| Brassinosteroids(BRs),are a class of steroid hormones that have been recognized as a new kind of phytohormones that play an essential role in plant growth and development.BR signal transduction has been greatly improved through the extensive use of genomics and proteomics in BR field within recently 30 years,multiple key components of BR signaling pathway have been identify and clarified.Now,the function of BR in plant growth and development,especially in root development,has increasingly attracted the attention of scientist.Because of its simple cellular organization,the Arabidopsis root system has proven to be a valuable model for studying the molecular mechanisms of the cell-to-cell communication.The fine-tuned balance between cell elongation and cell division drives the root growth.BRs affect both of these determinants in a dose-dependent manner,hence,promoting this class of hormones as one of the crucial factors for the control of the root meristem size,but its molecular mechanism remains unclear.Here,in this study,we had combined the advantage of plant physiology,genetics,molecular biology and biochemistry to gain a deep insight into the molecular mechanism of BR regulation of the middle cortex development in Arabidopsis root.Our results showed that less MC appeared in BR-deficient or insensitive mutants,whereas more MC appearing in function-gained mutants.SHORT-ROOT(SHR)and SCARECROW(SCR)of the plant-specific GRAS family affect MC formation in all stages.Genetic data showed that bzrl-ID failed to restore the root phenotype of shr-2,indicating BZR1 function was limited due to the absence of SHR.We further demonstrated that BZR1 interacted with SHR in vitro and in vivo.We thus concluded that BZR1-SHR complex regulates the expression of MGP and NUC and eventually regulates root pattern.Our research expands understanding of BR’s function in root development and we provide theoretical guidance and genetic resources to use phytohormones to cultivate ideal root types. |
PDF Full Text Request