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Cambodia: Ninth International Conference on Management of the Diamondback Moth and Other Crucifer Insect Pests

Posted in Biological control, Host plant resistance, Insects, Meetings, natural enemies, Pest diagnostics, Plant breeding, Plant health on March 6, 2023| Leave a Comment »

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

  1. Diamondback moth and other crucifer pests: The global challenge in a changing climate
  2. Biology, ecology and behavior of diamondback moth and other crucifer pests: What’s new?
  3. Insect plant interactions, host plant resistance and chemical ecology of crucifer pests and their natural enemies
  4. Insecticide resistance and management in crucifer pests: the on-going challenge 
  5. Biological and non-chemical methods of management of crucifer pests (including organic agriculture) 
  6. Genetic approaches to manage crucifer pests: transgenic plants, CRISPR, RNAi, and genetic pest management
  7. Constraints and opportunities to the sustained adoption of integrated pest management (IPM) for the management of DBM and other crucifer pests
Photo by Dr. Subramanian Sevgan

Photo by Dr. Subramanian Sevgan
Photo by Dr. Subramanian Sevgan

Photo by Dr. Subramanian Sevgan

Details

CALL FOR ABSTRACTS / PAPERS

  • 6 February – 31 March 2023

REGISTRATION

REGISTRATION FEE

  • Scientists (Outside Cambodia USD 400)
  • Scientists (From Cambodia USD 200)
  • Students (USD 200)
  • Accompanying person (USD 200)

ABSTRACT SUBMISSION

Scientific Committee

Dr. SRINIVASAN RAMASAMY

World Vegetable Center, Taiwan

Dr. PAOLA SOTELO-CARDONA

World Vegetable Center, Taiwan

Dr. Li-Hsin Huang

Taiwan Agricultural Chemicals andToxic Substances Research Institute, Taiwan

Dr. THO KIM EANG

Royal University of Agriculture, Cambodia

Dr. MYRON P. ZALUCKI

University of Queensland, Australia

Dr. MICHAEL FURLONG

University of Queensland, Australia

Dr. ZHENYU LI

Guangdong Academy of Agricultural Sciences, China

Dr. SUBRAMANIAN SEVGAN

International Centre of Insect Physiology and Ecology, Kenya

Dr. HUGH A. SMITH

University of Florida, USA

Dr. FRANCISCO RUBEN BADENES PEREZ

Institute of Agricultural Sciences, Spain

CONTACT

Dr. SRINIVASAN RAMASAMY

Flagship Program Leader for Safe and Sustainable Value Chains & Lead Entomologist

World Vegetable Center, Shanhua, Tainan 74151, Taiwan

Tel: +886-6-5837801

Fax: +886-6-5830009

E-mail: srini.ramasamy@worldveg.org 

Dr. PAOLA SOTELO-CARDONA

Scientist (Entomology)

World Vegetable Center, Shanhua, Tainan 74151, Taiwan

Tel: +886-6-5837801

Fax: +886-6-5830009

E-mail: paola.sotelo@worldveg.org 

BACKGROUND

Photo by Dr. Christian Ulrichs

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.

Additional details and proceedings of these workshops / conference can be found at https://avrdc.org/diamondback-moth-working-group/

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Soil fungus confers plant resistance against a phytophagous insect

Posted in Biological control, Host plant resistance, Insect-plant interaction, Insects on March 4, 2023| Leave a Comment »

Friday, 03 March 2023 06:47:24

PestNet

Grahame Jackson posted a new submission ‘A soil fungus confers plant resistance against a phytophagous insect by disrupting the symbiotic role of its gut microbiota’

Submission

A soil fungus confers plant resistance against a phytophagous insect by disrupting the symbiotic role of its gut microbiota

PNAS

Ilaria Di Lelio https://orcid.org/0000-0001-8933-0919, Giobbe Forni, Giulia Magoga https://orcid.org/0000-0002-0662-5840, +16, and Francesco Pennacchio https://orcid.org/0000-0002-8794-9328 f.pennacchio@unina.itAuthors Info & Affiliations

Edited by David Denlinger, The Ohio State University, Columbus, OH; received October 7, 2022; accepted December 16, 2022

February 27, 2023

120 (10) e2216922120

https://doi.org/10.1073/pnas.22169221

Significance

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.

