LbCu/ZnSOD and LbMnSOD involved in drought stress tolerance induced by strigolactones of cut lily

In this study, LbCu/ZnSOD, LbFeSOD, and LbMnSOD genes were cloned, the role of strigolactones (SLs), a novel plant hormone that is ubiquitous in plants in modulating plant responses to abiotic stress, on the three superoxide dismutases (SODs) under polyethylene glycol PEG-6000 stress were researched in the petals of cut lily flowers. The results indicated that during the development of the lily bud, the expression levels of LbMnSOD gradually increased and those of LbCu/ZnSOD decreased, while the LbFeSOD expression remained at a very low level. When the cut lily flowers were subjected to 10% PEG-6000 stress, the relative water content (RWC) declined, the malondialdehyde (MDA) content and relative electrical conductivity (REC) dramatically increased in the petals. However, when exogenous SLs were employed, the RWC were improved, while the MDA and REC were reduced. Meanwhile, the SLs significantly increased the activities of the total SOD (T-SOD), Cu/ZnSOD and MnSOD, the expression levels of LbCu/ZnSOD and LbMnSOD, especially LbCu/ZnSOD, were markedly up-regulated in the petals. In conclusion, our research indicates that SOD enzymes, especially Cu/ZnSOD and MnSOD, are involved in the drought stress tolerance; the application of strigolactones can enhance the activities of the two SODs, and may increase the expression of LbCu/ZnSOD and LbMnSOD via a positive feedback mechanism in the cut lily petals.