State Key Laboratory of Crop Biology, National Research Center for Apple Engineering and Technology, College of Horticulture Science and Engineering, Shandong Agricultural University, Tai-An, Shandong 271018, China.
Plant Sci. 2012 Apr;185-186:105-11. doi: 10.1016/j.plantsci.2011.09.004. Epub 2011 Sep 21.
The products of the FIS genes play important regulatory roles in diverse developmental processes, especially in seed formation after fertilization. In this study, a FIS-class gene MhFIE was isolated from apple. It encoded a predicted protein highly similar to polycomb group (PcG) protein FERTILIZATION-INDEPENDENT ENDOSPERM (FIE). MhFIE functioned as an Arabidopsis FIE homologue, as indicated by functional complementation experiment using Arabidopsis fie mutant. In addition, BiFC assay showed that MhFIE protein interacted with AtCLF. Furthermore, transgenic Arabidopsis ectopically expressing MhFIE produced less APETALA3 (AtAP3) and AGAMOUS (AtAG) transcripts than WT control, and therefore exhibited abnormal flower, seed development. These results suggested that polycomb complex including FIE and CLF proteins played an important role in reproductive development by regulating the expression of its downstream genes. In addition, it was found that MhFIE constitutively expressed in various tissues tested. Its expression levels were lower in apomictic apple species than the sexual reproductive species, suggested it was possibly involved into apomixis in apple. Furthermore, the hybrids of tea crabapple generated MhFIE transcripts at different levels. The parthenogenesis capacity was negatively correlated with MhFIE expression level in these hybrids. These results suggested that MhFIE was involved into the regulation of flower development and apomixis in apple.
FIS 基因的产物在多种发育过程中发挥着重要的调节作用，尤其是在受精后种子的形成过程中。本研究从苹果中分离出一个 FIS 类基因 MhFIE。它编码的预测蛋白与多梳组（PcG）蛋白 FERTILIZATION-INDEPENDENT ENDOSPERM（FIE）高度相似。MhFIE 作为拟南芥 FIE 的同源物发挥作用，这可以通过利用拟南芥 fie 突变体进行功能互补实验来证明。此外，BiFC 测定表明 MhFIE 蛋白与 AtCLF 相互作用。此外，过表达 MhFIE 的转基因拟南芥产生的 APETALA3（AtAP3）和 AGAMOUS（AtAG）转录物比 WT 对照少，因此表现出异常的花和种子发育。这些结果表明，包括 FIE 和 CLF 蛋白在内的多梳复合物通过调节其下游基因的表达，在生殖发育中发挥重要作用。此外，发现 MhFIE 在测试的各种组织中持续表达。在无融合生殖的苹果物种中，其表达水平低于有性生殖物种，这表明它可能参与了苹果的无融合生殖。此外，茶海棠杂种产生了不同水平的 MhFIE 转录物。这些杂种的孤雌生殖能力与 MhFIE 的表达水平呈负相关。这些结果表明，MhFIE 参与了苹果花发育和无融合生殖的调控。
