Department of Genetics, North Carolina State University, Raleigh, NC 27695, USA.
BMC Plant Biol. 2010 Sep 13;10:198. doi: 10.1186/1471-2229-10-198.
The Arabidopsis SEUSS (SEU) gene encodes a transcriptional adaptor protein that is required for a diverse set of developmental events, including floral organ identity specification, as well as gynoecium, ovule and embryo development. In order to better understand the molecular mechanisms of SEUSS action we undertook a genetic modifier screen to identify seuss-modifier (sum) mutations.
Screening of M2 lines representing approximately 5,000 M1 individuals identified mutations that enhance the seuss mutant phenotypic disruptions in ovules and gynoecia; here we describe the phenotype of the sum63 mutant and enhanced disruptions of ovule and gynoecial development in the seu sum63 double mutant. Mapping and genetic complementation tests indicate that sum63 is allelic to CYP85A2 (AT3G30180) a cytochrome p450 enzyme that catalyzes the final steps in the synthesis of the phytohormone brassinolide.
Our identification of mutations in CYP85A2 as enhancers of the seuss mutant phenotype suggests a previously unrecognized role for brassinolide synthesis in gynoecial and ovule outer integument development. The work also suggests that seuss mutants may be more sensitive to the loss or reduction of brassinolide synthesis than are wild type plants.
拟南芥 SEUSS（SEU）基因编码一种转录衔接蛋白，对于多种发育事件是必需的，包括花器官身份特化，以及雌蕊、胚珠和胚胎发育。为了更好地理解 SEUSS 作用的分子机制，我们进行了遗传修饰子筛选，以鉴定 seuss 修饰子（sum）突变。
筛选约 5000 个 M1 个体的 M2 系，鉴定到增强 seuss 突变体在胚珠和雌蕊中表型破坏的突变；此处我们描述了 sum63 突变体的表型以及 seu sum63 双突变体中胚珠和雌蕊发育的增强破坏。定位和遗传互补测试表明，sum63 等位基因是 CYP85A2（AT3G30180）的突变，CYP85A2 是细胞色素 P450 酶，催化植物激素油菜素内酯合成的最后步骤。
我们鉴定到 CYP85A2 突变作为 seuss 突变体表型的增强子，表明油菜素内酯合成在雌蕊和胚珠外种皮发育中具有以前未被认识到的作用。该工作还表明 seuss 突变体可能比野生型植物对油菜素内酯合成的缺失或减少更敏感。
