BoPRR9, a pseudo-response regulator protein from cabbage, plays a negative regulatory role in the response to cold stress

Abstract

Cold stress can adversely affect the growth, development, and yield of plants. Exploring the cabbage cold-stress-related genes and their regulatory mechanisms is crucial for cultivating high-quality varieties of cabbage. The PSEUDO RESPONSE REGULATOR (PRR) factor plays an important role in plant response to abiotic stress. However, cabbage BoPRRs in cold tolerance are rarely reported. In this study, the PRR family gene BoPRR9 was isolated from cabbage (Brassica oleracea var. capitata L) and functionally characterized in transgenic Arabidopsis and cabbage in cold stress response. BoPRR9 encodes a protein located in the nucleus. The gene was strongly induced by cold treatment, and the transcription level of BoPRR9 was up regulated under cold stress. Under cold stress, overexpression of BoPRR9 resulted in enhanced cold sensitivity in transgenic Arabidopsis and cabbage, lower antioxidant enzyme activity and maximum photosynthetic efficiency of photosystem II(Fv/Fm), and higher relative electrolyte leakage (REL) and malondialdehyde (MDA) content. Meanwhile, the ability of the transgenic plants to remove reactive oxygen species (ROS) was significantly reduced. Additionally, the expression levels of cold-related genes were downregulated in BoPRR9-overexpressing plants. The results showed that the BoPRR9 gene negatively regulates cold stress, which provides clues for further understanding of the molecular mechanism of PRR-mediated cold stress response.