Read on: https://www.pnas.org/doi/10.1073/pnas.2216922120

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Iron treatment boosts rice immunity to blast

Posted in Fungi, Host plant resistance, RNA on February 25, 2023| Leave a Comment »

FEBRUARY 22, 2023

Iron treatment boosts rice immune system, shows study

by Center for Research in Agricultural Genomics (CRAG)

Iron boosts rice immune system
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)

Explore further

Rice blast fungus study sheds new light on virulence mechanisms of plant pathogenic fungi

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Plant’s defence system against pathogens

Posted in Control tactics, Host plant resistance, Pathogen-host interaction on February 8, 2023| Leave a Comment »

NEWS RELEASE 1-FEB-2023

Water pores in leaves proven to be part of plant’s defence system against pathogens

Peer-Reviewed Publication

UNIVERSITEIT VAN AMSTERDAM

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How do plants defend themselves against pathogenic micro-organisms? This is a complex puzzle, of which a team of biologists from the University of Amsterdam has solved a new piece. The team, led by Harrold van den Burg, discovered that while the water pores (hydathodes) in leaves provide an entry point for bacteria, they are also an active part of the defence against these invaders. Their research has now been published in the journal Current Biology.

Anyone who is used to giving plants plenty of water might know the phenomenon: small droplets of plant sap that sometimes appear at the edge of the leaves. Especially at night times. When plants take up more water via their roots than they lose through evaporation, they can use their water pores on the leaf margins to release excess water. The pores literally prevent root water pressure from becoming too high. An important mechanism – but at the same time, risky. Pathogenic microorganisms can enter the plant’s veins through these sap droplets to colonize the water pores.

Biologists have therefore been asking themselves for a long time: how do plants defend themselves against this wide-open entry point? Are those water pores—the scientific name is hydathodes— defenceless glands that allow ample entry of harmful pests? Or have they evolved in such a way that they are part of the plant’s line of defence against pathogens?

Line of defence

A team of researchers from the Swammerdam Institute for Life Sciences at the University of Amsterdam has found evidence that the latter is the case. In the journal Current Biology they describe their experiments with the model plant Arabidopsis and two types of harmful bacteria. Arabidopsis, or thale cress, is related to all types of cabbage and other edible plants in the Brassicaceae family. The biologists discovered that the water pores are part of both the plant’s first and second line of defence against bacteria. In other words, they are involved in both the rapid initial response and the follow-up actions against the invaders.

Harrold van den Burg, who led the team of researchers, explains: ‘For this study, we used Arabidopsis mutants with deficits in their immune system that made them more susceptible to infection with the bacteria Xanthomonas campestris and Pseudomonas syringae. We selected these bacteria because they cause notorious problems in agriculture. Here they were used to help unravel the plant immune system. We were able to establish that two protein complexes (for those interested: BAK1 and EDS1-PAD4-ADR1) prevent the bacteria from multiplying in the water pores. The same immune responses also prevent these bacteria from advancing further into the plant interior. In addition, we discovered that when this first line of defence occurs, the water pores produce a signal that causes the plant to produce hormones that suppress further spread of the invading bacteria along the vascular system.’

Make agricultural crops more resilient

The team thus provides an important fundamental insight into how these natural entry points for bacteria have evolved and are protected by the plant’s immune system. In the long term, this may help to make agricultural crops more resistant to bacterial diseases.

Van den Burg: For now we will continue with this line of research. For example, we now know which protein complexes are involved in preventing bacteria from multiplying in the water pores, but not how this happens. Do they for instance regulate the production of antimicrobial substances in hydathodes that inhibit bacterial growth? That would be interesting to know. The better we understand this, the closer we get to a practical application for better protection of agricultural crops.’

Details of the publication:

Misha Paauw, Marieke van Hulten, Sayantani Chatterjee, Jeroen A. Berg, Nanne W. Taks, Marcel Giesbers, Manon M. S. Richard, and Harrold A. van den Burg: Hydathode immunity protects the Arabidopsis leaf vasculature against colonization by bacterial pathogens, in: Current Biology, 1 February 2023.

