Garton Sarah, Knight Heather, Warren Gareth J, Knight Marc R, Thorlby Glenn J
School of Biological Sciences, Royal Holloway, University of London, Egham, Surrey TW20 0EX, UK.
Plant J. 2007 Apr;50(1):118-27. doi: 10.1111/j.1365-313X.2007.03035.x. Epub 2007 Mar 5.
The crinkled leaves8 (cls8) mutant of Arabidopsis thaliana displays a developmental phenotype of abnormal leaf and flower morphology, reduced root growth and bleached leaf sections. Map-based cloning identified the mutation as being within the gene encoding the large subunit of ribonucleotide reductase (RNR1), the enzyme that catalyses the rate-limiting step in the production of deoxyribonucleoside triphosphates (dNTPs) for DNA synthesis and repair. Levels of dTTP and dATP were significantly reduced in cls8. Two further mutant cls8 alleles and cls8::RNAi plants show similar or more severe phenotypes. The cls8-1 mutant has fewer copies of the chloroplast genome, and fewer, larger chloroplasts than wild-type plants. The ultrastructure of the chloroplast, however, appears normal in cls8-1 leaves. We present evidence that, under conditions of limited dNTP supply, the inhibition of chloroplast DNA replication may be the primary factor in inducing aberrant growth.
拟南芥的皱叶8（cls8）突变体表现出叶片和花形态异常、根系生长受抑制以及叶片部分白化的发育表型。图位克隆确定该突变位于编码核糖核苷酸还原酶大亚基（RNR1）的基因内，该酶催化DNA合成和修复所需的脱氧核糖核苷三磷酸（dNTPs）生产中的限速步骤。cls8中dTTP和dATP水平显著降低。另外两个cls8突变等位基因和cls8::RNAi植株表现出相似或更严重的表型。cls8-1突变体的叶绿体基因组拷贝数比野生型植株少，叶绿体数量更少但更大。然而，cls8-1叶片中叶绿体的超微结构看起来正常。我们提供的证据表明，在dNTP供应有限的条件下，叶绿体DNA复制的抑制可能是诱导异常生长的主要因素。
