植物的原植物 -- -- 先进

Tropisms
::花原主义

The Greek word trope means “to turn” or “to change”. A tropism is indeed a turning - a directional response of an organism (usually a plant) to a directional environmental stimulus . The turning may be directed toward the stimulus, in which case it is considered positive tropism, or away from the stimulus – negative tropism.
::希腊的Thoope一词意味着“转变 ” 或“改变 ” 。 三极主义确实是一个转折 — — 一个有机体(通常是植物)向向环境定向刺激的方向反应。 转折可能针对刺激,在这种情况下,它被视为积极的三极主义,或者远离刺激 — — 消极的三极主义。

Chemotropism is movement in response to a chemical stimulus. According to Alice Cheung and Hen-ming Wu, the paired synergid , which flank the egg cell at the entrance to the ovule ( Figure  ), release chemicals which guide pollen tubes in their growth through the pistil toward the micropyle and egg. Growth of the pollen tube toward the ovule is thus a positive chemotropism.
::Chemotroticism是针对化学刺激的动向。 根据Alice 张和Hen-ming Wu(Alice 张和Hen-ming Wu)的说法,双胞胎合唱团在卵巢入口处侧侧侧的蛋细胞(Figure ) , 释放了引导花粉管通过活塞向微和蛋生长的化学物质。 因此,花粉管向卵巢的生长是一种积极的化学化学。

Charles Darwin was one of the first to demonstrate  gravitropism (or geotropism) – a growth movement in response to the stimulus of gravity. grow toward gravity (a positive response) and shoots grow away from gravity (a negative response. If a normal, vertical plant is laid on its side, the plant will bend upward. Under the same circumstances, the plant’s root will grow downward. How does this happen?
::查尔斯·达尔文(Charles Darwn)是最早表现出重力(或地产主义 ) — — 重力刺激下的增长运动。 向重力(积极反应)发展,射击脱离重力(负反应 ) 。 如果正常的垂直植物被倒在一边,植物会向上倾斜。 在同样的情况下,植物的根部会向下增长。 这如何发生呢?

If the root tip is removed, the positive response of the root disappears. This is because the root cap contains statocyte cells ( Figure  ) , which in turn contain statoliths – starchy plastids which can settle through the cytoplasm toward the pull of gravity. Statocytes therefore detect changes in the direction of gravity (as when a potted plant is turned on its side), and communicate this information (exactly how is not understood) to the growth zone, located some distance back on the root tip. The result is a redistribution of , with higher concentrations of auxin in cells on the underside of the root. Because auxin inhibits root cell elongation , cells underneath the root will grow more slowly than cells on the upper side of the root, so the root bends and grows in a downward direction.
::如果根尖被移除,根根的正反应就会消失。这是因为根盖含有石细胞细胞(Figure ) 。 根盖中也含有固态细胞(Figure ) , 而这反过来又含有固态细胞 — — 恒星悬浮,它们可以通过细胞顶部结结结结结到引力拉动。 因此, Statocytes 检测到重力方向的变化( 当被浇注的植物翻转到其侧面时 ) , 并将这一信息( 确切地如何不理解) 传递到生长区, 位于根尖的某个距离。 其结果是在根底部的细胞中重新分配, 并增加聚积聚。 由于抑制根细胞的延长, 根底的细胞会比根上部的细胞生长慢得多, 因此根弯和向下向增长。

In the , auxin has the opposite effect – that is, higher concentrations stimulate cell elongation. As in the root, auxin accumulates on the side of the stem toward the pull of gravity, but in the stem this causes cells underneath the stem to grow faster than cells above the stem, so the stem bends and grows in an upward direction.
::轴心在干线中具有相反的效果 — — 即高浓度刺激细胞延长。 在根部,轴心在干线的侧端积累到引力拉动,但在干线中,这导致干线下细胞的生长速度快于干线上方的细胞,因此干线弯曲,向上增长。

You have probably seen plants lean toward a source of light – perhaps the most famous example of a positive phototropism . Most plant shoots show positive phototropism, and roots, negative phototropism, although gravitropism may be a stronger force for roots. Light-sensitive called phototropins absorb light and initiate phototropic responses mediated by auxins. Auxins act on the dark side of the plant, changing pH to relax cell walls and initiate cell elongation and growth. Because the growth rate is faster on the dark side of the stem than on the light, the stem bends toward the light ( Figure  ).
::你可能已经看到过植物倾向于光源 — — 也许是最有名的正面光栖植物的例子。 多数植物的拍摄都显示了积极的光栖动物和根,负光原,尽管重力植物可能是根的强大力量。 光质光质吸收光源并启动由助产物调节的光谱反应。 Auxins在植物的黑暗面采取行动,改变pH值以放松细胞壁并启动细胞延长和增长。 由于干叶的黑暗面的生长速度比光速更快,干叶会转向光(Figure ) 。

