Functional Characterization of Gene Involved in Cold Tolerance in Tobacco through Alleviation of ROS Damage to the Plasma Membrane.

Cold stress is a key environmental factor affecting plant growth and development, crop productivity, and geographic distribution. Thioredoxins (Trxs) are small proteins that are ubiquitously expressed in all organisms and implicated in several cellular processes, including redox reactions. However, their role in the regulation of cold stress in the halophyte plant remains unknown. We recently showed that overexpression of , which is the gene that encodes the h-type Trx protein previously isolated from , led to an enhanced tolerance to salt and osmotic stress in transgenic tobacco. This study functionally characterized the gene via its overexpression in tobacco and explored its cold tolerance mechanisms. Results of the RT-qPCR and western blot analyses indicated differential temporal and spatial regulation of in under cold stress at 4 °C. overexpression enhanced the cold tolerance of transgenic tobacco, as evidenced by increased germination rate, fresh weight and catalase (CAT), superoxide dismutase (SOD) and peroxidase (POD) activities; reduced malondialdehyde levels, membrane leakage, superoxide anion (O), and hydrogen peroxide (HO) levels; and higher retention of chlorophyll than in non-transgenic plants (NT). Furthermore, the transcript levels of reactive oxygen species (ROS)-related genes ( and ), stress-responsive late embryogenis abundant protein 5 (), early response to dehydration 10C (), DRE-binding proteins 1A (), and cold-responsive () genes (, , and ) were upregulated in transgenic lines compared with those in NT plants under cold stress, indicating that conferred cold stress tolerance by enhancing the ROS scavenging ability of plants, thus enabling them to maintain membrane integrity. These results suggest that promotes cold tolerance in tobacco and provide new insight into the improvement of cold-stress resistance to cold stress in non-halophyte plants and crops.