Soil Tillage Reduces Availability of ‘Longevity Vitamin’ Ergothioneine in Crops
Soil tillage on farms may significantly reduce the availability in crops of ergothioneine (ERGO), an amino acid produced by certain types of soilborne fungi and bacteria that is known as a “longevity vitamin” due to its potent antioxidant properties, according to new research by an interdisciplinary team at Penn State. The study is among the first to demonstrate that soil disturbance can directly impact a key dietary factor associated with long-term human health.
“Research suggests that a lack of ergothioneine in the diet may result in increased incidences of chronic diseases of aging, such as Parkinson’s Disease and Alzheimer’s Disease, and reduced life expectancy,” said Robert Beelman, professor emeritus of food science.
Beelman noted that ERGO is produced by fungi, which is why mushrooms are among the leading dietary source of this amino acid. However, ERGO produced by soilborne fungi also makes its way into plants.
“Research has demonstrated that tillage of agricultural soils can disrupt fungi populations in the soil and compromise the availability of this important amino acid,” said Sjoerd Duiker, professor of soil management and applied soil physics. “This led us to speculate that agricultural soils that receive minimal or no tillage may have higher levels of fungi, and therefore, crops grown in these soils may have higher ERGO levels than crops grown with aggressive tillage.”
To study the effects of tillage on ERGO content of crop plants, the team turned to an ongoing tillage study that began in 1978 at the Russell E. Larson Agricultural Research Center at Rock Springs in central Pennsylvania. The study comprised a randomized complete block design with three tillage treatments — moldboard plowing/disking/harrowing, which represents the most intense tillage; chisel plowing/disking/harrowing, which represents a medium amount of tillage; and no-till — each replicated four times. The crops grown in the study included maize, soybeans and oats. The team collected grain samples from each of the treatments, ground them into powder and used liquid chromatography and mass spectroscopy to analyze their ERGO content.
The researchers found that ERGO concentrations declined as tillage intensity increased. Specifically, from no-till to moldboard, ERGO content declined by 32 percent for maize, 33 percent for soybeans and 28 percent for oats. In addition to being associated with reduced ERGO concentrations, increased tillage was also associated with reduced crop yields.
The team’s results appear in a recent issue of the journal Agronomy.
“Recently, there has been growing interest in replacing conventional agricultural methods with regenerative agriculture — which includes the use of no-till or minimal tillage — to restore soil health,” said Beelman. “This is important, not only for the environment, but also for human health, as our research suggests that healthy soils produce healthier foods. The fact that we found that crop yields are also higher when tillage is reduced indicates that this practice may also be profitable for farmers.”
Why Does This Matter for Growers? From Dr. Kris Nichols:
Consumers are demanding more nutrient-dense food and are looking to farmers and ranchers to provide it by implementing regenerative agricultural practices to build healthy soils and stimulate microbial activity. To date, linking soil and microbial health to increased human health is difficult to prove conclusively. However, this study demonstrates the negative impacts of tillage on ergothioneine, an antioxidant and anti-inflammatory produced by soil fungi and bacteria that can mitigate chronic diseases of aging (e.g., Parkinson’s, Alzheimer’s). Ergothioneine levels were about 30 percent higher with the lowest amounts of soil disturbance in the no-till system.
Fungi, such as beneficial, symbiotic mycorrhizal fungi and residue-decomposing, mushroom-producing fungi, increase their growth and activities in regenerative systems under low soil disturbance and good residue management, and with the use of cover crops or cropping systems that maintain living roots for as many days a year as possible. For ergothioneine to move from the soil into the human body, it may be ingested directly in the form of mushrooms or by eating plants that have absorbed ergothioneine or animals that have eaten grains containing ergothioneine. Consequently, regenerative agriculture is key to increasing concentrations of ergothioneine — an important antioxidant for long-term human health.
Seed Microbiota Revealed by Meta-analysis of 50 Plant Species
Everyone today recognizes the role of the gut microbiome in human health, as well as the role soil microbiota play in the health of plants. It is thus not surprising that a diverse microbiome is also associated with plants’ seeds.
A new report in the journal New Phytologist shows that seed microbiota constitutes a primary inoculum for plants, aiding in plant health and productivity.
The research team performed a meta-analysis on 63 seed microbiota studies covering 50 plant species to synthesize knowledge on the diversity of this habitat. Seed microbiota are diverse and extremely variable, with taxa richness varying from one to thousands of taxa.
