Muñoz-Nortes Tamara, Pérez-Pérez José Manuel, Ponce María Rosa, Candela Héctor, Micol José Luis
Instituto de Bioingeniería, Universidad Miguel Hernández, Campus de Elche, Elche, 03202, Spain.
Plant J. 2017 Mar;89(5):870-884. doi: 10.1111/tpj.13466. Epub 2017 Feb 11.
The characterization of mutants with altered leaf shape and pigmentation has previously allowed the identification of nuclear genes that encode plastid-localized proteins that perform essential functions in leaf growth and development. A large-scale screen previously allowed us to isolate ethyl methanesulfonate-induced mutants with small rosettes and pale green leaves with prominent marginal teeth, which were assigned to a phenotypic class that we dubbed Angulata. The molecular characterization of the 12 genes assigned to this phenotypic class should help us to advance our understanding of the still poorly understood relationship between chloroplast biogenesis and leaf morphogenesis. In this article, we report the phenotypic and molecular characterization of the angulata7-1 (anu7-1) mutant of Arabidopsis thaliana, which we found to be a hypomorphic allele of the EMB2737 gene, which was previously known only for its embryonic-lethal mutations. ANU7 encodes a plant-specific protein that contains a domain similar to the central cysteine-rich domain of DnaJ proteins. The observed genetic interaction of anu7-1 with a loss-of-function allele of GENOMES UNCOUPLED1 suggests that the anu7-1 mutation triggers a retrograde signal that leads to changes in the expression of many genes that normally function in the chloroplasts. Many such genes are expressed at higher levels in anu7-1 rosettes, with a significant overrepresentation of those required for the expression of plastid genome genes. Like in other mutants with altered expression of plastid-encoded genes, we found that anu7-1 exhibits defects in the arrangement of thylakoidal membranes, which appear locally unappressed.
先前对叶形和色素沉着改变的突变体进行的表征，使得能够鉴定出编码定位于质体的蛋白质的核基因，这些蛋白质在叶片生长和发育中发挥着重要作用。此前通过大规模筛选，我们分离出了甲磺酸乙酯诱导的突变体，其莲座叶小，叶片呈淡绿色且边缘有明显的齿，这些突变体被归为一个我们称为Angulata的表型类别。对归属于该表型类别的12个基因进行分子表征，应有助于我们进一步理解叶绿体生物发生与叶片形态发生之间仍知之甚少的关系。在本文中，我们报告了拟南芥angulata7-1（anu7-1）突变体的表型和分子特征，我们发现它是EMB2737基因的一个亚效等位基因，该基因此前仅因其胚胎致死突变而为人所知。ANU7编码一种植物特异性蛋白，该蛋白含有一个与DnaJ蛋白富含半胱氨酸的中央结构域相似的结构域。观察到的anu7-1与GENOMES UNCOUPLED1功能缺失等位基因之间的遗传相互作用表明，anu7-1突变触发了一种逆行信号，导致许多通常在叶绿体中发挥作用的基因的表达发生变化。许多此类基因在anu7-1莲座叶中的表达水平更高，其中质体基因组基因表达所需的基因明显过多。与其他质体编码基因表达改变的突变体一样，我们发现anu7-1在类囊体膜的排列上存在缺陷，这些类囊体膜在局部看起来没有紧密堆积。
