Plant Disease and Plant Health Part I A

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Plant Disease and Plant Health – Part I A comparison with human disease; what

Plant Disease and Plant Health – Part I A comparison with human disease; what causes plant disease; some examples; historical context The first of a series of resources to support GCSE and A-level curricula. Published Feb. 2016

Fighting for their lives: Plants and pathogens Photos courtesy of CIMMYT, Scott Bauer, USDA

Fighting for their lives: Plants and pathogens Photos courtesy of CIMMYT, Scott Bauer, USDA Agricultural Research Service, IRRI, IITA

Humans get sick. Diseases are caused by micro-organisms • Bacteria • Fungi • Viruses

Humans get sick. Diseases are caused by micro-organisms • Bacteria • Fungi • Viruses

Human pathogens (1) - bacteria Bacterial meningitis symptoms, caused by Meningococcal meningitis (1) Scanning

Human pathogens (1) - bacteria Bacterial meningitis symptoms, caused by Meningococcal meningitis (1) Scanning Electron Micrograph of Mycobacterium tuberculosis the causal agent on Tuberculosis or TB (2)

Human pathogens (2) - fungi Athletes Foot symptoms caused by the fungus Tinea pedis

Human pathogens (2) - fungi Athletes Foot symptoms caused by the fungus Tinea pedis (3) Symptoms of ringworm infection on the scalp, caused by the fungus Tinea corporis (4)

Human pathogens (3) - viruses Cut-away model of the HIV-virus the causal agent of

Human pathogens (3) - viruses Cut-away model of the HIV-virus the causal agent of human immunodeficiency virus (5). The virus attacks the immune system, and weakens your ability to fight infections and disease. Mainly transmitted through sexual contact Influenza particles spread upon sneezing. Salivary droplets being expelled from the man’s open mouth (6)

Plants get sick. Diseases are caused by micro-organisms • Bacteria • Fungi • Viruses

Plants get sick. Diseases are caused by micro-organisms • Bacteria • Fungi • Viruses

The disease-causing agents that makes plants sick are called plant pathogens • Plant pathogens

The disease-causing agents that makes plants sick are called plant pathogens • Plant pathogens cause 10 – 30% crop yield losses annually • Most plants are resistant to most pathogens; disease is the exception, not the rule

Plant pathogens (1) - bacteria Ring rot is caused by the bacterium Clavibacter michiganensis

Plant pathogens (1) - bacteria Ring rot is caused by the bacterium Clavibacter michiganensis subsp. sepedonicus. (7) Crown Gall Disease (8)

Plant pathogens (2) - fungi Black Sigatoka symptoms in banana caused by the fungus

Plant pathogens (2) - fungi Black Sigatoka symptoms in banana caused by the fungus Mycosphaerella fijiensis (9) Symptoms of powdery mildew infection on barley, caused by the fungus Blumeria gramins (10)

Plant pathogens (3) - viruses Symptoms of Tobacco Mosaic Virus (TMV) infection in tobacco

Plant pathogens (3) - viruses Symptoms of Tobacco Mosaic Virus (TMV) infection in tobacco (11) Electron-micrograph of Tobacco Mosaic Virus (TMV) – (12) Replace with Keith Saunders images and credit

Fungi, bacteria & viruses cause disease in humans & plants Fungi (eukaryotes) Bacteria (prokaryotes)

Fungi, bacteria & viruses cause disease in humans & plants Fungi (eukaryotes) Bacteria (prokaryotes) Virus (non-cellular, packaged nucleic acid)

Some plant pathogens belong to the Kingdom Protoctista • Protists are eukaryotes. They’re not

Some plant pathogens belong to the Kingdom Protoctista • Protists are eukaryotes. They’re not plants, animals or fungi. Protists fall into four general subgroups: unicellular algae, protozoa, slime moulds, and water moulds. They include 2 major disease causing organisms • Phytophthora infestans (an oomycete). Which causes Potato Blight and was the cause of the Irish Potato Famine (1846) • Plasmodium spp. the malaria parasite carried by mosquitoes

