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Plant Interactions with Other Organisms Lectures 17 and 18
© McGraw-Hill Companies Mason et al. 2011 Biology 9e Fig 40.10
300802 Biodiversity 2013 Qihan Dong and Tony Haigh
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Reading • Mason et al. 2011 • Chapter 31 • 31.8 Ecology of fungi • 31.9 Fungal parasites and pathogens
• Chapter 39 • 39.3 Special nutritional strategies
• Chapter 40 • 40.1 Physical defenses • 40.2 Chemical defenses • 40.3 Animals that protect plants
• Chapter 42 • 42.4 Pollination and fertilization
© McGraw-Hill Companies Mason et al. 2011 Biology 9e Chapter 42 title image
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Types of Interactions • • • • • • •
Mutualism Symbiosis Parasitism Disease Herbivory Defence Pollination
© McGraw-Hill Companies Mason et al. 2011 Biology 9e Figs Chapter 40 Title image, 40.06
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Mutualism • • • • •
Mutually beneficial interaction Different species Lichen Symbiosis Fungal host • • 15,000 species
• Photosynthetic symbiont • Green alga • Cyanobacterium
• Penetrate cell wall • © McGraw-Hill Companies Mason et al. 2011 Biology 9e Fig. 31.16 4
Mycorrhizae Arbuscular Mycorrhizae Root
• Fungus and plant root • Extension of root system • Increase soil contact • Absorption
3.7 µm
a.
• Nutrients • Water
• Two principal types • Ectomycorrhizae
Ectomycorrhizae
• Fungal sheath • • Forest trees
• Arbuscular mycorrhizae 50 µm
b.
© Dr. Gerald Van Dyke/Visuals Unlimited
© McGraw-Hill Companies Mason et al. 2011 Biology 9e Fig. 31.17
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Ectomycorrhizae Tuber melanosporum
Fly agaric Amanita muscaria
Truffles
Tuber aestivum Photos Gerald Holmes, Valent USA Corporation, Bugwood.org and Arpingstone
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Ectomycorrhizae • • • •
Form sheath Around root Hartig net Penetrate root
• Root tip of Pinus nigra colonised by ectomycorrhizal fungus Source Plett, Martin, (2011) Blurred boundaries: lifestyle lessons from ectomycorrhizal fungal genomes. Trends in Genetics 27: 14-22 © Elsevier. Photo M. Vohník
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Arbuscular Mycorrhizae Arbuscular Mycorrhizae
• Inside root cell wall • 80 % of plants • No not penetrate plasma membrane
Root
• • Zygomycetes
3.7 µm
• No above ground fruiting bodies • Infertile soils • Known from fossils
• Non-photosynthetic plants • Epiparasite © McGraw-Hill Companies Mason et al. 2011 Biology 9e Fig. 31.17
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> 400 Million Years Old 400 million year old AM within plant cell
Aglaophyton major fossilized Devonian tracheophyte
Modern arbuscular mycorrhizae within plant cell Remy, Taylor, Hass, Kerp (1994) Four hundred-million-year-old vesicular arbuscular mycorrhizae. PNAS USA 91: 11841-11843. © National Academy of Sciences, USA; Images Griensteidl, Mark Brundrett
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Plant – Bacteria Interactions • • • • • • • •
Special nutritional strategy Root nodules Nitrogen-fixing bacteria Frankia, Parasponia – actinomycetes Nostoc – cyanobacterium Rhizobium – alphaproteobacterium Legumes Nitrogen fixation • •
• • • •
© McGraw-Hill Companies Mason et al. 2011 Biology 9e Fig. 39.09
Most energy expensive reaction in cells Energy required to break triple bond
Rhizobium Carbohydrate from phloem Oxygen regulation by leghemoglobin Produced by plant
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Epidermal cell Cortex cells Root hair
Rhizobium
Nodule Development
Infection thread
Vesicles with differentiating bacteroids Cell division starts making nodule Differentiated bacteroids fixing nitrogen Mature nodule
• Root releases chemical signal to Rhizobium • Rhizobium releases chemical signal to roots • Root hair grows • Infection thread • Cell division • Rhizobium changes shape • Bacteroid
• Nodule matures
© McGraw-Hill Companies Mason et al. 2011 Biology 9e Fig. 39.10