Around 30 bacterial and fungal taxa are present in most plant species and in samples from all over the world. Core taxa, such as Pantoea agglomerans, Pseudomonas viridiflava, P. fluorescens, Cladosporium perangustum and Alternaria sp., are dominant seed taxa.
The researchers believe that the characterization of the core and flexible seed microbiota provided in this report will help uncover seed microbiota roles for plant health and may help design effective microbiome engineering.
How Can Growers Use This Information? From plant biologist Dr. James White:
This study is a genomic examination of the microbes that are present within seeds of 50 species of plants. The authors detected genes of both fungi and bacteria in plants. Along with another paper (Johnston-Monje et al., 2021) that examined seed microbes that later become seedling microbes, this paper suggests that the microbes on seeds may be important for seedlings.
Many of these microbes have been found to play important roles as endophytes in plants. Their presence in seeds enables plants to gain nutrients from soils, and they are important in assisting plant seedlings in developing larger roots, growing root hairs and generally becoming oxidatively resistant (White et al., 2019).
Seed microbes are important to maintain on seeds to promote seedling growth and health. Seed treatments that strip microbes from seeds may cause problems in seedling and plant growth.
Simonin et al. (2022) suggested potential for modifying or engineering plant microbiomes. This is not referring to genetic engineering, but rather to building plant microbiomes to improve plant growth. Genetically engineering microbes is probably not a good idea, or a logical outcome of this research, because genetically modified microbes cannot be limited to a single plant and environmental contamination with genetically modified microbes would result. Many of these microbes move out from plants into soils and colonize other plant species. Scientists are still focused on understanding how plant microbes improve the growth and health of plants, rather than genetically manipulating the microbes.
Health-Promoting Phytonutrients Are Higher in Grass-Fed Meat and Milk
While commission reports and nutritional guidelines raise concerns about the effects of consuming red meat on human health, the impacts of how livestock are raised and finished on consumer health are generally ignored.
Meat and milk — irrespective of rearing practices — provide many essential nutrients, including bioavailable protein, zinc, iron, selenium, calcium and/or B12. Emerging data — detailed in a new meta-analysis published in Frontiers in Sustainable Food Systems — indicate that when livestock are eating a diverse array of plants on pasture, additional health-promoting phytonutrients — terpenoids, phenols, carotenoids and antioxidants — become concentrated in their meat and milk.
Several phytochemicals found in grass-fed meat and milk are in quantities comparable to those found in plant foods known to have anti-inflammatory, anti-carcinogenic and cardioprotective effects. As meat and milk are often not considered sources of phytochemicals, their presence has remained largely underappreciated in discussions of nutritional differences between feedlot-fed (grain-fed) and pasture-finished (grass-fed) meat and dairy, which have predominantly centered around the omega-3 fatty acids and conjugated linoleic acid.
Grazing livestock on plant-species diverse pastures concentrates a wider variety and higher amounts of phytochemicals in meat and milk compared to grazing monoculture pastures, while phytochemicals are further reduced or absent in meat and milk of grain-fed animals. Plants/crops are more productive when grazed in accordance with agroecological principles. The increased phytochemical richness of productive vegetation has potential to improve the health of animals and to upscale these nutrients to also benefit human health.
Several studies have found increased antioxidant activity in meat and milk of grass-fed vs. grain-fed animals. Only a handful of studies have investigated the effects of grass-fed meat and dairy consumption on human health and show potential for anti-inflammatory effects and improved lipoprotein profiles.
However, current knowledge does not allow for direct linking of livestock production practices to human health. Future research should systematically assess linkages between the phytochemical richness of livestock diets, the nutrient density of animal foods and subsequent effects on human metabolic health. This is important given current societal concerns about red meat consumption and human health. Addressing this research gap will require greater collaborative efforts from the fields of agriculture and medicine.
Why Is this Important? From Fred Provenza:
Commission reports and nutrition guidelines raise concerns about the effects of eating red meat on human and environmental health, but the impacts of how livestock are raised and finished are generally ignored. Meat and milk, regardless of rearing practices, provide many essential nutrients including bioavailable protein, zinc, iron, selenium, calcium, and B12.
But that’s not the whole story. When livestock eat diverse arrays of plants, health-promoting phytochemicals are concentrated in their meat and milk. That includes not only energy, protein, minerals, and vitamins, but tens of thousands of compounds such as terpenoids, phenols, carotenoids, and antioxidants. Some phytochemicals in grass-fed meat and milk are in quantities akin to those in plants with anti-inflammatory, anti-carcinogenic, and cardioprotective effects. Plant diversity thus enriches the health of livestock and may, in turn, boost the health of humans.
