The BABY BOOM Transcription Factor Activates the LEC1-ABI3-FUS3-LEC2 Network to Induce Somatic Embryogenesis
The BABY BOOM Transcription Factor Activates the LEC1-ABI3-FUS3-LEC2 Network to Induce Somatic Embryogenesis
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DOI：
10.1104/pp.17.00232
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发表时间：
2017-10-01
期刊：
影响因子：
7.4
通讯作者：
Boutilier, Kim
中科院分区：
文献类型：
--
作者：
Horstman, Anneke;Li, Mengfan;Boutilier, Kim
体细胞胚胎发生是诱导细胞全能性的一个例子，其中胚胎从营养细胞而不是配子融合发育。体细胞胚胎发生可以通过将外植体暴露于生长调节剂和/或胁迫处理来体外诱导。BABY BOOM（BBM）和LEAFY COTYLEDON 1（LEC 1）和LEC 2转录因子是植物细胞全能性的关键调节因子，因为在没有外源生长调节剂或胁迫处理的情况下，任一转录因子的异位过表达诱导拟南芥（Arabidopsis thaliana）幼苗的体细胞胚形成。尽管LEC和BBM蛋白调节相同的发育过程，但尚不清楚它们是否在相同的分子途径中发挥作用。我们发现，BBM转录调节LEC 1和LEC 2，以及其他两个LAFL基因，FUSCA 3（FUS 3）和脱落酸不敏感3（ABI 3）。LEC 2和ABI 3定量调节BBM介导的体细胞胚胎发生，而FUS 3和LEC 1是这个过程所必需的。BBM介导的体细胞胚胎发生是剂量和环境依赖性的，并且环境依赖性表型与LAFL的差异表达相关。我们还发现了其他拟南芥BBM样蛋白之间的体细胞胚胎发生的功能冗余，并表明这些蛋白质之一，PLETHORA 2，也调节LAFL基因的表达。我们的数据将BBM置于植物胚胎身份和全能性的其他主要调节剂的上游。
Somatic embryogenesis is an example of induced cellular totipotency, where embryos develop from vegetative cells rather than from gamete fusion. Somatic embryogenesis can be induced in vitro by exposing explants to growth regulators and/or stress treatments. The BABY BOOM (BBM) and LEAFY COTYLEDON1 (LEC1) and LEC2 transcription factors are key regulators of plant cell totipotency, as ectopic overexpression of either transcription factor induces somatic embryo formation from Arabidopsis (Arabidopsis thaliana) seedlings without exogenous growth regulators or stress treatments. Although LEC and BBM proteins regulate the same developmental process, it is not known whether they function in the same molecular pathway. We show that BBM transcriptionally regulates LEC1 and LEC2, as well as the two other LAFL genes, FUSCA3 (FUS3) and ABSCISIC ACID INSENSITIVE3 (ABI3). LEC2 and ABI3 quantitatively regulate BBM-mediated somatic embryogenesis, while FUS3 and LEC1 are essential for this process. BBM-mediated somatic embryogenesis is dose and context dependent, and the context-dependent phenotypes are associated with differential LAFL expression. We also uncover functional redundancy for somatic embryogenesis among other Arabidopsis BBM-like proteins and show that one of these proteins, PLETHORA2, also regulates LAFL gene expression. Our data place BBM upstream of other major regulators of plant embryo identity and totipotency.