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    Dandelion

    Although the dandelion is native to Europe and Asia, it is also wildly (or “weedily”) successful across the United States. Everyone recognizes its bright yellow flowers as a sign of early spring and the feathery, parachuted seed heads as either delightful toys or unwelcome invaders of lawns. However, modern genetic and molecular analysis reveals that dandelion is not at all familiar - and fits none of our traditional categories for reproduction. In fact, dandelions illustrate the plant equivalent of “virgin birth.”
    ::尽管花朵是欧洲和亚洲的本土,但它在美国各地也很狂野(或“杂草 ” ) 。 所有人都承认它亮黄色的花朵是初春的标志,而羽毛、降落伞的种子头则是令人愉快的玩具或不受欢迎的草坪入侵者。 然而,现代遗传和分子分析显示,花朵根本不为人所熟知 — — 也不适合我们的传统生殖类别。 事实上,花朵说明植物相当于“病毒出生 ” 。

    Vegetative Reproduction
    ::植物复制

    In southern Europe and Asia, dandelions reproduce sexually, like most flowering plants. However, in northern Europe and most regions of the world where it is not native, dandelions are either triploid, with three sets of , or tetraploid, with four sets. You may recall that triploid individuals, such as the cultivated banana, are normally sterile, because orderly requires matched pairs of chromosomes. Surprisingly, triploid (and many tetraploid) dandelions manage to reproduce quite successfully - by eliminating meiosis altogether, and producing seeds without pollination . Such seeds are clones, genetically identical to the female parent. Therefore, although dandelion seed production looks very much like , it is actually asexual.
    ::在南欧和亚洲,花朵像大多数花卉植物一样在性繁殖。然而,在北欧和世界上大部分非本地植物的地区,花朵要么是三合一的三合一,要么是四合一的四合一。你可能记得,三合一的人,如种植香蕉,通常都是不育的,因为有秩序需要配对的染色体。 奇怪的是,三合一(和许多四合金)花朵能够非常成功地繁殖 — — 完全消灭美化,在没有授粉的情况下生产种子。这些种子是克隆的,与母性基因相同。因此,虽然种菜籽的生产看起来非常相似,但它实际上是性。

    The process of producing seeds containing genetic material from just one parent is apomixis ,  and despite its obvious circumvention of sexual reproduction, it is not rare among plants. Hawthorns, mountain ash, blackberries, and hawkweeds use apomixis. Most produce seeds with unfertilized eggs which have not undergone meiosis, so the egg is diploid , but some produce seed from unfertilized endosperm ; in both cases, offspring contain only genes of the female parent. The Saharan cypress produces offspring containing only male genes – developing seeds from unfertilized pollen .
    ::仅从父母一方生产含有遗传材料的种子的过程就是一种杂物,尽管这种过程明显绕过性生殖,但在植物中并不罕见。 霍松、山灰、黑莓和鹰草都使用杂草。 多数种种着未经过美化的未受精卵的种子,所以蛋是浸泡的,但有些种来自未受精内分泌的种子;在这两种情况下,后代只含有雌性父母的基因。 撒哈拉的cypress只产生含有男性基因的后代 — — 开发未受精花的种子。

    “Virgin birth” may seem at first to be a trivial oddity of the plant . However, apomixis not only illustrates the variety of methods of plant reproduction, but also suggests methods for reproducing desirable genetic combinations – and raises theoretical questions about the importance of sexual reproduction.
    ::最初,“病毒出生”似乎只是植物中一个微不足道的奇特。 然而,垄断者不仅说明了植物繁殖方法的多样性,而且还提出了复制理想基因组合的方法 — — 并提出了关于性繁殖重要性的理论问题。

    In , hybrid vigor is highly valued. However, because crossbreeding involves sexual reproduction and often results in sterility, hybrid genetic combinations are usually impossible to replicate. Apomixis has the potential for of hybrid genotypes , so horticulturists are actively exploring its genetics in the hope that they will be able to harness its power.
    ::然而,由于交叉繁殖涉及性生殖,而且往往导致不育,混合基因组合通常无法复制。 混合基因组合具有混合基因型的潜力,因此园艺家正在积极探索其遗传学,希望他们能够掌握其力量。

    In contrast to this practical application, other scientists are comparing the advantages and disadvantages of sexual and using a small apomictic (a rotifer), which has apparently survived without sexual reproduction for millions of years. Their initial results suggest that asexual reproduction avoids exposure to damaging “genetic parasites” – segments of that can move around within genomes, causing and loss of genetic material.
    ::与这种实际应用相反,其他科学家正在比较性活动以及使用一个小粒子(转子)的利弊,它显然已经存活了数百万年而没有发生性繁殖。 其初步结果表明,性生殖避免接触破坏性的“遗传寄生虫 ” — —其中一部分可能在基因组内部流动,导致和丧失遗传物质。

