Genetic Evidence for the Reduction of Brassinosteroid Levels by a BAHD Acyltransferase-Like Protein in Arabidopsis
Genetic Evidence for the Reduction of Brassinosteroid Levels by a BAHD Acyltransferase-Like Protein in Arabidopsis
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DOI：
10.1104/pp.112.197202
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发表时间：
2012-06-01
期刊：
影响因子：
7.4
通讯作者：
Lee, Jong Seob
中科院分区：
文献类型：
--
作者：
Roh, Hyungmin;Jeong, Cheol Woong;Lee, Jong Seob
类甾醇（BRs）是一类参与植物生长发育的甾体激素。虽然BR生物合成途径的特点，BR失活过程，这有助于BR的稳态，是了解较少。在这里，我们表明，BAHD（苄醇O-乙酰转移酶，花青素O-羟基肉桂酰基转移酶，邻氨基苯甲酸N-羟基肉桂酰基/苯甲酰基转移酶，脱乙酰vindoline 4-O-乙酰转移酶）酰基转移酶家族的成员可能在拟南芥（拟南芥）的BR稳态中发挥作用。我们分离了两个功能获得性突变体，油菜素类固醇失活剂1 - 1显性（bia 1 -1D）和bia 1 -2D，其中一种新的BAHD酰基转移酶样蛋白被转录激活。这两个突变体表现出矮化，雄性育性降低，在黑暗中，这是典型的表型的植物BR生物合成缺陷。外源BR处理挽救了bia 1 -1D突变体的表型。内源性BR水平在bia 1 -1D突变体中降低，表明BIA 1调节内源性BR水平。当生长在黑暗中，bia 1功能丧失突变体表现出较长的下胚轴表型，比野生型植物更响应外源BR处理。BIA 1表达主要在根中观察到，其中检测到低水平的BR。这些结果表明由BIA 1编码的BAHD酰基转移酶家族成员在控制BR水平中起作用，特别是在黑暗中的根和下胚轴中。总之，我们的研究提供了新的见解的机制，保持BR在拟南芥中的稳态，可能通过酰基共轭的BR。
Brassinosteroids (BRs) are a group of steroidal hormones involved in plant development. Although the BR biosynthesis pathways are well characterized, the BR inactivation process, which contributes to BR homeostasis, is less understood. Here, we show that a member of the BAHD (for benzylalcohol O-acetyltransferase, anthocyanin O-hydroxycinnamoyltransferase, anthranilate N-hydroxycinnamoyl/benzoyltransferase, and deacetylvindoline 4-O-acetyltransferase) acyltransferase family may play a role in BR homeostasis in Arabidopsis (Arabidopsis thaliana). We isolated two gain-of-function mutants, brassinosteroid inactivator1-1Dominant (bia1-1D) and bia1-2D, in which a novel BAHD acyltransferase-like protein was transcriptionally activated. Both mutants exhibited dwarfism, reduced male fertility, and deetiolation in darkness, which are typical phenotypes of plants defective in BR biosynthesis. Exogenous BR treatment rescued the phenotypes of the bia1-1D mutant. Endogenous levels of BRs were reduced in the bia1-1D mutant, demonstrating that BIA1 regulates endogenous BR levels. When grown in darkness, the bia1 loss-of-function mutant showed a longer hypocotyl phenotype and was more responsive to exogenous BR treatment than the wild-type plant. BIA1 expression was predominantly observed in the root, where low levels of BRs were detected. These results indicate that the BAHD acyltransferase family member encoded by BIA1 plays a role in controlling BR levels, particularly in the root and hypocotyl in darkness. Taken together, our study provides new insights into a mechanism that maintains BR homeostasis in Arabidopsis, likely via acyl conjugation of BRs.