Investigations On The Mechanisms For Root Architecture Regulated By RAM1in Arabidospsis

In order to absorb and utilize nutrients from the soil, the plasticity of plant roots could run up to a highlevel. Our research about the high plasticity of plant roots is very important for improving the efficiency ofplants utilize nutrients.The abnormal root architecture mutants in this experiment are provided by my research group, we gotthis mutant via mutating Col-0seedings by0.3%EMS, and the mutant has shorter primary root, morelateral roots, higher root hair length and density than WT, as we research on Arabidopsis root architecture,then the mutant we discussed was named ram1（root architecture mutant1）. We have found the mutationalgene is AT4G37650by map-based cloning. It has been reported that mutants of this gene has short root,dark cotyledon color, and named the gene as SHR（SHORT-ROOT）.ABA was the condition in our screen process, so we observed phenotypes about ram1and WT with5μM ABA treatment firstly, then we discovered that lateral root number of ram1decreased closing to WTafter5μM ABA treatment. RT-PCR also demonstrated that ABA is involved in the process of regulationabout root architecture by RAM1. The level of H₂O₂was higher in ram1, and H₂O₂could inhibit growth ofprimary root, promote lateral root development, so the high content of H₂O₂in ram1may be the reason ofits shorter primary root and more lateral root number. Treatment with exogenous1.5mM H₂O₂, the lateralroot number of ram1was decreased compared to WT, demonstrated that H₂O₂is involved in the processthat the regulation of lateral root development by RAM1. Exogenous MV could promote primary rootlength of ram1, and has no influence on lateral root number, proved that high content of H₂O₂inchloroplast of ram1involved in the regulation of primary root development, but didn’t involve in theprocess of lateral root development.We observed two lines of ram1/RAM1, these two transgene lines both recovered phenotypes of ram1,testified that changes of root architecture in ram1were caused by the dot mutation of RAM1. Subsequently,we observed phenotypes about ram1, two lines of ram1/RAM1and WT with auxin and its polar-transportinhibitor, lateral root density and primary root length of ram1also decreased closing to WT, so wespeculated that the way of RAM1regulated auxin polar transport was changed in ram1, then leads to a series of different phenotypes.Literatures offered many evidences that RAM1could involve in the regulation process of rootmorphogenesis. For the moment, RAM1is not only the direct regulation factors that take part in radialpatterning, but also participate in maintaining activity of root apical meristem, at the same time RAM1alsoas a short signal to regulate root morphogenesis. As regulation network of root is complicated, specificsignal pathway is not clear right now. we have seen many reports about RAM1, but our research about ram1could enrich functions of RAM1, and enrich the research about regulation network of root morphogenesis.