Name: how plant microbes affect growth
Uploaded: 2026-03-12T13:57:28.000Z
Duration: 1 min 9 s
Channel: JoVE

微生物と植物の相互作用は双方向の化学シグナル伝達に依存し、有益な場合もあれば中立的場合もあれば有害な場合もあります。内生微生物は植物組織内に生息し、しばしば宿主と共生関係を築きます。例えば、大豆などのマメ科植物には根茎を形成する窒素固定細菌である根茎が存在します。これらは糖分と引き換えに固定を通じて植物に利用可能な窒素を提供する相互に有益な相互作用を持っています。しかし、トマトのような非マメ科植物は、リゾビアと中立的な相互作用を示します。彼らはお互いの生存や機能に大きな影響を与えることなく共存しています。一方で、有害な微生物も存在します。ア グロバクテリウム・トゥメファシエンスのような細菌性病原体は傷口から侵入し、冠胆腫瘍を引き起こします。白カビ菌のような壊死栄養菌は、毒素や酵素を使って植物細胞を殺します。

微生物と植物の相互作用

Microbe-Plant Interactions

微生物と植物の相互作用は、複雑な化学シグナルによって形成された動的な関係スペクトルを表します。これらの相互作用は中立的、有益、または有害であり、植物の生理学、成長、生態系の機能に深い影響を与えます。細菌、菌類、古細菌、原生生物、ウイルスからなる植物マイクロバイオームは、表面の定着、内部定着、または全身的な共生を通じてこれらの影響を媒介する上で重要な役割を果たします。特に菌根菌との相利関係は、植物の健康の基盤となります。これらの菌類はアーバスキュラー菌根菌根菌(アーバスキュラー菌根菌根菌)に分類され、植物根と広範なネットワークを形成し、土壌由来の栄養素や水を植物固定炭水化物と交換します。この共生は特にリンや微量栄養素などの栄養素の吸収を促進し、非生物的ストレスからの保護を提供します。植物表面に生息するス フィンゴモナスのような着生微生物は、紫外線(UV)吸収色素を生成することで光保護を提供し、間接的に病原体の定着を抑止する可能性があります。内生微生物は植物組織内に害を及ぼすことなく存在し、しばしば宿主のレジリエンスを向上させます。共生窒素固定細菌、例えば リゾビウム 属は、マメ科植物の根の結節のような特殊な構造を形成し、大気中の窒素(N₂)をアンモニア(NH₃)に変換することで、植物による窒素同化を促進し、土壌の肥沃度を高めます。対照的に、病原性微生物は植物の機能を妨げ、農業に大きな損失をもたらすことがあります。 プッチニア・レコンディタ (小麦葉さび病)のような生物栄養菌類は、即死を引き起こすことなく生きた細胞から栄養を抽出します。 Sclerotinia sclerotiorum (白カビ)を含む壊死栄養性菌類は、酵素分解と毒素生成を通じて宿主細胞を殺し、その後残骸を消費します。アグロバクテリウム・トゥメファシエンスのような細菌病原体は、水平遺伝子移動を通じて植物ゲノム発現を操作し、腫瘍様の胆嚢を誘発します。晩性枯病の病原であるPhytophthora infestansのような原生生物や、タバコモザイクウイルス(TMV)のようなウイルスは、植物を標的とする多様な病原性戦略をさらに示しています。これらの相互作用を理解することで、作物生産性の向上、病気抵抗性の向上、持続可能な農業実践の洞察が得られます。

Microbe-plant interactions represent a dynamic spectrum of associations shaped by intricate chemical signaling. These interactions can be neutral, ...

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Education

JoVE Core

Microbiology

微生物学

Unit

ユニット

Microbial Ecology

微生物生態学

KEY TERMS AND CONCEPTS

主要用語と概念

how plant microbes affect growth

Plant microbes can help, harm, or simply live alongside their hosts. These microbe-plant interactions shape plant growth, health, and ecosystem function. The plant microbiome includes bacteria, fungi, archaea, protists, and viruses, and these organisms may live on the plant surface, inside plant tissues, or in symbiosis throughout the plant.

