The Crosstalk Analysis Between Brassinosteroids And Auxin

Brassinosteroids (BRs) are important growth regulating substances in plant growth and development. In this study, a microarray analysis was performed onBR receptor mutant bri1-5, its enhancer bri-5bak1-1D, and WS2(wild type). The result shows that BR regulates a broad of processes in plant. Interestingly, there is a class of genes changed significantly in bri1-5, but failed to rescue when the BAK1over-express, and thus indicate these genes may not be affected by BAK1. These results may suggest there is a BAK1independent BR signal pathway in arabidopsis. However, a class of genes which include DWF4and BR6OX2show exactly expessed level with the BR signal status. All the10genes in this class could be considered as typical BR feedback genes to evaluate the BR pathway status. Morever, microarray data show that TIR1maybe another key candidate in the crosstalk between BR and auxin. The TIR1up-regulated its expression in bri1-5and bri1-5bak1-1D with same fold. And correspondingly, the2mutants show more sensitive to auxin. Both microarray data and genetic analysis suggest that TIR1up-expression depend on the BR signalling inhibition. In brief, The TIR1is up-regulated and plant show more sensitive to auxin when the BR signal pathway is inhibited. All these data may suggest a compensation mechanism:the plant can increase the auxin signal to compensate the BR inhibition to keep their growth and development.