Transcription factor ZmGBF1 enhances heat stress tolerance in maize by directly increasing expression of ZmCXE2 involved in GA pathway

Abstract

Maize is one of the most important food and feed crop and it is more susceptible to heat stress (HS) compared to other plant species. This significantly impedes the growth of plants and reduces productivity. Plants have developed many molecular regulatory mechanisms to perceive, respond, and to adapt the elevated temperatures, with the aim of mitigating the detrimental impacts induced by heat. Understanding the molecular regulatory mechanisms that control HS is crucial to develop climate-resistant crops. In this study, we established transcriptome datasets of five maize inbred lines under normal and HS conditions. By co-expression network analysis we identified multiple transcription factors (TFs), including G-box-binding factor (GBF) ZmGBF1. Our results showed that ZmGBF1 positively regulates maize HS tolerance. The DNA affinity purification sequencing and yeast one-hybrid (Y₁H) assay, along with dual luciferase (Dual-LUC) activity, provided evidence that ZmGBF1 specifically interacts with the promoters of carboxylesterase (ZmCXE2), hence enhancing its transcription. The result illustrated that ZmCXE2 promotes maize HS response. ZmGBF1 and ZmCXE2 exhibited increased expression levels in response to gibberellin (GA) stimulation. In present study we suggested an improved model of the HS response in maize. ZmGBF1 increase maize HS tolerance by enhancing the activity of ZmCXE2. This mechanism helps to maintain a balance between maize growth and environmental stresses.