Some of the most important beneficial partnerships involve mycorrhizal fungi. These fungi form close connections with roots and are grouped as arbuscular mycorrhizae or ectomycorrhizae. In exchange for plant-made carbohydrates, they help plants take up water, phosphorus, and other micronutrients. They can also improve tolerance to abiotic stress.

Other helpful microbes live on the plant surface or inside plant tissue. Epiphytic microbes, such as Sphingomonas, live on plant surfaces and can produce pigments that absorb ultraviolet light. This can protect plants from UV damage and may also make it harder for pathogens to colonize. Endophytic microorganisms live inside plant tissues without causing harm, and they often increase host resilience.

Nitrogen-fixing bacteria also support plant nutrition. Rhizobium species form root nodules in legumes and convert atmospheric nitrogen (N2) into ammonia (NH3). This gives the plant a usable form of nitrogen and can improve soil fertility.

Not all plant microbes are helpful. Biotrophic fungi, such as Puccinia recondita, take nutrients from living cells without killing them right away. Necrotrophic fungi, including Sclerotinia sclerotiorum, kill host cells with enzymes and toxins before feeding on the dead tissue. Bacterial pathogens like Agrobacterium tumefaciens can change plant gene expression by horizontal gene transfer and cause tumor-like galls. Protists such as Phytophthora infestans and viruses like Tobacco mosaic virus also damage plants. Studying these interactions helps explain crop loss and supports better disease resistance and sustainable agriculture.

How Plant Microbes Affect Growth

introduction to microbial ecology

Microbial Communities in Soil and Extremes

Microbial ecology looks at how microorganisms live, interact, and adapt in different ecosystems. It also shows how these tiny organisms help shape nutrient cycling, energy flow, and environmental balance. An ecosystem includes living parts and non-living parts, and microbes respond to both. Microorganisms can form populations, which are groups of the same species living together at the same time. When populations from different species live and interact in the same place, they form a microbial...

ecological niche

Microbial Niches in Ecosystems

Microbial niches describe how microorganisms survive, grow, and interact in an ecosystem. A niche includes how a microbe gets resources, reproduces, and relates to other species in its environment. This idea helps explain microbial community dynamics, biogeography, and ecosystem function. A microorganism’s fundamental niche is the full range of conditions where it could survive, grow, and reproduce. These conditions include both biotic factors, such as living interactions, and abiotic factors,...

methods to assess microbial populations

Measuring Microbes in Samples

Measuring microbes in a sample helps scientists study health, ecology, and industry. Microbial counts can show how many cells are present, how diverse they are, and what they may be doing. To do this, researchers use both culture-based and molecular methods. A viable plate count is a classic culture method for estimating living microbes. The sample is first diluted step by step, then spread on nutrient agar plates. Each viable cell can grow into a visible colony, so the colonies can be counted.

methods to assess microbial communities

Measuring Microbial Diversity and Activity

Microbial communities include bacteria, archaea, and eukaryotic microorganisms. They live in many ecosystems and affect important environmental and biological processes. Scientists study these communities by looking at how many species are present, how many individuals each species has, and how evenly the species are spread out. Species richness is the number of different species in a sample. Species abundance is the relative amount of each species. Species evenness describes how uniformly the...

the winogradsky column

Microbial Layers Inside a Winogradsky Column

A Winogradsky column shows how microbial layers form in a simple, sealed ecosystem. It is a clear model for studying microbial ecology and how different metabolisms interact in sediment over time. The setup uses a transparent glass cylinder. Half of it is filled with sediment mixed with cellulose, such as shredded paper, calcium carbonate, and gypsum. The cellulose provides a carbon source. Calcium carbonate buffers pH, and gypsum supplies sulfate. The rest of the cylinder is filled with pond...

microenvironments

Microbial Niches in Tiny Habitats

Microorganisms live in tiny habitats called microenvironments. These spaces have their own physical and chemical conditions. Oxygen level, pH, temperature, light, and nutrient supply can all differ from the surrounding area. These local conditions strongly affect microbial growth, metabolism, and which species can live there. Microenvironments often have sharp gradients over very small distances. In soil, oxygen may be available at the particle surface but drop off just a few millimeters below.

