Abstract

Rubber tree ( Hevea brasiliensis ) is an economically important tropical tree species that produces natural rubber (cis-1,4-polyisoprene). Climate change leads to an increasing frequency of drought, posing significant challenges to natural rubber production. Superoxide dismutase (SOD) is a crucial enzyme that plays a vital role in the response to abiotic stresses in plants, but its function in the rubber tree is still unclear. In this study, we identified an iron SOD gene ( HbFSD1 ) from the rubber tree. Subcellular localization analysis indicated that the HbFSD1 protein localizes in the chloroplasts. Overexpression of the HbFSD1 gene enhanced drought tolerance in transgenic Arabidopsis thaliana by increasing the activities of SOD, catalase (CAT), and peroxidase (POD), while reducing the accumulation of reactive oxygen species (ROS). In addition, a GUS staining assay showed that drought stress could promote the expression of the GUS gene by driving the HbFSD1 promoter. Through yeast one-hybrid (Y1H) screening, a basic leucine zipper transcription factor ( HbbZIP37 ) was identified as interacting with HbFSD1 , and their interaction was further confirmed by a Y1H assay and dual-luciferase reporter assay. These findings highlight a synergistic mechanism by which the HbbZIP37 transcription factor binds to the promoter region of HbFSD1 , thereby activating its expression and enhancing ROS scavenging capacity, ultimately improving drought tolerance. Our findings provide valuable information on the molecular mechanisms underlying HbFSD1 -mediated drought tolerance, while also providing a potential target gene for improving drought tolerance in rubber trees through transgenic strategies.