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J EXP BOT:拟南芥新的BAHD基因家族成员参与BR内稳态调节

已有 3863 次阅读 2018-2-20 21:34 |个人分类:每日摘要|系统分类:论文交流


Arabidopsis BRASSINOSTEROID INACTIVATOR2 is a typical BAHD acyltransferase involved in brassinosteroid homeostasis


First author: Zhiqiang Zhang; Affiliations: Huazhong Agricultural University (华中农业大学): Wuhan, China
Corresponding author: Liping Xu


Brassinosteroids (BRs; 油菜素内酯) are plant-specific steroidal hormones (甾体激素), the homeostasis of which is crucial for various aspects of plant growth and development. However, to date, the BR inactivation (失活) process has not been thoroughly (完全地) elucidated. In this study, we identified and characterized a novel BAHD family acyltransferase (酰基转移酶) gene, BRASSINOSTEROID INACTIVATOR2 (BIA2), involved in BR inactivation. Plants overexpressing BIA2 displayed typical BR-deficient phenotypes, which were rescued by exogenous BR treatment. Real-time qRT-PCR and transcriptome analyses showed that virtually (实质上) all of the BR-biosynthetic gene expression levels were increased, whereas the expression of many BR- inactivation genes was reduced in OE-BIA2 plants. Root inhibition assays showed that the root growth of OE-BIA2 plants was inhibited. We obtained plants with an intermediate (中间的) phenotype by crossing the OE-BIA2 plants with OE-BRASSINOSTEROID-INSENSITIVE1 (BRI1) plants. The null (失效的) BIA2 mutants had longer hypocotyls (下胚轴) in the dark. BIA2 was predominantly (主要是) expressed in roots, and its expression was induced by 24-epiBL or dark treatment but exhibited a differential expression pattern compared with its homologue BIA1. Furthermore, genetic transformation with point mutant and deleted BIA2 constructs confirmed that the HXXXD motif is essential for the function of BIA2. Taken together, these findings indicate that BIA2 is a typical BAHD acyltransferase that is involved in BR homeostasis, which may inactivate bioactive BRs by esterification (酯化反应), particularly in roots and hypocotyls under dark condition.




油菜素内酯BR是一类植物特有的甾体激素,其在植物体中的内稳态对于植物生长和发育的多个阶段起着非常重要的作用。然而,到目前为止,对于BR失活过程的研究还没有完全阐释清楚。本文鉴定了一个新的BAHD酰基转移酶基因家族的一个成员BIA2基因,该基因参与植物体内的BR失活过程。过表达BIA2的植株表现出典型的BR缺陷表型,通过外源的BR处理可以拯救过表达植株的表型。实时定量qRT-PCR和转录组分析显示所有的BR合成相关基因的表达水平均有所上升,而许多的BR失活相关基因在过表达BIA2植株中的表达水平有所下降。根抑制试验显示过表达BIA2植株的根生长受到抑制。作者通过将过表达BIA2植株和过表达BRI1植株杂交获得了表型处于中间类型的植株。在黑暗条件下,BIA2突变体具有更长的下胚轴。BIA2基因主要在根中表达,该基因的表达可以被24-epiBL或是黑暗处理所诱导,但与其同源基因BIA1的基因表达模式不同。此外,通过点突变和BIA2基因缺失的遗传转化试验揭示了HXXXD基序对于BIA2功能实现是必要的。综上,本文的发现揭示了BIA2是一个典型的BAHD酰基转移酶,该酶可能通过酯化反应导致BR生物活性丧失进而参与BR的内稳态调节,并由此部分参与黑暗条件下根和下胚轴的生长。




doi: https://doi.org/10.1093/jxb/ery057


Journal: Journal of Experimental Botany
Published date: 15 February, 2018

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