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International Conference on Plant Health Management ICPHM 2023 – Innovation and Sustainability
The International Conference on Plant Health Management (ICPHM) 2023 – Innovation and Sustainability will be held in the city of Hyderabad, India, during 15th – 18th November 2023. The conference is being organized by the Plant Protection Association of India (PPAI). PPAI, since its inception in 1972, completed 50 years of yeoman service for the cause of Plant Protection both at National and International level in 2022. The main objective of this international conference is to pursue global opportunities in innovation and sustainability of research and entrepreneurship related to the field of Plant Health Management.
Women in Latin American Entomology, 2nd cycle of conferences
To acknowledge International Women’s Day and the contribution of women in the study of insects and other arthropods, the Latin American Federation of Entomology (FELA) together with the Mexican Academy of Entomology (AEM-SME) and the Ecuadorian Entomological Society (SEE) organized the 2nd Cycle of Conferences of Women in Latin American Entomology, held between March 8 and 10, 2023.
Juana María Coronado Blanco, President of FELA, opened the event on March 8, welcoming participants and presenting the program of activities. Entomologists from Argentina, Bolivia, Brazil, Chile, Colombia, Panama, Peru and Uruguay made their presentations that same day. The moderators were representatives of the Argentine Entomological Society (SEA) and the Colombian Entomological Society (SOCOLEN). Eight entomologists from Mexico made their presentations on March 9, and nine entomologists from Ecuador did the same on March 10. Both days were moderated by representatives from the AEM-SME and the SEE. Closing the event was Dr. Coronado Blanco, who thanked the speakers and the audience for their participation.
Twenty-five entomologists from 10 Latin American countries generously shared their research, knowledge and experience in entomology, and contributed with valuable input regarding the challenges they had to overcome and those they still face in their professional development.
À l’indépendance, la production nationale de la Côte d’Ivoire en café était de 185.000 tonnes. Dans les années 1980, la production est passée à 320.000 tonnes. Ce qui faisait de notre pays, le 1er producteur de café en Afrique. Au début des années 2000, la production a commencé à baisser pour atteindre 120.000 tonnes. Depuis 2020, la barre de production est en dessous de 80.000 tonnes. Faisant perdre à la Côte d’Ivoire, la 1ere place Africaine pour se retrouver au 4e rang. Derrière l’Ethiopie, l’Ouganda, et la Tanzanie. Dans le classement mondial, la Côte d’Ivoire occupe la 17e place. Pourquoi cette baisse de production ?
L’importance du café dans l’économie de la Côte d’Ivoire n’est plus à démontrer. Toutefois, cette culture rencontre de nombreuses difficultés telles que le vieillissement du verger, l’action néfaste des insectes ravageurs, les effets du changement climatique. Mais surtout la trachéomycose, une maladie qu’on qualifie de « Sida du café ».
État des lieux
Selon le Centre national de recherche agronomique (Cnra), trachéomycose a fait son apparition en Côte d’Ivoire dans les années 1930-1950, détruisant de nombreuses plantations agricoles. A cette époque-là, le colonisateur a trouvé comme solution d’introduire de nouvelles variétés de café plus résistantes. C’est ainsi que le café robusta a fait son apparition dans l’univers agricole ivoirien. Plus d’un demi-siècle après, revoilà la trachéomycose. On la retrouve dans toutes les zones productrices du café du territoire national.
Une enquête menée l’an dernier par le Cnra révèle qu’à Gagnoa, 14,2% du verger est atteint par la trachéomycose, sur 169 parcelles visitées. Dans la sous-préfecture de Guépaho, dans le département d’Oumé, vers les années 2000, on avait 16000 hectares de café, contre 5000 hectares aujourd’hui. Dans la région du haut Sassandra par exemple, le taux de contamination du verger est estimé à 50%.
