Kwon Chang Seob, Hibara Ken-ichiro, Pfluger Jennifer, Bezhani Staver, Metha Heral, Aida Mitsuhiro, Tasaka Masao, Wagner Doris
Department of Biology, University of Pennsylvania, Philadelphia, PA 19104, USA.
Development. 2006 Aug;133(16):3223-30. doi: 10.1242/dev.02508. Epub 2006 Jul 19.
The CUP-SHAPED COTYLEDON (CUC) genes CUC1, CUC2 and CUC3 act redundantly to control cotyledon separation in Arabidopsis. In order to identify novel regulators of this process, we have performed a phenotypical enhancer screen using a null allele of cuc2, cuc2-1. We identified three nonsense alleles of AtBRM, an Arabidopsis SWI/SNF chromatin remodeling ATPase, that result in strong cotyledon fusion in cuc2-1. atbrm also enhances cotyledon fusion in loss-of-function cuc1 and cuc3 mutants, suggesting a general requirement for this ATPase in cotyledon separation. By contrast, a null allele of SPLAYED (SYD), the closest homolog of AtBRM in Arabidopsis, enhances only the loss-of-function cuc1 mutant. By investigating the activities of the CUC promoters in the cotyledon boundary during embryogenesis in sensitized backgrounds, we demonstrate that AtBRM upregulates the transcription of all three CUC genes, whereas SYD upregulates the expression of CUC2. Our results uncover a specific role for both chromatin remodeling ATPases in the formation and/or maintenance of boundary cells during embryogenesis.
杯状子叶（CUC）基因CUC1、CUC2和CUC3在拟南芥中发挥冗余作用以控制子叶分离。为了鉴定这一过程的新调控因子，我们利用cuc2的无效等位基因cuc2-1进行了表型增强子筛选。我们鉴定出了拟南芥SWI/SNF染色质重塑ATP酶AtBRM的三个无义等位基因，它们在cuc2-1中导致强烈的子叶融合。atbrm也增强了功能缺失型cuc1和cuc3突变体中的子叶融合，表明这种ATP酶在子叶分离中具有普遍需求。相比之下，拟南芥中与AtBRM最接近的同源物SPLAYED（SYD）的无效等位基因仅增强功能缺失型cuc1突变体的表型。通过在敏感背景下研究胚胎发育期间子叶边界中CUC启动子的活性，我们证明AtBRM上调所有三个CUC基因的转录，而SYD上调CUC2的表达。我们的结果揭示了这两种染色质重塑ATP酶在胚胎发育期间边界细胞的形成和/或维持中的特定作用。