microbial mats

Microbial Mats and Oxygen Gradients

Microbial mats are layered communities of microbes that grow in response to changes in light, oxygen, and nutrients. These ecosystems are highly organized, and different microorganisms live at different depths. Biofilms are the early stage of this growth and are only a few millimeters thick. Mature microbial mats can grow to centimeter scale and show clear vertical structure. This layered arrangement lets microbes fill separate niches within a very small space. In cyanobacterial mats from hot...

microbial interactions: mutualism

Mutualistic Partnerships in Nature

Mutualistic partnerships in nature show how two or more organisms can benefit from living together. These symbiotic relationships can be obligate, meaning the partners depend on each other, or facultative, meaning the association is helpful but not required. Mutualism helps support many ecosystem functions across land and water. One common example is the partnership between plant roots and mycorrhizal fungi, such as Rhizophagus species. The fungal hyphae grow into the root hairs and epidermis,...

microbial interactions: cooperation

Microbial Cooperation in Soil and Hosts

Microbial cooperation describes helpful interactions between different species. In these partnerships, microbes work together for one or mutual benefit. These interactions can shape ecosystems and evolution. They also play major roles in symbiosis and disease. One clear example involves the Gram-negative bacterium Xenorhabdus nematophila and the parasitic nematode Steinernema carpocapsae. Juvenile nematodes carry the bacteria in the soil and need an insect host to mature. When the nematode...

microbial interactions: predation

How Microbes Hunt and Defend

Microbial predation is a form of interaction in which one microorganism kills and eats another to gain nutrients and energy. It includes both bacterial predators and protozoan predators. This process helps shape microbial communities and affects how nutrients move through the environment. Some bacterial predators attack from the outside, while others enter the prey cell. Epibiotic predators, such as Vampirococcus, attach to the surface of a prey cell and release hydrolytic enzymes. These...

microbial interactions: competition

Microbial Competition and Niche Partitioning

Microbial competition shapes how bacteria and other microbes share space and resources. In shared environments, they compete for nutrients, space, or light. The strength of this competition depends on the environment, including nutrient levels, space limits, and how many microbial species are present. These interactions help determine the structure, function, and resilience of microbial communities. Microbial competition is usually grouped into exploitative competition and interference...

microbial interactions: parasitism

Microbial Parasites and Host Dependence

Microbial parasites depend on a host for nutrients and shelter, and this dependence often harms the host. In parasitism, only the parasite benefits. This is different from mutualism, where both organisms gain from the relationship. Microbial parasites are classified by where they live in or on the host. Ectoparasites stay on the host’s surface, such as the skin or outer tissues, and take in nutrients from outside. Endoparasites live inside the host’s body and invade tissues or organs.

microbe-plant interactions

Plant microbes can help, harm, or simply live alongside their hosts. These microbe-plant interactions shape plant growth, health, and ecosystem function. The plant microbiome includes bacteria, fungi, archaea, protists, and viruses, and these organisms may live on the plant surface, inside plant tissues, or in symbiosis throughout the plant. Some of the most important beneficial partnerships involve mycorrhizal fungi. These fungi form close connections with roots and are grouped as arbuscular...

microbes and the carbon cycle

How Microbes Move Carbon Through Earth

Microbes move carbon through Earth’s major reservoirs and help drive the carbon cycle. Carbon shifts among the biosphere, lithosphere, atmosphere, and hydrosphere, where it supports life and helps regulate climate. It commonly cycles as carbon dioxide (CO2), the oxidized form of carbon, but methane (CH4) and organic compounds also matter. Photosynthetic microbes take in atmospheric CO2 and turn it into organic carbon. Cyanobacteria are especially important because they carry out oxygenic...

microbes and methanogenesis

How Microbes Produce Methane

Methane production in anaerobic ecosystems depends on methanogenic archaea and the microbes that work with them. This process happens where oxygen is absent, such as wetlands, sediments, and animal gastrointestinal tracts. In these anoxic habitats, aerobic respiration cannot run, so microbes use other pathways to break down organic matter. Anaerobic decomposition starts when cellulolytic bacteria, or cellulose-digesting bacteria, hydrolyze dead organic material into simple sugars. Other...

