Year: 2023

Chloroplasts are a key player in plant immunity

December 4, 2023 by IAPPS

by UC Davis

Scientists have long known that chloroplasts help plants turn the sun’s energy into food, but a new study, led by plant biologists at the University of California, Davis, shows that they are also essential for plant immunity to viral and bacterial pathogens.

Chloroplasts are generally spherical, but a small percentage of them change their shape and send out tube-like projections called “stromules.” First observed over a century ago, the biological function of stromules has remained enigmatic.

Previous studies have shown that chloroplasts produce more stromules when a plant detects an infection. Stromules aid in clustering chloroplasts around the nucleus and function as conduits to transport pro-defense signals from chloroplasts to the nucleus. Despite these findings, researchers have not been able to determine the role of stromules in immunity, as no genes involved with the formation of stromules have been identified.

In the new study, Savithramma Dinesh-Kumar, professor and chair in the Department of Plant Biology, graduate student Nathan Meier and colleagues have identified a key protein involved in stromule biogenesis during immunity. Their findings were published Oct. 25 in Science Advances.

A hidden player in immune defense

In order to test the stromules’ role in immunity, researchers need to switch them off and then observe how stromule-less plant cells fare when faced with a pathogen. However, without knowing which genes are involved with the creation of stromules, researchers have had no way to know which genes to switch off.

To overcome this roadblock, Dinesh-Kumar and his colleagues turned to kinesins, proteins that function as tiny motors that allow molecules and organelles to move around a cell. This intracellular movement usually involves the cell’s cytoskeleton, which is made up of two different types of fiber: large microtubules and smaller actin filaments.

The researchers wanted to investigate a type of kinesin that is unique to plants and capable of binding both microtubules and actin filaments. The researchers found that overexpression of one of these kinesins, KIS1, induced stromule formation in the absence of pathogen infection.

When the researchers manipulated tobacco and Arabidopsis plants so that they could not produce the KIS1 kinesin, they found that neither plant was able to form stromules, and their chloroplasts did not migrate toward the nucleus. This left the plants unable to defend themselves from introduced pathogens.

Secrets of chloroplast movement

To disentangle the roles of microtubules and actin, the researchers engineered one set of KIS1 variants that could only bind to microtubules, and another that could only bind to actin. Expression of these variants in tobacco showed that KIS1 needs to bind to microtubules in order for chloroplasts to form stromules, but in order for chloroplasts to move toward the nucleus, it must also bind to actin.

The team also wanted to know how stromules fit into the bigger picture of plant immunity. By using genetic manipulation to switch different immune signals off, they found that stromule formation is triggered by molecular signaling and that an intact immune signaling system is needed in order for stromules to form.

“If we remove any of the known immune signaling genes, the chloroplasts lose the ability to make stromules, which suggests that these structures are an integral part of the immune signaling pathways that activate defense,” said Dinesh-Kumar.

New light on plant immunity

This study is the first evidence of a plant kinesin directly involved in plant immunity. It’s also the first time that scientists have identified a gene—KIS1—involved in chloroplast stromule biogenesis, which opens the door to understanding the role of chloroplast stromules and why chloroplasts cluster around the nucleus during plant immune defense.

“If we can better understand at the cellular level how organelles like chloroplasts help cells to defend themselves, we could help to engineer resistance to the pathogen,” Dinesh-Kumar said.

More information: Nathan Meier et al, Calponin-homology domain containing kinesin, KIS1, regulates chloroplast stromule formation and immunity, Science Advances (2023). DOI: 10.1126/sciadv.adi7407. www.science.org/doi/10.1126/sciadv.adi7407

Journal information: Science Advances 

Provided by UC Davis 

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MOROCCO: TOMATO BROWN RUGOSE FRUIT VIRUS – FIRST REPORT

December 4, 2023 by IAPPS

Monday, 20 November 2023 12:05:05

Grahame Jackson posted a new submission ‘TOMATO BROWN RUGOSE FRUIT VIRUS – MOROCCO: FIRST REPORT’

Submission

TOMATO BROWN RUGOSE FRUIT VIRUS – MOROCCO: FIRST REPORT

ProMED
https://promedmail.org/

Source: European Plant Protection Organisation (EPPO) Reporting Service 10/2023/235 [summ. Mod.DHA, edited]
https://gd.eppo.int/reporting/article-7717
The NPPO [National Plant Protection Organisation] of Morocco recently informed EPPO of the occurrence of _Tomato brown rugose fruit virus_ (_Tobamovirus_, ToBRFV – EPPO A2 List) on its territory. During the production season 2022-2023, about 10 outbreaks have been confirmed on tomato (_Solanum lycopersicum_) grown in glasshouses for fruit production. The sources of the outbreaks are infected imported seed.

