章节大纲

  • Close-up of ripe peach hanging on a tree branch amidst green leaves.

    How do fruits know when to fall?
    ::水果怎么会知道什么时候掉下来?

    Fruits, such as these peaches, do not leave their trees until it's the right time. The seeds are mature, and the fruit is ripe. But what tells the fruits it's time to drop? The signal that is sent through the tree is a type of hormone . Hormones also send signals through your body.
    ::果实,如桃子,不要离开树,直到时机成熟。种子成熟了,水果成熟了。但果实该落地了。通过树发出的信号是一种荷尔蒙。荷尔蒙也通过你的身体发出信号。

    Plant Hormones
    ::植物激素

    Plants may not move, but that does not mean they don't respond to their environment. Plants can sense gravity, light, touch, and seasonal changes. For example, you might have noticed how a house plant bends toward a bright window. Plants can sense and then grow toward the source of light. Scientists say that plants are able to respond to " stimuli ," or something—usually in the environment—that results in a response . For instance, light is the stimulus, and the plant moving toward the light is the "response."
    ::植物可能不会移动,但这并不意味着它们对环境没有反应。植物可以感知引力、光、触摸和季节性变化。例如,你可能已经注意到家庭植物如何弯曲到明亮的窗口。植物可以感知,然后成长到光源。科学家说,植物能够对“刺激”或通常在环境中产生的反应作出反应。例如,灯光是刺激因素,而向灯光移动的植物是“反应”。

    Hormones are special chemical messengers molecules that help organisms , including plants, respond to stimuli in their environment. In order for plants to respond to the environment, their cells must be able to communicate with other cells. Hormones send messages between the cells. Animals , like humans, also have hormones, such as testosterone or estrogen , to carry messages from cell to cell. In both plants and animals, hormones travel from cell to cell in response to a stimulus; they also activate a specific response.
    ::荷尔蒙是特殊的化学信使分子,有助于生物体(包括植物)应对环境中的刺激。为了让植物对环境作出反应,它们的细胞必须能够与其他细胞进行交流。荷尔蒙在细胞之间发出信息。动物和人类一样,也有荷尔蒙,如睾丸酮或雌激素,将信息从细胞传送到细胞。在植物和动物中,荷尔蒙随着刺激因素而从细胞传到细胞;它们还激活特定的反应。

    Types of Plant Hormones
    ::植物激素类型

    Five different types of plant hormones are involved in the main responses of plants, and they each have different functions ( Table ).
    ::植物的主要反应涉及五种不同类型的植物激素,各有不同的功能(表)。

    Hormone Function
    Ethylene Fruit ripening and abscission
    Gibberellins Break the dormancy of seeds and buds; promote growth
    Cytokinins Promote ; prevent senescence
    Abscisic Acid Close the stomata ; maintain dormancy
    Auxins Involved in and apical dominance

    Ethylene
    ::乙烯

    The hormone ethylene has two functions. It (1) helps ripen fruit and (2) is involved in the process of abscission , the dropping of leaves, fruits, and flowers . When a flower is done blooming or a fruit is ripe and ready to be eaten, ethylene causes the petals or fruit to fall from a plant ( Figure and Figure ).
    ::乙烯具有两种功能伤心1)帮助成熟的水果,(2)参与消除过程,即叶子、水果和鲜花的落下;当花朵开花或水果成熟并准备吃时,乙烯导致花瓣或水果从植物中掉落(图和图)。

    Ethylene is an unusual plant hormone because it is a gas. That means it can move through the air, and a ripening apple can cause another apple to ripen, or even over-ripen. That’s why one rotten apple spoils the whole barrel! Some farmers spray their green peppers with ethylene gas to cause them to ripen faster and become red peppers.
    ::乙烯是一种不寻常的植物荷尔蒙,因为它是一种气体。 这意味着它可以在空气中流动,成熟的苹果可以导致另一个苹果成熟,甚至过度成熟。 这就是为什么一个腐烂的苹果可以破坏整个桶。 一些农民用乙烯气喷洒绿胡椒,让他们更快地成熟,成为红胡椒。

    You can try to see how ethylene works by putting a ripe apple or banana with another unripe fruit in a closed container or paper bag. What do you think will happen to the unripe fruit?
    ::通过把成熟的苹果或香蕉和未成熟的水果放在封闭的容器或纸袋中,你可以看到乙烯是如何运作的。你认为未成熟的水果会发生什么?

    Tomatoes in various stages of ripeness, influenced by the hormone ethylene.

    The hormone ethylene is signaling these tomatoes to ripen.
    ::荷尔蒙乙烯表示这些西红柿已经成熟

    Pink flower petals scattered on the ground, indicating the abscission process in plants.

    The hormone ethylene causes flower petals to fall from a plant, a process known as abscission.
    ::荷尔蒙乙烯导致花瓣从植物中掉落,这个过程被称为撤销。

    Gibberellins
    ::吉贝林

    Gibberellins are hormones that cause the plant to grow. When gibberellins are applied to plants by scientists, the stems grow longer. Some gardeners or horticulture scientists add gibberellins to increase the growth of plants. Dwarf plants (small plants), on the other hand, have low levels of gibberellins ( Figure ). Another function of gibberellins is to stop dormancy (resting time) of seeds and buds. Gibberellins signal that it’s time for a seed to germinate (sprout) or for a bud to open.
    ::Gibellins是导致植物生长的荷尔蒙。当科学家对植物施用胡贝尔林时,树枝会长长。一些园丁或园艺科学家会添加胡贝尔林来增加植物生长。另一方面,Dwarf植物(小型植物)的胡贝尔林(Figure ) 水平较低。 胡贝林的另一个功能是停止种子和芽的耐久性(延缓时间 ) 。 Gibelellins会发出种子发芽(发芽)或开芽的信号。

    A bonsai tree illustrating a dwarf plant, showcasing low gibberellin levels.

