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Эволюция растений и грибов. - Coggle Diagram

- - - - the lineages that gave rise to plants and fungi diverged more than a billion years ago
        
        From a modest beginning, plants diversified into the roughly 290,000 present-day species with adaptations that enable them to live in all kinds of environments
- - - - The algal ancestors of plants may have carpeted moist fringes of lakes or coastal salt marshes more than 500 million years ago.
        These shallow-water habitats were subject to occasional drying, and natural selection would have favored algae that could survive periodic droughts. Some species accumulated adaptations that enabled them to live permanently above the water line.
        
        The modern-day green algae Coleochaete, which grows at the edges of lakes as disklike, multicellular col-onies, may resemble one of these early plant ancestors.
        
        Adaptations making life on dry land possible had accumulated by about 470 million years ago, the age of the oldest-known land plant fossils
        
        Early plant life would have thrived in the new environment. Bright sunlight was virtually lim-itless on land; the atmosphere had an abundance of carbon dioxide (CO2); and at first there were relatively few pathogens and plant-eating animals.
        
        On the other hand, life on land poses a number of chal-lenges. Because terrestrial organisms are surrounded by air rather than water, they must be able to maintain moisture inside their cells, support the body in a nonbuoyant medium, and reproduce and disperse offspring without water.
        
        multicellular algae like Chara differ from plants such as mosses, ferns, and pines.
        
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- - - - The mat is spongy and retains water. Other bryophytes grow flat against the ground.
        Growth in dense mats facilitates fertilization by flagellated sperm swimming through a film of water left by rain or dew.
        
        The origin of vascular plants occurred about 425 million years ago. Their lignin-hardened vascular tissues provide strong support, enabling stems to stand upright and grow tall on land. Two clades of vascular plants are informally called seedless vascular plants the lycophytes (such as club mosses) and the widespread monilophytes (ferns and their relatives).
        
        The first vascular plants with seeds evolved about 360 million years ago. Today, the seed plant lineage accounts for more than 90% of the approximately 290,000 species of living plants. S
        
        A seed consists of an embryo packaged with a food supply within a protective covering.
        
        Club moss (a lycophyte). Spores are produced in the upright tan-colored structures.
        
        Gymnosperms (from the Greek gymnos, naked, and sperma, seed) were among the earliest seed plants. Seeds of gymnosperms are said to be “naked” because they are not produced in specialized chambers. The largest clade of gymnosperms is the conifers, consisting mainly of cone- bearing trees, such as pine, spruce, and fir. (The term conifer means “cone-bearing.”) Some examples of gymnosperms that are less common are the ornamental ginkgo tree, the palmlike cycads, and desert shrubs in the genus Ephedra
        
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- - - - The feeding structures of a fungus are a network of threadlike filaments called hyphae (singular hypha).
        Hyphae branch repeatedly as they grow, forming a mass known as a mycelium (plural, mycelia)
        
        Unlike plants, which have cellulose cell walls, most fungi have cell walls made of chitin, a strong, flexible nitrogen-containing poly-saccharide, identical to the chitin found in the external skel-etons of insects.
        
        the symbiosis between fungi and plant roots, called a mycorrhiza (plural, mycorrhizae), is of special sig-nificance.fungi that are parasites, obtaining their nutrients at the expense of living plants or animals.
- - - - Populations of frogs in mountainous regions of Central America and Australia have suffered massive mortality from this emerging disease
        
        The zygomycetes are characterized by their protective zygosporangium, where zygotes produce haploid spores by meiosis. This diverse group includes fast-growing molds, such as black bread mold and molds that rot pro-duce such as peaches, strawberries, and sweet potatoes.
        
        The glomeromycetes (from the Latin glomer, ball) form a distinct type of mycorrhiza in which hyphae invade plant root cells, where they branch into tiny treelike structures known as arbuscules.
        
        About 80% of all plants have such symbiotic partnerships with glomeromycetes, which deliver phosphate and other minerals to plants while receiving organic nutrients in exchange.
        
        The ascomycetes, or sac fungi, are named for saclike structures called asci (from the Greek asco, pouch) that produce spores in sexual reproduction. They live in a variety of marine, freshwater, and terrestrial habitats and range in size from unicellular yeasts to elaborate morels and cup fungi.
        
        basidiomycetes, or club fungi. They are named for their club-shaped, spore-producing structure, called a basidium (meaning “little pedestal” in Latin;
        plural, basidia). Many basidiomycete species excel at breaking down the lignin found in wood and thus play key roles as decomposers. For example, shelf fungi often break down the wood of weak or damaged trees and con-tinue to decompose the wood after the tree dies. The basidiomycetes also include two groups of particularly destructive plant parasites, the rusts and smuts
- - - - the clear area between the mold and the bacterial growth is where the antibiotic produced by Penicillium has inhibited the growth of the bacteria (Staphylococcus aureus).
        