ToBRFV has been a priority quarantine pest in Morocco since 2018, and official measures are taken in case of findings. They include the destruction of infected plants, restriction on cultivation of host plants and hygiene measures. In 2023, yield losses were observed, as well as increased management costs.
—
Communicated by:
ProMED
[_Tomato brown rugose fruit virus_ (ToBRFV) was identified as a new member of the genus _Tobamovirus_ (type member _Tobacco mosaic virus_, TMV) in Jordan and soon after in Israel (see links below). Since then, it has also been reported from Europe and the Mediterranean region, where it continues to spread (see links below), as well as from China and North America, but so far not from South America. The virus was shown to affect also capsicum and has been detected in both plants and seeds of both crops. ToBRFV symptoms on tomato vary depending on host cultivar but may include chlorosis, mottling, mosaic, crinkling (rugosis) on leaves; necrotic spots on petioles and calyces; yellowish mottling, brown spots and rugosis on fruit to make them unmarketable. On capsicum, leaf symptoms are similar; fruits may be deformed with yellow mottling or green stripes. Almost 100% incidence was reported for some outbreaks in tomato, but not every fruit on an infected plant may show symptoms.

ToBRFV (like many tobamoviruses) is seed transmitted and can also be spread by mechanical means, contaminated equipment, as well as with plant or other materials. It is very stable and can remain infectious for months outside a host. Bumblebees, which are used widely as commercial pollinators in glasshouse tomato production, have been shown to be effective vectors of ToBRFV (see link below). Volunteer crop plants and solanaceous weed species are likely pathogen reservoirs. The Tm-22 resistance gene used in some tomato cultivars to protect from other tobamoviruses (such as _Tomato mosaic virus_) does not appear to be effective against ToBRFV. Disease management relies mainly on exclusion but may include phytosanitation (disinfecting tools, removing crop debris) and control of virus reservoirs. Use of certified clean seeds or crop transplants is crucial. Research on possible seed treatments to eliminate the virus is being carried out (see link below). Tomato seeds are traded widely and are known to pose a risk of spreading viruses and other pathogens internationally (e.g., ProMED post 20140122.2222560).

Coinfection of ToBRFV with _Pepino mosaic virus_ (genus _Potexvirus_) and _Tomato spotted wilt virus_ (TSWV; genus _Orthotospovirus_) has been found in tomato (ProMED posts 20191029.6751082, 20200507.7307615), as well as with TSWV in capsicum (see link below). It is thought that the respective symptoms may have been due to either virus or synergism. Further research is needed to clarify a potential role of ToBRFV in coinfections and to determine whether its presence in coinfections may have led to earlier cases of misdiagnosis and delayed identification of this new virus.
Pictures
ToBRFV on tomato:
https://gd.eppo.int/media/data/taxon/T/TOBRFV/pics/1024×0/4137.jpg and
https://gd.eppo.int/media/data/taxon/T/TOBRFV/pics/1024×0/4138.jpg
ToBRFV symptoms on capsicum:
https://agriculture.vic.gov.au/__data/assets/image/0009/555759/TOBRFV_figure-5.jpg

Links
Information and characterisation of ToBRFV:
https://gd.eppo.int/taxon/TOBRFV (with distribution and host list),
https://doi.org/10.1007/s00705-015-2677-7 (Jordan),
https://doi.org/10.1371/journal.pone.0170429 (Israel),
https://doi.org/10.1007/s42161-023-01436-8 (TSWV co-infection, capsicum) and via
https://www.semanticscholar.org/topic/Tomato-brown-rugose-fruit-virus/3579397
ToBRFV spread:
https://doi.org/10.1371/journal.pone.0282441 (new reservoir hosts) and
https://doi.org/10.1371/journal.pone.0210871 (by pollinators)
Tomato resistance breeding:
https://www.hortidaily.com/article/9544570/intermediate-resistance-ir-to-tobrfv-in-tomato-varieties-confirmed/,
https://www.hortidaily.com/article/9265808/we-can-eradicate-tobrfv-from-the-tomato-industry-with-our-newly-found-resistance/ and
https://www.hortidaily.com/article/9272889/commercial-tomato-variety-with-tobrfv-resistance-to-be-offered-in-early-2021/
ToBRFV seed treatment:
https://doi.org/10.1007/s10658-020-02151-1
Recent ToBRFV updates. Europe:
https://www.hortidaily.com/article/9574147/greece-tobrfv-found-in-laconia,
https://www.hortidaily.com/article/9571654/italy-tobrfv-virus-officially-confirmed- in-sardinia,
https://www.freshplaza.com/europe/article/9544392/new-measures-to-prevent-the-spread-of-the-tobrfv-virus-in-the-eu-will-apply-from-september/,
https://gd.eppo.int/reporting/article-7531 (1st report Slovakia, ex Austria) and
https://www.hortidaily.com/article/9507097/thirteen-new-tobrfv-infections-in-the-netherlands/ (first at seed production and breeding site)
International spread of tobamoviruses by seeds (review):
https://doi.org/10.5772/intechopen.70244
Virus taxonomy via:
https://ictv.global/taxonomy
EPPO A2 quarantine list:
https://www.eppo.int/ACTIVITIES/plant_quarantine/A2_list
– Mod.DHA

The power of underground fungi to shape forests.