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Other Nutritional Strategies Canopy protects pitcher from being flooded by rainwater
Slippery or hairy sides prevent escape of prey Prey
Prey After two hairs are touched, leaf trap closes
Digestive fluid secreted
Digestive fluid
• Nepenthes • Pitcher plant © McGraw-Hill Companies Mason et al. 2011 Biology 9e Fig. 39.11
• Dionaea • Venus fly trap • 100 ms 12
Other Nutritional Strategies Sticky mucilage secreted Prey attracted to droplet Prey held by several trichomes as it is digested
• Drosera • Sundew • Relative of Venus fly trap © McGraw-Hill Companies Mason et al. 2011 Biology 9e Fig. 39.11
Prey
• Aldrovanda • Aquatic waterwheel • Relative of Venus fly trap 13
Parasitic Plants
Striga on maize (L), drooping mistletoe on eucalypt (UR), dodder (LR) Image sources USDA APHIS PPQ Archive, Tony Haigh, John D. Byrd, Mississippi State University
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Plants and Pathogens • Diseases cause crop losses • Fungi • Bacteria • Viruses
Ustilago (UL) on maize Aspergillus conidia (UR) © McGraw-Hill Companies Mason et al. 2011 Biology 9e Fig. 31.20 Bacterial blast of rice (ML, LL) Yellow mosaic virus in soybean
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Viruses African Cassava Mosaic Virus resistant cassava variety (left) and susceptible cassava variety (right)
Photo courtesy of IITA Photo Library 16
Bacteria Maize infected with bacterial leaf stripe (Acidovorax avenae subsp. avenae)
Banana infected with Xanthomonas
Photos courtesy of IITA Photo Library and CIMMYT
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Fungi Wheat infected with wheat stem rust Puccinia graminis Basidiomycete Photo ARS USDA
• • • •
Fungal infection Attachment Entry via stomate Cell penetration
© McGraw-Hill Companies Mason et al. 2011 Biology 9e Fig. 40.05
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Nematodes • Round worms • 0.1 mm diameter • Found everywhere
• Plant pests •
© McGraw-Hill Companies Mason et al. 2011 Biology 9e Fig. 40.03
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Disease Resistance Susceptible
Resistant
Tomato on right has a resistance gene that confers resistance to the bacterial pathogen Pseudomonas syringae pv. Tomato Gammaproteobacteria
©AAAS. Source Martin et al. (1993) Map-based cloning of a protein kinase gene conferring disease resistance in tomato. Science. 262: 1432-1436.
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Herbivores
Boll weevil (Anthonomus grandis grandis) on cotton (Gossypium hirsutum)
Leaf beetle (Phratora laticollis) on European aspen (Populus tremula)
Image credits: Petr Kapitola, State Phytosanitary Administration, Bugwood.org ; Alton N. Sparks University of Georgia, Bugwood.org, Louisa Howard, Dartmouth College
Aphid on unknown plant
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Animals Eat Plants
Phloem-sucking aphids Leaf-chewing larvae
Mesophyll-grazing leaf miners
Mesophyllsucking mites
Root-vascular cylinder sucking nematodes
• Plants store energy via photosynthesis • Animals eat plants • Animals eat plant-eaters
Photo credits: Sate Al Abbasi; David Cappaert, Michigan State University, Bugwood.org; University of Missouri. Published by MU Extension, all rights reserved. William Wergi; John R. Meyer, North Carolina State University; Scott Bauer, USDA
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Herbivory: an Ongoing Conflict • Plants eaten by many animals • Insect larvae
© McGraw-Hill Companies Mason et al. 2011 Biology 9e Fig. 40.06
Parasitoid larvae
Parasitised herbivore larva © Bugwood.org
• Angiosperms and insects coevolved • Predatory or parasitic insects protect plants • Most angiosperms use insects for pollination •
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Plants have evolved many ways to defend against herbivory Chemical Physical
Nicotine Ranger and Hower (2001). Glandular morphology from a perennial alfalfa clone resistant to the potato leafhopper. Crop Science 41: 1427-1434.