JOURNAL

Current Biology

DOI

10.1016/j.cub.2023.01.013 

METHOD OF RESEARCH

Experimental study

SUBJECT OF RESEARCH

Cells

ARTICLE TITLE

Water pores in leaves proven to be part of plant’s defence system against pathogens

ARTICLE PUBLICATION DATE

1-Feb-2023

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A gene that could help sorghum withstand the fungus that causes anthracnose

Posted in Fungi, Host plant resistance, Plant Pathogens on February 6, 2023| Leave a Comment »

View as a webpage ARS News Service ARS News Sorghum stalks and some products produced from sorghum grain.

ARS and Purdue University scientists identified a gene that could help sorghum withstand the fungus that causes anthracnose disease. Strengthening Sorghum Against a Worldwide Fungal Threat For media inquiries contact: Jan Suszkiw, (202) 734-1176
February 2, 2023 A gene discovered by a team of Agricultural Research Service (ARS) and Purdue University scientists could help fortify the defenses of sorghum to anthracnose, a disease of the cereal grain crop that can inflict yield losses of up to 50 percent. The discovery, to be reported in an upcoming issue of The Plant Journal, opens the door to breeding disease-resistant sorghum cultivars that are less reliant on fungicides to protect them, reducing growers’ production costs and safeguarding grain yields and quality, among other benefits. Sorghum is the fifth-most widely grown cereal grain crop worldwide, providing consumers not only with a source of food containing 12 essential nutrients, but also forage for livestock and material for bio-based energy. However, unchecked with fungicides or other measures, anthracnose will attack all parts of a susceptible cultivar, often forming reddish lesions on leaves and the stem as well as causing damage to the plant’s panicles and grain heads. Genetic-based disease resistance is the most effective and sustainable approach to combating anthracnose in sorghum. However, how this resistance actually works in the plant is poorly understood, according to Matthew Helm, a research molecular biologist at ARS’s Crop Production and Pest Control Research Unit in West Lafayette, Indiana. That knowledge gap is worrisome because of the genetic variability among different races (or types) of the anthracnose fungus and their potential to overcome a cultivar’s resistance genes over time. Additionally, anthracnose resistance can be temperature-dependent, potentially leaving a sorghum crop vulnerable to infection if temperatures soar above a certain threshold. Fortunately, Helm and a team of Purdue University scientists led by Demeke Mewa have begun to close this gap. They identified a disease-resistance gene that orchestrates a series of defense responses to early infection by the anthracnose fungus, preventing its spread to the rest of the plant and grain heads. Additionally, sorghum plants carrying the resistance gene, known as “ANTHRACNOSE RESISTANCE GENE 2” (ARG2), successfully withstood the fungus even when greenhouse temperatures were increased to 100 degrees Fahrenheit (38 degrees Celsius). This temperature stability could be a potential boon for sorghum production regions of the world where growing season temperatures can reach those levels.  The team also determined that ARG2 helps make (“encodes for”) a protein that is concentrated in the plasma membrane of resistant sorghum cells. There, it acts as a kind of intruder alert that’s triggered by certain proteins used by the anthracnose fungus to infect the plant. “These results significantly advance our understanding of how sorghum detects fungal pathogens and opens the door for engineering new disease resistances against plant pathogens of cereal grains,” the team writes in an abstract summarizing their findings in The Plant Journal paper. ARG2 and its protein don’t protect sorghum from all races of anthracnose. However, combining ARG2 with other similar genes could help broaden that protection—either through conventional plant breeding methods or biotechnological ones. With ARG2’s discovery, scientists now have a key to unlocking a fuller understanding of how the mechanisms of anthracnose resistance work and making the best use of them as a disease defense that growers worldwide can count on. In addition to Mewa and Helm, the The Plant Journal paper’s other authors are Sanghun Lee, Chao-Jan Liao, Augusto Souza, Adedayo Adeyanju, Damon Lisch and Tesfaye Mengiste—all of Purdue 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. Interested in reading more about ARS research? Visit our news archive U.S. DEPARTMENT OF AGRICULTURE
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Bacterial volatile organic compounds attenuate pathogen virulence via evolutionary trade-offs

