Vernalizing cold is registered digitally at FLC
Vernalizing cold is registered digitally at FLC
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DOI：
10.1073/pnas.1503100112
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发表时间：
2015-03-31
影响因子：
11.1
通讯作者：
Howard, Martin
中科院分区：
文献类型：
--
作者：
Angel, Andrew;Song, Jie;Howard, Martin
许多生物体的一个基本特性是感知、评估和响应环境信号的能力。在某些情况下，产生适当的反应需要长期的信息存储。一个经典的例子是春化作用，植物定量地感知长期的寒冷，并在表观遗传学上储存这种寒冷暴露信息，以调节开花时间。在拟南芥中，冷的稳定表观遗传记忆是数字化的：在长期的冷暴露后，细胞以全有或全无的方式自主响应，随着冷暴露持续时间的增加，稳定沉默花阻遏物FLOWERLOCUS C（FLC）的细胞比例增加。然而，在冷暴露期间，尚不清楚春化冷是否以全有或全无（数字）的方式或连续变化（模拟）的方式记录在单个细胞的FLC中。使用数学建模，我们发现，模拟登记的冷温度是有问题的，由于受损的模数转换成稳定的记忆。这一缺点在应对短时间寒冷时尤为严重，但在FLC数字记录寒冷温度时就不存在了。我们通过实验测试了这一预测，将植物暴露在短时间的寒冷中，中间有更短的温暖间歇。对于FLC表达，我们发现该系统对中断和不间断的寒冷都有类似的反应，认为这是一种整合长期温度暴露的数字机制。
A fundamental property of many organisms is an ability to sense, evaluate, and respond to environmental signals. In some situations, generation of an appropriate response requires long-term information storage. A classic example is vernalization, where plants quantitatively sense long-term cold and epigenetically store this cold-exposure information to regulate flowering time. In Arabidopsis thaliana, stable epigenetic memory of cold is digital: following long-term cold exposure, cells respond autonomously in an all-or-nothing fashion, with the fraction of cells that stably silence the floral repressor FLOWERING LOCUS C (FLC) increasing with the cold exposure duration. However, during cold exposure itself it is unknown whether vernalizing cold is registered at FLC in individual cells in an all-or-nothing (digital) manner or is continuously varying (analog). Using mathematical modeling, we found that analog registration of cold temperature is problematic due to impaired analog-to-digital conversion into stable memory. This disadvantage is particularly acute when responding to short cold periods, but is absent when cold temperatures are registered digitally at FLC. We tested this prediction experimentally, exposing plants to short periods of cold interrupted with even shorter warm breaks. For FLC expression, we found that the system responds similarly to both interrupted and uninterrupted cold, arguing for a digital mechanism integrating long-term temperature exposure.