« La maladie a fait beaucoup de ravage, si bien que le café est en voie de disparition », fait remarquer un agent de l’Anader. Parmi les planteurs qui ont tourné le dos à la caféiculture, se trouve N’goran Clément. Il y a une vingtaine d’année qu’il a hérité de la plantation de café de son défunt père, à Danielkro. Un campement Baoulé dans la sous-préfecture de Seriho, dans le département de Gagnoa. « Quand la maladie s’est déclarée dans mon champ de café, la production a chuté, mes gains ont commencé à baisser. Je n’avais plus qu’à laisser tomber le café pour le cacao », a-t-il expliqué, le paysan, les raisons de sa reconversion dans la culture du cacao.
« Je dis aux planteurs de café de ne pas désespérer. Les scientifiques travaillent sur cette maladie. Nous allons leur apporter les techniques afin qu’ils puissent arriver à bout de la maladie. Ils peuvent garder espoir parce que le café vivra encore en Côte d’Ivoire », a exhorté Koffi Sara.
Tout est en train d’être mis en œuvre pour que la culture du café retrouve ses lettres de noblesse.
Ph: DR
Solutions
« Compte tenu des perturbations climatiques, liées à la longueur des sécheresses, il faut développer des techniques qui permettent d’économiser l’eau du sol pour la mettre à la disposition de la plante afin qu’elle survive », renseigne un agronome. Il a passé en revue les différentes techniques de conservation de l’eau, telle que l’irrigation, l’hydro-détenteur et le paillage.
« L’irrigation est très chère pour le petit producteur », a fait savoir le formateur. « Il y a aussi d’autres techniques comme l’utilisation des hydro-détenteurs qui sont des granulés qui captent l’eau pendant la pluie et, en saison sèche, rétrocède cette eau à la plante. Cette technique est facile pour le producteur », fait-il savoir. Toutefois, l’agronome conseille la pratique du paillage. Elle consiste à mettre des débris végétaux autours du pied du caféier. Ce qui permettra à la plante de conserver l’eau du sol. Comment faire le paillage ? Pourquoi le faire ? A quel moment le faire ? Voilà autant d’exercices pratiques qu’il faut maitriser pour garder sa plante en bonne santé.
Some food grown in the US, especially high-cost luxuries like almonds, are pollinated using bees. Since bees are most often rented and transported for such purposes, keeping them alive is important to owners and growers. As their value for higher-cost foods has grown, so have bee numbers; they are up 85 percent in the last 60 years. You would just never know it if your source is Greenpeace, so when you use verbiage identical to Greenpeace press releases in an academic paper press release your work is going to be suspect. And that is a paper on bee deaths we’ll discuss today.
No matter how much effort is put into prevention, bees die. A lot. Some years more than others, and when that happens environmentalists promote campaigns against weedkillers and other agricultural tools, but the number one killer of bees is not climate change or land use, it is parasites. Bees live in a small enclosed space and diseases can devastate them in a short amount of time. The only way to prevent losses of 50 percent or more is with modern medicine against pests like varroa mites and others. Parasites are all three of the top three reasons bees die of external causes.
There are other factors, severe weather will cause more deaths, and for the few bee species that can be estimated (7 out of approximately 25,000 – that’s right, we don’t even know how many bee species exist) land use changes can be implicated. If someone tries hard enough, they can even find a way to “correlate’ farming to dead bees.
That is not the goal of a recent paper, but they use flawed ‘false equivalence’ to enable that, by acknowledging mites but then putting farming and weather events right next to them. I like bees, I want them to stick around, but no one is helped if pesticides are given false equivalence with the pests they kill in bee deaths.
Farming is a non-existent peril for bees outside the statistical noise range but even weather events are not worth mentioning beyond creating an average. Yes, hurricanes sometimes happen but listing those alongside the top killer is a way to boost their credibility the same way as if a journalist talks to an expert on climate change and then drops in a denier for ‘balance.’
