The indeterminate gametophyte1 gene of maize encodes a LOB domain protein required for embryo sac and leaf development
The indeterminate gametophyte1 gene of maize encodes a LOB domain protein required for embryo sac and leaf development
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DOI：
10.1105/tpc.106.047506
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发表时间：
2007-01-01
期刊：
影响因子：
11.6
通讯作者：
Evans, Matthew M. S.
中科院分区：
文献类型：
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作者：
Evans, Matthew M. S.
被子植物胚囊的发育始于核的自由分裂，随后是细胞化和细胞类型的分化。玉米（Zea mays）的不定配子体1（ig 1）基因限制雌配子体发育的增殖期。ig 1突变体雌配子体具有延长的自由核分裂期，导致多种胚囊异常，包括额外的卵细胞、额外的极核和额外的助细胞。根据水稻ig 1基因的正向区基因组序列，进行了ig 1基因的定位克隆。ig 1编码一个与拟南芥不对称叶2高度相似的侧器官边界结构域蛋白。ig 1的第二个突变等位基因被确定在一个非互补屏幕使用活性突变转座因子线。纯合ig 1突变体具有异常的叶形态以及异常的胚囊发育。受影响的叶片已经破坏了近轴-远轴极性，并且未能抑制叶原基中分生组织特异性的打结样同源异型盒（knox）基因的表达，导致这些细胞中持续存在增殖的干细胞身份。尽管ig 1-O叶和胚囊的表面相似，异位knox基因的表达不能检测到ig 1-O胚囊。
Angiosperm embryo sac development begins with a phase of free nuclear division followed by cellularization and differentiation of cell types. The indeterminate gametophyte1 (ig1) gene of maize (Zea mays) restricts the proliferative phase of female gametophyte development. ig1 mutant female gametophytes have a prolonged phase of free nuclear divisions leading to a variety of embryo sac abnormalities, including extra egg cells, extra polar nuclei, and extra synergids. Positional cloning of ig1 was performed based on the genome sequence of the orthologous region in rice. ig1 encodes a LATERAL ORGAN BOUNDARIES domain protein with high similarity to ASYMMETRIC LEAVES2 of Arabidopsis thaliana. A second mutant allele of ig1 was identified in a noncomplementation screen using active Mutator transposable element lines. Homozygous ig1 mutants have abnormal leaf morphology as well as abnormal embryo sac development. Affected leaves have disrupted abaxial-adaxial polarity and fail to repress the expression of meristem-specific knotted-like homeobox (knox) genes in leaf primordia, causing a proliferative, stem cell identity to persist in these cells. Despite the superficial similarity of ig1-O leaves and embryo sacs, ectopic knox gene expression cannot be detected in ig1-O embryo sacs.