November 28, 2023 by IAPPS

NOVEMBER 10, 2023

 Editors’ notes

by Chris Woolston, Washington University in St. Louis

A large study involving 43 research plots in the Forest Global Earth Observatory (ForestGEO) Network—including a swath of trees at Tyson Research Center, the environmental field station of Washington University in St. Louis—has helped clarify the power of underground fungi to shape forests.

From the tropics to the far north, fungi in the soil seem to directly determine the number and types of trees that can thrive in a given area, said Jonathan Myers, an associate professor of biology whose work at Tyson contributed to the global findings. The study was published in Communications Biology.

Many trees depend on a special partnership with mycorrhizal fungi that grow around their roots. The fungi provide the tree with nitrogen, phosphorus and other nutrients, and the tree gives the fungi carbon in the form of sugar and lipids for energy. “It’s a mutually beneficial arrangement,” Myers said.

The results from this study suggest that fungi are more than casual acquaintances with their tree companions: the fungi drive diversity—or lack thereof.

Specifically, the underground back-and-forth helps explain why tropical forests can support multiple species of trees in a small area, why forests in the far north and south are often dominated by just a few species, and why the oak and hickory forests at Tyson fall near the middle of the diversity spectrum. “The study really zeroed in on one of the basic patterns in ecology, which is that forests become more diverse the closer you get to the equator,” Myers said.

Researchers used mathematical models and tree surveys to track the impact of different types of mycorrhizal fungi on diversity. As Myers explained, these come in two main types: arbuscular mycorrhizae (AM) and ectomycorrhizae (EM). AM fungi—”living fossils” that are essentially identical to the fungi that partnered with the earliest plants known to science—are especially abundant in the tropics. EM fungi, a newer arrival to the scene, become increasingly common farther from the equator.

The study suggests that a shift from one type of fungi to another has had major consequences for tree diversity. AM fungi are equal-opportunity partners that will support just about any AM tree species that happen to live nearby. Because the fungi are not too picky, any AM seedling or sapling trying to grow in a given spot can expect a boost from the local mycorrhizae.

EM fungi, in contrast, are much more discerning and will only help certain tree species—spurning all others. As a result, a sapling that depends on EM fungi is more likely to thrive if it can share space—and fungi—with a member of its own species. In that way, choosy fungi encourage communities of trees of the same species to cluster together.

EM fungi also help protect their favored species of trees from diseases. As Myers explained, this helpful action actually makes forests less diverse. If a forest suffers a disease outbreak that targets a specific type of tree, it could be risky to grow too close to a neighbor of the same species. But EM fungi reduce that risk, making it safer for trees to grow close to their own kind. AM fungi don’t offer as much disease protection, so trees in tropical forests find safety in diversity.

A better understanding of fungi helps put the trees of Tyson into perspective, Myers said. Roughly halfway between the tropics and the boreal forests of northern Canada, Tyson is home to both of the kinds of fungi examined in the study. It also boasts a moderate mix of trees—mostly varieties of hickories and oaks— that is neither wildly diverse nor unrelentingly monotonous. Tyson’s position between the extremes made it a valuable source of data for the global study, Myers said.

“We have just over 40 different species of trees on the plot that we studied, which is the size of about 45 football fields,” Myers said. “In most tropical forests, there would be hundreds of different species in a plot that size. In the boreal forests of northern Canada, there might be fewer than 10.”

To further understand the forces driving forest diversity, researchers should study exactly how fungi interact with tree roots at a physical and chemical level, Myers said. “We have a lot more work to do underground,” he said.

More information: Camille S. Delavaux et al, Mycorrhizal feedbacks influence global forest structure and diversity, Communications Biology (2023). DOI: 10.1038/s42003-023-05410-z

Journal information: Communications Biology 

Provided by Washington University in St. Louis 

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Forests found to benefit from tree species variety and genetic diversity

By David Coyle, Ph.D.

