How plants tell time - Dasha Savage

翻译人员: Yuanqing Edberg 校对人员: Gabriella Hu

In the 18th century,

十八世纪的时候，

Swedish botanist Carolus Linnaeus designed the flower clock,

一位瑞典植物学家Carolus Linnaeus设计了花钟表。

a timepiece made of flowering plants

一种用花做的时钟

that bloom and close at specific times of day.

在一天中某个特定的时间开花和合拢。

Linnaeus's plan wasn't perfect, but the idea behind it was correct.

Linnaeus 的计划并不完美， 但是他的想法是对的。

Flowers can indeed sense time, after a fashion.

花朵在某种程度上的确可以感知时间，

Mornings glories unfurl their petals like clockwork in the early morning.

早晨的光线展开它们的花瓣， 就像清晨的发条装置。

A closing white water lily signals that it's late afternoon,

一朵合拢的白色的水莲意味着是下午。

and moon flowers, as the name suggests, only bloom under the night sky.

还有月光花，就像它的名字一样， 只在月光下开花。

But what gives plants this innate sense of time?

但是什么给了花天生的时间感觉？

It's not just plants, in fact.

而且不只是植物

Many organisms on Earth have a seemingly inherent awareness

地球上很多生物貌似 都有天生的时间感，

of where they are in the day's cycle.

知道它们在这一天中身处何时。

That's because of circadian rhythms,

这是因为昼夜的节律，

the internal timekeepers that tick away inside many living things.

许多生物都有内部计时

These biological clocks allow organisms to keep track of time

这些生物钟让有机体记录时间，

and pick up on environmental cues that help them adapt.

并且利用环境线索帮助他们适应。

That's important, because the planet's rotations and revolutions

这很重要，因为行星的自转和公转，

put us in a state of constant flux,

把我们放在一种不停波动的状态，

although it plays out in a repetitive, predictable way.

不过它是以一种重复的， 可预知的方式在展现。

Circadian rhythms incorporate various cues

昼夜节律整合各种线索

to regulate when an organism should wake and sleep,

来调节生物何时作息，

and perform certain activities.

和固定活动。

For plants, light and temperature are the cues which trigger reactions

对植物而言，光线和温度 是触发反应的线索，

that play out at a molecular scale.

它可以作为分子生物测量表。

The cells in stems, leaves, and flowers contain phytochromes,

根茎里的细胞，叶子和花朵都包含着 光敏色素，

tiny molecules that detect light.

能够检测光线的分子。

When that happens, phytochromes initiate a chain of chemical reactions,

当这发生的时候， 光敏色素启动一系列的化学反应，

passing the message down into the cellular nuclei.

把信息传到细胞核，

There, transcription factors trigger the manufacture of proteins

在那儿，转录因子启动了蛋白的合成

required to carry out light-dependent processes,

这种蛋白合成需要完成光依赖进程，

like photosynthesis.

比如光合作用。

These phytochromes not only sense the amount of light the plant receives,

光敏色素不仅能感受植物收到光的量，

but can also detect tiny differences

而且能检测到

in the distribution of wavelengths the plant takes in.

吸收光谱的微小不同。

With this fine-tuned sensing,

带着这个微调感知

phytochromes allow the plant to discern both time,

光感色素可以让植物 辨别白天和晚上

the difference between the middle of the day and the evening,

时间的不同，

and place, whether it is in direct sunlight or shade,

还可以辨别地点是向光还是在阴影处。

enabling the plant to match its chemical reactions to its environment.

使植物以化学反应来适应它的环境

This makes for early risers.

这使得有些植物早起，

A few hours before sunrise, a typical plant is already active,

在太阳升起几小时之前就开始活动，

creating mRNA templates for its photosynthesizing machinery.

为它的光合作用制造信息核糖核酸。

As the phytochromes detect increasing sunlight,

当光敏色素检测到增加的阳光，

the plant readies its light-capturing molecules

植物就准备好它的捕光分子

so it can photosynthesize and grow throughout the morning.

这样它就能够光合合成 在整个早晨生长。

After harvesting their morning light,

在它们收获了早晨的阳光后，

plants use the rest of the day to build long chains of energy

植物就在剩下的一天里制造很长的能量链，

in the form of glucose polymers, like starch.

这些能量链是多糖的形式，比如说淀粉。

The sun sets, and the day's work is done,

太阳落山了，一天的工作已经完成，

though a plant is anything but inactive at night.

不过植物在晚上还是在活动，

In the absence of sunlight,

在没有光的情况下，

they metabolize and grow,

它们代谢并且生长。

breaking down the starch from the previous day's energy harvest.

分解前一天的能量收获里得来的淀粉链。

Many plants have seasonal rhythms as well.

许多植物还有季节的韵律。

As spring melts the winter frost,

当春天融化冬天的霜冻时，

phytochromes sense the longer days and increasing light,

光敏色素感知渐增的阳光和白天，

and a currently unknown mechanism detects the temperature change.

检测温度的变化是目前还不知的机制。

These systems pass the news throughout the plant

这个系统在整株植物之间传递信息

and make it produce blooming flowers

让它开花

in preparation for the pollinators brought out by warmer weather.

以准备由温暖天气带来的花粉传播。

Circadian rhythms act as a link between a plant and its environment.

昼夜节律形成植物和环境之间的联络。

These oscillations come from the plants themselves.

这些波动来自植物自身。

Each one has a default rhythm.

每一株都有自动的节律。

Even so, these clocks can adapt their oscillations

即使如此，这些钟表能以它们的波动

to environmental changes and cues.

和暗示来适应环境的变化。

On a planet that's in constant flux,

在行星上面，这是不断的波动。

it's the circadian rhythms that enable a plant to stay true to its schedule

是昼夜节律使得一株植物 真实地表达自己的作息时间

and to keep its own time.

并且保持自己的时间。