The Function Of ZmBSK1 In BR-induced Antioxidant Defense

Brassinolide as a multi-hydroxyation of steroid hormone widely found in fungi, animals and plants, and implicated in the plant response to environmental stresses-Mounting evidences shows that BRs enhance the plant stress tolerance by increasing the antioxidant defense level. Many components of the BR signaling pathway have been identified and studied in detail. However, BSK1 as the receptor-like kinases(RLKs) of BR signaling pathway remains unkown.BSK1 is how to be involved in antioxidant defense, and play what role in the process. In this report, the role of BR-signaling kinase 1(BSK1) in the BR-induced antioxidant defense was studied using maize(Zea maize, L) Nongda 108 as material.To investigate subcellular location of ZmBSK1, we inserted the ORF of ZmBSK1 into pXZP008. On one hand we transformed the construct (35S-ZmBSK1-YFP) into maize protoplasts, on the other hand we incorporated BSK1-YFP into onion (Allium cepa L.)epidermis by particle bombardment. Images of BSK1-YFP fusion were then captured with the confocal laser scanning microscope.We initially identified that BSK1-YFP was located to cytomembrane.To investigate the role of BSK1 in BR induced antioxidant denfense in maize protoplast. Treatment with BR can induce the gene expression of ZmBSKl. We inserted ZmBSK1’s ORF into the sites of pXZP008 vector. The construct (35S-ZmBSK1-YFP) was then transformed into maize protoplasts by PEG method. We found that, sixteen hours later, the total activities of ascorbate peroxidase (APX) and superoxide dismutase (SOD) largely increased; BR can significantly improve the activity of antioxidant protective enzymes SOD and APX; The over-expression by BR treated handle its enzymatic activity higher than the overexpression slightly. To investigate further, we also have established a maize seedling protoplasts system designed for the rapid characterization of large numbers of genes by transient double-stranded RNA interference (RNAi) which used for the analysis of the relationship between ZmBSKl and BR-induced antioxidant defense. The protoplasts were transfected with an in vitro-synthesized dsRNA against ZmBSK1, and treated with BR after 24 hours’culture. The results showed that, When ZmBSK1 was silenced, The total activities of SOD and APX reduced about 60% which restored little by BR treatment. These show that ZmBSKl really involved in BR-induced antioxidant defense response.This chapter investigated the role of ZmBSK1 gene induce the production of H2O2 in maize protoplasts. H2O2 significantly increased the expressions of ZmBSK1 gene; BR significantly increased the expressions of RBOH gene family, and expression levels of RBOH processing 10min are higher than 5min, Interference of ZmBSK1 makes the expression of RBOH significantly decreased, and it increased slightly after BR treatment. Overexpression of ZmBSK1 induce the expression of RBOH,and the expression of RBOH will rise higher by BR treat the overexpression of ZmBSK1;production of H2O2 in protoplast raised by BR treatment. Interference the BSK1,the production of H2O2 decreased and increased slightly by BR treatment. These results suggest that BSK1 is involved in the BR-induced the production of H2O2 in maize protoplast.These results suggests that BSK1 was located to cytomembrane. BSK1 is involved in brassinoteroid induced antioxidant defense and BSK1 is involved in the BR-induced the production of H2O2 in maize protoplast.