Cao Xueyuan, Li Kejian, Suh Sang-Gon, Guo Tao, Becraft Philip W
Department of Genetics, Development and Cell Biology, Iowa State University, Ames, IA 50011, USA.
Planta. 2005 Mar;220(5):645-57. doi: 10.1007/s00425-004-1378-3. Epub 2004 Nov 12.
The maize (Zea mays L.) CRINKLY4 (CR4) gene encodes a serine/threonine receptor-like kinase that controls an array of developmental processes in the plant and endosperm. The Arabidopsis thaliana (L.) Heynh. genome encodes an ortholog of CR4, ACR4, and four CRINKLY4-RELATED (CRR) proteins: AtCRR1, AtCRR2, AtCRR3 and AtCRK1. The available genome sequence of rice (Oryza sativa L.) encodes a CR4 ortholog, OsCR4, and four CRR proteins: OsCRR1, OsCRR2, OsCRR3 and OsCRR4, not necessarily orthologous to the Arabidopsis CRRs. A phylogenetic study showed that AtCRR1 and AtCRR2 form a clade closest to the CR4 group while all the other CRRs form a separate cluster. The five Arabidopsis genes are differentially expressed in various tissues. A construct formed by fusion of the ACR4 promoter and the GUS reporter, ACR4::GUS, is expressed primarily in developing tissues of the shoot. The ACR4 cytoplasmic domain functions in vitro as a serine/threonine kinase, while the AtCRR1 and AtCRR2 kinases are not active. The ability of ACR4 to phosphorylate AtCRR2 suggests that they might function in the same signal transduction pathway. T-DNA insertions were obtained in ACR4, AtCRR1, AtCRR2, AtCRR3 and AtCRK1. Mutations in acr4 show a phenotype restricted to the integuments and seed coat, suggesting that Arabidopsis might contain a redundant function that is lacking in maize. The lack of obvious mutant phenotypes in the crr mutants indicates they are not required for the hypothetical redundant function.
玉米（Zea mays L.）的CRINKLY4（CR4）基因编码一种丝氨酸/苏氨酸类受体激酶，该激酶控制着植物和胚乳中的一系列发育过程。拟南芥（Arabidopsis thaliana (L.) Heynh.）基因组编码CR4的一个直系同源基因ACR4，以及四种与CRINKLY4相关（CRR）的蛋白质：AtCRR1、AtCRR2、AtCRR3和AtCRK1。水稻（Oryza sativa L.）的现有基因组序列编码一个CR4直系同源基因OsCR4，以及四种CRR蛋白质：OsCRR1、OsCRR2、OsCRR3和OsCRR4，它们不一定与拟南芥的CRR直系同源。一项系统发育研究表明，AtCRR1和AtCRR2形成了一个最接近CR4组的进化枝，而所有其他CRR形成了一个单独的簇。拟南芥的这五个基因在不同组织中差异表达。由ACR4启动子和GUS报告基因融合形成的构建体ACR4::GUS主要在茎尖的发育组织中表达。ACR4的胞质结构域在体外作为丝氨酸/苏氨酸激酶发挥作用，而AtCRR1和AtCRR2激酶没有活性。ACR4磷酸化AtCRR2的能力表明它们可能在同一信号转导途径中发挥作用。在ACR4、AtCRR1、AtCRR2、AtCRR3和AtCRK1中获得了T-DNA插入。acr4中的突变表现出仅限于珠被和种皮的表型，这表明拟南芥可能含有玉米中缺乏的冗余功能。crr突变体中缺乏明显的突变表型表明它们对于假设的冗余功能不是必需的。