    Apomixis is just one of many natural forms of asexual reproduction, and our efforts to understand it and use it for our own ends only begin to illustrate the broad field of plant propagation. This lesson will explore the variety of natural and artificial methods of plant reproduction.
    ::Apomixis只是许多性生殖的自然形式之一,我们为了解它并将其用于我们自己的目的所作的努力,只是开始说明植物传播的广泛领域,这一教训将探讨各种自然和人工的植物生殖方法。

    Asexual (one-parent) plant reproduction, without seeds or spores, is vegetative reproduction . It is most common in perennial plants , whether woody or herbaceous plants. Because vegetative reproduction involves a single parent, offspring individuals are clones of that parent, and vegetative reproduction in many forms clonal colonies. Such colonies lack the characteristic of offspring of sexual reproduction, but have the advantage of multiplying rapidly in relatively stable environments. Vegetative reproduction can be compared not only to sexual reproduction, but also to simple growth of a single individual. Whether or not a new individual formed by vegetative reproduction “sets back the clock” or retains the “age” of its parents, as clones of mammals seem to do, remains under investigation.
    ::性(单亲家庭)植物生殖,没有种子或螺旋,是植物生殖,在常年植物中最为常见,无论是木质植物还是草原植物,由于植物生殖涉及单亲,后代是该父母的克隆人,并且以多种形式在阴道上进行植物生殖。这种聚居缺乏生殖后代的特征,但具有在相对稳定的环境下迅速繁殖的优势。植物生殖不仅可以与生殖相比,还可以与个体的简单生长相比。无论由植物生殖“反时钟”或保留其父母的“年龄”形成的一个新个体,正如哺乳动物的克隆人似乎所做的那样,都仍在调查之中。

    Vegetative reproduction may involve or leaves, but most often modifies . Natural structures of vegetative reproduction include rhizomes, stolons, adventitious buds, suckers, bulbs, tubers, and corms.
    ::植被生殖可能涉及植物繁殖或叶子,但往往会改变植物繁殖的自然结构,包括、石瓜、冒险胚胎、吸尘器、灯泡、管子和螺旋。

    Rhizomes
    ::碎声带Name

    If you have grated fresh ginger for cooking, you have worked with a rhizome – a horizontal stem which grows underground and sends out roots and shoots from its nodes to form new individual plants ( Figure ). Often, thickened rhizomes function for nutrient storage from one season to another, as in ginger. Plants such as Iris and many have rhizomes that run aboveground at the surface. Gardeners and horticulturists reproduce asparagus, Canna lilies, Lily of the Valley, and many orchids as well as Iris and fern by dividing rhizomes.
    ::如果你在烹饪时磨过新鲜的姜,你就会用一种红绿花做工作 — — 一种从地下长出来的水平干茎,从根部和节点发出根和射击,形成新的个体植物(Figure ) 。 通常,像姜一样,一个季节到另一个季节,养分储存的红绿花会变厚。 艾里斯等植物和许多植物在地表的地面上都有红绿花。 园艺人和园艺人繁殖成鹦鹉、坎娜百合、谷里百合、许多兰花以及伊里斯和羊毛,通过分分红花。

     

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    Rhizomes are horizontal, modified underground stems which produce roots and shoots for new individual plants at their nodes. Ginger is an example. Ferns also reproduce by rhizomes, but their stems run at or just above the surface of the soil.

    Stolons
    ::斯图层

    Quite similar to rhizomes are stolons ( Figure ), stems that grow horizontally – often seeking light - at or just below the soil surface, with the potential to produce new individual plants at the tip. These modified stems have leaves reduced to scales, long internodes, and adventitious roots (roots produced by stems rather than branching from other roots) at the nodes. They produce new plants (roots and shoots) from nodal buds. Unlike rhizomes, stolons often die away after new plants are established, and they less often store food .
    ::与Rhizomes非常相似的是石瓜(Figure ) , 石瓜(Figure ) , 它在土壤表面或土壤表面下水平增长 — — 常常寻求光亮 — — 并有可能在顶端生产新的植物。 这些改良的根茎在节点上被缩减为规模、长期的交错和冒险根(由根而不是从其他根根分产生 ) 。 它们从节点萌芽中产生新的植物( 草根和射击 ) 。 与Rhizomes不同的是,石瓜在新植物建立后往往会消失,它们也很少储存食物。

    Most familiar as the “runners” of strawberry plants, stolons are horizontal stems with long internodes, which produce new roots and shoots at their tips.
    Most familiar as the “runners” of strawberry plants, stolons are horizontal stems with long internodes, which produce new roots and shoots at their tips.