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Physical Defences
Mentzelia pumila trichomes and trapped insects
© National Academy of Sciences, USA. Eisner, Eisner and Hoebeke (1998). When defense backfires: detrimental effect of a plant’s protective trichomes on an insect beneficial to the plant. PNAS. USA 95: 4410-4414,
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Chemical Defences Manihotoxin
Metabolised to release cyanide
Genistein
Estrogen mimic
Taxol
© McGraw-Hill Companies Mason et al. 2011 Biology 9e Table 40.01
Anticancer drug
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Chemical Defences
Quinine
Antimalarial drug
Morphine
Narcotic pain relief
© McGraw-Hill Companies Mason et al. 2011 Biology 9e Table 40.01
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Chemical Defences Proricin —S — S— Animal digestive enzymes Ricin A
—S
S—
Ricin B
Ricin A
Ribosome
© McGraw-Hill Companies Mason et al. 2011 Biology 9e 40.08
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Trichomes can release chemical deterrents and toxins Tomato (Solanum lycopersicum) Pheromoneor repellentreleasing trichome
Tomato trichomes produce chemicals repellent to whiteflies
Wild-potato (Solanum berthaultii)
Stickyreleasing trichome
Many trichomes produce sticky substances © Macmillan Publishers Ltd. Source Gibson and Pickett (1983) Wild potato repels aphids by release of aphid alarm pheromone. Nature 302: 608-609.
Wild-potato trichomes produce aphid alarm pheromones Images © American Society of Plant Biologists
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Perception of Herbivory Biting and wounding damage
Piercing and saliva
Oral secretions and regurgitant
I-D-C-I N Inceptin G-V-C-V-D-A
ALARM
Volicitin
Egg laying damage and secretions Images © American Society of Plant Biologists Phillip Roberts, USDA Forest Service University of Georgia, Bugwood.org; Mithöfer and Boland (2008) Recognition of herbivory-associated molecular patterns. 30 Plant Physiology 146: 825-831; .
Some compounds are toxic, or can be converted to toxins, or are anti-nutritive A cyanogenic glycoside that releases toxic cyanide
Nicotine, a toxin found in tobacco and its relatives
HC
N
Cyanide Anti-nutritives interfere with herbivores’ digestion or assimilation of nutrients, impairing their growth and development
Images © American Society of Plant Biologists 31
Some herbivores have evolved tolerance to plant toxins toxin Rapid degradation
Herbivores can tolerate plant toxins through degradation, excretion and sequestration (through chemical modification and storage in specialized glands).
Sequestration
Rapid excretion
In some cases the target enzyme has been modified to now be unaffected by the toxin Target (e.g. enzyme)
Modified target
toxin toxin Images © American Society of Plant Biologists
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Alliances Plants and Carnivores or Parasitoids Lady beetle devours a pea aphid
Spider mite and predatory mite (and their eggs)
Assassin bug
Parasitoid larvae
Hyposoter ebeninus attacking a Pieris rapae larva
Pirate bug eating aphid
Parasitised caterpillar Photo: T. Bukovinszky / www.bugsinthepicture.com; Thailand IPM; R.J. Reynolds Tobacco Company Slide Set , Bradley Higbee, Paramount Farming; Bugworld.org; Scott Bauer, USDA
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Herbivore-induced plant volatiles can attract parasitoid arthropods Parasitoid wasps lay their eggs in other arthropods. When the larvae hatch they eat the host
Image © American Society of Plant Biologists 34
Parasitoid Wasps 1. A volatile signal
is released as the caterpillar eats a leaf.
© McGraw-Hill Companies Mason et al. 2011 Biology 9e 40.10
2.
Female wasp is attracted by the volatile signal, finds caterpillar, and lays eggs.
3.
Wasp larvae feed on the caterpillar and then emerge.
4. Larvae continue to feed on
the caterpillar after it dies, but not the plant. The larvae then spin cocoons to pupate.
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Some plants form longer-term alliances with resident bodyguards Acacias provide ants with shelter and food from extrafloral nectaries (EFN) and food bodies (FB), also known as Beltian bodies
EFN
Ants protect acacias from other plants and other arthropods.
