Arabidopsis actin gene ACT7 plays an essential role in germination and root growth
Arabidopsis actin gene ACT7 plays an essential role in germination and root growth
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DOI：
10.1046/j.1365-313x.2003.01626.x
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发表时间：
2003-01-01
期刊：
影响因子：
7.2
通讯作者：
Meagher, RB
中科院分区：
文献类型：
--
作者：
Gilliland, LU;Pawloski, LC;Meagher, RB
拟南芥含有八个肌动蛋白基因。其中 ACT7 在幼苗组织中表达最强烈，并且对生理信号表现出最大的反应。 act7 突变等位基因纯合的成年植物没有表现出明显的地上表型，这表明植物肌动蛋白之间存在高度的功能冗余。然而，act7-1突变体植物在与野生型植物竞争时处于强烈的选择劣势，因此必定具有未被检测到的物理缺陷。 act7-1 和 act7-4 等位基因分别在终止密码子之后和第一个内含子内包含 T-DNA 插入。两个等位基因的纯合突变幼苗表现出低于正常 ACT7 蛋白水平的 7%。突变体表现出发芽延迟和效率较低、根部扭曲和波动增加以及根系生长迟缓。 act7-4突变体表现出根生长最显着的减少。 act7-4 根尖细胞不呈直线排列，细胞之间包含倾斜连接，表明 ACT7 在确定细胞极性方面可能发挥作用。通过添加 ACT7 基因的外源拷贝，野生型根生长完全恢复到 act7-1 突变体。主要聚腺苷酸化位点（act7-2、act7-3）下游的 T-DNA 插入看起来完全野生型。 act7 突变体表型证明了根发育过程中对功能性 ACT7 蛋白的显着需求，并解释了 act7-1 突变体中所见的强负选择成分。
Arabidopsis contains eight actin genes. Of these ACT7 is the most strongly expressed in young plant tissues and shows the greatest response to physiological cues. Adult plants homozygous for the act7 mutant alleles show no obvious above-ground phenotypes, which suggests a high degree of functional redundancy among plant actins. However, act7-1 mutant plants are at a strong selective disadvantage when grown in competition with wild-type plants and therefore must have undetected physical defects. The act7-1 and act7-4 alleles contain T-DNA insertions just after the stop codon and within the first intron, respectively. Homozygous mutant seedlings of both alleles showed less than 7% of normal ACT7 protein levels. Mutants displayed delayed and less efficient germination, increased root twisting and waving, and retarded root growth. The act7-4 mutant showed the most dramatic reduction in root growth. The act7-4 root apical cells were not in straight files and contained oblique junctions between cells suggesting a possible role for ACT7 in determining cell polarity. Wild-type root growth was fully restored to the act7-1 mutant by the addition of an exogenous copy of the ACT7 gene. T-DNA insertions just downstream of the major polyadenylation sites (act7-2, act7-3 ) appeared fully wild type. The act7 mutant phenotypes demonstrate a significant requirement for functional ACT7 protein during root development and explain the strong negative selection component seen for the act7-1 mutant.