Folks outside the forest entomology realm have likely heard of the USDA Forest Service but may have little knowledge of what this group actually does. Truth be told, they do a lot—from trail and road maintenance to fire suppression and prevention to management, this group is responsible for managing millions of acres of our nation’s forestland. But, in addition to the management aspect, the Forest Service (USFS) also conducts and funds research—lots of research. In an article published in October in the Journal of Integrated Pest Management , several USFS scientists summarize the past decade’s USFS-funded forest health management, and, frankly, the impacts on U.S. forests are impressive.

Forest Health Protection is a unit of the USFS State, Private, and Tribal Forestry Deputy Area, and this group regularly works with personnel from academia, government, industry, and nonprofit organizations to monitor pests and improve management of forests. New and existing grants are funded annually, and, while many of these projects result in peer-reviewed publications, this is the first time their impact has been summarized in one place.

In total, over 2,400 forest pest-management projects were supported between 2011 and 2020, directly impacting 2,284,624 hectares (5,645,429 acres or 8,821 square miles). The list of pests impacted by this work reads as the Who’s Who of forest health issues and includes native species such as the mountain and southern pine beetle, Douglas-fir beetle, western spruce budworm, and Ips bark beetles. Invasive pests include the spongy moth, emerald ash borer, and hemlock woolly adelgid. Projects evaluated traditional and novel management methods, and the paper contains a plethora of interesting numbers and facts related to this program—way more than can be adequately summarized here.

But, as someone who works in the forest health realm and who works with the USFS very frequently, a few points are worth highlighting. First, the tables and figures alone in this paper hold so much information on where federal funding goes and what it impacts. This is a common criticism from those who might not appreciate what our federal government does or where tax dollars go, and this paper goes a long way to help answer some of these questions as they pertain to USFS work. From the data, it seems clear that a lot is being done because of this program. Second, the question of where in the country our federal dollars go is also largely answered, as the authors clearly break down where the projects took place, acres impacted in each region, and several other location-specific bits of information. Finally, the comprehensive nature of this program is well-documented in this paper. It’s not just bark beetles, or defoliators, or native or invasive species—it’s all of them at the same time. It’s broad-scale forest health work, which is an excellent goal and objective for an entity such as the USDA Forest Service.

Whether you work in forests or not, this paper does an excellent job of summarizing a decade of government-supported integrated pest management work.

David Coyle, Ph.D., is an assistant professor in the Department of Forestry and Environmental Conservation at Clemson University. Find him on all the socials as @drdavecoyle. Email: dcoyle@clemson.edu.

‘IT’S WORKING AS A SPIDER WEB FOR CATCHING SPIDERS’

ex Nebraska Today

by Scott Schrage | University Communication and Marketing

Gilbert Barrantes / Laura Segura Hernández / Diego Solano Brenes

Gelanor siquirres, a species of pirate spider, descends from its dragline while pursuing prey in a Costa Rican rainforest.

Headlamps alone illuminated the trail bisecting the Costa Rican rainforest. Having waded the black of the Tirimbina reserve so often before, Gilbert Barrantes, Laura Segura Hernández and Diego Solano Brenes knew the routine.

It was time, dusk informed the surrounding spiders, to let loose the wind-aided, floating lines of silk that might latch onto leaf, branch or ground, fortifying the first beams of the food-snaring webs to come. But even on a night so familiar, the team would encounter a hunting scene unfamiliar not just to these arachnologists, in this forest, but all of them, anywhere.

“It was completely serendipitous,” said Segura Hernández, who earned her doctorate from the University of Nebraska–Lincoln in August.

What the trio stumbled on was a trap: lines floated not for framing but for fishing, part of a gambit that gives other forest-dwelling spiders just enough silk to hang themselves. And at the center of the scheme, not to mention the lines? A venomous pirate.

Four lines of that silk, the researchers realized, were running horizontally and diagonally from the underside of the same leaf. From elsewhere, the end of another thread had drifted in and caught on one of those leaf-dangling lines. That thread was the product of a spiderling now skittering along it to inspect the joint and, with its silken pillar secured, commence the construction of a full-fledged web.

“And then,” Segura Hernández said, “we just saw this other spider shoot in out of nowhere.”

The interloper was Gelanor siquirres, a species from the family known as pirate spiders — named for their willingness to invade already-built spider webs, strategically pluck threads to draw out their eight-legged inhabitants, and dine on them. This was something different. This G. siquirres emerged from its hiding spot beneath the leaf, scuttled across its own floating line, paralyzed its harried, hapless prey with a bite, then retreated to the leaf with the spiderling clutched in its ultra-long jaws.

A close look at that leaf would reveal the swashbuckler’s identity. A close look at the research literature would reveal that no one had ever reported the devious hunting technique, which the team has since witnessed multiple times. With a recent paper in the journal Animal Behaviour, the Tirimbina-trekking team would become the first.

