Gene Cloning And Function Analysis Of Peroxidase During Lettuce Seed Germination

With the establishment of the function of ROS?O_<sup>2?—, ?OH, H₂O₂?, peroxidase?POD? involved in the generating of ROS become a hot issue. Many articles have mentioned that there is a change in POD activity during seed germination or radicle elongation. The function of POD in radicle elongation and endosperm weakening and its role in seed germination is unknown, so this paper mainly pay attention to gene cloning and the function of POD.Changes in the activity of POD in endosperm cap?CAP? and radicle?RAD? were investigated during lettuce?Lactuca sativa L. cv. Guasihong? seed germination with different medium in this study. POD activity in RAD showed the same trend with CAP,increased gradually during germination when seeds imbibed in water. 0.3% Sodium dichloroisocyanurate?SDIC? delayed seed germination, decreased the POD activity of CAP,but show nothing on the activity of POD in RAD. When came to 0.3m M Salicylhydroxamic acid?SHAM?, the POD inhibitor, the activity of POD became extremely low in both of RAD and CAP. But the germination time was advanced. TMB staining showed that POD was localized in whole endosperm and RAD tip.The full-length c DNA of POD cloned and named Ls POD1. Analysis of the transcript abundance of Ls POD1 showed that, the level of Ls POD1 expression is consistent with the level of POD activity in the same part of seed in water and 0.3% SDIC. Whilst, the expression levels of Ls POD1 in both of CAP and RAD were strongly increased with the duration of imbibition.From all the above, we could draw a conclusion that, POD contributes to breaking down cell walls, therefore promoting cell expansion, during seed germination.