How non-host plants participate in the plant mycorrhizal network in Tibet

How do non-host plants "join group chat" in the mycorrhizal network of plants underground in Tibet

How do non-host plants "join group chat" in the plant mycorrhizal network underground? How do non-host plants "join group chat" in the plant mycorrhizal network under Tibet

Mycorrhiza usually refers to the symbiosis of certain fungi and plant roots in the soil
.

Its main function is to expand the root absorption area, increase the absorption capacity of elements such as nitrogen and phosphorus outside the original root hair absorption range, and then increase plant nutrient absorption, growth and yield, and the fungus obtains photosynthetic absorption carbon from the host plant

In the roots, stems, leaves, flowers and fruits of plants, there are a large number of highly diversified bacteria, fungi, archaea, and protists.
They play an important role in plant growth and development, nutrient absorption, biological and abiotic stress resistance.
Sex and other aspects play an important role, forming a "symbiotic totality" with host plants, interacting with each other and co-evolving
.

More than 90% of terrestrial plants can form a mycorrhizal relationship with fungi
.

The common types in agroforestry ecosystems are arbuscular mycorrhizal and ectomycorrhizal, but at the same time, about 10% of plants are still non-mycorrhizal plants

In the English journal recently published "Plant Diversity", Chinese Kexue Yuan Kunming Institute of Botany (hereinafter referred to as Zhong Keyuan Kunming Institute of Botany) Researchers propose new ideas to participate in non-host plants mycorrhizal network, causing widespread concern
.

Academy of Sciences Zhong ASTRI ASTRI

Reciprocal symbiosis between host plant and mycorrhiza

Reciprocal symbiosis between host plant and mycorrhiza

Mycorrhiza usually refers to the symbiosis of certain fungi and plant roots in the soil
.

Its main function is to expand the root absorption area, increase the absorption capacity of elements such as nitrogen and phosphorus outside the original root hair absorption range, and then increase plant nutrient absorption, growth and yield, and the fungus obtains photosynthetic absorption carbon from the host plant

"Of the more than 10,000 common plants in the terrestrial ecosystem, about 80% to 90% symbiosis with mycorrhizal fungi to form mycorrhizas
.

This symbiosis is good for plants and fungi, thereby increasing their chances of survival

Zhong ASTRI ASTRI

Under natural conditions, a plant can co-exist with multiple fungi, and a fungus can also have multiple host plants.
When the roots of multiple plants are connected by underground mycorrhizal hyphae, a mycorrhizal network is formed
.

Through the mycorrhizal network, different plants can carry out water and nutrient transfer, disease and insect signal transduction and early warning, so as to promote plants to adapt to complex environments and shape specific plant communities

At present, mycorrhizal is divided into arbuscular mycorrhizal, branch mycorrhiza, ectomycorrhizal, couma mycorrhizal, unidirectional mycorrhiza, etc.
Among them, arbuscular mycorrhizal and ectomycorrhizal are common mycorrhizas, which are also agricultural And the most important mycorrhiza in the natural ecosystem
.

However, in nature, about 10% of plants are still non-mycorrhizal plants, such as Proteas, Chenopodiaceae, most species of Cruciferae, legumes and a small part of Cactaceae
.

Non-mycorrhizal plants and plants that cannot form a mycorrhizal with a specific fungus are called non-host plants of the mycorrhizal fungus

Long-term research believes that non-host plants do not participate in the mycorrhizal network, but is this really the case?

Hyphae can also infect non-host plants

Hyphae can also infect non-host plants

In the 1980s, it was discovered that some truffles, especially in fungus ponds such as black spore truffles and summer truffles, were rare in non-host plants such as weeds, and their growth was obviously inhibited, resulting in an obvious fire-like formation around the host.
After the same "ring", people call it "fire ring"
.

However, for a long time, people know little about the formation mechanism of the "burning circle", whether non-host plants participate in the mycorrhizal network, and the research on the interaction between mycorrhizal-mediated host and non-host plants is also very limited

In fact, the mycelium, mycorrhiza and fruiting bodies of Nigrosporium truffles that form the "burning circle" will produce volatile organic compounds and plant hormones, such as ethylene and auxins, which affect the germination and root growth of non-host plant seeds.
Morphogenesis and rhizosphere microbial communities inhibit their growth
.

"Similarly, we found that the growth of the cruciferous non-mycorrhizal plant Arabidopsis thaliana is also significantly inhibited when it is adjacent to the 37-month-old'Ilex Quercus-Nigrosporium' mycorrhizal seedling
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" Southwest China Yu Fuqiang, deputy director of the Wildlife Germplasm Bank and senior engineer of the Kunming Institute of Botany, said, but it should be noted that not all truffle species can form "burning circles" or similar phenomena

Yu Fuqiang, Wang Yanliang and others took the phenomenon of fungus ponds as the starting point and found that many arbuscular mycorrhizal and ectomycorrhizal hyphae can infect the roots of non-host plants under the premise of the presence of the host, but they do not form a characteristic mycorrhizal structure
.

