Roles of AtMAPR2 in brassinosteroid-mediated development of Arabidopsis
Date Issued
2014
Date
2014
Author(s)
Yu, Liang-Gui
Abstract
Arabidopsis thaliana membrane-associated progesterone receptors (AtMAPRs) share the conserved putative cytochrome b5-like heme/steroid-binding pockets. Among the four members, AtMAPR2 which locates on the second chromosome is the only member without a predicted transmembrane domain. We found that application of micromolar level concentration of BR would suppress the expression of AtMAPR2 under normal photoperiod. Furthermore, the gene silencing mutant of AtMAPR2 seemed insensitive to treatment of BR. In this thesis, a few evidences that linked AtMAPR2’s physiological roles to BR and plant’s responses to light were observed. First, transgenic plant of Arabidopsis that overexpress AtMAPR2 (AtMAPR2-OX) showed an increased elongation in hypocotyls and primary roots in response to treatment of nanomolar level concentration of BR in light. On the contrary, the antisense transgenic plant AtMAPR2-RNAi appeared insensitive to these BR-mediated responses. Furthermore, these differences were not observed when these mutants were grown in dark. Second, AtMAPR2-OX showed an early flowering phenotype and possessed an elongated primary shoot, while the AtMAPR2-RNAi showed late flowering and shorter primary shoot. These results suggested that AtMAPR2 might play a positive role in BR-mediated responses. The protein levels of AtMAPR2 in wild type under BR treatments were monitored using western blot. AtMAPR2 accumulated in the BR-treated Arabidopsis seedlings under light but not under dark, suggesting that illumination might affect the stability of AtMAPR2 via post-translational regulation.
Subjects
阿拉伯芥
油菜固醇
黃體素
光週期
Type
thesis
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