Becraft Philip W, Li Kejian, Dey Nrisingha, Asuncion-Crabb Yvonne
Zoology and Genetics Department, Iowa State University, Ames, IA 50011, USA.
Development. 2002 Nov;129(22):5217-25. doi: 10.1242/dev.129.22.5217.
Mutants in the maize defective kernel1 (dek1) gene are blocked in embryogenesis and the endosperm is chalky and lacks an aleurone layer. Here we show that intermediate alleles result in embryos that lack a shoot axis while weak alleles result in endosperms with mosaic aleurone and deformed plants with epidermal cells that resemble bulliform cells, a specialized epidermal cell type. This indicates that dek1 functions in embryonic pattern formation, cell fate specification and pattern formation in the leaf epidermis, and cell fate specification in the endosperm. Thus, the dek1 gene product appears to control different cellular-developmental processes depending on cellular context. The phenotype of the weak dek1-Dooner allele resembles the crinkly4 (cr4) mutant phenotype. Double mutants between dek1 and cr4 showed elements of epistasis, additivity and synergy, suggesting that the gene products may function in overlapping developmental processes. cr4 transcript was detectable in dek1 mutant kernels indicating that DEK1 was not required for Cr4 transcript accumulation. To test whether DEK1 regulated the ligand for the CR4 receptor kinase, a genetic mosaic analysis was performed. The dek1 phenotype appeared to be generally cell-autonomous, leading to the conclusion that it was not likely to produce a diffusible signal molecule, and therefore was not likely to regulate the CR4 ligand.
玉米缺陷型籽粒1（dek1）基因的突变体在胚胎发生过程中受阻，胚乳粉质且缺乏糊粉层。我们在此表明，中等等位基因导致缺乏茎轴的胚胎，而弱等位基因导致具有镶嵌糊粉层的胚乳以及具有类似泡状细胞（一种特化的表皮细胞类型）的表皮细胞的畸形植株。这表明dek1在胚胎模式形成、细胞命运决定以及叶片表皮的模式形成和胚乳中的细胞命运决定中发挥作用。因此，dek1基因产物似乎根据细胞环境控制不同的细胞发育过程。弱dek1 - Dooner等位基因的表型类似于皱缩4（cr4）突变体表型。dek1和cr4之间的双突变体表现出上位性、加性和协同性的特征，表明这两个基因产物可能在重叠的发育过程中发挥作用。在dek1突变体籽粒中可检测到cr4转录本，这表明DEK1对于Cr4转录本的积累不是必需的。为了测试DEK1是否调节CR4受体激酶的配体，进行了遗传镶嵌分析。dek1表型似乎总体上是细胞自主的，由此得出结论，它不太可能产生可扩散的信号分子，因此不太可能调节CR4配体。