Thorns provide shelter, called domatia
Photos courtesy of Dan Janzen, University of Pennsylvania
FB
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Plants, Psyllids and Disease Citrus disease Huanglongbing Caused by α-proteobacteria Spread by Asiatic citrus psyllid
Electropenetrograph Electrical signal from psyllid body 50x
-
+
Ri
5
0
0
300
np
600
pathway
900
1200
1500
1800
E
© Cen et al (2012) Feeding behaviour of the Asiatic citrus psyllid, Diaphorina citri, on healthy and huanglongbing-infected citrus. Entomologica Experimentalis et Applicata.143: 13-22.
2100
2400
C & E1
2700
3000
3300
3600
G
37
Psyllid Feeding np
pathway
xf
pathway & ps
ps & pf
5
0
0
300
600
900
1200
1500
1800
2100
2400
2700
3000
3300
3600
Phloem and xylem feeding phases E1
E2
Contractions of salivary pump muscles
G
Contractions of pharyngial pump muscles
Tjallingii (2006) Journal of Experimental Botany 57:739-745
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Disease and Psyllid Feeding
Healthy (noninoculted
Mild
Moderate
Severe
Citrus leaf responds to HLB Develops tougher cells around infected phloem Changes feeding behaviour, but restricts transport in vascular tissue © Cen et al (2012) Feeding behaviour of the Asiatic citrus psyllid, Diaphorina citri, on health and huanglongbing-infected citrus. Entomologica Experimentalis et Applicata.143: 13-22.
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Angiosperm Pollination • Wind-pollinated plants • Large quantities of pollen
• Animal pollinators • Brightly coloured flowers • Nectar • Pollen • Mimicry
• Bees, wasps, beetles, moths, flies, butterflies, lizards, birds, bats, mammals © McGraw-Hill Companies Mason et al. 2011 Biology 9e Figs 42.23, 42.26
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Flowers and Pollinators
Photos by Jack Dykinga; Rob Flynn, USDA-ARS; Hans Hillewaert
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Flowers and Bees
Visible light
Simulated bee vision
Bees also have lower spatial resolution than humans, which is represented in the third row
• Flower pigments also reflect or absorb UV-light which is visible to bees © McGraw-Hill Companies Mason et al. 2011 Biology 9e 42.24
Source: Wertlen and Cocucci (2007) How to look like a mallow: evidence of floral mimicry between Turneraceae and Malvaceae. Proc. Roy. Soc. B. 274: 2239-2248.
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Nectar Nectar was an early innovation of flowers and is an important contributor to the success of angiosperms
150 million year old insect with nectarfeeding mouthparts
Many pollinators have tongues or other mouthparts specialized for nectar sipping
Ren (1998) Flower-associated brachycera flies as fossil evidence for Jurassic angiosperm origins. Science 280: 85-88., © AAAS; Image by artist Joseph Scheer. David Cappaert, Michigan State University, Bugwood.org
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Some flowers have complex shapes and patterns to enhance pollination
Some flowers have honey-guides to direct pollinators to nectar.
Others produce nectar at the tips of spurs, the length of which correlates with the length of their pollinators tongues.
Observations of plants and their pollinators helped Darwin refine his ideas about natural selection Photo Tom Donald; Source Whittall, Hodges (2007) Pollinator shifts drive increasingly long nectar spurs in columbine flowers. Nature 447: 706 – 712.
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Summary • • • • • • • •
Plants interact with all other organisms Viruses, bacteria, fungi Disease, beneficial relationships Plant responses Herbivory Plant defences Complex relationships Pollination 45
Final Examination • Examination period for all students • Weeks 16 – 18 (June 11 – June 30) • Examination may be held on Saturday • Examination room as advised
• 40% of unit total • 2 hour closed book examination • Exam conditions • No books, notes, iPads, phones, etc
• Paper based, not online • 2 B pencil, eraser, pencil sharpener, student ID card
• 90 multiple choice questions • All content Weeks 1 to 14 • Chapters 1, 20 – 24, 26 – 35, 40 46
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