He Chaoying, Sommer Hans, Grosardt Britta, Huijser Peter, Saedler Heinz
Department of Molecular Plant Genetics, Max-Planck-Institute for Plant Breeding Research, Cologne, Germany.
Mol Biol Evol. 2007 May;24(5):1229-41. doi: 10.1093/molbev/msm041. Epub 2007 Mar 5.
MADS-domain proteins serve as regulators of plant development and often form dimers and higher order complexes to function. Heterotopic expression of MPF2, a MADS-box gene, in reproductive tissues is a key component in the evolution of the inflated calyx syndrome in Physalis, but RNAi studies demonstrate that MPF2 has also acquired a role in male fertility in Physalis floridana. Using the yeast 2-hybrid system, we have now identified numerous MPF2-interacting MADS-domain proteins from Physalis, including homologs of SOC1, AP1, SEP1, SEP3, AG, and AGL6. Among the many non-MADS-domain proteins recovered was a homolog of MAGO NASHI, a highly conserved RNA-binding protein known to be involved in many developmental processes including germ cell differentiation. Two MAGO genes, termed P. floridana mago nashi1 (PFMAGO1) and PFMAGO2, were isolated from P. floridana. Both copies were found to be coexpressed in leaves, fruits, and, albeit at lower level, also in roots, stems, and flowers. DNA sequence analysis revealed that, although the coding sequences of the 2 genes are highly conserved, they differ substantially in their intron and promoter sequences. Two-hybrid screening of a Physalis expression library with both PFMAGO1 and PFMAGO2 as baits yielded numerous gene products, including an Y14-like protein. Y14 is an RNA-binding protein that forms part of various "gene expression machines." The function of MPF2 and 2 PFMAGO proteins in ensuring male fertility and evolution of calyx development in Physalis is discussed.
MADS结构域蛋白作为植物发育的调节因子，常形成二聚体和高阶复合物来发挥功能。MADS盒基因MPF2在生殖组织中的异位表达是酸浆膨大花萼综合征进化的关键组成部分，但RNA干扰研究表明，MPF2在弗罗里达酸浆的雄性育性中也发挥了作用。利用酵母双杂交系统，我们现已从酸浆中鉴定出许多与MPF2相互作用的MADS结构域蛋白，包括SOC1、AP1、SEP1、SEP3、AG和AGL6的同源物。在回收的许多非MADS结构域蛋白中，有一种是MAGO NASHI的同源物，MAGO NASHI是一种高度保守的RNA结合蛋白，已知参与包括生殖细胞分化在内的许多发育过程。从弗罗里达酸浆中分离出两个MAGO基因，分别命名为弗罗里达酸浆mago nashi1（PFMAGO1）和PFMAGO2。发现这两个拷贝在叶、果实中共同表达，尽管在根、茎和花中的表达水平较低。DNA序列分析表明，虽然这两个基因的编码序列高度保守，但它们的内含子和启动子序列存在很大差异。以PFMAGO1和PFMAGO2为诱饵对酸浆表达文库进行双杂交筛选，得到了许多基因产物，包括一种Y14样蛋白。Y14是一种RNA结合蛋白，是各种“基因表达机器”的一部分。本文讨论了MPF2和两种PFMAGO蛋白在确保酸浆雄性育性和花萼发育进化中的作用。
