Chamomile: "Crazy" plant killer

Behind the beauty, hidden killing machines, in the plant world is also the same.
, the name is sweet and fresh. Unbeknowed, it is an invasive "crazy" plant killer, with "death entanglement" as the killer, can be transformed into a "carpet", can also be formed along the vine cover, to other plants and ecological hazards.
to recognize the invasion path and growth mechanism of chamomile, and develop techniques to inhibit the spread of chamomile reproduction, has become a major demand and major problem in the affected areas.
Recently, Researchers Wan Fanghao, Qian Wanqiang and Yan Wei, researchers of Shenzhen Agricultural Genome Research Institute of the Chinese Academy of Agricultural Sciences, jointly constructed a high-quality chromosome-level chrysanthemum reference genome, revealing the molecular mechanism of the environmental adaptation evolution and rapid growth of chamomile in the global invasion process from many angles, and providing new ideas and methods for the research of new techniques for targeted molecular intervention and prevention and control of chamomile. The findings were published In Nature -Newsletter on January 17.native to South and Central America, Chamomile is now widely distributed in more than 70 countries and regions in Asia, the South Pacific and other regions, becoming one of the most harmful invasive alien weeds in the tropical and subtropical regions of the world today.
, one of the authors of the paper, told the China Science Daily that chamomile is a vine plant with strong reproductive capacity, both sexual and asexual. The growth capacity is extremely strong, a section each year about 1000 meters cumulative growth, each section will also produce countless sections, foreign countries also called it "a minute a mile weed."
"they are good at winding and clinging to other plants, covering them and preventing other plants from photodecilysing, causing them to die." In addition, chamomile releases chemicals that affect the soil environment, which inhibits seed germination in other plants. Wan Fanghao said. As a result, chamomile has been dubbed the "ultimate killer of biodiversity", which leads to the loss of biodiversity in invasive areas, thereby destroying ecosystems.
is one of the first invasive alien species in China. Mr Wan said hong Kong first entered the region at the beginning of the last century, invading The Island of Inner Shenzhen in the 1980s and finding large-scale damage in the Pearl River Delta in the 1990s. Subsequently, the expansion and spread of chamomile, invasion of China's Guangdong, Guangxi, Yunnan, Hainan and other places, and a large-scale damage to local agroforestry production, ecological environment and biodiversity caused huge economic losses and serious biosecurity threats.
rough estimate, the ecological economic losses caused by the proliferation of chamomile in the Pearl River Delta region alone amount to about 500 million yuan per year, and the direct and indirect economic losses in the whole distribution area are estimated to be in the billions of dollars.Liu Bo, the first author of the
paper and an associate researcher at the Shenzhen Agricultural Genomics Research Institute of the Chinese Academy of Agricultural Sciences, said there was no genetic evidence of the way chamomile was invaded, transmitted and spread, and the relevant research on prevention and control was weak.
"We hope to analyze the molecular mechanism of the rapid growth of chamomile 'one minute and one mile' through genomic analysis techniques, providing a basis and theoretical basis for the study of intrusive biological intrusion mechanisms, biological characteristics, and molecular targeting prevention and control techniques (RNA interference or gene editing). Liu Bo said.The study constructed a high-quality chromomal-level reference genome, using comparative genomics, metabolomics, transcriptomics and soil macrogenomics, and revealed the molecular mechanism of the adaptive evolution and rapid growth of chamomile environment in many ways.
study found that chamomile has a strong photogasing ability.
"Vi chamomile is a very 'hard-working' plant, it in other plants during rest time 'overtime' absorption of CO2." Peng Changlian, one of the authors of the paper and a professor at South China Normal University, described the important mechanism of photomassing for the rapid growth of chamomile with "working during the day and working overtime at night".
Chamomile genus C3 plant, through genome-wide sequencing analysis, the researchers found that in normal environments (non-arid high temperatures, desert Gobi and other harsh environmental conditions) growth of chamomile may have another pathway of photodeteal carbon assification - jingtian acid metabolism pathway (CAM approach). Cam pathway is generally a kind of photogastic metabolism pathway that some meaty plants grow in tropical and subtropical arid and semi-arid areas, and its leaf pores are closed during the day and open at night, which is a photogastic metabolism pathway adapted to extreme environments.
" plants with this pathway generally have lower photolysal rates and slow growth, but can survive and grow in harsh environmental conditions, such as cacti, pineapples, etc. Peng Changlian said.
Researchers analyzed the results of day and night changes in transcription groups, organic acids, enzyme activity, and leaf pore electron microscopes to find that the pores of chamomile leaves were open day or night, and that the photolyzyme PEPC and NADP-ME that fixed CO2 in the night CAM pathway were significantly more active than during the day, and accumulated large amounts of organic acids , machi acid. This may be an important reason why chamomile has a significantly higher net photogastoty rate than other C3 plants, or even close to C4 plants.
