ASYMMETRIC LEAVES2 and Elongator, a Histone Acetyltransferase Complex, Mediate the Establishment of Polarity in Leaves of Arabidopsis thaliana
ASYMMETRIC LEAVES2 and Elongator, a Histone Acetyltransferase Complex, Mediate the Establishment of Polarity in Leaves of Arabidopsis thaliana
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DOI：
10.1093/pcp/pcr083
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发表时间：
2011-08-01
影响因子：
4.9
通讯作者：
Machida, Chiyoko
中科院分区：
文献类型：
--
作者：
Kojima, Shoko;Iwasaki, Mayumi;Machida, Chiyoko
叶原基发生在茎尖分生组织周围。拟南芥（Arabidopsis thaliana）ASYMMETRIC LEAVES2（AS2）基因的突变导致叶片分生和不定状态的抑制、近轴-远轴极性的建立和左右对称性的缺陷。AS2抑制分生组织特异性1类KNOX同源框基因和远轴决定基因ETTIN/ARF3、KANADI2和YABBY5的转录。为了阐明AS2在建立叶极性中的作用，我们分离了增强与AS2相关的极性缺陷的突变。我们在这里描述的增强子-不对称叶-2（east1）突变，这导致形成丝状叶与abaxialized表皮的as2 - 1背景。1类KNOX和abaxial决定基因的转录水平显着高于as2 - 1 east1 - 1突变体植物比野生型和相应的单突变体植物。EAST 1编码组蛋白乙酰转移酶ELONGATA 3（ELONGATA 3），它是延长子复合物的一个组成部分。使用参与反式作用小干扰RNA（ta-siRNA）的生物发生的基因中的突变进行的遗传分析揭示，AS3介导的叶极性的建立独立于AS2和ta-siRNA相关途径。治疗组蛋白脱乙酰酶（HDACs）的抑制剂引起的添加剂极性缺陷的as2 - 1 east1 - 1突变体植物，表明在极性的测定中，独立于HDAC途径的一个EST3途径的操作。我们建议，多个途径发挥重要作用，抑制类1 KNOX和abaxial-determinant基因的表达在叶的近轴域的发展，因此，在建立叶极性。
Leaf primordia are generated around the shoot apical meristem. Mutation of the ASYMMETRIC LEAVES2 (AS2) gene of Arabidopsis thaliana results in defects in repression of the meristematic and indeterminate state, establishment of adaxial-abaxial polarity and left-right symmetry in leaves. AS2 represses transcription of meristem-specific class 1 KNOX homeobox genes and of the abaxial-determinant genes ETTIN/ARF3, KANADI2 and YABBY5. To clarify the role of AS2 in the establishment of leaf polarity, we isolated mutations that enhanced the polarity defects associated with as2. We describe here the enhancer-of-asymmetric-leaves-two1 (east1) mutation, which caused the formation of filamentous leaves with abaxialized epidermis on the as2-1 background. Levels of transcripts of class 1 KNOX and abaxial-determinant genes were markedly higher in as2-1 east1-1 mutant plants than in the wild-type and corresponding single-mutant plants. EAST1 encodes the histone acetyltransferase ELONGATA3 (ELO3), a component of the Elongator complex. Genetic analysis, using mutations in genes involved in the biogenesis of a trans-acting small interfering RNA (ta-siRNA), revealed that ELO3 mediated establishment of leaf polarity independently of AS2 and the ta-siRNA-related pathway. Treatment with an inhibitor of histone deacetylases (HDACs) caused additive polarity defects in as2-1 east1-1 mutant plants, suggesting the operation of an ELO3 pathway, independent of the HDAC pathway, in the determination of polarity. We propose that multiple pathways play important roles in repression of the expression of class 1 KNOX and abaxial-determinant genes in the development of the adaxial domain of leaves and, thus, in the establishment of leaf polarity.