Credit: Overturf et. al.
if they invoke global warming, hurricanes, and pesticides in their false equivalence with mites, how do I argue they may be going after farming? The authors use pleas for action by Greenpeace that have no evidence basis – a manufactured claim that one third of the world’s food, 100 crops, etc. need bees or we are doomed. It was entirely made up. USDA knows it, scientists know it, everyone who reads Google outside the first 20 results knows it. But the authors ignore USDA data showing pollinators are only involved in about $15 billion of food and instead blindly repeat the Greenpeace claim that it is 1,000% greater.
Here is the science truth. The 12 crops that provide 90 percent of our food are not pollinated by bees. Some are wind pollinated, some are self-pollinated or propagate asexually or parthenocarpically – they don’t need fertilization. Not by bees or the tens of thousands of flying insects that would take their place if that one species of bees disappeared tomorrow.
Bees are not vital pollinators for 100 vital crops or even 10 percent of food. They are not even declining. We have to look at their methodology a lot more critically when they make breezy statements that a USA Today fact checker would have asked them to cite.
Greenpeace did not invent that business about 100 crops from nothing, it was an unsubstantiated claim in a 1976 Pollinator Handbook, but everyone knows better by now, but that is no excuse. The general rule on old literature is that if you don’t accept claims that a low-fat diet will make you lose weight, also believed in 1976, don’t accept claims on other things because it matches your bias.
Back to the paper. The authors used survey claims of losses by beekeepers – unfortunately that is the best we can do – and combined those with publicly available data on land use, weather, and farming, and rightly agree that mites are a problem but strangely declare that pesticides and climate change are also big culprits.
Yet the data don’t show it.
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How they seem to show it is statistical manipulation but don’t let that part alarm you. Statistical ‘manipulation’ and even ‘trick’ does not carry the colloquial negative connotation those terms have in culture. If you have data created using different methods you have to make them relevant to each other. There is no meta-analysis without manipulation so it’s important. Shedding light on arcane parts of data is a positive force in statistics, but if someone is averaging and upscaling to show a result they perhaps wanted to show it is more like data dredging or HARK-ing; Hypothesis After Results Known. A real no-no.
Credit: Sketchplanations.com
I am not sure how to feel about their data period. Mostly, why? USDA has been surveying beekeepers since 1986 but this analysis only goes back to 2015. Using recent results may be causing sampling bias. They included a hurricane event – since bees only live a few weeks why a hurricane should he included to implicate weather in a long-term decline is unknown – and they touch on culture and accept they have no way to know how competent beekeepers are, but still wave it away in their press kit.
That cultural confounder, which finer resolution upscaling can’t help with, is that beekeeping became a fad.
Since the surge of Greenpeace claims that bees are keeling over en masse, there has been a surge in amateur beekeeping. Which has meant a surge in bee deaths by amateur beekeepers who buy into ‘power of nature’ mythology that they can just put up a hive and Gaia’s supernatural abilities will kick in. Which is completely false. With a surge in amateur beekeeping there has also been a surge in deaths due to overuse of needed chemicals to cure diseases – and deaths due to not using chemicals at all. Are new beekeepers going to blame their own incompetence? I have no idea, but if an aggressive statistician looks at a map and sees a farm near where a bunch of bees died, it is easy to correlate the farm to the deaths rather than nature or even misuse of chemicals by a beekeeper. It is also the completely wrong conclusion but it can be gained with statistical significance. Upscaling and statistical tricks magnify incomplete national data in that instance, while a neutral examination would catch that bees dying from truck accidents on the way to an almond farm did not die due to pesticides used by the farmers at the almond farm even though a statistician can claim they are ‘linked’ because of geography, especially if the resolution is only by state.
Statistics can link anything to anything, that is why their claims are only exploratory. In the real world, science and evidence is what matters. Evidence shows that bees are not in decline, our food supply is not at risk, and the top killer by far is mites, with other pests way behind, and chemicals that are not misused are down in the statistical noise area.
