Department of Plant Science, University of Manitoba, Winnipeg, Manitoba R3T2N2, Canada.
Physiol Plant. 2011 Sep;143(1):93-106. doi: 10.1111/j.1399-3054.2011.01490.x. Epub 2011 Jul 12.
The RNA binding protein, flowering control locus A, (FCA) regulates flowering in rice and Arabidopsis. FCA interacts with FY to auto-regulate its own transcripts as well as to control flowering by downregulating flowering locus C (FLC). We report the cloning and characterization of the gamma (γ) isoform of FCA from barley (Hordeum vulgare cv. McLeod). The deduced protein contained two RNA recognition motifs (RRMs), a glycine-rich region at the N-terminal end, a polyglutamine region immediately downstream of a WW domain. Barley FCA had greater protein sequence homology to wheat and rice FCA than to its Arabidopsis homolog. In developing barley embryos, FCA transcripts could be detected from 2 days after pollination (DAP) up to 40 DAP. FCA transcript levels in mature barley embryo were more abundant in non-germinated than in germinated seeds, with the levels declining as germination progressed. ABA inhibition of germination inhibited the decline of barley embryo FCA. Transient co-expression of FCA or a truncated FCA (lacking RRM) with maize VP1 promoter or wheat Em gene promoter in barley aleurone protoplasts led to increased VP1 and Em gene promoter activity. Barley FCA or truncated FCA localized in the nucleus suggested its role in gene regulation.
RNA 结合蛋白 FCA（开花控制位点 A）在调控水稻和拟南芥开花中发挥作用。FCA 与 FY 相互作用，既能自我调控自身转录本，又能通过下调 FLC（开花位点 C）来控制开花。我们从大麦（cv. McLeod）中克隆并鉴定了 FCA 的γ同工型。推断的蛋白包含两个 RNA 识别基序（RRMs）、N 端富含甘氨酸的区域、WW 结构域下游的多谷氨酰胺区。大麦 FCA 与小麦和水稻 FCA 的蛋白序列同源性大于与拟南芥同源蛋白的同源性。在发育中的大麦胚中，可从授粉后 2 天（DAP）检测到 FCA 转录本，直到 40 DAP。成熟大麦胚中的 FCA 转录本在未发芽种子中比在发芽种子中更为丰富，随着发芽的进行，其水平逐渐下降。ABA 抑制发芽抑制了大麦胚胎 FCA 的下降。瞬时共表达 FCA 或缺失 RRM 的 FCA 与玉米 VP1 启动子或小麦 Em 基因启动子在大麦糊粉层原生质体中，导致 VP1 和 Em 基因启动子活性增加。大麦 FCA 或缺失 RRM 的 FCA 定位于细胞核中，提示其在基因调控中的作用。
