Overexpression of the Arabidopsis ceramide synthase gene AtLOH1 enhances plant cold stress tolerance

The Arabidopsis ceramide synthase gene AtLOH1 plays important roles in cell growth and abiotic stress responses. However, we do not know if the AtLOH1 gene play a role in low temperature stress in plant cells. In this investigation, overexpression of the AtLOH1 gene was performed in rice (Oryza sativa L.), cotton (Gossypium hirsutum L.), and white pine (Pinus strobus L.) using Agrobacterium tumefaciens strain GV3101-mediated transformation. Overexpression of the AtLOH1 gene in O. sativa, G. hirsutum, and P. strobus was confirmed by molecular methods including PCR, Southern, and northern blotting analyses. Low temperature stress was examined in O. sativa, G. hirsutum, and P. strobus by analyzing three AtLOH1 transgenic cell lines from each of rice, cotton, and pine. Increasing cell viability and cell growth rate, decreasing lipid peroxidation and ion leakage, as well as elevating the activity of antioxidative enzymes and the content of polyamines, suggest that overexpression of the AtLOH1 gene enhanced low temperature stress tolerance. Overexpression of the AtLOH1 increases expression of polyamines biosynthesis genes in transgenic O. sativa cells and improves survival rate of transgenic P. strobus shoots and plantlets under cold stress. These results indicated that overexpression of the AtLOH1 gene in plant cells enhanced cold stress tolerance by elevating polyamines content, antioxidative enzyme activity, and expression of polyamine biosynthesis genes. Overexpression of the AtLOH1 gene could be a valuable approach for engineering plant cold stress tolerance.