Posted in Bacteria, Host plant resistance on January 16, 2023| Leave a Comment »

Saturday, 14 January 2023 16:05:11

PestNet

Grahame Jackson posted a new submission ‘Bacterial volatile organic compounds attenuate pathogen virulence via evolutionary trade-offs’

Submission

Bacterial volatile organic compounds attenuate pathogen virulence via evolutionary trade-offs

Nature

Jianing Wang, Waseem Raza, Gaofei Jiang, Zhang Yi, Bryden Fields, Samuel Greenrod, Ville-Petri Friman, Alexandre Jousset, Qirong Shen & Zhong Wei 

The ISME Journal (2023)

Abstract

Volatile organic compounds (VOCs) produced by soil bacteria have been shown to exert plant pathogen biocontrol potential owing to their strong antimicrobial activity. While the impact of VOCs on soil microbial ecology is well established, their effect on plant pathogen evolution is yet poorly understood. Here we experimentally investigated how plant-pathogenic Ralstonia solanacearum bacterium adapts to VOC-mixture produced by a biocontrol Bacillus amyloliquefaciens T-5 bacterium and how these adaptations might affect its virulence. We found that VOC selection led to a clear increase in VOC-tolerance, which was accompanied with cross-tolerance to several antibiotics commonly produced by soil bacteria. The increasing VOC-tolerance led to trade-offs with R. solanacearum virulence, resulting in almost complete loss of pathogenicity in planta. At the genetic level, these phenotypic changes were associated with parallel mutations in genes encoding lipopolysaccharide O-antigen (wecA) and type-4 pilus biosynthesis (pilM), which both have been linked with outer membrane permeability to antimicrobials and plant pathogen virulence. Reverse genetic engineering revealed that both mutations were important, with pilM having a relatively larger negative effect on the virulence, while wecA having a relatively larger effect on increased antimicrobial tolerance. Together, our results suggest that microbial VOCs are important drivers of bacterial evolution and could potentially be used in biocontrol to select for less virulent pathogens via evolutionary trade-offs.

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Molecular mechanism behind nutrient element-induced plant disease resistance discovered

Posted in Host plant resistance on January 16, 2023| Leave a Comment »

Science News

from research organizations

Molecular mechanism behind nutrient element-induced plant disease resistance discovered

Date:January 10, 2023Source:American Phytopathological SocietySummary:In one of the few studies to directly investigate the mechanism underlying the effect of essential elements on plant disease resistance, scientists demonstrate that nutrient elements activate immune responses in tomato plants through different defense signaling pathways.Share:

    

FULL STORY

Just like humans can’t subsist on a diet of only French fries and brownies, plants must also consume a balanced diet to maintain optimal health and bolster their immune responses. Nutrient element uptake is necessary for plant growth, development, and reproduction. In some cases, treatment with essential elements has been shown to induce plant disease resistance, but conclusive research on the molecular basis of this remedy has been limited.

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In one of the few studies to directly investigate the mechanism underlying the effect of essential elements on plant disease resistance, Rupali Gupta of Volcani Institute and colleagues demonstrate that nutrient elements activate immune responses in tomato plants through different defense signaling pathways.

Their paper, recently published in Phytopathology, outlines the molecular mode of action that potassium, calcium, magnesium, and sodium take to minimize both fungal and bacterial plant diseases. Using straightforward laboratory methods, the authors demonstrate that essential element spray treatment sufficiently activates immune responses in tomato — including defense gene expression, cellular leakage, reactive oxygen species production, and ethylene production — leading to disease resistance. Their results suggest that different defense signaling pathways are required for induction of immunity in response to different elements.

Understanding the genetic mechanism underlying this process may provide new insights into crop improvement. Corresponding author Maya Bar comments, “We are excited to probe the molecular basis of this phenomenon, define another facet of induced resistance, and provide data that will assist in applying this principle to agricultural systems in a more purposeful, reproducible manner.”