    Adventitious Buds
    ::基督复临公德组织

    If you visit Redwoods National Park, you may be able to purchase a piece of redwood trunk sold as a “burl.” Placed in light in a pan of , the trunk will develop buds and eventually shoots, which leaf out into miniature “trees” ( Figure ). Such buds are adventitious buds. Normally, buds develop at the tips of stems from apical meristem tissues , or at nodes as axillary buds. A bud that develops from another part of the stem or roots or leaves is adventitious. In nature, adventitious buds allow new redwoods to sprout from the trunks of trees that have died, or lateral buds to form on the trunks of trees that suddenly receive more light due to windfall of neighboring trees. Adventitious buds can form on leaves, as well; plantlets eventually drop off and further as new individuals. Examples include “piggyback plants” and “mother of thousands.”
    ::如果你参观红木国家公园,你也许能够购买一块红木树干,作为“爆破”出售。 在灯光中,树干将发芽并最终射击,这些芽将叶片变成微型的“树 ” ( Figure ) 。 这些芽是冒险的芽。 通常,芽片从皮质的面部组织或结晶的花蕾中发芽,或者在节点上发芽。从树干或树根或树叶的另一部分发芽的芽是冒险的。 在自然中,冒险的芽片允许新红木从已死亡的树木的树干丛中发芽,或者在树树干上形成横向芽,这些树干因邻近的树木的风落而突然获得更多光。 腐烂的芽可以在树叶上形成,植物最终会消失,并且作为新的人进一步生长。例子包括“蜂蜜植物 ” 和 “ 数千人之母 ” 。

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    Adventitious buds and shoots grow on trunks, leaves, or stems other than at the tips. Pieces of redwood trunk placed in water can produce new shoots (left), as can leaves of Kalanchoe “mother of thousands” (right).

    Suckers
    ::笨蛋

    Sprawled across 43 hectares (107 acres) of the Wasatch Mountains of Utah lives “The Trembling Giant,” a clonal colony of 47,000 genetically identical Quaking Aspen trees, which all “stem” (literally!) from the roots of a single parent, arguably 80,000 years old. The Trembling Giant, also known as “Pando” (Latin for “I spread”), weighs an estimated 6,000 tonnes (6,615 tons), the heaviest known organism . How did Pando arise? Adventitious buds that develop on roots may produce shoots known as suckers, which extend some distance from the parent plant. Quaking Aspen, like a number of other trees and plants such as Canada thistle and many grasses, readily reproduce by means of suckers. For Aspen, although individual neighboring trees may appear above ground to be separate, genetic analysis often reveals that they are clones, and interconnected roots reveal their common ancestry. “Individual” trees may die back, but the interconnected roots develop new buds and suckers to replace them.
    ::犹他州瓦萨奇山的43公顷(107英亩)横跨犹他州瓦萨奇山的43公顷(107英亩),“Trembbling Giant”,是一个由47 000个基因相同的昆虫树组成的阴性聚居区,这些树都是来自单亲的根部,大概有80,000岁左右。Trembling Giant,又称“Pando” (Latera for “I discle”),体重大约6,000吨,是已知的生物体。Pando是如何产生的?根部形成的复仇芽可能会产生被称为吸虫的镜头,它会延伸到母植物的某些距离。Quaking Aspen,像加拿大的和许多草丛一样,很容易通过吸虫繁殖。对于阿斯彭来说,尽管单个邻近的树木可能出现在地面上,但遗传分析往往表明它们是克隆物,而相互关联的根揭示了它们共同的祖先。 “Idividual”树木可能会死,但相互关联的根会形成新的芽和吸食。

    Bulbs
    ::散积

    Onions, lilies, tulips, and some other reproduce by multiplying bulbs - vertical, underground shoots whose layers of thickened, modified leaves (or leaf bases) store food ( Figure ). The stored food often sustains the plant over winter and promotes rapid growth in early spring.
    ::洋葱、百合、郁金香和其他一些由倍增灯泡复制的植物 — — 垂直的、地下的,其层层厚厚的叶子(或叶基)储存着食物(图示 ) 。 储存的食物通常在冬季维持植物,并在早春促进快速生长。

    Onions and many other monocots produce bulbs – modified, underground shoots - for food storage and for vegetative reproduction.
    Onions and many other monocots produce bulbs – modified, underground shoots - for food storage and for vegetative reproduction.

