Kumar Rachana A, Oldenburg Delene J, Bendich Arnold J
Department of Biology, University of Washington, Seattle, WA 98195-5325, USA.
Department of Biology, University of Washington, Seattle, WA 98195-5325, USA
J Exp Bot. 2014 Dec;65(22):6425-39. doi: 10.1093/jxb/eru359. Epub 2014 Sep 26.
The amount and structural integrity of organellar DNAs change during plant development, although the mechanisms of change are poorly understood. Using PCR-based methods, we quantified DNA damage, molecular integrity, and genome copy number for plastid and mitochondrial DNAs of maize seedlings. A DNA repair assay was also used to assess DNA impediments. During development, DNA damage increased and molecules with impediments that prevented amplification by Taq DNA polymerase increased, with light causing the greatest change. DNA copy number values depended on the assay method, with standard real-time quantitative PCR (qPCR) values exceeding those determined by long-PCR by 100- to 1000-fold. As the organelles develop, their DNAs may be damaged in oxidative environments created by photo-oxidative reactions and photosynthetic/respiratory electron transfer. Some molecules may be repaired, while molecules with unrepaired damage may be degraded to non-functional fragments measured by standard qPCR but not by long-PCR.
尽管细胞器DNA变化的机制尚不清楚，但在植物发育过程中，细胞器DNA的数量和结构完整性会发生变化。我们采用基于PCR的方法，对玉米幼苗质体和线粒体DNA的DNA损伤、分子完整性和基因组拷贝数进行了定量分析。还使用了DNA修复试验来评估DNA障碍。在发育过程中，DNA损伤增加，具有阻碍Taq DNA聚合酶扩增的障碍的分子增加，其中光照引起的变化最大。DNA拷贝数的值取决于检测方法，标准实时定量PCR（qPCR）的值比长PCR测定的值高出100至1000倍。随着细胞器的发育，它们的DNA可能在光氧化反应和光合/呼吸电子传递产生的氧化环境中受损。一些分子可能会被修复，而具有未修复损伤的分子可能会被降解为标准qPCR可检测到但长PCR无法检测到的无功能片段。
