Maize Rough Endosperm3 Encodes an RNA Splicing Factor Required for Endosperm Cell Differentiation and Has a Nonautonomous Effect on Embryo Development
Maize Rough Endosperm3 Encodes an RNA Splicing Factor Required for Endosperm Cell Differentiation and Has a Nonautonomous Effect on Embryo Development
复制标题
DOI：
10.1105/tpc.111.092163
复制
发表时间：
2011-12-01
期刊：
影响因子：
11.6
通讯作者：
Settles, A. Mark
中科院分区：
文献类型：
--
作者：
Fouquet, Romain;Martin, Federico;Settles, A. Mark
胚乳和胚胎的发育是通过表观遗传调控和这些组织之间的信号传递来协调的。在玉米(Zea Mays)中，胚乳-胚胎信号未知，但胚乳细胞化是胚胎形成芽和根的关键事件。我们用遗传不一致的种子筛选胚乳和胚胎发育中的非自主功能的种子突变体，并鉴定了隐性突变体粗胚乳(Rgh3)。野生型Rgh3等位基因在胚乳中是胚胎发育所必需的，在胚胎和幼苗的发育中具有自主作用。Rgh3胚乳细胞分化不良。胚乳细胞培养结果表明，rgh3突变体在种子中期发育过程中保持增殖状态。Rgh3编码玉米U2AF(35)相关蛋白(URP)，这是一种参与U2和U12剪接的RNA剪接因子。Rgh3等位基因产生至少19个选择性剪接变体，其中只有一个亚型编码URP的全长直系同源基因。全长RGH3α亚型定位于核仁，并在核质内显示斑点图案，RGH3α与U2AF(65)共存。一项对选择性剪接转录本的调查发现，在rgh3突变体中，一小部分非规范剪接事件发生了改变。我们的研究结果表明，玉米胚乳细胞类型的分化对于胚胎的发育是必要的。Rgh3的分子克隆表明，细胞分化、发育和植物存活需要选择性的RNA剪接。
Endosperm and embryo development are coordinated via epigenetic regulation and signaling between these tissues. In maize (Zea mays), the endosperm-embryo signals are not known, but endosperm cellularization is a key event for embryos to form shoots and roots. We screened seed mutants for nonautonomous functions in endosperm and embryo development with genetically nonconcordant seeds and identified the recessive mutant rough endosperm3 (rgh3). The wild-type Rgh3 allele is required in the endosperm for embryos to develop and has an autonomous role in embryo and seedling development. Endosperm cell differentiation is defective in rgh3. Results from endosperm cell culture indicate that rgh3 mutants remain in a proliferative state through mid-seed development. Rgh3 encodes the maize U2AF(35) Related Protein (URP), an RNA splicing factor involved in both U2 and U12 splicing. The Rgh3 allele produces at least 19 alternative splice variants with only one isoform encoding a full-length ortholog to URP. The full-length RGH3 alpha isoform localizes to the nucleolus and displays a speckled pattern within the nucleoplasm, and RGH3 alpha colocalizes with U2AF(65). A survey of alternatively spliced transcripts found that, in the rgh3 mutant, a fraction of noncanonical splicing events are altered. Our findings suggest that differentiation of maize endosperm cell types is necessary for embryos to develop. The molecular cloning of Rgh3 suggests that alternative RNA splicing is needed for cell differentiation, development, and plant viability.