were identified as putative heat sensors in plants, coordination between them has not been uncovered. In this study, the deficiency in bZIP28 did not affect heat tolerance in plants. However, the plants lacking bZIP28 showed enhanced activation of APXs-, MBF1c-and HSPs-dependent pathways as well as higher level of HsfA2 transcripts and HO accumulation, suggesting that these pathways might compensate for the deficiency in bZIP28 during heat stress. In addition, requirement of HSFA2 for the activation of APXs-dependent pathway during heat stress was supported by the analyses of plants lacking HSFA2. Our study demonstrated the flexible mode of heat response pathways involving bZIP28, HSFA2 and ROS-dependent signals.