“It’s working as a spider web for catching spiders,” Segura Hernández said of the lines floated by G. siquirres, which, like its pirate brethren, does not build circular webs. “That’s one of the cool things about it.”

Not the only thing, though. Pirate spiders are known as slow, deliberate killers: While venturing onto another spider’s web, Segura Hernández said, some pirates might advance no more than a few centimeters in an hour, lest they risk triggering any unwanted vibrations. The stealth makes sense when considering that the prey are also accomplished predators with venom of their own, and that G. siquirres, at no more than a half-inch long, is more David than Goliath.

Yet when another spider approaches one of its floating lines, G. siquirres darts forward with an alacrity that initially stunned Segura Hernández and her colleagues — the equivalent of a sloth turning cheetah.

“So it’s not just a modification of web-building behavior,” she said. “It’s a modification of the spider’s locomotion, as well.”

Footage of a pirate spider capturing a smaller arachnid before retreating to a leaf.

G. siquirres seems to have adapted its schedule, too, getting an early start to ensure that its floating lines are in place by the time its potential prey is releasing its own.

“It’s not like spiders make webs all night,” Segura Hernández said. “There’s clearly a peak period of activity, right after dark, where you see all of these floating lines on the trail. So it’s not like (G. siquirres) can do this in the morning. They are targeting this specific time period.”

There remains a lot to learn about G. siquirres, which was officially described and named in 2016 but had not, until now, been the subject of any peer-reviewed research. The fact that the first G. siquirres behavior ever documented happens to double as a behavior never seen in any spider speaks to how much remains unknown about the eight-legged wonders as a whole, Segura Hernández said, especially those residing in prey-rich rainforests.

G. siquirres feeding on its prey, an immature spider (white arrow) that touched the silk line its predator had earlier floated as a trap.

For her, it also underscores the value of not overlooking observation itself, of remembering to seek ideas, questions and answers not just in pages but the wild. She hasn’t forgotten the words of Bill Eberhard, who mentored her as an undergrad at the University of Costa Rica and was commemorated in the same journal issue that features the G. siquirres study.

“One of my favorite things about this paper is that it highlights how important it is — what Bill Eberhard taught us — to observe and just pay attention to detail,” she said. “Sometimes people are so focused on hypotheses and questions that they kind of forget about the organisms. But I think both things are equally important.

“Can we even envision how many more incredible hunting strategies there are just waiting to be observed?”

It was that spirit, in part, that encouraged her to spend so much time wandering in Tirimbina. At this point, she can’t recall any specific reason that she and the others were out that fateful night. Not that she needed one. The rainforest itself — the trill of insects and pattering of lizards, the aromas of wildflowers floating, like the spider silk, on a breeze — offered its own draw.

“Everything is alive. And at night, it has a mystery. You realize how much you rely on vision, because you’re restricted to what your headlamp can show.

“But that one time, we were just walking down the trail, talking about something,” she said, “and then we noticed the silk.”

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Bacteria make lunar soil more fertile

November 25, 2023 by IAPPS

by Bob Yirka , Phys.org

A team of agronomists and biotechnicians at China Agricultural University has found that adding bacteria to simulated lunar regolith increased the amount of phosphate in the soil for use by plants. In their study, published in the journal Communications Biology, the group added three types of bacteria to samples of volcanic material and then tested them for acidity and their ability to grow plants.

https://7dec37ccb6d1a85685906406b7021d19.safeframe.googlesyndication.com/safeframe/1-0-40/html/container.html

As several countries make plans to send humans back to the moon, they must address several issues—one of the most basic is figuring out a way to feed people working there for an extended period of time. The obvious solution is for workers to grow their own food. But that presents problems, as well, such as how to transport soil for growing edible plants from Earth to the moon.

Some have suggested that moon soil, known as lunar regolith, might be treated to make it amenable to plant growth. Last year, a team in the U.S. showed that it is possible to grow plants in lunar regolith by growing a small number of weeds called thale cress in real lunar soil samples. That test showed that lunar soil can work, but not well enough for plants to mature and produce food. In this new study, the research team found that adding microbes to lunar soil can improve its ability to host plant life.

To test the possibility of using microbes such as bacteria to make lunar regolith more hospitable to plant life, the research team obtained samples of volcanic material from a mountain in China—testing showed it to be a reasonable stand-in for regolith. The researchers then added one of three types of bacteria to three test pots filled with the volcanic material: Pseudomonas fluorescens, Bacillus megaterium and Bacillus mucilaginosus.

