Regulation of ovule initiation by gibberellins and brassinosteroids in tomato and Arabidopsis: two plant species, two molecular mechanisms

First author: Daniela Barro‐Trastoy; Affiliations: Universidad Politécnica de Valencia (瓦伦西亚理工大学): Valencia, Spain

Corresponding author: Miguel A. Pérez‐Amador

Ovule primordia formation is a complex developmental process with a strong impact on the production of seeds. In Arabidopsis this process is controlled by a gene network, including components of the signaling pathways of auxin, brassinosteroids (BRs) and cytokinins. Recently, we have shown that gibberellins (GAs) also play an important role in ovule primordia initiation, inhibiting ovule formation in both Arabidopsis and tomato. Here we reveal that BRs also participate in the control of ovule initiation in tomato, by promoting an increase on ovule primordia formation. Moreover, molecular and genetic analyses of the co‐regulation by GAs and BRs of the control of ovule initiation indicate that two different mechanisms occur in tomato and Arabidopsis. In tomato, GAs act downstream of BRs. BRs regulate ovule number through the downregulation of GA biosynthesis, which provokes a stabilization of DELLA proteins that will finally promote ovule primordia initiation. In contrast, in Arabidopsis both GAs and BRs regulate ovule number independently of the activity levels of the other hormone. Taking together, our data strongly suggest that different molecular mechanisms could operate in different plant species to regulate identical developmental processes even, as in the case of ovule primordia initiation, when the same set of hormones trigger similar responses, adding a new level of complexity.

胚珠原基的形成是一个复杂的发育进程，其对于种子产量具有非常强烈的影响。在拟南芥中，胚珠原基的形成由一个基因网络调控，包括生长素、油菜素内酯以及细胞分裂素的信号通路上的组分。最近，作者发现赤霉素在胚珠原基的起始过程中也发挥重要作用，在拟南芥和西红柿中均能够抑制胚珠的形成。本文中，作者发现西红柿中油菜素内酯通过促进胚珠原基的形成作用于胚珠的起始。此外，针对赤霉素和油菜素内酯共调控胚珠起始的分子和遗传学试验显示西红柿和拟南芥中采用了两套不同的分子机制。在西红柿中，赤霉素作用于油菜素内酯的下游。油菜素内酯能够下调赤霉素的生物合成，减少由赤霉素诱导的DELLA蛋白降解，最终促进胚珠原基的起始，从而调控胚珠的数量。相反，在拟南芥中，赤霉素和油菜素内酯都独立于其它植物激素的影响，调控胚珠的数量。综上，本文的研究说明了不同的植物物种发展出了不同的分子机制来实现共同的发育进程，本文中也就是胚珠原基的起始，而同一类的植物激素诱导了相似的响应，所以增加了新的复杂程度。

通讯：Miguel A. Pérez‐Amador  (http://www.ibmcp.upv.es/es/personas/mperezaibmcpupves)

个人简介：1990年，瓦伦西亚大学，学士；1991-1995年，西班牙IBMCP，博士；1996-2001年，密西根州立大学，博士后。

研究方向：植物激素对于坐果和果实发育的影响，尤其是赤霉素在胚珠和种子发育中的作用。

doi: https://doi.org/10.1111/tpj.14684

Journal: the plant journal

First Published: January 13, 2020