The tenets of mineral nutrient-induced disease resistance discovered in this study can be exploited in agricultural practices — benefiting growers/farmers and protecting valuable crops.

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Story Source:

Materials provided by American Phytopathological Society. Note: Content may be edited for style and length.

Journal Reference:

  1. Rupali Gupta, Meirav Leibman-Markus, Gautam Anand, Dalia Rav-David, Uri Yermiyahu, Yigal Elad, Maya Bar. Nutrient Elements Promote Disease Resistance in Tomato by Differentially Activating Immune Pathways. Phytopathology®, 2022; 112 (11): 2360 DOI: 10.1094/PHYTO-02-22-0052-R

Cite This Page:

American Phytopathological Society. “Molecular mechanism behind nutrient element-induced plant disease resistance discovered.” ScienceDaily. ScienceDaily, 10 January 2023. <www.sciencedaily.com/releases/2023/01/230110150941.htm>.

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South Africa: Rodade variety tomato resistant to bacterial wilt

Posted in Bacteria, Host plant resistance on December 23, 2022| Leave a Comment »

Bacterial wilt still threatens crops in tropical and subtropical areas

For tomatoes and more than 200 other plant species, bacterial wilt is an extremely destructive disease. Although some may not show symptoms, they keep the pathogen alive in the soil. The disease is caused by Ralstonia solanacearum, a bacterium found mainly in moist, hot areas.

The first sign of R. solanacearum is plants that start to wilt during the day and recover by nightfall. Later, they remain wilted and die. The disease usually starts in patches and spreads fairly rapidly to neighboring plants. It is almost impossible to control once it takes hold.

Fortunately for farmers, resistant genes are available. However, there are several races of R. solanacearum, with only one occurring in South Africa, namely race 1 biovar 2. It is therefore crucial to choose a tomato variety that has resistance to this race, or it will be ineffective. Varieties with the resistant gene can extend the harvest season into warmer conditions, but when the soil becomes too hot, the gene becomes less effective.

The resistant gene for race 1 biovar 2 was developed at the Agricultural Research Council station in Mbombela, and the resistant variety is named Rodade. This gene is used by other countries for our strain of the pathogen, and was hailed as a major breakthrough at the time.

Source: farmersweekly.co.za

Publication date: Thu 22 Dec 2022

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Master regulator of plant immunity discovered

Posted in Host plant resistance on December 16, 2022| Leave a Comment »

DECEMBER 5, 2022

Researchers discover a master regulator of plant immunity

by King Abdullah University of Science and Technology

A master regulator of plant immunity
KAUST plant scientists have revealed the role that the regulatory protein OXI1 plays in anti-pathogen immunity in plants. In this image, the plant specimens overexpressed OXI1, which manifests in the brown coloring when stained with a special dye. Credit: KAUST

The demonstration that a regulatory protein linked to stress responses in plants also serves as a master switch for anti-pathogen immunity could help breeders develop more pest-resistant and climate-resilient crops.

The KAUST-led discovery suggests that, rather than focusing on individual immune signals involved in plant defenses, agricultural scientists looking to implement sustainable crop protection strategies could simply focus their efforts on this one all-important protein.

“The identification of OXI1 as a single molecular switch of immunity offers a number of big advantages in molecular breeding,” says study lead Heribert Hirt, a professor of plant science at KAUST.

Hirt’s finding was nearly two decades in the making. In 2004, he and his colleagues first identified a gene called OXI1—short for oxidative signal-inducible 1 kinase—that was critical to plant responses in the face of environmental stresses.

Over the next 18 years, Hirt and others then connected OXI1 with various aspects of plant immunity and growth, but it was not entirely clear how the protein exerted its biological effects. And while scientists had detailed the ways in which three key immune-related metabolites—salicylic acid (SA), N-hydroxy pipecolic acid (NHP) and camalexin—contribute to pathogen defenses, their connection to OXI1 signaling was unknown.

It took Hirt and Anamika Rawat, a postdoctoral research fellow in his lab, to connect the dots. The researchers created mutant forms of Arabidopsis plants that either lacked OXI1 function or had elevated expression of the regulatory protein. Together with collaborators in Germany and France, they then comprehensively profiled gene activity patterns, protein abundances and metabolite levels in these plants.