As meat and milk are often not considered sources of phytochemicals, their presence has remained largely underappreciated in discussions of nutritional differences between pasture- and feedlot-finished livestock, which have focused on omega-3 fatty acids and conjugated linoleic acid. However, livestock grazing diverse pastures concentrate a wider variety and higher amounts of phytochemicals in meat and milk compared to grazing monoculture pastures. Phytochemicals are further reduced or absent in the meat and milk of grain-fed animals.
Long-term studies show diverse mixtures of plants have, relative to monocultures of the same species, ∼150 to 370 percent greater amounts of nitrogen, potassium, calcium and magnesium in plant tissues, and they have ∼30 to 90 percent more soil N, K, Ca, Mg, cation exchange capacity and water- and nutrient-holding carbon. Hence, they store more atmospheric carbon than annual cereal grains. Plants thus turn dirt into soil, and in diverse mixes, they turn soil into homes, grocery stores and pharmacies for countless species of animals below and above ground.
Microbes Found on Raw Fruit Essential to Human Health
Not only are apples delicious but they are also proven to be good for us. And, according to a new study published in Environmental Microbiome, the microbiome and resistome (the organism’s antibiotic resistance genes) of apples change after harvest, but their nutritional benefits are not diminished by storage.
Lise Korsten, a professor at the University of Pretoria, says the study shows that beneficial microbes are prevalent on apples. “From other studies, several species have been described as benefitting the gut microbiome contributing to health and wellness. So the old saying — an apple a day keeps the doctor away — is actually so true. In our paper, we showed these populations are prevalent on our locally produced apples.
“It has also been shown in other studies that these core favorable microbiome populations enhance nutrient absorption in the gut, and one can thus draw parallels between fresh apples favoring a healthy gut microbiome versus other food products — such as processed food — often devoid of healthy microbes and thus not contributing to the maintenance of a healthy gut,” Korsten says.
Why Is This Important? From Kathleen DiChiara:
The gastrointestinal (GI) tract represents one of the largest interfaces between humans and the environment. The collection of bacteria colonizing the GI tract — known as the “gut microbiota” — has co-evolved with the human host over thousands of years to form an intricate and mutually beneficial relationship.
On average, humans eat about 35 tons of food during a lifetime, along with an abundance of microorganisms from the environment. Apples are among the most consumed fruits world-wide. A typical apple contains 100 million bacteria — 1,755 different types. This sounds alarming, but keep in mind that the number of microorganisms inhabiting the GI tract has been estimated to exceed 1014.
The gut microbiota offers a wide range of benefits to the host, from strengthening gut integrity to regulating host immunity. However, there is potential for these mechanisms to be disrupted as a result of an altered microbial composition, known as dysbiosis.
At harvest, all fruit and vegetable microbiomes harbor a large proportion of microorganisms. Overall, the apple microbiome is diverse and versatile, however the current excessive usage of chemicals and antibiotics in agricultural and clinical settings can provoke a shift within produce resistomes that could stress the microbial partnership that humans share with fresh food.
According to a study published in Frontiers in Microbiology, organic apples conceivably feature favorable health effects for the consumer, the plant and the environment in contrast to conventional apples, which were more likely to harbor potential food-borne pathogens.
Exchanging microbial information with the food we eat is a testament to how profoundly interconnected we are with nature. As a long-time proponent of “food is information,” it is pleasing to see the growing body of research supporting the positive impact of plant microbiota on human health.
We are learning more and more about the various ways that the fresh foods we eat everyday may exert synergistic effects in course-correcting our gut microbiology for better health. May this nudge us one step further away from processed food and provide a deeper appreciation for the timeless adage — “An apple a day keeps the doctor away.”
New Technique Allows Precise Imaging of Rhizosphere
The ecosystems made up of bacteria, fungi, plants and the soil — the rhizosphere — are some of the most complex and least understood of all places on earth. Very few of the interactions in these worlds are well understood, and much of what we do know is via inference — not direct observation. Viewing these biogeochemical interactions at the soil-root interface is complicated because this environment includes many different three-dimensional objects that have a wide range of optical properties.
Researchers have now developed a technique to image these interactions, though. Their findings were published in the journal Environmental Science Technology.