microbes and the nitrogen cycle

Microbial Steps in the Nitrogen Cycle

Microbes drive the nitrogen cycle by changing nitrogen into forms that plants and other organisms can use. This biogeochemical cycle keeps nitrogenous compounds balanced in ecosystems. It also supports plant growth and microbial growth. Nitrogen fixation begins the cycle by converting inert atmospheric nitrogen gas, N2, into ammonia, NH3. This step depends on nitrogenase enzymes. Free-living diazotrophs do this on their own. Aerobic bacteria such as Azotobacter spp. and anaerobic bacteria such...

microbes and the sulfur cycle

Sulfur Cycling Through Microbial Reactions

Sulfur cycling depends on microbial reactions that move sulfur through rocks, water, soil, and the air. In Earth systems, sulfur shifts among inorganic forms such as sulfate, elemental sulfur, and sulfide. These changes happen through both abiotic processes and biological activity in oxic and anoxic environments. Sulfate is the most oxidized form of sulfur. It is stored mainly in rocks, marine sediments, and ocean water, where it acts as a long-term reservoir in the global sulfur cycle. In...

microbes and other elemental cycles

Microbes Driving Iron and Manganese Cycles

Microbes drive iron and manganese cycling in aquatic environments by changing these metals between reduced and oxidized forms. These reactions are especially important along redox gradients, where oxygen levels shift across stratified water layers. The microbes use these metals for energy, growth, and structural needs. In oxygen-rich surface waters, iron is usually present as insoluble ferric iron, Fe(III). Some bacteria release siderophores, which are small organic molecules that bind ferric...

marine microbial ecology

Microbial Life in the Ocean

Marine microbial life is shaped by salinity, low nutrients, and changing oxygen levels. These physical and chemical limits influence which microbes can survive and how they function. They also affect how ocean microbes help drive nutrient and carbon cycling. Small cell size is common in these environments because it gives microbes a larger surface-to-volume ratio. That helps them take up nutrients more efficiently when nutrients are scarce. In estuaries, where salinity changes often,...

deep sea microbial ecology

Deep Sea Microbes and Extreme Conditions

Deep sea microbes live in one of Earth’s harshest environments. The deep ocean is far below the sunlit photic zone, which usually reaches the upper 100 to 200 meters of open water. Below that layer, the bathypelagic and abyssal zones stretch from about 1,000 to 6,000 meters, and hadal trenches go even deeper. This region is dark, cold, and highly pressurized. Temperatures are usually around 2 to 3°C, although hydrothermal vents can be slightly warmer. Pressure rises by about 1 atmosphere for...

freshwater microbial ecology

Microbes in Streams, Lakes, and Rivers

Freshwater microbes live in streams, rivers, lakes, ponds, and marshes, but their communities change with water movement, light, depth, and nutrients. These systems are often grouped into lotic waters, which flow, and lentic waters, which are still or slow-moving. The physical setting shapes where microbes grow and how they get energy. In lentic systems, phytoplankton are the main producers. They make autochthonous organic carbon, which means carbon made within the water body. In lotic...

soil microbial ecology

How Soil Microbes Cycle Nutrients

Soil microbes drive nutrient cycling, organic matter turnover, and ecosystem stability. A gram of soil can contain thousands of bacterial and archaeal taxa, but their shared job is what helps sustain land ecosystems. Their activity changes the way carbon, nitrogen, and other nutrients move through soil. Soil is a patchwork of minerals, organic matter, water, and air. Microbes live in tiny microhabitats shaped by pore size, moisture, oxygen, and nutrients. Sandy soils drain fast and tend to...

key terms and concepts

Learn how helpful and harmful microbes interact with plants, from mycorrhizal fungi and Rhizobium to rust fungi, blight, and plant viruses.

How Plant Microbes Affect Growth | JoVE K12

JoVE Core Microbiology provides an engaging introduction to the microbial world and its influence on health, industry, and the environment. This comprehensive collection covers key concepts such as microbial structure, metabolism, genetics, and ecology. It introduces essential laboratory techniques and microscopy methods through visually engaging animations. Corresponding scientist-in-action videos bridge classroom concepts with real-world research and applications.

microbiology

How Plant Microbes Affect Growth

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