Collectively, the researchers showed how OXI1 triggers a handful of genes that promote the synthesis of SA, NHP and camalexin. The buildup of these three immune-promoting molecules then confers greater protection against plant pathogens.

But the extra immunity brought on by OXI1 activity comes at a cost: it makes for stunted plants that show a greater propensity for cell death. Plants with lower OXI1 levels, while more susceptible to infection by bacterial and fungal pests, tend to grow bigger, with more active photosynthetic machinery.

Crop developers will therefore have to find the right balance of OXI1 activity for their agricultural applications. As a protein kinase, OXI1 should be amenable to manipulation, Hirt points out.

Already, there are dozens of kinase-targeted small-molecule drugs in widespread use in human medicine. Knowledge gleaned from the development of those agents, he says, should now be put to use in the discovery of OXI1 modulators for crop improvement.

The group’s findings are published in New Phytologist.

More information: Anamika A. Rawat et al, OXIDATIVE SIGNAL‐INDUCIBLE1 induces immunity by coordinating N‐hydroxypipecolic acid, salicylic acid, and camalexin synthesis, New Phytologist (2022). DOI: 10.1111/nph.18592

Journal information: New Phytologist 

Provided by King Abdullah University of Science and Technology 

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ToBRFV-resistant tomato varieties

Posted in Host plant resistance, Viruses on December 8, 2022| Leave a Comment »

Rijk Zwaan launches ToBRFV-resistant tomato varieties

The Tomato Brown Rugose Fruit Virus or ToBRFV has been causing major economic losses in tomato cultivation worldwide. Rijk Zwaan’s team of researchers found new ToBRFV-resistant genetics .

HR ToBRFV – Rugose Defense
Soon after this discovery, breeders started to develop resistant varieties in all worldwide breeding programs and extensively tested these varieties internally as well as with growers to assess their agronomic value. Rijk Zwaan now offers growers the best-performing hybrids under the Rugose Defense label, including mini plum, cherry TOV, cocktail, and medium TOV tomato varieties.

Compatible with all commercial rootstocks
Rijk Zwaan tomato varieties with high resistance to ToBRFV are compatible with all commercially available rootstocks. Trials have shown that rootstock variety Suzuka RZ performs strongly in combination with both susceptible and resistant tomato varieties.

Contact for more information
In the coming period, Rijk Zwaan will continue to introduce new varieties suitable for high-tech and protected cultivation. Rijk Zwaan would like to thank all growers who supported the company in testing the first HR resistant tomatoes for high-tech cultivation. Keen to know more? Visit Rijk Zwaan’s local Rugose Defense page.

For more information:
Rijk Zwaan
info@rijkzwaan.com
www.rijkzwaan.com

Publication date: Tue 6 Dec 2022

   

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West Africa: Farmers need more ways to combat pests

Posted in Biological control, Biopesticide, Botanical pesticides, Climate change, Control tactics, Cultural control, Emerging/invasive pests, Host plant resistance, IPM, natural enemies, Pests on December 1, 2022| Leave a Comment »

Climate change means farmers in West Africa need more ways to combat pests

by Loko Yêyinou Laura Estelle, The Conversation

worm on corn
Credit: Unsplash/CC0 Public Domain

The link between climate change and the spread of crop pests has been established by research and evidence.

Farmers are noticing the link themselves, alongside higher temperatures and greater variability in rainfall. All these changes are having an impact on harvests across Africa.

Changing conditions sometimes allow insects and diseases to spread and thrive in new places. The threat is greatest when there are no natural predators to keep pests in check, and when human control strategies are limited to the use of unsuitable synthetic insecticides.

Invasive pests can take hold in a new environment and cause very costly damage before national authorities and researchers are able to devise and fund ways to protect crops, harvests and livelihoods.

Early research into biological control methods (use of other organisms to control pests) shows promise for safeguarding harvests and food security. Rapid climate change, however, means researchers are racing against time to develop the full range of tools needed for a growing threat.