    Tubers
    ::图纸

    Similar to bulbs, in which leaves of shoots thicken to store food, are tubers , in which stems or roots thicken to form food storage and reproductive organs . Stem tubers may develop from stolons or rhizomes. Potato tubers, for example, develop from stolons. The “eyes” of potatoes are the stem nodes; if you have kept potatoes a bit too long, they will develop buds at these nodes, revealing their potential for vegetative reproduction. Potatoes are often planted from “seed” – not seeds at all, but sections of potato tuber containing at least one eye; when shoots from these reach the surface, they grow roots and leaves to become new plants.
    ::土豆的“眼”是干节点;土豆的“眼”是干节点;如果让土豆保持时间过长,它们就会在这些节点上培育芽芽,揭示其植物繁殖潜力。 土豆往往是从“种子”种植的 — — 根本不是种子,而是含有至少一只眼睛的土豆管管子的一部分;当从这些地方射到地表时,它们就会种植树根和树叶,成为新的植物。

    In some plants, tubers may grow from roots rather than stems. Sweet potatoes differ in origin from unrelated white potatoes in this way. As roots, sweet potatoes lack nodes, internodes, and reduced leaves. Therefore, they sprout only from the crown end, growing roots from the opposite end.
    ::在某些植物中,管茎可能从根部而不是根部生长。 甜土豆从根源上与不相关的白土豆不同。 由于根部,甜土豆缺乏节点、插头和叶子减少。 因此,甜土豆只从冠端发芽,从相反端生根。

    Corms
    ::高温

    Another plant storage organ that may double as a reproductive organ is a short vertical swollen stem, known as a corm. Corms have one or more internodes with at least one growing point; thin, papery leaves form a protective skin. Because the storage structure is solid stem tissue, corms differ from bulbs, in which layers of thickened leaves provide storage tissue. Corms store food (usually starch) to help plants to survive inhospitable conditions such as excessive cold, heat, or drought. They may form short stolons terminating in new “cormlets” as a means of asexual reproduction. Plants that form corms include Crocus, Gladiolus, and taro. Taro corms are among the oldest cultivated crops, and remain an important food source in southern Asia and Western Africa.
    ::另一个作为生殖器官可能加倍的植物贮存器官是短垂直膨胀的干叶,称为阴道。 火山口有一个或几个插头,至少有一个生长点;薄的、纸质的叶子形成保护性皮肤。由于储存结构是固体干组织,腐烂与灯泡不同,在灯泡中,厚厚的叶叶层提供贮存组织。 火山口储存食物(通常是淀粉),以帮助植物在寒冷、热或干旱等不适宜的条件下生存。 它们可能形成短质,在新的“圆筒”中结束,作为性生殖的一种手段。 形成阴道的植物包括克罗克斯、格拉迪奥卢斯和塔罗。 塔罗科姆是最早的作物之一,并且仍然是南亚和西非的重要食物来源。

    Summary
    ::摘要

    • Most dandelions are triploid or tetraploid, and make seeds containing only female genetic material.
      ::大部分花层是三重或四面体,种子只含有女性遗传物质。
    • Understanding apomixis allows horticulturists to reproduce otherwise sterile hybrids with desirable genes.
      ::了解popomixis允许园艺学家繁殖具有理想基因的不育杂交。
    • Studying apomictic species shows they have few genetic parasites, common in sexual species.
      ::研究潮湿物种表明,他们几乎没有遗传寄生虫,这在性物种中很常见。
    • Alternative methods of reproduction are important to both horticulture and theoretical biology.
      ::替代生殖方法对园艺和理论生物学都很重要。
    • Vegetative reproduction in plants is asexual reproduction without seeds or spores.
      ::植物中的植物生殖是没有种子或种子的性生殖。
    • Vegetative reproduction produces clones, which lack variation but rapidly reproduce in stable habitats.
      ::植物繁殖产生克隆,这种克隆没有变化,但在稳定的生境中迅速繁殖。
    • The rhizomes of ginger and stolons of strawberries are stems modified for vegetative reproduction.
      ::生姜和草莓的金瓜 都经过改良以进行植物繁殖
    • Adventitious buds on redwood trunks and suckers of aspen roots can produce vast clonal colonies.
      ::红木树干上的复古芽 和骨本根的吸虫 可以产生巨大的阴道殖民地。
    • Food storage organs that double as vegetative reproductive organs include bulbs, tubers, and corms.
      ::食物储存器官,包括灯泡、管子和电流,可加倍成为植物生殖器官。