Study on brassinosteroid-mediated regulation of stem cell regeneration in roots

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I have experimentally tested the effects of brassinosteriod (brassinolide) application and the effects of inhibiting brassinosteroid biosynthesis (by brassinozole treatment) on DNA damage induced stem cell death and the replenishing cell division afterwards. The results showed that brassinosteroid plays a positive role both in promoting DNA damage-induced stem cell death and the replenishing cell division afterwards.I have examined the regeneration capacity of transgenic plants in which the feedback activation on BRL3 expression is defective. Quantification analysis revealed that the feedback defective lines showed less replenishing cell division than brl3 mutant but not comparable to the wildtype, indicating that the feedback effect BRL3 contributes to activate replenishing cell division.Using translational fusion of fluorescent proteins, I have examined the expression pattern of BRL3 in the root tip during genotoxic stress exposure (before and after stem cell death) and during the afterward stem cell regeneration phase. The result revealed a positive correlation between the expression level of BRL3 and the activation of replenishing cell division. At the time point prior to the activation of replenishing cell division, the expression level of the mutant version of BRL3, on which the feedback activation is defective, was significantly lower than that of the wild type BRL3.