" means that during the day and at night, chamomile uses different photogasing pathways to fix CO2, providing sufficient carbon hydration for its rapid growth. Peng Changlian said that if this photo-cooperative feature of chamomile can be realized in crops in the future through further research, so that it also "overtime" at night will help to improve its yield, which provides a new way of thinking and research for crop photolycering pathways to improve crop yields.
addition, chamomile's stems, like leaves, have strong photocrysive capabilities. Peng Changlian told reporters,
Usually, leaves are the nutrient organs used by plants for photomassing, and we often see that when the leaves of plants wither and fall, the plant basically dies, but chamomile is not." In
researchers conducted a leaf-cutting control experiment with a group of chamomile and six companion plants, in which all leaves of all plants were artificially cut off. It was found that after 30 days, chamomile was still able to grow normally, and more than 90% of the plants in the control plant died.
then transplication group analysis, it was found that the expression of key genes in the Calvin cycle after chamomile leaf shearing showed a significant increase.
results show that the stems of chamomile have strong photolysaling compensation ability, which supports their invasion, planting and rapid growth in the new environment. also has a "biological weapon" - the chemical effect. It affects the soil by secreting some organic compounds through the root, which inhibits the seed germination and growth of plants, thus rapidly forming single-optimal populations and destroying the biodiversity of invasive areas. Yan Jian, one of the authors of the
paper and a professor at South China Agricultural University, said that the study isolated and extracted five compounds of the chemically sensing substances specific to Jazeran on the basis of previous work, and constructed its gene co-expression network using transcription data, which laid the foundation for further study of the synthetic path of metabolic substances.
, how does Vecry Chamomile's "biological weapon" work?
researchers used soil physiculation, 16S rRNA and root soil macrogenomics to systematically analyze the nitrogen circulation of soil by chamomile endosperm, and initially analyzed the mechanism of action of these five chemically sensing substances to promote soil nutrient circulation.
results showed that the mineralization of soil nutrients such as nitrogen, phosphorus and potassium was significantly lower than that of the control group, but the effective nitrogen was significantly higher than that of the control group. Compared with the control group, the ethyl chamomile root soil was significantly rich in key enzymes associated with microbial nitrogen fixation, while reducing the abundance of anti-nitrotic bacteria.
" in the process of anti-nitrification, anti-nitrification bacteria under the action of a variety of enzymes to convert nitrates into nitrogen and nitrous oxide. When nitrogen fixation bacteria increase and anti-nitrification bacteria decrease, more nitrogen in the atmosphere can be stored in the soil, so that plants can get more nitrogen sources to help plants grow. Zhai Wei explained.
Through the addition of 5 kinds of chamomile endoenthyl experiments in blank soil, it is further proved that the effective nitrogen content, soil breathing effect, nitrogen fixation bacteria and the number of ammonia bacteria were significantly increased in the soil with the addition of chamomile endoensurium.
The above results show that chamomile may release a large amount of chemically sensing material in the soil through the fall of leaves and flowers, and accelerate the nutrient cycle of the root soil through chemically sensing material, providing sufficient nutrients for its rapid growth, which provides new research ideas for further study of bio-fertilizers.
" this study combines high-flung sequencing, multi-histology, physiological biochemistry and molecular biology, from plant self-evolution to the collaborative evolution of plant metabolites to the microenn environment of the root soil, and initially reveals the molecular mechanism of the environmental adaptability and rapid growth of chamomile, which lays a solid theoretical foundation for further study of the genetic mechanism of excellent characteristics and the development of bio-targeted molecular intervention and control technology. Liu Bo said. in the report " Vecry Chamomile - Invasion of Alien Species to China": "Experts have calculated by mathematical formulas that a seed of Chamomile can reproduce in a number of megaseeds over a five-year basis ... Not only is it enough to sow the entire earth's surface, it can even cover all the planets of the solar system. "
about chamomile, people don't fully understand it.
"We found that chamomile has a high photogasing capability, but to find out its specific molecular mechanism is what needs to be studied next." In addition, the function of the key genes or enzymes involved in the synthesis path of the main effect-sensing substance of chamomile has not been verified, and the molecular mechanism of compounds to promote soil nutrient circulation, as well as the mechanism of the interoperability between chamomile and soil, also need to be further studied and excavated. Qian Wanqiang said.
prevention and control of chamomile, has become a global action.
Liu Bo, the current global chamomile prevention and control, mainly divided into manual removal, chemical pesticide control and biological prevention and control. Manual removal is time-time-and-effort, chemical pesticides on ecosystems, soil nutrients, poultry and livestock and human health are serious hazards, biological control is currently taking natural enemy insect control and fungal control.
"We are now exploring biological control methods, the introduction of a fungus from abroad, a large number of experiments abroad have verified that the fungus is highly specialized in chamomile, will not harm other organisms, in the South Pacific and other places after the effect is quite significant. Since our introduction, many native plants have been added for testing, and experiments in the laboratory have been successful, only harmful to chamomile, and other plants have not been infected. When all conditions are ripe, they will likely be phased in. Wan Fanghao said.
relevant paper information: