Reduced Expression of the Arabidopsis minE Gene Affects Size and Number of Chloroplasts.

Arabidopsis thaliana possesses 5 eubacteria-derived and nuclear-encoded genes, AtFtsZ1-1, AtFtsZ2-1, AtFtsZ2-2, AtMinD1, and AtMinE1, which are involved in chloroplast division. AtMinE1 is a homologue of the eubacterial septum site-determining factor minE. It has been demonstrated that the overexpression of AtMinE1 in Arabidopsis leads to the disruption of chloroplast division. To further confirm the role of AtMinE1 in chloroplast division, we newly constructed antisensetransgenic Arabidopsis plants with 3 to 4 fold reduced AtMinE1 expression. Chloroplasts of these lines were reduced in number, but individually enlarged, which indicates retarded chloroplast division. The results of this study demonstrate the requirement for a proper level of AtMinE1 expression, for normal control of chloroplast division.