    Dwarf plants like this bonsai tree often have unusually low concentrations of gibberellins.
    ::像这棵邦萨树这样的矮矮人植物 通常有非常低的 胡言乱语的浓度。

    Cytokinins
    ::青金素

    Cytokinins are hormones that cause plant cells to divide. Cytokinins were discovered from attempts to grow plant tissue in artificial environments ( Figure ). Cytokinins prevent the process of aging (senescence). So florists sometimes apply cytokinins to cut flowers, so they do not get old and die.
    ::环金因是导致植物细胞分裂的荷尔蒙。 环金因是在人工环境中种植植物组织的努力中发现的(图 ) 。 环金因防止了老化过程(senescence ) 。 因此花匠有时会用环金因切花,这样他们就不会老死。

    A hand adjusting lids on jars containing plant tissue cultures in sterile conditions.

    Cytokinins promote cell division and are necessary for growing plants in tissue culture. A small piece of a plant is placed in sterile conditions to regenerate a new plant.
    ::在组织培养中培养植物所必须的切除细胞。 将一小块植物置于不育条件下以再生新植物。

    Abscisic Acid
    ::缩略酸

    Abscisic acid is misnamed because it was once believed to play a role in abscission (the dropping of leaves, fruits, and flowers), but we now know abscission is caused by ethylene. The actual role of abscisic acid is to close the stomata, the tiny openings in leaves that allow substances to enter and leave, and to maintain dormancy. When a plant is stressed due to lack of water, abscisic acid tells the stomata to close. This prevents water loss through the stomata.
    ::氨酸之所以被误命名,是因为它曾经被认为在撤销(叶子、水果和花卉的落地)中起到作用,但我们现在知道取消是因为乙烯。 氨酸的实际作用是关闭stomata(允许物质进出的叶子中的小孔),保持住住。 当植物因缺水而紧张时,氨酸会让stomata关闭。这防止了通过stomata的水流失。

    When the environment is not good for a seed to germinate, abscisic acid signals for the dormancy period of the seed to continue. Abscisic acid also tells the buds of plants to stay in the dormancy stage. When conditions improve, the levels of abscisic acid drop and the levels of gibberellins increase, signaling that is time to break dormancy ( Figure ).
    ::当环境不利于种子发芽时,种子的休眠期会继续出现急性酸信号; 吸食性酸还让植物的芽保持在休眠阶段; 当条件改善时, 催产性酸滴落水平和增加水平, 表明现在是打破休眠期的时候了( Figure ) 。

    Close-up of tree branches with new green leaves emerging in spring.

    A decrease in levels of abscisic acid allows these buds to break dormancy and put out leaves.
    ::腹痛酸水平的下降 使得这些芽 打破了宿舍,放出叶子。

    Auxins
    ::辅助器

    Auxins are hormones that play a role in plant growth. Auxins produced at the tip of the plant are involved in apical dominance , when the main central stem grows more strongly than other stems and branches. When the tip of the plant is removed, the auxins are no longer present, and the side branches begin to grow. Auxins are also involved in tropisms, responses to stimuli in the environment
    ::助产素是植物生长中发挥作用的激素。在植物端端生产的助产素在主要中央干茎比其他根茎和树枝生长得更强劲的情况下,处于极致支配地位。当工厂端被去除后,助产素不再存在,副分支开始成长。助产素还参与对流,对环境刺激的反应。

    Summary
    ::摘要

    • Plant hormones are chemical signals that control different processes in plants.
      ::植物荷尔蒙是化学信号 控制工厂的不同过程
    • Plant hormones include ethylene, gibberellins, cytokinins, absciscic acid, and auxins.
      ::植物荷尔蒙包括乙烯、脂、cytokinins、腹腔硬化酸和。

    Explore More
    ::探索更多

    Use the resource below to answer the questions that follow.
    ::利用以下资源回答以下问题。

    • Plant Hormones at (5:39)
      ::5:39时(5:39)的植物激素
    1. What hormones stimulate plant growth?
      ::什么荷尔蒙刺激植物生长?
    2. What hormones inhibit plant growth?
      ::什么荷尔蒙抑制植物生长?
    3. Why is it important for a plant to be able to both stimulate and inhibit growth? Explain your answer.
      ::为什么植物既能刺激又能抑制增长很重要?
    4. Do you think hormones are more important to plants or mammals? Explain your thinking.
      ::你觉得荷尔蒙对植物或哺乳动物更重要吗?

    Review
    ::回顾

    1. What are three stimuli that plants respond to?
      ::植物反应的三种刺激是什么?
    2. List the roles of gibberellins.
      ::列出胡言乱语的角色。
    3. What hormone is involved in fruit ripening?
      ::水果成熟涉及到什么荷尔蒙?
    4. What happens to an unripe fruit when placed in a paper bag with a ripe fruit?
      ::在一个装满成熟水果的纸袋里放上未熟水果时,会怎样?
    5. What is apical dominance?
      ::什么是典型的主导地位?