Effect Of In Vitro Application Of Ethylene On Stamen Development In Arabidopsis

As a gaseous plant hormone,ethylene plays an important role during plant development and is used widely in agriculture.At present,the signal transduction pathway from ethylene perception on the endoplasmic reticulum membrane to transcriptional regulation in the nucleus has been established in Arabidopsis.It has been reported that ethylene plays critical roles on programmed cell death,environmental stress response and unisexual flower sex determination.However,the exact mechanisms and the roles of ethylene in sex determination during flower development remained unclear.In order to clarify the detailed function of ethylene during this process,we firstly performed the exogenous ethylene treatment on Arabidopsis.Through phenotypic observation,semi-thin section and Alexander's staining,we found that the exogenous ethylene treatment inhibited filaments elongation and influenced the normal stamen development After the treatment of ethylene,the tapetum cells and microspores degenerated at anther development stages6-11.However,we found that these abnormal phenotypes in WT almost disappeared in ein3 and ein3 eil1 mutant after ethylene treatment,this results indicated that the effect of ethylene on plants anther development was dependent on the generally accepted ethylene signaling transduction pathway in Arabidopsis.Consistent with this results,the in situ hybridization experiment revealed that EIN3 was highly expressed in tapetum,microspore mother cells and microspores at anther stages 6-8 and reached its expression peak in anther at stages 7.At the same time,we discovered that in the absence of ETR1 and ERS1,two key ethylene receptors,the tapetum cells started to degenerate from anther stage 7 and consequently the majority of pollens aborted in the etr1-7 ers1-2 double mutants.These results implied that the ethylene and the related signaling pathway should be precisely regulated during Arabidopsis anther development.Lastly,transcripts analysis revealed that the expression level of the genes required for tapetum development,filaments elongation and encoding some nuclease were obviously changed after the treatment of ethylene.The ChIP and EMSA assay confirmed that EIN3 could directly bind to the promoter of TDF1,which played essential roles during tapetum development.We thus concluded that ethylene might accurately control the development of stamens by influencing the expression of several group of genes directly or indirectly via EIN3.