Credit: Giuliade via CC-BY-SA-4.0
As an observational paper, this is fine, even their press release concedes that ‘other’ is a large killer compared to things like pesticides. They know they are working with limited data, much of it is subjective and changes from year to year, and they need to make a lot of assumptions to try and get it all similar enough to make sense. But for 13 years prior to COVID-19 we warned about the problems of statisticians and epidemiologists and even some biologists creating ‘red meat’ papers for anti-science activists, because it could cause real harm (and did) when it came to vaccines and trust in our food supply.
Expect to see this paper trotted out in the same way. It is not going to be compelling to the science community but for Pesticide Action Network and others, it is pure honey.
Hank Campbell founded Science 2.0 in 2006, and writes for USA Today, Wall Street Journal, CNN, and more. His first book, Science Left Behind, was the #1 bestseller on Amazon for environmental policy books. Follow Hank on Twitter @HankCampbell
A version of this article was posted at Science 2.0 and is used here with permission. Any reposts of this article should credit the original author and provide links to both the GLP and the original article.Check out Science 2.0 on Twitter @science2_0
A new set of quantitative models that incorporates pH into the metabolic theory of ecology (MTE) has been developed by an international team that includes Penn State assistant professor of plant science Francisco Dini-Andreote.
The work is included in a new paper published by the Proceedings of the National Academy of Sciences, titled, “Integrating pH into the metabolic theory of ecology to predict bacterial diversity in soil.”
“Soils are the most complex and biodiverse ecosystems on Earth,” said Dini-Andreote, a member of Penn State’s Microbiome Center. “In soils, microbial diversity plays indispensable roles in the anabolic and catabolic cycles of carbon, nitrogen and sulfur, without which the diversity of life forms—including plants, animals and other microbes—that evolved on our planet would not have been possible. In addition, advancing our ability to predict patterns of soil biodiversity is critical to better understanding how climate change will affect soil functioning and how soil microbes will respond to shifts in temperature and precipitation regimes.”
In general terms, the metabolic theory of ecology links rates of organism diversification (i.e., the metabolic rate of an organism) with the organisms’ body size and body temperature, explained Dini-Andreote. Building upon the factors that are parametrized in the MTE, the researchers introduced variation in local pH as an additional variable that acts as a stringent selective filter of biodiversity in soils, impacting the species of microbes acting and surviving in the soil.
By considering all these factors—the metabolic rate, mass, and temperature as well as pH—the researchers were able to capture and account for previously unexplained variation in the relationship between soil edaphic properties (the physical, chemical, and biological properties of the soil), temperature, and biogeographical patterns of bacterial diversity. The team then continued to test and validate their models across multiple scales—such as single bacterial strain diversification rates, local and continental scale soil communities—yielding robust results.
“By layering these models, researchers can start to better understand patterns of microbial distribution in soils and start to answer long-standing questions in this field, such as: ‘What determines variation in soil biodiversity?’ and “How dynamic changes in soil biodiversity can be modeled and predicted?” said Dini-Andreote.
“With that, we will be able to better harness the genomic and functional potential of these soil microorganisms to effectively manipulate them for desirable outcomes. These outcomes vary from essential ecosystem functions, such as carbon storage in soil, to the manipulation of beneficial plant-associated microorganisms to enhance crop productivity in agriculture.”
This study also represents a nexus point for the integration of other variables into these quantitative models, such as variation in soil moisture and salinity, among others. The authors foresee new avenues of research ahead that will greatly improve scientists’ ability to understand the distribution of soil microbial species, and the diverse ways they operate as engineers of essential ecosystem processes and services in soils.
“Dr. Dini-Andreote’s scholarship shines a bright light on the abundance of the soil microbiome and the processes and mechanisms that shape soil health. From the soil on up, microbial communities connect different ecosystems as microorganisms flow from soil to hosts and back. With soil as the largest reservoir of microbial diversity on Earth, this important work raises the call to action as soils vary and degrade due to climate change, erosion, and chemical contamination,” said Seth Bordenstein, director of the Penn State Microbiome Center, Dorothy Foehr Huck and J. Lloyd Huck Chair in Microbiome Sciences, professor of biology and entomology.
