The Role Of ERF In Extracellular ATP-regulated Root Growth Of Arabidopsis Thaliana

Root is in charge of plant nutrients absorption and growth&developmentregulation. The regulatory mechanism of root development is an important topic inplant biology. Extracellular ATP (eATP) is an apoplast messenger in plant cell, andplays an essential role in plant growth and development. Ethylene responsive factors(ERF) are transcription factors which are involved in plant development and stressadaptation. Here, to clarify the signal transduction of eATP, lost-of-function mutantsof ethylene responsive factor ERFy (erfy), ethylene receptor ETR1(etr1) and keycomponent of ethylene signal transduction pathway EIN2(ein2) and their wild type(col-0ecotype) were used as material, the role of these signal transducing moleculesin eATP-regulated root growth was investigated.Firstly, added ATP was found to effectively stimulate gene expression of ERFy inroot of wild-type seedlings. While in root of ethylene-related mutants, eATP-inducedgene expression was significantly supressed, indicating that these signal transductioncomponents may be involved in eATP regulated ERF gene expression.Then, results from physiological experiments showed that ATP remarkablyinhibited main root elongation growth in a close-dependent manner in wild-type ofArabidopis. In ERFy gene null mutant (erfy), eATP only slightly affected root growth.The ERFy mutant was unable to respond to eATP stimulation, indicating that ERFymay be a key signal transduction component in eATP-regulated root growth.After that, ethylene biosynthesis inhibitor AOA was found to block eATP-regulated root growth. Meanwhile, eATP-inhibited root growth was also impaired innull mutant of ETR1and EIN2. These results indicate that ethylene biosynthesis andits signal transduction components possibly participate eATP signalling in root cellsof Arabidopsis thaliana.Based on these results, we suggest that eATP may stimulated ethylenebiosynthesis, then induced gene expression of ERFy partially through ethylene signaltransduction pathway, and finally inhibit root growth of Arabidopsis seedlings.