After cultivating the bacteria in the soil samples, the researchers tested the samples to see the effects. They found that the addition of all three types of bacteria had made the soil samples more acidic, which resulted in reducing the pH level of the soil. That dissolved the insoluble phosphate-containing minerals in the soil, which released phosphorus, making it available for plants.

The research team then directly tested the treated soil by planting Nicotiana benthamiana (benth). They found that the enhanced soil produce plants with more robust roots, longer stems and bigger leaves compared to untreated samples.

More information: Yitong Xia et al, Phosphorus-solubilizing bacteria improve the growth of Nicotiana benthamiana on lunar regolith simulant by dissociating insoluble inorganic phosphorus, Communications Biology (2023). DOI: 10.1038/s42003-023-05391-z

Journal information: Communications Biology 

© 2023 Science X Network

Championing sustainable agriculture by promoting lower-risk plant protection solutions to tackle crop health challenges is a key objective of CABI’s PlantwisePlus programme. In particular, the managing of plant pests and diseases. A cornerstone of this work is setting up local facilities for the mass rearing of lower-risk plant protection solutions. 

As of early 2022, PlantwisePlus in Pakistan had seen advancements in this area. The programme established collaborative agreements with provincial governments to introduce low-cost, low-tech mass rearing facilities in Khyber Pakhtunkhwa (KPK) and Punjab. The focus? Producing the biological control (biocontrol) agent, Trichogramma chilonis. While this parasitic wasp is available in Pakistan, the PlantwisePlus programme aims to introduce a more commercial-scale production. Thus increasing the capacity to produce and supply Trichogramma to farmers.

What is Trichogramma?

Trichogramma chilonis is a tiny parasitic wasp that targets Helicoverpa armigera, also known as the tomato fruit borer. In Pakistan, the tomato fruit borer is a significant pest of tomato. The presence of the pest has historically led farmers to resort to heavy pesticide applications, but Trichogramma offers a sustainable solution. 

Compared to other countries, tomato crop production is low in Pakistan, due to pests and diseases. Studies have found that the tomato fruit borer causes over 50% of fruit losses in the Peshawar district of KPK.  

Trichogramma is a natural enemy of the tomato fruit borer and can be used as a biological control (biocontrol) agent. Biocontrol is an effective method of controlling a pest’s numbers and spread without harming the environment. It is a safe alternative to the use of pesticides and, in particular, highly hazardous pesticides.

Trichogramma mass rearing in Pakistan

Although several government agricultural departments in Pakistan already produce lower-risk plant protection products, their facilities and processes can be optimized.

So far, PlantwisePlus and local government partners have established three Trichogramma mass rearing facilities (TRF) in Pakistan. The first TRF was set up in 2022 in Mardan, KPK. This facility is now operational, producing and distributing Trichogramma cards to farmers.  Earlier this year, the programme also established a facility in Muzaffargarh, South Punjab. And most recently, work has begun on a third facility in Muzaffarabad, Azad Jammu and Kashmir.

As well as working with local partners to construct or renovate these facilities, PlantwisePlus has also provided expert training to facility staff. Staff from CABI’s Regional Centre in Rawalpindi has provided technical support to the establishment of the TRFs in KPK and South Punjab. Whilst more detailed training, on the establishment of a large-scale rearing approach and quality control, has been supported by international experts from CABI Switzerland.

This training helps local staff move from laboratory-scale production to mass rearing that serves the wider farming community.

Using mass rearing to help smallholder communities

Making Trichogramma more widely available to smallholder farmers ensures they spend less on chemical controls. Although periodic releases of Trichogramma are necessary, they are far less frequent than spraying pesticides. 

The reduction in chemical use also benefits farmers’ health and supports biodiversity. Chemical pesticides are indiscriminate, also harming populations of beneficial insects. Biocontrol uses nature’s in-built mechanisms to help restore balance. 

Used as part of an Integrated Pest Management or IPM strategy, Trichogramma complements other physical, cultural, and (judicious) chemical techniques. In light of this, PlantwisePlus also supports local extension staff with training. This ensures that smallholder farmers can access sound agricultural advice and apply IPM techniques appropriately and to their full potential in the field.

Pesticide risk reduction with PlantwisePlus

PlantwisePlus aims to increase awareness of, access to, and use of affordable IPM solutions. This includes biocontrol as part of an IPM system. The programme recognizes the urgent need to increase the uptake of lower-risk plant protection products. And reduce reliance on high-risk farm inputs.  

Through establishing these mass rearing facilities, PlantwisePlus is enhancing partners’ ability to produce their own augmentative biological control solutions. This creates opportunities for farmers to apply safer practices in place of chemical pesticides.   

