Abstract: In this study,different stages of anthers of Nicotiana tabacum L.were detailed investigated.With the aid of DAPI(4’,6-diamidino-2-phenylindole)staining,the process of pollen development was observed,and the relationship between the anther developmental stages and the length of flowers were determined.The distribution of Indole-3-acetic acid(IAA)during anther and pollen development was studied with auxin IAA monoantibody,immunohistochemistry techniques and GUS activity assay of DR5∶∶GUS transgenic plants.The results of immunoenzyme localization displayed that IAA level differed evidently in different stages of anther and pollen development.In microspore mother cell stage,strong IAA signal was detected in the whole anther,and condensed in the nucleus of late stage of microspore mother cells.With the formation of tetrad through meiosis,the signal of IAA was gradually reduced,and almost disappeared in late stage of tetrad.In the stage of mono-nucleate pollens,IAA signal was decreased further,and was merely present in anther wall.With the further development of microspores,strong IAA signal was present in mature dual-nucleate pollens and the whole anther wall.GUS activity assay showed that the GUS signal of anthers and pollens in DR5∶∶GUS transgenic plants were basically in accordance with IAA immunoenzyme localization.Overall,the accumulation of free auxin IAA during anther and pollen development of tobacco presented a pattern from high level to low level and then to high level again,suggesting that IAA may play functional and essential roles in anther and pollen development of angiosperm.