The team developed a label-free multiphoton nonlinear imaging approach to provide contrast and chemical information for soil microorganisms in roots and minerals with epi-illumination by simultaneously imaging two-photon excitation fluorescence (TPEF), coherent anti-Stokes Raman scattering (CARS), second-harmonic generation (SHG), and sum-frequency mixing (SFM). They combined these detections to maximize image contrast for live fungi and bacteria in roots and soil matrices without fluorescence labeling.
Using this technique, they were able to image symbiotic arbuscular mycorrhizal fungi (AMF) structures within unstained plant roots in 3D to a depth of 60 microns. High-quality imaging was possible at up to 30 microns in a clay-particle matrix and at 15 microns in a complex soil preparation. It allowed the researcers to identify previously unknown lipid droplets in the symbiotic fungus Serendipita bescii. They also visualized unstained putative bacteria associated with the roots of Brachypodium distachyon in a soil microcosm.
The results show that this multimodal approach holds significant promise for rhizosphere and soil science research.
Why Does This Matter for Growers? From Dr. Robert Kremer:
“A tablespoon of soil contains billions of microorganisms” is a colloquialism frequently expressed by many soil health specialists to provide a relatable, nontechnical description of the biological component of soil health. Although this simple description suggests a great abundance of soil microorganisms, it lacks information in terms of visual evidence of where within the soil matrix they exist, what they do, and how many are actually alive and active.
Visualization of microorganisms directly in the soil habitat has always been challenging. Early techniques — many of which are still in use today — relied on soil or roots mounted on slides and stained for microscopic examination that yielded estimates of numbers and classification of only broad microbial groups based on shape and size, including fungi, bacteria, spores and spore-forming bacteria, actinobacteria, protists and nematodes. Electron microscopic examination yielded images of microorganisms in soils and on roots at magnifications of 10,000 times or more, but the ability to distinguish microbial diversity or function was poor and the sample preparation killed the organisms that appeared in the micrographs. And the advanced techniques of metagenomics, which yields information on taxonomic and functional diversity based on detection of microbial genes extracted from soil and rhizospheres, may be misleading because only about 40 to 60 percent of the total microbiome in the sample is actively functioning, and these techniques cannot distinguish between active and dormant states.
With the availability of multiple imaging systems, as described in the research article, we can now visualize bacteria and fungi as they appear in their microhabitats on soil particles and roots in a live state, because no sample preparation that would disrupt the soil microenvironment and likely kill the microorganisms is required. The images using these techniques show bacteria and fungi, including mycorrhizal structures, established at preferred microsites on soil particles — including organic matter fragments, and on and within roots — showing the variable distribution of these microbial groups within the soil environment. This validates the fact that the soil microbial community is variably distributed due to differences in soil components, presence/absence of roots, moisture, etc. — it is not a homogenous mix in the soil.
Although the images were acquired from simulated systems that promoted microbial growth within soil and roots, future advancements in sensor and optic technology will allow these techniques to be adapted to in-field observations that will have the capability to monitor live microbial and root development over time. This can be useful to growers because these approaches may provide information on how management affects critical soil health indicators.
Regenerative Almond Production Systems Improve Soil Health, Biodiversity, and Profit
Almonds are the dominant crop in California agriculture in terms of acreage and revenue generated. A new article published in Frontiers in Sustainable Food Systems studied the soil health, biodiversity, yield and profit of regenerative and conventional almond production systems that represented farmer-derived best management practices.
Regenerative practices included abandoning some or all synthetic agrichemicals, planting perennial ground covers, integrating livestock, maintaining non-crop habitat and using composts and compost teas.
The study found that total soil carbon, soil organic matter, total soil nitrogen, total soil phosphorous, calcium, sulfur and soil health test scores were all significantly greater in regenerative soils. Water infiltrated regenerative soils six-fold faster than conventional soils. Total microbial biomass, total bacterial biomass, Gram+ bacteria and Actinobacteria were significantly greater in regenerative soils. There was more plant biomass, species diversity and percent cover in regenerative orchards. Invertebrate richness and diversity, and earthworm abundance and biomass, were significantly greater in regenerative orchards.
Pest populations, yields and nutrient density of the almonds were similar in the two systems, but profit was twice as high in the regenerative orchards relative to their conventional counterparts.
No one practice was responsible for the success of regenerative farms — their success was the result of simultaneously combining multiple regenerative practices into a single, functional farm system.
Does Regenerative Grazing Work?
Photos courtesy of Derek and Kirrily Blomfield; the top image was taken in 2014 and the bottom one in 2016. Kirrily says, “The only thing we did was use the cattle to heal this area.”
