Analysis of a gene regulatory network underlying trait divergence between annual and perennial plants

在一年生和多年生植物中，繁殖的时间对适合度和产量有很大的影响。在这里，我们的目的是破译分子机制和调控逻辑，控制开关的分生组织身份发生在花的转变，并随后稳定在花序发育过程中。我们对一年生和多年生植物（包括一种经济上重要的作物）进行了比较，以扩大我们研究结果的相关性，并确定不同发育背景下潜在机制的灵活性，以及对不同环境和内源信号的响应。花的转变是植物繁殖的第一步，受环境和内源因素的控制，其时机对自然种群的适应性或农业产量至关重要。在花的转变过程中，茎尖分生组织和/或腋生分生组织的发育特性发生改变，导致它们从形成叶原基的营养分生组织转变为产生花原基的花序分生组织。这种转变是一种二元转换，通常是不可逆的，因此在转换后，花序分生组织的身份是稳定的，不会恢复到营养分生组织。我们提出由反馈回路加强的双稳态开关机制在芽分生组织中起作用以控制过渡，并且开关机制受环境信号的偏置以允许过渡发生。我们的模型表明，APETALA2 （AP2）和APETALA2- like （AP2- like）转录因子维持了植物状态，而CONSTANS 1过表达抑制因子（SOC1）和FRUITFULL (FUL) MADS盒转录因子与非编码microRNA172 （miR172）一起维持了生殖状态。这两组因子形成了一个相互抑制的基序，通过诱导茎部分生组织中SOC1、FUL和MIR172转录的环境线索，从营养状态偏向生殖状态。我们建议利用最新的转录组学、转基因和遗传方法，分别在一年生和多年生十字花科植物Arabidopsis thaliana和Arabis alpina以及苹果树上测试该模型。这些实验将为植物发育的关键阶段花过渡的定量建模奠定基础。此外，我们建议确定在苹果树的开关机制中是否存在与不希望的交替结果现象相关的遗传变异。这将对操纵作物的繁殖模式和产量具有实际意义。

The timing of reproduction strongly contributes to fitness and yield in annual and perennial plants. Here, we aim to decipher molecular mechanisms and the regulatory logic that control the switch in meristem identity that occurs during floral transition, and its subsequent stabilization during inflorescence development. We use a comparative approach among annual and perennial species, including an economically important crop, to broaden the relevance of our findings and to determine the flexibility in the underlying mechanisms in different developmental contexts and in response to different environmental and endogenous signals. Floral transition is the first step in plant reproduction, it is controlled by environmental and endogenous cues, and its timing is critical to fitness in natural populations or to yield in agriculture. During floral transition the developmental identity of the shoot apical meristem and/or axillary meristems is altered causing them to switch from vegetative meristems that form leaf primordia to inflorescence meristems that produce floral primordia. This transition is a binary switch that is usually irreversible, so that after the switch the identity of the inflorescence meristem is stable and does not revert back to a vegetative meristem. We propose that a bistable-switch mechanism reinforced by feedback loops acts at the shoot meristem to control the transition, and that the switch mechanism is biased by environmental signals to allow the transition to occur. Our model proposes that APETALA2 (AP2) and APETALA2-LIKE (AP2-LIKE) transcription factors maintain the vegetative state, while the SUPPRESSOR OF OVEREXPRESSION OF CONSTANS 1 (SOC1) and FRUITFULL (FUL) MADS box transcription factors together with the non-coding microRNA172 (miR172) maintain the reproductive state. These two sets of factors form a mutually repressive motif that is biased from the vegetative to reproductive state by environmental cues that induce SOC1, FUL and MIR172 transcription in the shoot meristem. We propose to test this model in annual and perennial crucifer species, Arabidopsis thaliana and Arabis alpina, respectively, as well as in apple trees using state of the art transcriptomics, transgenic and genetic approaches. These experiments will form a basis for quantitative modelling of the floral transition, a crucial stage in plant development. Furthermore, we propose to identify whether there is genetic variability in the switch mechanism in apple trees in relation to the undesired alternate bearing phenomenon. This will have practical significance in manipulating reproduction patterns and yield of crops.