Plasmodium vivax parasitising blood cells

Plasmodium vivax parasitising blood cells

Phytophthora infestans

Phytophthora infestans

For as long as man as grown crops he has battled with their diseases

For as long as man as grown crops he has battled with their diseases

Diseases were often blamed on the gods Once it was thought that gods and

Diseases were often blamed on the gods Once it was thought that gods and goddesses controlled natural events. The Greek goddess of the harvest was Demeter, while the Roman equivalent was Ceres or Demeter was the goddess of grain Demeter (13) Ceres (14)

“Robigalia” – to save the crops • A Roman Festival for the god, Robigus,

“Robigalia” – to save the crops • A Roman Festival for the god, Robigus, held on the 25 th April • Roman’s believed Robigus would prevent crop disease if they made sacrifices in his honour • The main ritual was a dog sacrifice to protect the grain fields from wheat rust, a fungal disease with a reddish/brown coloured spores. • The dogs would usually have a red coats

‘Robigus’ protected against this fungus – wheat stem rust

‘Robigus’ protected against this fungus – wheat stem rust

Its not just the disease … • As well as crop yield losses, some

Its not just the disease … • As well as crop yield losses, some fungal infections are accompanied by toxins, secondary metabolites produced by the fungus (mycotoxins) • These mycotoxins can be deadly to both humans and livestock.

Mad Grain Burning and convulsions Hallucinations with imaginary sounds Gangrene and loss of limbs

Mad Grain Burning and convulsions Hallucinations with imaginary sounds Gangrene and loss of limbs Permanent insanity • Initial burning sensation > Latin name, Ignis sacer meaning holy fire. • A religious order dedicated to St. Anthony was founded in 1083 to help the afflicted. The condition became known as St. Anthony’s fire

Ergotism & Witchcraft • 990 – 1129 AD ergotism believed to have killed 50

Ergotism & Witchcraft • 990 – 1129 AD ergotism believed to have killed 50 K people in South of France • 1692 – convulsive ergotism may have caused symptoms that led to the Salem Witch Trials in which 20 people executed • 1926 – 11 K victims in USSR • Takes 2 forms – gangrenous / convulsive – both fatal

Ergot (from French for cock’s spur, argot) • Link with a fungus (Claviceps purpurea)

Ergot (from French for cock’s spur, argot) • Link with a fungus (Claviceps purpurea) made in 1670. • Ergots are sclerotia (fungal overwintering survival structures) that replace developing grain in the ear. • Ergots contain several alkaloids. Some are potent vasoconstrictors (e. g. ergotamine) while others are psychoactive (LSD, lysergic acid diethylamide). • Spores released from sclerotia infect cereals at flowering, completing the cycle.

Potato Blighted potatoes (15) Dublin memorial to the 1. 5 million killed by starvation

Potato Blighted potatoes (15) Dublin memorial to the 1. 5 million killed by starvation during the Irish Potato Famine, 184552 (16)

Impact of Blight on Irish population Phytophthora infestans was introduced to Ireland from South

Impact of Blight on Irish population Phytophthora infestans was introduced to Ireland from South America (where the potato originates) Population Cool, wet summers provided ideal conditions for the fungus to flourish Irish labourer ate ~5. 4 kg potatoes a day spread across 3 meals Many emigrated to the United States to flee from the famine Population yet to recover Blight outbreak

Alimentary Toxic Aleukia (ATA) • ATA caused the deaths of thousands of people in

Alimentary Toxic Aleukia (ATA) • ATA caused the deaths of thousands of people in the USSR, especially in the Orenburg District around the Caspian Sea, from 1942 to 1948. • It causes fever, bleeding from the skin, nose, throat and gums, necrosis, and suppression of the immune system. • During World War II, food was very scarce, causing consumption of poor quality grain.

