A Robust Auxin Response Network Controls Embryo and Suspensor Development through a bHLH Transcriptional Module

First author: Tatyana Radoeva; Affiliations: Wageningen University (瓦赫宁根大学): Wageningen, Netherlands

Corresponding author:Dolf Weijers

Land plants can reproduce sexually by developing an embryo from a fertilized egg cell. However, embryos can also be formed from other cell types in many plant species. A key question is thus how embryo identity in plants is controlled, and how this process is modified during non-zygotic embryogenesis. The Arabidopsis zygote divides to produce an embryonic lineage and an extra-embryonic suspensor. Yet, normally quiescent suspensor cells can develop a second embryo when the initial embryo is damaged, or when response to the signaling molecule auxin is locally blocked. Here we have used auxin-dependent suspensor embryogenesis as a model to determine transcriptome changes during embryonic reprogramming. We find that reprogramming is complex and accompanied by large transcriptomic changes prior to anatomic changes. This analysis revealed a strong enrichment for genes encoding components of auxin homeostasis and response among misregulated genes. Strikingly, deregulation among multiple auxin-related gene families converged upon re-establishment of cellular auxin levels or response. This suggests a remarkable degree of feedback regulation to create resilience in auxin response during embryo development. Starting from the transcriptome of auxin-deregulated embryos, we identify an auxin-dependent bHLH transcription factor network that mediates the activity of this hormone in suppressing embryo development from the suspensor.

陆地植物可以通过受精卵细胞发育形成胚的方式进行有性生殖。然而，在许多植物中，胚也可以通过其它类型的细胞发育而来。其中关键的问题在于植物中胚特征的是如何调控的，以及在非合子胚中该过程是如何调控的。拟南芥的合子分裂成两个细胞，一个发育成胚，一个发育成胚柄。正常情况下，当原来的胚损坏后或者响应于生长素的信号通路被阻断后，静止的胚柄细胞也能发育形成一个次级胚。本文，作者利用由生长素诱导胚柄进行胚胎发生作为平台研究胚胎重编程中的基因转录动态变化。作者发现重编程非常的复杂，并且相比于解剖学上的改变，基因转录的变化更大。该研究揭示了在失调的基因中，显著富集了参与生长素内稳态及响应的编码基因。有趣的是，多个生长素相关基因家族的解除调控最终重新建立起了细胞生长素水平和响应。这说明在胚胎发育过程中存在一个反馈调控大大恢复了生长素的响应。从生长素解除调控胚胎的转录组中，作者鉴定到了一个生长素依赖性的bHLH转录因子网络，该网络介导了生长素在抑制胚柄发育形成胚胎方面的活性。

通讯：Dolf Weijers (https://f1000.com/prime/thefaculty/member/1058938112246895)

个人简介：1997年，荷兰恩斯赫德，生物化学学士；2002年，荷兰莱顿大学，发育遗传学博士；2002-2006年，德国图宾根大学，Gerd Jürgens实验室博士后。

研究方向：以拟南芥早期胚胎会材料研究细胞如何获取其特性。

doi: https://doi.org/10.1105/tpc.18.00518

Journal: Plant Cell

First Published: 20 December, 2018