More information: Lu Luan et al, Integrating pH into the metabolic theory of ecology to predict bacterial diversity in soil, Proceedings of the National Academy of Sciences (2023). DOI: 10.1073/pnas.2207832120
Hisar: A team of scientists from the department of plant pathology, Haryana Agricultural University (HAU), engaged in finding out causes of dwarfism in paddy crops (basmati, non-basmati, hybrid etc.), has found that the disease is not only caused by Southern Rice Black Streaked Dwarf Virus (SRBSDV), but also the Rice Gall Dwarf Virus (RGDV). Information has also been obtained about whom these two viruses, belonging to the spinareoviridae virus group, have made their host. HAU vice-chancellor professor BR Kamboj said SRBSDV infection has been found more in this disease and this virus has made Pova Anova, a weed of the Rabi season wheat crop, its host which is a matter of concern. There has not been any instance of this virus infecting the wheat crop. Therefore, if the farmer destroys this weed from the wheat crop, the possibility of this disease in the paddy crop next year will almost end. For this, apart from mechanical methods, farmers can also spray weed killer Clodinafop 200 grams and Matribugene 240 grams per acre, VC said. VC informed that the varsity’s plant pathologist, Vinod Kumar Malik, and biotechnologist Shikha Yashveer had decoded the virus in nucleic acid and coat protein regions. This has been confirmed by the use of virus-specific primers and molecular studies of the S4, S9 and S10 segments of the virus. University scientists O P Lathwal, Promil, Mahavir Singh, Rakesh Kharb, Ankit Judd, Sumit Saini, Manjunath, Vishal and Amit Kumar are working on the problem of dwarfism in paddy, VC said.
HAU director of research Jeet Ram Sharma said they were regularly studying the path of the virus. Emphasizing on clean farming, Hawa Singh Saharan, head of the department of plant disease, asked for regular cleaning of drains, so that further transfer of virus could be prevented.
Ninth International Conference on Management of the Diamondback Moth and Other Crucifer Insect Pests
Photo by Dr. Srinivasan Ramasamy
The Ninth International Conference on Management of the Diamondback Moth and other Crucifer Insect Pests will be organized by the World Vegetable Center in association with Royal University of Agriculture (RUA) in Cambodia and Taiwan Agricultural Chemicals and Toxic Substances Research Institute (TACTRI). The conference will be held during May 2-5, 2023 at Phnom Penh, Cambodia. About 100 – 150 researchers worldwide are expected to participate and present research papers. The conference is designed to provide a common forum for the researchers to share their findings in bio-ecology of insect pests, host plant resistance, biological control, pesticides and insect resistance management on crucifer crops and integrated pest management. As with previous workshops / conference, a comprehensive publication of the proceedings will be published.
Scientific Sessions
Diamondback moth and other crucifer pests: The global challenge in a changing climate
Biology, ecology and behavior of diamondback moth and other crucifer pests: What’s new?
Insect plant interactions, host plant resistance and chemical ecology of crucifer pests and their natural enemies
Insecticide resistance and management in crucifer pests: the on-going challenge
Biological and non-chemical methods of management of crucifer pests (including organic agriculture)
Genetic approaches to manage crucifer pests: transgenic plants, CRISPR, RNAi, and genetic pest management
Constraints and opportunities to the sustained adoption of integrated pest management (IPM) for the management of DBM and other crucifer pests
Cruciferous crops such as cabbage, cauliflower, broccoli, mustard, radish, and several leafy greens are economically important vegetables vital for human health. These nutritious vegetables provide much-needed vitamins and minerals to the human diet—especially vitamins A and C, iron, calcium, folic acid, and dietary fiber. Crucifers also are capable of preventing different types of cancer.