"So far, many studies have shown that arbuscular mycorrhizal hyphae can infect the roots of non-host plants
.
" Yu Fuqiang said, but arbuscular mycorrhizal invading the roots of non-mycorrhizal plants such as Arabidopsis requires an arbuscular mycorrhizal host The coexistence of plants indicates that arbuscular mycorrhizal fungal hyphae alone may not be able to colonize the roots of non-host plants
.
Only a few studies have shown that host plants are not necessary, and that mycorrhizal hyphae infect the roots of non-host plants may be driven by host plants
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Some ectomycorrhizal fungal hyphae can also colonize the living roots of non-exomycorrhizal plants.
For example, truffle hyphae can be detected inside the roots of plants in the "fire ring" of truffles
.
These ectomycorrhizal fungi may colonize the roots of non-ectomycorrhizal plants in a loose manner, but do not form an ectomycorrhizal structure, similar to endophytes in plant roots
.

"In general, many studies have shown that non-mycorrhizal plants can be connected by the mycorrhizal hyphae supported by the host.
This is a prerequisite for the establishment of a mycorrhizal network
.
" Wang Yanliang said that although a typical mycorrhizal structure is not formed, it is determined The colonized mycorrhizal hyphae can survive on the roots of non-host plants and have certain functions
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Mycorrhizal hyphae significantly inhibit the growth of non-host plants

Mycorrhizal hyphae significantly inhibit the growth of non-host plants

It has long been known that arbuscular mycorrhizal plants have obvious adverse effects on the growth of non-mycorrhizal plants "neighbors", especially for the cruciferous family
.
When mycorrhizal hypha exists, the root branches, root hair development and above-ground biomass of non-mycorrhizal plants "neighbors" are inhibited
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"Experimental data directly proves that the mycorrhizal hyphae supported by the host can penetrate or colonize the roots of non-host plants without forming a typical mycorrhizal structure
.
" Yu Fuqiang said that non-host plants are most susceptible to the mycorrhiza supported by the host.
Due to the adverse effects of fungi, the growth of the host is also affected to varying degrees
.
Arbuscular mycorrhizal and ectomycorrhizal fungi have different effects on the growth and nutrient acquisition of host and non-host plants in the tripartite system of "host plant-mycorrhizal fungus-non-host plant"
.
The tripartite system formed by "host plant-mycorrhizal fungus-non-host plant" has a significant inhibitory effect on the growth and nutrient absorption of non-host plants; interestingly, the presence of non-host plants can significantly improve the nigrospore tuber-Ilex oak Mycorrhizal seedlings rhizosphere tuber mycelium quantity, and promote the nitrogen absorption of holly oak
.

Studies using arbuscular mycorrhizal-Arabidopsis thaliana as a model found that mycorrhizal hyphae infecting the roots of non-host plants induce the early fungal-host recognition signal mechanism, but the defense mechanism is activated later
.
This process is different from the process of pathogenic bacteria and plant endophytic fungi infecting plants, and it is also different from the molecular response mechanism of hyphae infecting host plants
.
At the same time, mycorrhizal hyphae infect the roots of non-host plants, which can enhance the immunity of non-host plants
.

Based on the above facts, the research team proposed that non-host plants can also participate in the regulation of mycorrhizal network, and listed some urgent scientific questions in this research direction: Can mycorrhizal fungi colonize non-host plants through hyphae? Acquire and or transfer carbon, nitrogen and other mineral nutrients? Does the mycorrhizal hyphae supported by the host always negatively affect the growth of non-host plants? What are the effects on the growth and development of the host plant itself? What is the mechanism behind the influence of the tripartite system of "host plant-mycorrhizal fungus-non-host plant" on the growth and nutrient acquisition of host and non-host plants? .
.
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"At present, crop intercropping has attracted much attention because of its low input, high yield and control of diseases and insect pests
.
" Yu Fuqiang said, the impact of mycorrhizal plant grain or legume intercropping with non-mycorrhizal crop rape is worthy of attention
.
In the future, interplanting of gramineous cereals and cruciferous crops will be a good system for studying the interaction between mycorrhiza-mediated host and non-host plants
.
The application of multiple new technologies such as secondary ion mass spectrometry, stable carbon and nitrogen isotopes, transcriptome, metabolome, etc.
will promote research in this direction
.