Key Laboratory of Plant Molecular Physiology, Institute of Botany, Chinese Academy of Sciences, Beijing 100093, China.
University of Chinese Academy of Sciences, Beijing 100049, China.
J Integr Plant Biol. 2017 Sep;59(9):680-692. doi: 10.1111/jipb.12561.
In sexual organisms, division of the zygote initiates a new life cycle. Although several genes involved in zygote division are known in plants, how the zygote is activated to start embryogenesis has remained elusive. Here, we showed that a mutation in ZYGOTE-ARREST 3 (ZYG3) in Arabidopsis led to a tight zygote-lethal phenotype. Map-based cloning revealed that ZYG3 encodes the transfer RNA (tRNA) ligase AtRNL, which is a single-copy gene in the Arabidopsis genome. Expression analyses showed that AtRNL is expressed throughout zygotic embryogenesis, and in meristematic tissues. Using pAtRNL::cAtRNL-sYFP-complemented zyg3/zyg3 plants, we showed that AtRNL is localized exclusively in the cytoplasm, suggesting that tRNA splicing occurs primarily in the cytoplasm. Analyses using partially rescued embryos showed that mutation in AtRNL compromised splicing of intron-containing tRNA. Mutations of two tRNA endonuclease genes, SEN1 and SEN2, also led to a zygote-lethal phenotype. These results together suggest that tRNA splicing is critical for initiating zygote division in Arabidopsis.
在有性生物中，受精卵的分裂启动了一个新的生命周期。尽管已经在植物中发现了几个参与受精卵分裂的基因，但受精卵如何被激活开始胚胎发生仍然难以捉摸。在这里，我们表明拟南芥中的 ZYGOTE-ARREST 3（ZYG3）突变导致紧密的受精卵致死表型。基于图谱的克隆表明，ZYG3 编码转移 RNA（tRNA）连接酶 AtRNL，这是拟南芥基因组中的一个单拷贝基因。表达分析表明，AtRNL 在整个合子胚胎发生过程中以及在分生组织中表达。使用 pAtRNL::cAtRNL-sYFP 互补的 zyg3/zyg3 植物，我们表明 AtRNL 仅定位于细胞质中，表明 tRNA 剪接主要发生在细胞质中。使用部分挽救的胚胎进行的分析表明，AtRNL 突变会影响含内含子的 tRNA 的剪接。两个 tRNA 内切酶基因 SEN1 和 SEN2 的突变也导致受精卵致死表型。这些结果共同表明，tRNA 剪接对于启动拟南芥受精卵分裂至关重要。
