Calcium Distribution in Developing Anther Cells of No-pollen Type CMS and Maintainer Lines of Rice(Oryza sativa L.)

Ca²⁺ is a well-known "second messenger" in higher plants and is related to their sexual reproduction.To test the effects of calcium localization on pollen abortion in developing rice anthers,calcium distribution during anther development in no-pollen type cytoplasmic male sterile(CMS) rice G37A and its maintainer line G37B at different stages was examined by potassium antimonate precipitation method.Our study showed that many differences existed in Ca²⁺ distribution in developing anthers between the two studied rice lines.In the fertile anthers of G37B,few Ca²⁺ precipitates were detected at the pollen mother cell stage and the dyad stage.However,Ca²⁺ precipitates dramatically increased in the tapetal cells,on the exine of pollen grains and the surface of Ubisch Bodies at the uninucleate pollen stage.After this,Ca²⁺ precipitates decreased on the anther wall,although many Ca²⁺ precipitates still existed on the exine of pollen grains.In the sterile anthers of G37A,abundant Ca²⁺ precipitates accumulated in the microsporocyte,on the anther wall and especially in the middle layer,the tapetum and the ubisch bodies located at the pollen mother cell stage and the dyad stage.After the tetrad stage,Ca²⁺ precipitates in sterile anthers of G37A decreased generally,and could not be detected at the inner longitudinal plasma membrane of the tapetum.The results proposed that redundant calcium precipitates in sterile anthers may be related with pollen abortion.