As the facilities develop and become fully operational, PlantwisePlus will investigate whether they can provide a model for successful local agribusinesses. Can they create sustainable employment as well as change farmers’ attitudes to using lower-risk plant protection products? The hope is that they can, and the model can be scaled up in Pakistan and out to other programme countries in the future.

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Find out more

Biological control of invasive insects 

Conserving biodiversity: biocontrol for sustainable agriculture 

Overcoming gender barriers to tomato farming in Pakistan 

Pest risk training to help detect Pakistan’s potential invaders 

Bio-protection roadshow promotes low-risk plant protection products in Pakistan 

Factsheet for Farmers – Tomato Fruit Borer: Helicoverpa armigera

PlantwisePlus gratefully acknowledges the financial support of the Directorate-General for International Cooperation (DGIS), Netherlands; European Commission Directorate General for International Partnerships (INTPA, EU); the Foreign, Commonwealth & Development Office (FCDO), United Kingdom; the Swiss Agency for Development and Cooperation (SDC); the Australian Centre for International Agricultural Research (ACIAR); the Ministry of Agriculture of the People’s Republic of China (MARA)  

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What are bioprotection products, and how do they work?

November 23, 2023 by IAPPS

August 16, 2023 

Laura Hollis 

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What are bioprotection products, and how do they work?

Bioprotection products are nature-based solutions to managing crop pests and diseases. More and more growers are turning to environmentally sustainable crop pest and disease management solutions, such as bioprotection products. Reasons for choosing more sustainable solutions include pest and disease resistance to chemical pesticides and concerns for human health and the environment.    

Bioprotection products use living organisms such as insects (macrobials) and bacteria, viruses or fungi (microbials). They also include extracts or mimics of naturally occurring substances (semiochemicals).   

What are the main types of bioprotection products?  

Continue reading to discover the key product categories and how they can help manage crop pests and diseases.   

Macrobial bioprotection products   

Macrobial products include predator insects, parasitoid insects and nematodes. They all work slightly differently in killing pest insects.  

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Predators   

Predator insects work to reduce pest numbers by attacking and feeding on other insects, usually killing several individuals during their life cycle.  

Parasitoids   

Parasitoid insects kill pest insects by inserting their eggs inside the bodies of pest insects. The eggs then develop and grow inside the body of the pest insect, killing it. The adult parasitoids then emerge from the bodies of the pest insects.   

Entomopathogenic nematodes 

Entomopathogenic nematodes are elongated, cylindrical worms of the order Nematoda. They are parasitic in animals, insects, or plants. They can also be free-living in soil or water. Nematodes kill pest insects by entering the body of the pest insect and infecting it with deadly bacteria. Some species of nematode reproduce within the body of the pest insect, with multiple nematodes exiting the body of the pest, ready to infect more pest insects.   

Microbial bioprotection products   

Microbial products include bacteria, viruses and fungi or other microorganisms or their metabolites or cell fragments that have the capacity to kill pests or outcompete and prevent diseases.  

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Bacterial products   

Bacteria are single-celled, microscopic organisms that lack a nucleus. When applied to crops, bacterial microbial products do not harm the crop itself. However, they are deadly to pest insects that eat the plant and become infected with the bacteria.   

Viral products 

Viruses are tiny, infectious particles consisting of nucleic acid and a protein coat, which can only reproduce within the cell of a living host. As with bacterial products, growers can apply viral products to crops without harm to the crop itself. When pest insects eat the plant, the insect becomes infected by the bacteria, causing the insect to die.   

Fungal products   

Fungi are multicellular organisms that lack chlorophyll and derive nutrients from other organisms. The fungal body generally consists of filamentous strands called mycelium. Fungal products usually work by landing on the body of the pest insect, with spores entering the body. The fungus branches and forms a network of branches inside the body of the insect, killing it. As well as destroying insects, microbial products kill plant-damaging diseases too.   

Semiochemicals   

Semiochemicals are message-bearing compounds produced by animals or plants that can be used to change and disrupt a pest’s normal behaviour (including sex and aggregation pheromones or various scented plant extracts that attract insect pests to traps). 

CABI Academy Introduction to Bioprotection Products Course   

Would you like to discover more about bioprotection products? The CABI Academy Introduction to Bioprotection Products course explains what they are, why they’re important and how they work. It gives a practical guide and set of resources to help advise farmers about choosing, using and interpreting the results of such products. The course is online and self-paced and takes approximately 8-10 hours to complete. Topics covered include: 

• – What are bioprotection products, and how do they work? 
• – Using bioprotection products to monitor pest insects 
• – Safety information and interpreting product labels 
• – Access to products 
• – How to transport and store products 
• – Making the most of bioprotection products 
• – Application and interpretation of results 

Sign up to the CABI Academy course 

CABI Bioprotection Portal 

The CABI BioProtection Portal is an open-access tool that provides users with information about registered biocontrol and biopesticide products in their country. It aims to help growers and agricultural advisors identify, source and correctly apply these products against problematic pests in their crops.  

