An analysis of the response of the plastid division genes to the internal and external environments

在细胞分裂过程中，质体的复制和分配对细胞的功能至关重要。然而，质体分裂似乎对植物发育影响不大，因为大多数影响叶绿体数量的突变体生长正常。拟南芥（Arabidopsis thaliana）的皱叶（crl）是在质体分裂和植物发育中表现出严重异常的例外之一。结果表明，拟南芥质体分裂突变ftsZ1-1增强了这些异常。这些结果表明，抑制质体分裂是导致crl形态异常的原因之一。我们的结果还表明，crl不是FtsZ环形成所必需的，因为FtsZ1-1: GFP在crl中定位于质体赤道。我们发现crl突变体在成熟胚胎的子叶中含有缺乏可检测到的质体的细胞。这样的细胞可能是由于质体不均匀地分配给每个子细胞而产生的，因为在胚胎中存在分裂细胞，其中质体被分配给其中一个子细胞。拟南芥的另一种质体分裂突变体——叶绿体6 （arc6）在积累和复制过程中缺乏可检测质体的细胞，而该突变体在植物形态上没有明显缺陷，这表明产生不可检测质体的细胞是导致叶绿体发育异常的原因之一。

It is essential for cell functionality that plastids are replicated and allocated to each daughter cell during cell division. However, plastid division seems to have little effect on plant development because most mutants that affect chloroplast numbers grow normally. The crumpled leaf (crl) of Arabidopsis thaliana is one of the exceptions that display severe abnormalities in plastid division and plant development. Our results indicated that ftsZ1-1, a plastid division mutation of A. thaliana enhanced all of the abnormality in crl. These results suggested that inhibition of plastid division is one of the causes of morphological abnormalities in crl Our results also indicated that CRL is not required for the formation of FtsZ ring because FtsZ1-1: GFP was localized at plastid equator in crl. We showed that crl mutant contains cells lacking detectable plastids in cotyledon of mature embryos. Such cells were probably generated by an uneven partition of plastids to each daughter cell, because of the presence of the dividing cells in which plastids were allocated to one of the daughter cells in crl embryos. The absence of cells lacking detectable plastids in the accumulation and replication of chloroplasts 6 (arc6), another plastid division mutant of A. thaliana having no significant defects in plant morphology, suggests that the generation of cells without detectable plastids is one of the causes of developmental abnormalities in crl.