The most notable of recent invasive pests to arrive in Africa was the fall armyworm, which spread to the continent from the Americas in 2016.

Since then, 78 countries have reported the caterpillar, which attacks a range of crops including staples like maize and has caused an estimated US$9.4 billion in losses a year.

African farmers are still struggling to contain the larger grain borer, or Prostephanus truncatus Horn, which reached the continent in the 1970s. It can destroy up to 40% of stored maize in just four months. In Benin, it is a particular threat to cassava chips, and can cause losses of up to 50% in three months.

It’s expected that the larger grain borer will continue to spread as climatic conditions become more favorable. African countries urgently need more support and research into different control strategies, including the use of natural enemies, varietal resistance and biopesticides.

My research work is at the interface between plants, insects and genetics. It’s intended to contribute to more productive agriculture that respects the environment and human health by controlling insect pests with innovative biological methods.

For example, we have demonstrated that a species of insect called Alloeocranum biannulipes Montr. and Sign. eats some crop pests. Certain kinds of fungi (Metarhizium anisopliae and Beauveria bassiana), too, can kill these pests. They are potential biological control agents of the larger grain borer and other pests.

Improved pest control is especially important for women farmers, who make up a significant share of the agricultural workforce.

In Benin, for example, around 70% of production is carried out by women, yet high rates of illiteracy mean many are unable to read the labels of synthetic pesticides.

This can result in misuse or overuse of chemical crop protection products, which poses a risk to the health of the farmers applying the product and a risk of environmental pollution.

Moreover, the unsuitable and intensive use of synthetic insecticides could lead to the development of insecticide resistance and a proliferation of resistant insects.

Biological alternatives to the rescue

Various studies have shown that the use of the following biological alternatives would not only benefit food security but would also help farmers who have limited formal education:

  1. Natural predators like other insects can be effective in controlling pests. For example I found that the predator Alloeocranum biannulipes Montr. and Sign. is an effective biological control agent against a beetle called Dinoderus porcellus Lesne in stored yam chips and the larger grain borer in stored cassava chips. Under farm storage conditions, the release of this predator in infested yam chips significantly reduced the numbers of pests and the weight loss. In Benin, yams are a staple food and important cash crop. The tubers are dried into chips to prevent them from rotting.
  2. Strains of fungi such as Metarhizium anisopliae and Beauveria bassiana also showed their effectiveness as biological control agents against some pests. For example, isolate Bb115 of B. bassiana significantly reduced D. porcellus populations and weight loss of yam chips. The fungus also had an effect on the survival of an insect species, Helicoverpa armigera (Hübner), known as the cotton bollworm. It did this by invading the tissues of crop plants that the insect larva eats. The larvae then ate less of those plants.
  3. The use of botanical extracts and powdered plant parts is another biological alternative to the use of harmful synthetic pesticides. For example, I found that botanical extracts of plants grown in Benin, Bridelia ferruginea, Blighia sapida and Khaya senegalensis, have insecticidal, repellent and antifeedant activities against D. porcellus and can also be used in powder form to protect yam chips.
  4. My research also found that essential oils of certain leaves can be used as a natural way to stop D. porcellus feeding on yam chips.
  5. I’ve done research on varietal (genetic) resistance too and found five varieties of yam (Gaboubaba, Boniwouré, Alahina, Yakanougo and Wonmangou) were resistant to the D. porcellus beetle.

Next generation tools

To develop efficient integrated pest management strategies, researchers need support and funding. They need to test these potential biocontrol methods and their combinations with other eco-friendly methods in farm conditions.

Investing in further research would help to bolster the African Union’s 2021–2030 Strategy for Managing Invasive Species, and protect farmers, countries and economies from more devastating losses as climate change brings new threats.

Initiatives like the One Planet Fellowship, coordinated by African Women in Agricultural Research and Development, have helped further the research and leadership of early-career scientists in this area, where climate and gender overlap.

But much more is needed to unlock the full expertise of women and men across the continent to equip farmers with next generation tools for next generation threats.

Provided by The Conversation 

This article is republished from The Conversation under a Creative Commons license. Read the original article.

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