ATA, bread and Fusarium • ATA was found to be caused by the toxin

ATA, bread and Fusarium • ATA was found to be caused by the toxin T-2. The toxin was produced in the grain by the growth of Fusarium species, F. sporotrichioides and F. poae. • Grain allowed to remain in the fields unharvested during winter was colonised by these fungi. Chemical structure of T 2 -toxin

Brief History of Plant Disease 1863 Anton de Bary shows potato blight caused by

Brief History of Plant Disease 1863 Anton de Bary shows potato blight caused by Phytophthora Germ Theory Louis Pasteur (1881) T. J. Burrill (1878) demonstrated that fire blight of pear and apple was caused by a bacterium, Erwinia amylovora 1890 TMV shown to be caused by a virus (1898) By the end of the 19 th century, pathologists knew why plants got sick

Research in the 20 th century focused on the prevention and control of disease

Research in the 20 th century focused on the prevention and control of disease outbreaks 1. Chemical Control 2. Cultural Control 3. Genetic Control

Chemical Warfare ! Pathogens can evolve resistance to the chemicals; environmental concerns about spraying

Chemical Warfare ! Pathogens can evolve resistance to the chemicals; environmental concerns about spraying limits

Better crop hygiene – ‘ploughing-in’ Burning crop residues / stubble burning effectively banned in

Better crop hygiene – ‘ploughing-in’ Burning crop residues / stubble burning effectively banned in UK since 1993 (due to pollution fears)

Genetics of Disease Resistance Change to my PM or Rust image Resistant Sensitive Plant

Genetics of Disease Resistance Change to my PM or Rust image Resistant Sensitive Plant Breeders try to introduce disease resistance genes into susceptible varieties

The Disease triangle ge Pa tho The disease triangle (it takes three) Environment st

The Disease triangle ge Pa tho The disease triangle (it takes three) Environment st Ho The pathogen must be able to overcome plant defenses n Plants are exposed to countless microbes, but very, very few of these interactions lead to disease. Why? The host plant must be susceptible to the pathogen The environment must tip the balance in favour of the pathogen

Humans influence diseases Migrations of people and plants Humans add another dimension (making a

Humans influence diseases Migrations of people and plants Humans add another dimension (making a disease pyramid…. ) Monoculture n ma Hu s Introduced pathogens and vectors Envi ronm Ho st Pathogen ent Growing practices

The environment affects whether the plant or pathogen wins – many factors Temperature Rain

The environment affects whether the plant or pathogen wins – many factors Temperature Rain Wind Planting density Pollution Other organisms Moisture content Nutrient availability

ge Pa tho The disease triangle (it takes three) Environment st Avoid or eliminate

ge Pa tho The disease triangle (it takes three) Environment st Avoid or eliminate the pathogen Ho n Strategies to prevent and manage disease Make the plant resistant through genetic or other methods Manipulate the environment to favour the plant

What makes a successful pathogen? • Pathogenesis genes and effectors allow the pathogen to

What makes a successful pathogen? • Pathogenesis genes and effectors allow the pathogen to enter into the plant, evade the plant’s defenses, and survive and reproduce • Numbers – more pathogens increases the chance of success What makes a vulnerable host? • Poor health – wounded or weakened plants can be more vulnerable • A lack of disease resistance genes Phytophthora colocasiae Fraser fir (Abies fraseri) killed by phytophthora root disease

More about host: pathogen interactions in Part II

More about host: pathogen interactions in Part II

Acknowledgements (1 of 4) • The BSPP gratefully acknowledges the ASPB for granting access

Acknowledgements (1 of 4) • The BSPP gratefully acknowledges the ASPB for granting access to its Teaching Tools in Plant Biology series. The presentation “Fighting for their lives: plants and pathogens” helped frame this presentation and some slides have been used directly with the editors permission. • This presentation is prepared under a CC-? ? Licence permiting …. • • Additional images have been sourced as follows. Slide 4. (1) – Wellcome Photo Library, Wellcome Images, N 0000730 (2) - Janice Carr: CDC/ Dr. Ray Butler; Janice Carr - This media comes from the Centre for Disease control and Prevention’s Pubic Health Library id no. #8438 Slide 5. (3) - Wes Washinton, Wikipedia Creative Commons (4) - http: //www. nhs. uk/Conditions/Ringworm/Pages/Symptoms. aspx Slide 6. (5) John Wildgoose, Wellcome Images Cut-away model of HIV; (6) James Gathany - CDC Public Health Image library ID 11162 • •

