| Auxin response factor(ARF)is a transcription factor that plays a key role in the regulation of plant growth and development.Several studies of auxin response factors have been reported in both dicotyledonous and monocotyledonous,such as Arabidopsis and rice.However,the mechanisms of ARF participated in low phosphate(LP)-modulated rice growth remain need further study.In this study,two homozygous T-DNA insertion mutant lines(arf18-1 and arf18-2),overexpression of OsARF18 and Pro ARF18::GUS lines were used.By analyzing the amino acid sequence of OsARF18,the root morphology,tissue expression pattern and subcellular localization,P uptake and the expression of P transporter gene to explore the molecular mechanism of OsARF18 in response to P supply.The results are as follows:1.The amino acid sequence analysis showed that OsARF18 was a classical auxin response factor containing B3 DNA binding domain and Auxin_resp conserved domain.The evolutionary tree analysis showed that the similarity between OsARF18 and Os ARF22 was high.2.The OsARF18 protein was located in the nucleus.The results of transient transfection of tobacco showed that the green fluorescence signal of 35S::OsARF18-GFP vector only appeared in the nucleus,demonstrating that the OsARF18 was nucleoprotein.3.OsARF18 was widely expressed in rice tissues and organs.The expression pattern of OsARF18 was analyzed by q RT-PCR,and via GUS driven by its promoter.The results showed that OsARF18 was expressed in different degrees in root,spikelet,leaf,leaf sheath,floral organ,pistil and anther.4.OsARF18 inhibited the elongation of primary root,and affected the plant height of rice.5.The transcription levels of OsARF18 was induced by auxin and LP conditions.And OsARF18 was involved in LP-modulated root elongation and development,with the involvement of auxin response.6.Mutation of OsARF18 positively modulated P absorption and transport by upreglating the expression levels of high affinity phosphate transporter under both normal P and LP conditions.In conclusion,the expression levels of OsARF18 was upregulated by auxin and LP supplies.OsARF18 was involved in LP-modulated root growth and development in rice.OsARF18 negatively modulated P absorption by affecting the transcription levels of high affinity phosphate transporter. |
