Key Laboratory of Plant Molecular Physiology, Institute of Botany, Chinese Academy of Sciences, Beijing 100093, China.
J Integr Plant Biol. 2012 Jan;54(1):55-64. doi: 10.1111/j.1744-7909.2011.01089.x.
Early embryogenesis is the most fundamental developmental process in biology. Screening of ethyl methanesulfonate (EMS)-mutagenized populations of Arabidopsis thaliana led to the identification of a zygote-lethal mutant embryonic factor 19 (fac19) in which embryo development was arrested at the elongated zygote to octant stage. The number of endosperm nuclei decreased significantly in fac19 embryos. Genetic analysis showed fac19 was caused by a single recessive mutation with typical mendelian segregation, suggesting equal maternal and paternal contributions of FAC19 towards zygotic embryogenesis. Positional cloning showed that FAC19 encodes a putative mitochondrial protein with 16 conserved pentatricopeptide repeat (PPR) motifs. The fac19 mutation caused a conversion from hydrophilic serine located in a previously unknown domain to hydrophobic leucine. Crosses between FAC19/fac19 and the T-DNA insertion mutants in the same gene failed to complement the fac19 defects, confirming the identity of the gene. This study revealed the critical importance of a PPR protein-mediated mitochondrial function in early embryogenesis.
早期胚胎发生是生物学中最基本的发育过程。对经过乙基甲磺酸（EMS）诱变的拟南芥种群进行筛选，导致鉴定出一个合子致死突变体胚胎因子 19（fac19），其中胚胎发育在伸长合子到八分位阶段被阻断。fac19 胚胎中的胚乳核数量显著减少。遗传分析表明 fac19 是由单个隐性突变引起的，具有典型的孟德尔分离，表明 FAC19 对合子胚胎发生的母本和父本贡献相等。定位克隆表明 FAC19 编码一种具有 16 个保守五肽重复（PPR）基序的假定线粒体蛋白。fac19 突变导致先前未知结构域中亲水丝氨酸转换为疏水性亮氨酸。在相同基因中的 FAC19/fac19 和 T-DNA 插入突变体之间的杂交未能互补 fac19 的缺陷，证实了该基因的身份。本研究揭示了 PPR 蛋白介导的线粒体功能在早期胚胎发生中的关键重要性。