The diamondback moth (DBM), Plutella xylostella, is the most serious crucifer pest worldwide. In addition, head caterpillar (Crocidolomia pavonana), web worm (Hellula undalis), butterflies (Pieris spp.), flea beetle (Phyllotreta spp.) and aphids (Brevicoryne brassicae, Lipaphis erysimi, Myzus persicae) also cause significant yield losses in crucifers. Farmers prefer to use chemical pesticides for controlling this pest because they have an immediate knock-down effect and are easily available when needed in local markets. Pesticides constitute a major share in the total production cost of crucifer crops, accounting for about one-third to half of the cost of production of major crucifer crops in Asia, for instance. As a result, pest resistance to insecticides is on the rise, leading farmers to spray even more pesticides. Insecticide resistance, environmental degradation, human health impacts, resource loss and economic concerns have triggered a growing interest in integrated pest management (IPM).
Previous International Workshop / Conference(s) on Management of the Diamondback Moth and other Crucifer Insect Pests
Photo by Dr. Srinivasan Ramasamy
The International Working Group on DBM and other Crucifer Insects is an informal group of researchers worldwide who are actively engaged in research and development in crucifer pest management.
This research group participates in an international workshop on the management of DBM and other crucifer insect pests that occurs every five to six years.
The first and second workshops were organized by Asian Vegetable Research and Development Center (AVRDC) in Taiwan in 1985 and 1990.
The third workshop was organized by the Malaysian Agricultural Research and Development Institute in Kuala Lumpur in 1996.
The fourth workshop was organized in Australia in 2001 and the fifth workshop was organized by the Chinese Academy of Agricultural Sciences in Beijing in 2006.
The sixth workshop was organized by AVRDC – the World Vegetable Center in Thailand in 2011 and the seventh workshop was organized by the University Agricultural Sciences Bangalore in 2015.
The eighth International Conference on Management of the Diamondback Moth and other Crucifer Insect Pests was organized by the World Vegetable Center in Taiwan in 2019.
Four pathogenic bacterial species of the genus ‘Candidatus Liberibacter’, transmitted by psyllid vectors, have been associated with serious diseases affecting economically important crops of Rutaceae, Apiaceae and Solanaceae families. The most severe disease of citrus plants, huanglongbing (HLB), is associated with ‘Ca. Liberibacter asiaticus’ (CaLas), ‘Ca. Liberibacter americanus’ (CaLam) and ‘Ca. Liberibacter africanus’ (CaLaf), while ‘Ca. Liberibacter solanacearum’ (CaLsol) is associated with zebra chip disease in potatoes and vegetative disorders in apiaceous plants. Since these bacteria remain non-culturable and their symptoms are non-specific, their detection and identification are done by molecular methods, mainly based on PCR protocols. In this study, a new quantitative real-time PCR protocol based on TaqMan probe, which can also be performed in a conventional PCR version, has been developed to detect the four known phytopathogenic species of the genus Liberibacter. The new protocol has been validated according to European Plant Protection Organization (EPPO) guidelines and is able to detect CaLas, CaLam, CaLaf and CaLsol in both plants and vectors, not only using purified DNA but also using crude extracts of potato and citrus or psyllids. A comparative analysis with other previously described qPCR protocols revealed that this new one developed in this study is more specific and equally or more sensitive. Thus, other genus-specific qPCR protocols have important drawbacks regarding the lack of specificity, while with the new protocol there was no cross-reactions in 250 samples from 24 different plant and insect species from eight different geographical origins. Therefore, it can be used as a rapid and time-saving screening test, as it allows simultaneous detection of all plant pathogenic species of ‘Ca. Liberibacter’ in a one-step assay.
Plant multitrophic interactions are extremely complex, and the underlying mechanisms are not easy to unravel. Using tomato plants as a model system, we demonstrated that a soil fungus, Trichoderma afroharzianum, widely used as a biocontrol agent of plant pathogens, negatively affects the development and survival of the lepidopteran pest Spodoptera littoralis by altering the gut microbiota and its symbiotic contribution to larval nutrition. Our results indicate that insect-plant interactions can be correctly interpreted only at the metaorganism level, focusing on the broad network of interacting holobionts which spans across the soil and the above-ground biosphere. Here, we provide a new functional framework for studying these intricate trophic networks and their ecological relevance.
