The amazing ways plants defend themselves - Valentin Hammoudi

翻译人员: xiao gu 校对人员: Lipeng Chen

This is a tomato plant,

这是西红柿，

and this is an aphid slowly killing the tomato plant

这只蚜虫正通过叶片吮吸汁液

by sucking the juice out of its leaves.

缓慢的杀死西红柿。

The tomato is putting up a fight using both physical and chemical defenses

西红柿用物理和化学武器反击，

to repel the attacking insects.

来击退攻击者。

But that's not all.

但这不是全部。

The tomato is also releasing compounds that signal nearby tomato plants

西红柿会释放信号给周围的西红柿，

to release their own insect repellent.

让它们释放自己的杀虫剂。

Plants are constantly under attack.

植物总是被攻击。

They face threats ranging from microscopic fungi and bacteria,

面临的威胁来自于：真菌、细菌，

small herbivores, like aphids, caterpillars, and grasshoppers,

小草食动物：蚜虫、毛毛虫、蚂蚱，

up to large herbivores, like tortoises, koalas, and elephants.

到大草食动物：乌龟、考拉、大象。

All are looking to devour plants to access the plentiful nutrients

动物都在寻找并吞噬植物以获得 它们叶片、茎、花和种子中的

and water in their leaves, stems, fruits, and seeds.

丰富的营养和水分。

But plants are ready with a whole series of internal and external defenses

但植物有一系列从内到外的保护，

that make them a much less appealing meal,

让它们显不太可口，

or even a deadly one.

甚至有毒。

Plants' defenses start at their surface.

植物防御从表面开始。

The bark covering tree trunks is full of lignin,

覆盖树干的皮充满木质素，

a rigid web of compounds that's tough to chew

这是一种难以下咽并且

and highly impermeable to pathogens.

病原体不可渗透的坚硬物质。

Leaves are protected by a waxy cuticle

叶片覆盖蜡状角质层，

that deters insects and microbes.

能阻止昆虫和微生物。

Some plants go a step further with painful structures

有些植物更进一步， 形成能造成疼痛的结构，

to warn would-be predators.

警告潜在的猎食者。

Thorns, spines, and prickles discourage bigger herbivores.

刺，各种刺，让大型草食动物退缩。

To deal with smaller pests, some plants' leaves have sharp hair-like structures

对于小害虫，一些植物叶片有尖锐的发状结构，

called trichomes.

称为表皮毛。

The kidney bean plant sports tiny hooks to stab the feet of bed bugs

四季豆用小挂钩来刺伤臭虫

and other insects.

和其他昆虫的脚。

In some species, trichomes also dispense chemical irritants.

某些种类的植物，表皮毛能释放化学刺激。

Stinging nettles release a mixture of histamine and other toxins

刺荨麻释放组胺和毒素混合物，

that cause pain and inflammation when touched.

当触摸时，会引发疼痛和发炎。

For other plant species, the pain comes after an herbivore's first bite.

对于其他种类的植物， 食草动物咀嚼后会产生疼痛。

Spinach,

kiwi fruit,

菠菜、

pineapple,

猕猴桃、

菠萝、

fuchsia

灯笼海棠、

and rhubarb all produce microscopic needle-shaped crystals called raphides.

大黄，都会产生微小的称为针晶体的晶状物质。

They can cause tiny wounds in the inside of animals' mouths,

它们会在动物嘴巴中形成小伤口，

which create entry points for toxins.

可以让毒素进入。

The mimosa plant has a strategy designed to prevent herbivores

含羞草的策略则是

from taking a bite at all.

完全阻止草食者吞食。

Specialized mechanoreceptor cells detect touch

传感细胞侦察到被触摸时，

and shoot an electrical signal through the leaflet to its base

会从叶片释放电信号给根部，

causing cells there to release charged particles.

致使细胞释放带电粒子。

The buildup of charge draws water out of these cells

电荷让水离开细胞，

and they shrivel, pulling the leaflet closed.

让叶片收缩，并卷曲关闭。

The folding movement scares insects away

这种卷曲运动会吓退昆虫，

and the shrunken leaves look less appealing to larger animals.

而且收缩的叶片对大型动物吸引力更小。

If these external defenses are breached,

如果这些外部防御都无用，

the plant immune system springs into action.

植物免疫系统便开始启动。

Plants don't have a separate immune system like animals.

植物没有像动物一样有自己独立的免疫系统。

Instead, every cell has the ability to detect and defend against invaders.

相反，每个细胞都能侦察和防御入侵者。

Specialized receptors can recognize molecules that signal the presence

特别的接收器能识别可以显示

of dangerous microbes or insects.

危险微生物和昆虫存在的细胞。

In response, the immune system initiates a battery of defensive maneuvers.

相对应的，免疫系统启动一系列的防御机制。

To prevent more pathogens from making their way inside,

为了阻止更多的病原体进入，

the waxy cuticle thickens and cell walls get stronger.

蜡装角质层加厚，细胞壁增强。

Guard cells seal up pores in the leaves.

保护细胞封闭叶片中毛孔。

And if microbes are devouring one section of the plant,

如果微生物正在吞噬部分植物，

those cells can self-destruct to quarantine the infection.

细胞会通过自我毁灭来隔离感染。

Compounds toxic to microbes and insects are also produced,

对付微生物和昆虫的合成毒素也会被生产出来，

often tailor-made for a specific threat.

常常为特定的威胁量身定做。

Many of the plant molecules that humans have adopted

许多人类驯化为

as drugs, medicines and seasonings

如毒品、药品、调味品的植物，

evolved as part of plants' immune systems because they're antimicrobial,

它们的细胞已进化为免疫系统的一部分， 因为它们能够对抗微生物

or insecticidal.

或者能够抗菌。

An area of a plant under attack can alert other regions using hormones,

遭受攻击的部分区域会通过释放荷尔蒙，

airborne compounds,

挥发化合物，

or even electrical signals.

甚至电信号来提醒其他区域。

When other parts of the plant detect these signals,

当植物的其他部分探测到这些信号时，

they ramp up production of defensive compounds.

它们会加速生成防御性物质。

And for some species, like tomatoes,

对于某些品种，如西红柿，

this early warning system also alerts their neighbors.

早期警告系统也能提醒其他西红柿。

Some plants can even recruit allies to adopt a strong offense

还有些植物甚至能招募盟友加入

against their would-be attackers.

反对可能的攻击者的队列。

Cotton plants under siege by caterpillars

当棉花被毛毛虫包围时，

release a specific cocktail of ten to twelve chemicals into the air.

便会释放10到12种混合化学成分到空气中，

This mixture attracts parasitic wasps that lay eggs inside the caterpillars.

这些混合物吸引着能产卵到毛毛虫体内的寄生蜂。

Plants may not be able to flee the scene of an attack,

植物不能受到攻击后就逃离现场，

or fight off predators with teeth and claws,

或用牙齿和爪子来反抗捕食者，

but with sturdy armor,

但通过坚固的盔甲、

a well-stocked chemical arsenal,

丰富的化学武器、

a neighborhood watch,

协作系统、

and cross-species alliances,

以及跨物种联盟，

a plant isn't always an easy meal.

植物不总是弱者。