Studies On Gibberellin’s Regulation On Auxin Biosynthesis And Transportation Of Rice Root Tip And Cloning And Preliminary Analysis Of Rice OsRLMG1

Rice is not only an important monocotyledonous plant,but also an important food crop in China.Roots have important functions in uptake of nutrients and water.In addition to the rice plant type,ertility,the length of roots was closely related to rice yields.“Gibberellin influence auxin biosynthesis and polar auxin transport in rice root tips” and “Gene function analysis of root elongation gene in rice” were researched in this study,the main resulsts are as follows:Both gibberellin(GA)and auxin play essential roles in regulating root elongation as two critical signals,and many studies have been showed auxin influence GA biosynthesis and signalling.However,the mechanism which is about that GA affected auxin in root elongation is still unknown.In this study,root growth length and DR5-GUS activity were analyzed in rice seedlings.Paclobutrazol-induced short root phenotypes could be partly reversed by co-treatment with IAA,and the inhibition of root elongation caused by naphthylphthalamic acid could be partially reversed when co-treatment with GA.DR5-GUS activity was increased in the presence of GA and was reduced at the root tip of paclobutrazol-treated seedlings,indicating that GA could regulate local auxin biosynthesis and polar auxin transport(PAT)in the rice root tip.The results of our RNA-seq analysis showed that GA was involved in the regulation of flavonoid biosynthesis.Flavonoid accumulation levels in root tips increased in present of paclobutrazol and was reduced in GA-treated seedlings.GA could rescued the decrease DR5-GUS activity induced by quercetin in rice root tip,confirming that flavonoids act as an intermediary in GA-mediated auxin biosynthesis and PAT.Based on RNA-seq and qPCR approaches,we determined that GA regulates local auxin biosynthesis and polar auxin transport by modulating the expression of OsYUCCA6 and PIN.Our findings provide valuable new insights into the interactions between GA and auxin in the root tips of rice.The second part of the study based on screening for root elongation mutant,and we got short root mutant rlmg1.Folling flanking sequence isolated by nested PCR,we confirmed the cogregation between T-DNA insertion site and short root pheotype of rlmg1.Based on these results,we created transgenetic lines of promoter fusion,overexpression,complement,and crispr-cas9.Promoter fused GUS lines staining resultes showed that GUS expressed in meristem zone,elonagtion zone,and stele in primary root,as well as lateral root,which was consistent with short root phenotype of rlmg1.Moreover,auxin could partly restore lateral root phenotype indicated that OsRLMG1 modulated root elongation by auxin pathway.