Acknowledgements (2 of 4) • • • Slide 9. (7) Ring Rot, potatoes: FERA

Acknowledgements (2 of 4) • • • Slide 9. (7) Ring Rot, potatoes: FERA Crown Copyright (8) Crown Gall Disease – APS no permission Slide 10. (9) Black Sigatoka Virus (10) Powdery Mildew Slide 11. (11) R. J. Reynolds Tobacco Company Slide Set - USDA Forest Service, http: //www. forestryimages. org/browse/detail. cfm? imgnum=1402027 Photo of a tobacco leaf with symptoms of tobacco mosaic virus. UGA 1402027 (12) TMV – ASK KEITH Slide 14. Plasmodium CDC/Mae Melvin, by CDC/Dr. Mae Melvin http: //phil. cdc. gov/phil_images/20021230/12/PHIL_2720_lores. jpg. Mosquito: Wellcome Images Slide 15 Phytophthora infestans Slide 16 Photographic reproduction of a two-dimensional work of art in the public domain – ‘Pintura del Antiguo Egipto mostrando la trilla del trigo’ Wikipedia

Acknowledgements (3 of 4) • • • Slide 17 (13) Neustrelitz-goetter 2 -demeter by

Acknowledgements (3 of 4) • • • Slide 17 (13) Neustrelitz-goetter 2 -demeter by user Ruchhöft-Plau, class="int-own-work”. Licensed under Public Domain via Wikimedia Commons (14) Ceres - Dominikus Auliczek um 1770 -1. jpg. Nymphenburger Porzellanmanufaktur, Porzellanmuseum München Slide 19 © Marie-Lan Nguyen / Wikimedia Commons. Section of the Fasti Praenestini, calendar of Verrius Flaccus. VIN stands for Vinalia, a wine festival, and ROB for Robigalia, a festival to ward off crop disease. Slide 20 Bible image Slide 21 Mathis Gothart Grünewald 018 - The Yorck Project: 10. 000 Meisterwerke der Malerei. DVD-ROM, 2002. <a href="//commons. wikimedia. org/wiki/Special: Book. Sources/3936122202" class="internal mw-magiclink-isbn">ISBN 3936122202</a>. Distributed by DIRECTMEDIA Publishing Gmb. H. . Licensed under Public Domain via wikimedia Commons Slide 23 Ergots Slide 24 (15) Blifgted Pots (16) Dublin memorial Slide 25 The original uploader was Rannpháirtí anaithnid (old) at English Wikipedia - Transferred from en. wikipedia to Commons by Andreasmperu using Commons. Helper .

Acknowledgements (4 of 4) • • • Slide 26 Chickens Slide 27. . "<a

Acknowledgements (4 of 4) • • • Slide 26 Chickens Slide 27. . "<a href="https: //commons. wikimedia. org/wiki/File: T-2_mycotoxin. png#/media/File: T-2_mycotoxin. png">T-2 mycotoxin</a>" by <a href="//commons. wikimedia. org/wiki/User: Edgar 181" title="User: Edgar 181">Edgar 181</a> - <span class="int-own-work" lang="en" xml: lang="en">Own work</span>. Licensed under Public Domain via <a href="https: //commons. wikimedia. org/wiki/">Commons</a>. Slide 29 Tractor Spray Slide 30 Photo courtesy of Ryetech, http: //www. ryetec. net/ Slide 31 Photo courtesy Phil Smith, John Innes Centre, Norwich Slide 33. Photos courtesy Scott Bauer and Bob Nichols, USDA, and Geovantage, Inc Slide 34. Photo by Jack Dykinga Slide 36. Fred Brooks, University of Hawaii at Manoa; Linda Haugen, USDA Forest Service, Bugwood. org Slide 37 PM mscope ? ? ? This work has been released into the public domain by its author, Alan. Mc at English Wikipedia. This applies worldwide.