A maize heat shock factor ZmHsf11 negatively regulates heat stress tolerance in transgenic plants

Heat shock transcription factors (Hsfs) are highly conserved among eukaryote and always play vital role in plant stress responses. Whereas, function and mechanism of Hsfs in maize are limited.

In this study, an HSF gene ZmHsf11, a member of class B Hsfs, was cloned from maize, and it was up-regulated under heat treatment. ZmHsf11 was a nuclear protein with no transcriptional autoactivation activity in yeast. Overexpression of ZmHsf11 gene in Arabidopsis and rice significantly reduced the survival rate under heat shock treatment and decreased ABA sensitivity of transgenic plants. Under heat stress, transgenic rice accumulated more H₂O₂, increased cell death, and decreased proline content compared with wild type. In addition, RT-qPCR analysis revealed that ZmHsf11 negatively regulated some oxidative stress-related genes APX2, DREB2A, HsfA2e, NTL3, GR and HSP17 under heat stress treatment.

Our results indicate that ZmHsf11 decreases plant tolerance to heat stress by negatively regulating the expression of oxidative stress-related genes, increasing ROS levels and decreasing proline content. It is a negative regulator involved in high temperature stress response.