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BioProtection Portal, CABI Academy, bioprotection, plant diseases, plant health, plant pests

Agriculture and International Development

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Salicylic acid and RNA interference mediate antiviral immunity of plant stem cells

November 23, 2023 by IAPPS

by Sophie Fessl, Gregor Mendel Institut für Molekulare Pflanzenbiologie (GMI)

Viruses are a threat to all organisms, including plants. A small group of plant stem cells, however, successfully defends itself from infection.

Marco Incarbone, now at MPIMP Golm, Gabriele Bradamante and their co-authors at the Gregor Mendel Institute of Molecular Plant Biology (GMI) uncovered that salicylic acid and RNA interference mediate this antiviral immunity of plant stem cells. The findings were published in PNAS on October 12.

Plant viruses threaten the health of their hosts, can spread swiftly and globally, and challenge agricultural productivity. When viruses successfully infect plants, the infection often spreads through the entire organism. Well, not entirely: One small group of indomitable cells still holds out, the stem cells within the shoot tip. This small group of cells generates all plant tissues above ground, including the next plant generation, and for reasons still poorly understood, viruses are unable to proliferate in these cells.

Marco Incarbone, previously a postdoctoral researcher in the group of Ortrun Mittelsten Scheid at the Gregor Mendel Institute of the Austrian Academy of Sciences (GMI) and now a group leader at the Max Planck Institute of Molecular Plant Physiology in Germany sought to uncover the molecular bases of how stem cells in the shoot apical meristem fight off viruses together with Ph.D. student Gabriele Bradamante and other GMI group members.

To understand the strong antiviral defenses of this special group of cells, Incarbone, Bradamante and colleagues first established a screening platform. “We developed high-throughput microscopy techniques that allowed us to study many Arabidopsis meristems at several timepoints after the viral infection, to give a temporal dimension to our exploration,” Incarbone explains.

Using this dynamic, semi-quantitative approach, the researchers observed that Turnip mosaic virus—their plant model virus of choice—spreads in their model plant Arabidopsis thaliana, arrives at the stem cells within the shoot tip , and even enters these cells, but is then quickly excluded. “Surprisingly, these cells are really good at driving the virus out.”

Past work on a close relative of tobacco had provided clues that RNA interference—a pathway that inhibits virus proliferation in plants and many animals—plays a role in virus exclusion in plants. In the search for the defense’s molecular bases, the researchers therefore screened Arabidopsis mutant plants that miss certain components of the RNA interference pathway. In addition, they studied plants deficient in salicylic acid, a key plant defense hormone.

Through a series of targeted experiments, the researchers were able to see that during virus infection, salicylic acid production is activated. “The plant recognizes the virus and sets off salicylic acid as an alarm bell.” Salicylic acid in turn activates a key factor in RNA interference amplification, called RDR1. RDR1 ramps up production of double-stranded RNA from viral RNA, giving plants more virus-specific sequences to direct the defense mechanism against the invading virus.

“In the fight against Turnip mosaic virus, both salicylic acid and RDR1 are necessary to expel the virus from the stem cells—however, RDR1 is not produced within the stem cells themselves, but in the tissue below the stem cells and in the vasculature,” Incarbone adds.

“There it generates the RNA-based and most likely mobile information that immunizes the stem cells from the incoming virus. While we know infection triggers an overall increase in salicylic acid, we do not yet know where in the plant and at what time during infection this happens. We are currently trying to solve this puzzle.”

But every virus is different. In the fight against other viruses, salicylic acid and RDR1 are activated but not necessarily required. “Based on our experiments with other viruses we can, however, conclude that RNA interference is always necessary to defend stem cells from infection.”

Still, the stem cells keep a mystery: plant viruses frequently evade and suppress RNA interference in other plant tissues. “Why can viruses suppress RNA interference in most of the plant, but not in these special cells? This remains the big question.”

In follow-up work, Incarbone will now investigate how viruses are stopped from passing into an infected plant’s seeds and offspring– which develop from the protected stem cells. “Our findings add important knowledge about how stem cell antiviral defenses work and give a robust molecular framework to build upon.”

More information: Marco Incarbone et al, Salicylic acid and RNA interference mediate antiviral immunity of plant stem cells, Proceedings of the National Academy of Sciences (2023). DOI: 10.1073/pnas.2302069120

Journal information: Proceedings of the National Academy of Sciences 

Provided by Gregor Mendel Institut für Molekulare Pflanzenbiologie (GMI)

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