        Fungi may play a major role in the future production of biofuels from plants. Ideally, the biofuels would be derived from plants or plant parts that could not be used to feed people or livestock, such as straw, certain grasses, and wood.
        
        Researchers are currently investigating a variety of fungi that produce enzymes capable of digesting the toughest plant parts. Basidiomycetes called white rot fungi (because the enzymatic breakdown of lignin bleaches the brown color out of wood) are promising candidates for providing these enzymes (
- - - - Caribou eat lichens known as reindeer “moss”which grow in their winter feeding grounds of Alaska.
        
        When it rains, a lichen quickly absorbs water and photosynthesizes at a rapid rate. In dry air, it dehydrates and pho-tosynthesis may stop, but the lichen remains alive more or less indefinitely. Some lichens are thousands of years old, rivaling the longevity of the oldest plants and fungi.
        As tough as lichens are, many do not withstand air pollution. Because they get most of their minerals from the air, in the form of dust or compounds dissolved in raindrops, lichens are very sensitive to airborne pollutants.
        The death of lichens is often a sign that air quality in an area is deteriorating.
- - - - shows a reconstruction of an early land plant called Aglaophyton from the Rhynie chert. Although this small plant lacked leaves and roots, microscopic examination of ultrathin sections of Aglaophyton fossils revealed fungal hyphae winding among the plant’s cells.
        Arbuscules identical to those found in living mycorrhizal associations
      - Scientists have studied three of the genes, called sym (for symbiosis) genes, that encode the plant’s side of the molecular “handshake” with mycorrhizal fungi. In a recent paper, researchers reported that sym genes are found in all major lineages of land plants. These results imply that the genes were present in the common ances-tor of land plants. Furthermore, a phylogeny based on analysis of the three genes proved to be virtually identical to the widely accepted phylogeny
        
        The hypothesized importance of sym genes to plants also predicts that their function should have changed little over time. That is, the sym genes of liverworts should work simi-larly to those of flowering plants.
        
        using Agrobacterium to introduce a functional liverwort sym gene into an angiosperm possessing a nonfunctional version of the gene that could not form mycorrhizae. The investigators then applied fungal spores to the roots of transgenic plants and a control group of mutant plants. After several weeks, mycorrhizae were present in the transgenic plant—the result of the liverwort sym gene functioning normally. The control plant had no mycorrhizae.
- - - - In the male reproductive structures of seed plants, haploid spores develop into pollen grains, which are male gametophytes enclosed within a tough wall. Many species, including all coni-fers and many flowering trees, release millions of microscopic pollen grains in great clouds. You may have seen yellowish pollen covering cars or floating on puddles after a spring rain. If a pollen grain lands on a compatible female structure, an event known as pollination, it undergoes mitosis to produce a sperm. In seed plants, the sperm is reduced to a nucleus.
        
        Haploid spores in female reproductive structures develop into ovules, which contain the egg-producing female gametophytes
        
        In many plants, including pines, the seed coat is extended into a winglike structure that catches the breeze and carries the seed far from the parent plant.
- - - - Pollination occurs when a pollen grain, carried by the wind or an animal, lands on the stigma
        
        As in gymnosperms, a tube grows from the pollen grain to the ovule, and a sperm fertilizes the egg,forming a zygote. Also as in gymnosperms,a seed develops from each ovule. Each seed consists of an embryo (a new sporo-phyte) surrounded by a food supply and a seed coat derived from the tissues surrounding the ovule.
        
        Each seed consists of an embryo (a new sporo-phyte) surrounded by a food supply and a seed coat derived from the tissues surrounding the ovule. While the seeds develop the ovary’s wall thickens, forming the fruit that encloses the seeds.
        
        When conditions are favorable,a seed germinates, which means it begins to grow.
        
        Fertilization in angio-sperms usually occurs about 12 hours after pollination, making it possible for the plant to produce seeds in only a few days or weeks. A typical pine takes years to produce seeds.
        Rapid seed production is especially advantageous in harsh environments such as deserts, where growing seasons are extremely short.
        
        A fruit, the ripened ovary of a flower, is an adaptation that helps disperse seeds.
        
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