How plants tell time - Dasha Savage

譯者: Helen Chang 審譯者: 旻霏 郭

In the 18th century,

十八世紀的時候

Swedish botanist Carolus Linnaeus designed the flower clock,

一位瑞典植物學家卡爾·林奈設計了花鐘表

a timepiece made of flowering plants

一種用花做的時鐘

that bloom and close at specific times of day.

在一天中某個特定時間開花漢閉合

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

卡爾的計畫並不完美， 但是他的想法是對的

Flowers can indeed sense time, after a fashion.

花朵在某種程度上的確可以感知时間

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

早晨的光線展開它們的花瓣， 就像清晨的發條裝置

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

一朵合攏的白色的水蓮意味著下午

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

還有月光花，就像它的名字一樣， 只在月光下開花

But what gives plants this innate sense of time?

但是甚麼给了花天生的時間感覺？

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 都有天生的時間感覺

of where they are in the day's cycle.

知道它們在這一天中身處何時

That's because of circadian rhythms,

這是因為晝夜的節律

the internal timekeepers that tick away inside many living things.

許多生物都有內部計時

These biological clocks allow organisms to keep track of time

這些生物鐘讓有機體記錄時間

and pick up on environmental cues that help them adapt.

並且利用環境線索幫助他們適應

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

這很重要，因為行星的自轉和公轉

put us in a state of constant flux,

把我們放在一種不停波動的狀態

although it plays out in a repetitive, predictable way.

不過它是以一種重複的， 可預知的方式在展現

Circadian rhythms incorporate various cues

晝夜節律整合各種線索

to regulate when an organism should wake and sleep,

來調節生物何時作息

and perform certain activities.

和固定活動

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

對植物而言，光線和溫度 是觸發反應的線索

that play out at a molecular scale.

它可以作為分子生物測量表

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

根莖裡的細胞， 葉子和花朵都包含著光敏色素

tiny molecules that detect light.

能夠檢測光線的分子

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

當這發生的時候， 光敏色素啟動一系列的化學反應

passing the message down into the cellular nuclei.

把信息傳到細胞核

There, transcription factors trigger the manufacture of proteins

在那兒，轉錄因子啟動了蛋白的合成

required to carry out light-dependent processes,

這種蛋白合成需要完成光依賴進程

like photosynthesis.

比如光合作用

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

光敏色素不僅能感受植物收到光的量

but can also detect tiny differences

而且能檢測到

in the distribution of wavelengths the plant takes in.

吸收光譜的微小不同

With this fine-tuned sensing,

帶著這個微調感知

phytochromes allow the plant to discern both time,

光感色素可以讓植物

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

辨別白天和晚上時間的不同

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

還可以辨別地點是向光還是在陰影處

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

使植物以化學反應來適應它的環境

This makes for early risers.

這使得有些植物早起

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

在太陽升起幾小時之前就開始活動

creating mRNA templates for its photosynthesizing machinery.

為它的光合作用製造信息核糖核酸

As the phytochromes detect increasing sunlight,

當光敏色素檢測到增加的陽光

the plant readies its light-capturing molecules

植物就準備好它的捕光分子

so it can photosynthesize and grow throughout the morning.

這樣它就能夠光合合成 在整個早晨生長

After harvesting their morning light,

在它們收穫了早晨的陽光後

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

植物就在剩下的一天裡製造很長的能量鏈

in the form of glucose polymers, like starch.

這些能量鍊是多醣的形式，比如說澱粉

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

太陽落山了，一天的工作已經完成

though a plant is anything but inactive at night.

不過植物在晚上還是在活動

In the absence of sunlight,

在沒有光的情況下

they metabolize and grow,

它們代謝並且生長

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

分解前一天的能量收穫裡得來的澱粉鏈

Many plants have seasonal rhythms as well.

許多植物還有季節的韻律

As spring melts the winter frost,

當春天融化冬天的霜凍時

phytochromes sense the longer days and increasing light,

光敏色素感知漸增的陽光和白天

and a currently unknown mechanism detects the temperature change.

檢測溫度的變化是目前還不知的機制

These systems pass the news throughout the plant

這個系統在整株植物之間傳遞信息

and make it produce blooming flowers

讓它開花

in preparation for the pollinators brought out by warmer weather.

以準備由溫暖天氣帶來的花粉傳播

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

晝夜節律形成植物和環境之間的聯絡

These oscillations come from the plants themselves.

這些波動來自植物本身

Each one has a default rhythm.

每一株都有自動的節律

Even so, these clocks can adapt their oscillations

即使如此，這些鐘錶能以它們的波動

to environmental changes and cues.

和暗示來適應環境的變化

On a planet that's in constant flux,

在行星上面，這是不斷的波動

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

是晝夜節律使得一株植物 真實地表達自己的作息時間

and to keep its own time.

並且保持自己的時間