The Molecular Mechanism Of AP2/ERF Transcription Factor ERF114 In Salt Stress-inhibited Lateral Root Development In Arabidopsis Thaliana

Salt stress leads to serious soil salinization,which further restricts soil utilization,plant growth and development,reduces crop yield,and has gradually become a limiting factor for the development of agriculture.The adverse effects of salt stress on plants are due to the decrease of water availability caused by the accumulation of sodium ions in soil and the toxic effects of sodium and chloride ions on plants.Over the past decade,great advances have been made in understanding the mechanisms of salt stress response and salt tolerance in plants.However,it is still the most important task for us to explore the mechanism of plant salt tolerance and find more salt-tolerant plants.Lateral roots are a major determinant of the root system architecture in plants,and the plasticity of the lateral root development is essential for the survival of plants under stress conditions.Studies have shown that root endodermis is a key location for salt stress to regulate lateral root development.ABA prevents lateral roots from extending into the surrounding high-salt media.Studies have shown that plants try to bypass high-salt media by reorienting their roots,most likely due to salt-triggered auxin reactions.Auxin synthesis,transport and local response can coordinate the specific growth response of root tissues to salt.However,the mechanism of salt stress regulating lateral root development is still unclear.Therefore,it is of great significance to identify the regulatory factors in response to salt stress to further clarify the effects of salt stress on lateral root and plant growth and development.Arabidopsis AP2/ERF transcription factor ERF 114 rapidly responds to ROS.Using genetics,cytology,bioinformatics and biochemistry methods,we explored the mechanism of lateral root development under salt stress.1.ERF114 was activated by salt stress,which is partly dependent on ROS.The salt tolerance of 35S::ERF114 was significantly decreased,while the salt tolerance of 35S::ERF114-SRDX lines was significantly increased.2.In order to verify the role of ERF114 in salt stress,we analyzed the lateral root phenotypes of ERF 114 overexpression and mutant lines before and after salt treatment.35S::ERF114 has a reduced number of lateral root,whereas 35S::ERF114-SRDX has an increased number of lateral roots compared to the wild type.Previous reports have shown that salt stress can inhibit the production of lateral roots.We found that 35S::ERF114-SRDX plant can alleviate the inhibition of salt stress on the production of lateral roots,suggesting that salt stress inhibition on the production of lateral roots is partly dependent on ERF 114.3.To clarify the mechanism that ERF114 inhibits lateral root development under salt stress,we analyzed the key regulators involved in lateral root development under salt stress conditions.The results showed that arf7,arf7/19 and slr mutants were sensitive to salt,implying that ARF7 might be associated with ERF114.Expression analysis showed that ERF114 negatively regulates ARF7 transcription.4.To clarify the role of ERF 114 in lateral root development under salt conditions,we analyzed the salt-tolerant phenotype of QQS,an important element controlling C/N conversion.The results showed that QQS overexpressed lines showed salt tolerance and QQS RNAi was sensitive to salt.Next,through the detection of starch content,it was found that salt stress could promote the accumulation of starch,and inhibit the generation of lateral roots.Expression analysis showed that ERF114 negatively regulated the expression of QQS.5.Through ChIP and protoplast experiments,we founded that ERF114 could directly bind the promoters of ARF7 and QQS.In order to verify the regulatory effect of ERF114 on ARF7 and QQS,We constructed 35S::ERF114 hybrid plants with 35S::ARF7 and 35S::QQS.Phenotypic analysis showed that overexpression of ARF7 and QQS could partially restore 35S::ERF114 salt sensitivity and lateral root reduction phenotype,suggesting that ARF7 and QQS act downstream of ERF114 to involve in the development of lateral roots.In this study,we found two signaling pathways involved in salt induced ERF114 regulation of lateral root development.On the one hand,ERF114 regulates lateral roots by directly regulating ARF7 and inhibiting auxin signaling pathway;On the other hand,ERF114 regulates starch accumulation by directly regulating QQS,which is an important regulator of C/N conversion.It was also found that ERF114 not only directly regulates QQS,but also indirectly regulates starch metabolism and lateral root development by regulating ARF7.Furthermore,it was revealed that ERF114 was involved in the inhibition of lateral roots under salt stress by regulating auxin signaling pathway and starch metabolism.