Center for Plant Molecular Biology, University of Tübingen, 72076 Tübingen, Germany.
Proc Natl Acad Sci U S A. 2010 Dec 21;107(51):22350-5. doi: 10.1073/pnas.1012795108. Epub 2010 Dec 6.
Plant germ cells develop in specialized haploid structures, termed gametophytes. The female gametophyte patterns of flowering plants are diverse, with often unknown adaptive value. Here we present the Arabidopsis fiona mutant, which forms a female gametophyte that is structurally and functionally reminiscent of a phylogenetic distant female gametophyte. The respective changes include a modified reproductive behavior of one of the female germ cells (central cell) and an extended lifespan of three adjacent accessory cells (antipodals). FIONA encodes the cysteinyl t-RNA synthetase SYCO ARATH (SYCO), which is expressed and required in the central cell but not in the antipodals, suggesting that antipodal lifespan is controlled by the adjacent gamete. SYCO localizes to the mitochondria, and ultrastructural analysis of mutant central cells revealed that the protein is necessary for mitochondrial cristae integrity. Furthermore, a dominant ATP/ADP translocator caused mitochondrial cristae degeneration and extended antipodal lifespan when expressed in the central cell of wild-type plants. Notably, this construct did not affect antipodal lifespan when expressed in antipodals. Our results thus identify an unexpected noncell autonomous role for mitochondria in the regulation of cellular lifespan and provide a basis for the coordinated development of gametic and nongametic cells.
植物生殖细胞在特化的单倍体结构中发育，这些结构被称为配子体。开花植物的雌性配子体形态多样，其适应价值往往未知。在这里，我们介绍了拟南芥 fiona 突变体，其雌性配子体在结构和功能上类似于一个系统发育较远的雌性配子体。相应的变化包括一个雌性生殖细胞（中央细胞）的生殖行为改变和三个相邻的辅助细胞（反足细胞）的寿命延长。FIONA 编码半胱氨酰 tRNA 合成酶 SYCO ARATH（SYCO），该基因在中央细胞中表达并发挥作用，但不在反足细胞中表达，这表明反足细胞的寿命受相邻配子的控制。SYCO 定位于线粒体，对突变体中央细胞的超微结构分析表明，该蛋白对于线粒体嵴的完整性是必需的。此外，显性的 ATP/ADP 转运蛋白在野生型植物中央细胞中表达时，可导致线粒体嵴退化并延长反足细胞的寿命。值得注意的是，当该构建体在反足细胞中表达时，并不影响反足细胞的寿命。因此，我们的研究结果确定了线粒体在调节细胞寿命方面的一种出乎意料的非细胞自主作用，并为配子细胞和非配子细胞的协调发育提供了基础。