Abstract
Plants generate energy flows through natural food webs, driven by competition for resources among organisms, which are part of a complex network of multitrophic interactions. Here, we demonstrate that the interaction between tomato plants and a phytophagous insect is driven by a hidden interplay between their respective microbiotas. Tomato plants colonized by the soil fungus Trichoderma afroharzianum, a beneficial microorganism widely used in agriculture as a biocontrol agent, negatively affects the development and survival of the lepidopteran pest Spodoptera littoralis by altering the larval gut microbiota and its nutritional support to the host. Indeed, experiments aimed to restore the functional microbial community in the gut allow a complete rescue. Our results shed light on a novel role played by a soil microorganism in the modulation of plant–insect interaction, setting the stage for a more comprehensive analysis of the impact that biocontrol agents may have on ecological sustainability of agricultural systems.
Bioluminescence May Shine Light on Roundworm Secrets
USDA
For media inquiries contact: Jan Suszkiw Even though roundworms are nearly too small to be seen, they can pose major problems in corn, soybean, peanut and other crops. Collectively, these roundworms are known as plant-parasitic nematodes, and they cause $173 billion in crop losses worldwide each year.
These losses to crop yield and quality can occur even though chemical controls, resistant cultivars and other methods are available to farmers. So, a team of Agricultural Research Service (ARS) and university scientists decided to take a deeper dive into the basic biology of these nematodes and, more specifically, their genes for reproducing.
But the furtive nature of these millimeter-long pests and peculiarities of their lifecycle evaded the latest high-tech tools that the scientists had hoped to study them with.
Fortunately, they found a “work-around” in the form of electroporation. In short, the technique involves immersing nematodes in a plexiglass chamber with a buffer solution and pulsing it with small jolts of electricity. This stuns the creatures and temporarily opens pores in their bodies through which the solution’s chief “active ingredient” can enter—namely, bits of genetic material called NanoLuc luciferase mRNA.
Luciferase is an enzyme that oxidizes a compound called luciferin, producing a type of light called bioluminescence, such as that emitted by fireflies. In this instance, scientists “retooled” a luciferase coding sequence taken from a bioluminescent, deep-sea shrimp and electroporated it into the nematodes.
“Nematodes have primitive nervous systems,” explained Leslie Domier, a plant pathologist (retired) with the ARS Soybean/Maize Germplasm, Pathology, and Genetics Research unit in Urbana, Illinois. “When they were electroporated, they were immobilized for up to an hour, but then recovered and behaved normally.” Scientists then harvested the nematodes so that the contents of their cells, including luciferase, could be blended into a mixture called a “homogenate.” Next, they mixed the homogenate with a luciferin-like chemical called furamazine and presto—bioluminescence achieved!
Rather than observe this with the naked eye, the scientists used biochemical assays and sensitive light-detecting equipment to gauge the strength of the homogenate’s bioluminescence and determine how well their experiments had worked. So far, the researchers have successfully electroporated luciferase mRNA into the likes of soybean cyst nematodes (SCN) and root-knot nematodes—both costly crop pests—and Caenorhabditis elegans, a free-living species that doesn’t require a host in which to reproduce.
According to Glen Hartman, another plant pathologist (ARS retired) on the research team, the approach opens the door to introducing other synthetic mRNAs into nematodes to reveal how they change and where, as well as when the nematode’s own genes are activated in cells.
There may be pest-control applications, as well. For example, electroporation could offer a way to rear laboratory colonies of soybean cyst nematodes that carry pieces of genetic code whose sole purpose is to skew the ratio of male- to-female offspring. In theory, releasing these lab-reared nematodes to mate with those in the wild would eventually cause a generational population crash.
“We hypothesized that if we could interfere with the sex determination in nematodes, we could reduce nematode populations below crop-damaging thresholds,” said Domier. That, in turn, could diminish the need for chemical controls or help prolong the effectiveness of elite, resistant cultivars favored by growers, among other potential benefits.