Tendrils of vines gain support by “climbing” and growing around structures they “detect” by “touch” ( Figure  ). This type of growth response is thigmotropism . Touched cells produce auxin and then transfer it to untouched cells. Auxin causes the untouched cells to elongate and grow faster than the touched cells, causing the tendril or stem to coil around the touched object. Ethylene may contribute to the success of this maneuver by causing the stem to grow horizontally for a period; note the multiple coils in the photo.
::通过“攀爬”和“触摸”(图示)“探测”这些结构周围生长的藤条获得支持。这种增长反应是硫化物。触摸细胞产生抗生素,然后将其转移到未接触的细胞。Auxin导致未接触的细胞延长,生长速度比触摸的细胞更快,导致经管或干叶缠绕着被接触的物体。乙烯通过在一段时间内使干茎水平增长,可能有助于这一动作的成功;注意照片中的多圈圈。

If you have witnessed roots growing into or sewer pipes ( Figure  ), you may think that positive hydrotropism is a strong response in tree roots. However, roots cannot sense water through an unbroken pipe. Hydrotropism is a growth response to a moisture gradient. It is difficult to study because it interacts with much stronger gravitropism, and water readily diffuses through soil , eliminating gradients. Moreover, in nature, water tends to flow downward into the soil, creating a gradient identical to that of gravity. Positive hydrotropism in roots has been demonstrated in the , and may be important in microgravity environments in space. Mutants lacking hydrotropic responses may shed light on the mechanism of hydrotropism.
::如果你亲眼目睹了根植于或下水道管道(图 ) , 你可能会认为, 积极的水文作物主义是树根的强烈反应。 但是, 根无法通过不断的管道感知水。 水作物主义是湿度梯度的成长反应。 很难研究, 因为它与更强大的重水原体相互作用, 水很容易通过土壤扩散, 消除梯度。 此外, 在自然界, 水往往流入土壤, 形成与重力相同的梯度 。 根植的正水作物主义已经在空间的微重力环境中表现出来, 可能在空间的微重力环境中很重要 。 缺乏水文热带反应的突变物可能会揭示水原体的机理。

Thermotropism is similar to hydrotropism, because gradients in temperature do not persist. If we define thermotropism as any movement response to changing temperature, the curling of Rhododendron leaves in response to cold temperature is thermotropism. Another partial thermotropism is the temperature-dependent change in phototropism from positive to negative in plants such as lupines.
::由于温度梯度不会持续,热质作物学与水力作物学相似,因为温度梯度不会持续。 如果我们将热质作物学定义为对温度变化的任何运动反应,那么罗多登德龙叶对冷温反应的卷缩就是热质作物学。 另一个部分热质作物学是光质作物从正向负的温度变化。

Some plants ( flowers or leaves or both) follow the sun as it arcs across the sky each day; sunflowers ( Figure  ) are a well-known example. This behavior is misleadingly called heliotropism . Helio- does refer to the sun, but a tropism implies growth in a certain direction, and heliotropism does not involve growth. Heliotropism can be positive or negative, and some plants even change from positive to negative during periods of drought or excessive heat – turning away from the sun to avoid excessive heat and drying.
::有些植物(花叶或叶叶叶或两者兼而有之)日照太阳,日葵(Figure)是众所周知的例子。 这种行为被误导地称为太阳原教旨主义。 太阳确实指太阳,但三角主义意味着某一方向的增长,而太阳原教旨主义并不涉及增长。 太阳原教旨主义可以是正的,也可以是负的,有些植物甚至会在干旱或过度炎热期间从正的变为负的 — — 远离太阳以避免过度的热和干燥。

If heliotropism does not depend on , what mechanism controls this type of movement? As you will learn in the next section, heliotropism is more closely related to than to tropisms.
::如果血原主义不依赖于 , 那么什么机制来控制这种类型的运动? 正如你在下一节中将学到的, 血原主义比对流主义更紧密相关。

Summary
::摘要

播放段落
• A tropism is growth and movement toward (positive) or away from (negative) an environmental stimulus.
  ::三对立面是增长和向(正)或向(负)环境刺激的转变。
播放段落
• Receptors and unequal distribution of auxin lead to differential growth and responses known as tropisms.
  ::受体和辅助剂分配不均导致不同的增长和被称为对流主义的对策。
播放段落
• Pollen tubes demonstrate chemotropism; tendrils, thigmotropism; stems, phototropism; and roots, gravitropism.
  ::花粉管展示了化学作物主义;热带、大热带;花茎、光作物主义;以及根、重力主义。
播放段落
• Thermo- and hydro- tropisms are less directional than other tropisms, because gradients are less well defined.
  ::热对流体和水对流体与其他对流体相比方向性较低,因为梯度的定义不那么明确。
播放段落
• Plants that track toward or away from the sun throughout the day show heliotropism, not a true tropism.
  ::日复一日向太阳走来走去的植物 表现出了高血原主义, 而不是真正的对流主义。