More details about the technique and its implications for nematode control were reported in the journal Molecular & Biochemical Parasitology by Domier, Hartman and co-authors Thanuja Thekke-Veetil and Kris Lambert—both with the University of Illinois—Nancy McCoppin (ARS), Reza Hajimorad (University of Tennessee) and Hyoun-Sub Lim (Chungnam National University).
The Agricultural Research Service is the U.S. Department of Agriculture’s chief scientific in-house research agency. Daily, ARS focuses on solutions to agricultural problems affecting America. Each dollar invested in U.S. agricultural research results in $20 of economic impact.
Iron treatment boosts rice immune system, shows study
by Center for Research in Agricultural Genomics (CRAG)
Rice plant leaves which have been treated or not with iron (5 days) and infected with the fungus M. oryzae. Credit: CRAG
Rice (Oryza sativa L) is the world’s most widely used cereal for human consumption and the second most produced in the world after maize. However, rice production is seriously threatened by rice blast, a fungal disease that has been reported in more than 80 countries on all continents, including the growing areas of almost all rice-producing regions in Spain (Andalusia, Extremadura, Catalonia, Valencia, etc.).
A study recently published in the journal Rice and led by Blanca San Segundo, CSIC researcher at CRAG, has revealed that exposing rice plants to moderately high levels of iron increases resistance to infection by the pathogenic fungus Magnaporthe oryzae, the agent causing rice blast, the most common disease in this crop and responsible for large production losses worldwide.
Iron is an essential nutrient for plant growth and development. Although it is an abundant element in most agricultural soils, its availability to crops might be low. Depending on the soil characteristics, iron is found in its insoluble or soluble form, and therefore the plant can absorb it more or less effectively. In addition, both a deficiency and an excess of iron can become toxic to the plant. Thus, the precise control of the amount of iron as well as its bioavailability turn out to be crucial for the correct growth and productivity of the crops.
Using RNA sequencing methods, which enables the analysis of expression levels of different genes, the research team has detected the activation of several genes related to plant defenses when rice has been treated with iron for a short period of time. In addition, the presence of iron increases the expression of genes related to the generation of phytoalexins, molecules with antifungal activity which are able to inhibit the growth of Magnaporthe oryzae. Thus, it has been possible to demonstrate that a moderate treatment with iron activates the innate immune system of rice.
This work reveals that, under infection conditions, in the leaves of plants treated with iron, an accumulation of both reactive oxygen species (ROS) and iron is observed in specific and very localized regions of the infected leaf, which correspond to the pathogen entry points. This triggers a process of programmed cell death in the plant cells, known as ferroptosis, which limits the progression of the fungus in the infected tissue and therefore the infection is controlled by the plant itself.
“The cell suicide response or ferroptosis has been described in rice varieties resistant to infection by M. oryzae (incompatible interactions). However, it is the first time that this response has been observed in rice plants that are susceptible to infection by this fungus as a result of iron treatment. Iron has a function that enhances the immune response in the rice plant,” says Blanca San Segundo, the leading researcher of the study.
Previous studies by the same group already pointed out that nutrients could play a key role in the resistance or susceptibility to infection by this fungus. The same research team published in 2020 that excess of phosphate, as a consequence of the excessive use of phosphate fertilizers, has the opposite effect since it makes rice more susceptible to infection by the same fungus.
Understanding the relationship between the supply of nutrients (macronutrients and micronutrients) and the defense response of the plant against pathogens can be very useful when designing new protection strategies against blast disease and hence minimize the associated economic losses. In addition, this knowledge will contribute to establish more sustainable practices for growing rice by reducing the use of agrochemicals (fertilizers and pesticides).
More information: Ferran Sánchez-Sanuy et al, Iron Induces Resistance Against the Rice Blast Fungus Magnaporthe oryzae Through Potentiation of Immune Responses, Rice (2022). DOI: 10.1186/s12284-022-00609-w
Provided by Center for Research in Agricultural Genomics (CRAG)
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