Richard Karban
John Dryburgh
‘Personal’ History
• B.S. at Haverford College, PA
• Ph.D. at University of
Pennsylvania
• Currently at UCDavis
• Co-wrote “How to Do Ecology”
and “Induced Responses to
Herbivory”
• ~142 journal articles and 7
book chapters
Plant Behavior & Herbivory
• Plants respond to their environment
– Abiotic factors
– Biotic factors
– Other plants
Karban, 2008
Plant Defense Against Herbivory
• a
Induced Resistance
• Phenotypic plasticity in which herbivore attack
causes an increase in resistance to future
herbivore attack
– Includes physical, chemical, and biological
mechanisms, ‘tolerance’
Karban, 2011
Effects of Induced Resistance
• Herbivores
– Alters feeding behavior
– Decreases growth rate
– Affects host selection
– Death? (Natural enemies)
• Plants
– Fitness costs
– Fitness benefits
Karban and Myers, 1989
Why Induce Resistance?
• Less costly?
• “Defended Fortresses” vs. “Moving Targets”
• Are plants in nature ‘constantly induced?’
Adler and Karban, 1994; Karban and Myers, 1989
Costs of Resistance
• Is resistance costly?
– Phytotoxicity of defenses
– Resource allocation
• Difficult to measure experimentally
Adler and Karban, 1994; Karban and Myers, 1989
Evading Herbivores
• “Defended Fortresses” vs. “Moving Targets”
• Creates variance in environment
• Variability reduces herbivore performance
Adler and Karban, 1994; Karban et al, 1997
Are Plants Always Induced?
• Wide variety of inducers
– Biotic and abiotic
• Plants in the field may always be effectively
induced
Applications in Agriculture
• Spider mites in grape
– ‘Vaccinating’ against Pacific spider mites
• Jasmonic acid
Karban et al, 1991
Jasmonic Acid
• Plant hormone
• Involved in plant responses to herbivores
• Antagonistic to salicylic acid (“Crosstalk”)
Defense Against Herbivores
• JA and MeJA induce similar responses to
herbivory in tomato
– Induce proteinase inhibitors, lipoxygenase, et al
– Suppress herbivore populations
• ‘Cross talk’ with salicylic acid
Thaler et al, 2001; Thaler et al, 1995
Eavesdropping
• “Talking Trees” hypothesis
• Plant volatiles: VOC, green leaf volatiles, and
HIPV
• Can plants talk? To whom?
– Inter- and intra specific eavesdropping
Sagebrush and Wild Tobacco
• Inter- and intra specific eavesdropping
– Sagebrush volatiles induce resistance in
neighboring sagebrush
• Also induces insect resistance in neighboring
tobacco
– Net fitness benefit?
– Other effects?
Various Karban et al.
Evolution of Eavesdropping
• Volatiles as within-plant signaling?
• Signaling natural enemies?
• Kin selection?
Baldwin et al, 2006
Intra-plant Signaling and Kin Selection
• Sagebrush responds more strongly to cues
from genetically identical cuttings
– ‘Recognition of self’
• Possibly faster than vascular signaling
Karban and Shiojiri, 2009
Natural Enemies
• Purely physiological process
– Volatiles exploited by natural enemies
• “Deliberate” process
– VOC also induce traits such as EFN, direct defense
– ‘Synergistic interactions’ among defenses
Heil and Karban, 2009
Cipollini and Heil, 2010
Current Work
• Volatile communication
• What factors affect caterpillar densities?
– Parasitoids/predation
– Weather patterns
– Food resources
• 29 years of census data
• Dare to be naive. I think we are limited in
science (and life) by trying to be experts and
being unwilling to take chances and in many
cases to look dumb. By daring to be naive,
you are willing to put yourself out there, ask
questions that you think everyone else already
knows the answers to, stuff like that.
Questions?
References and Photo Credits
Photo Credits:
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Slides 2, 15, 20, 22: Karban lab website; karban.wordpress.com
Slide 4:Arab, A., and Bento, J.M.S. Plant Volatiles: New Perspectives For Research in Brazil. 2006, Holopainen, J.K., and Gershenzon, J. Multiple Stress Factors and the Emission of
Plant VOCs. 2010, Michelle Sherwood (http://michellesherwood.blogspot.com), Wikipedia
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–
Slide 19: Cipollini, D, and Heil, M. Costs and Benefits of Induced Resistance to Herbivores and Pathogens in Plants. 2010
Slide 16: Baldwin I.T. et al Volatile Signaling in Plant-Plant Interactions: Talking Trees in the Genomics Era
References:
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Adler, Frederick R. and Richard Karban. Defended fortresses or moving targets? Another model of inducible defenses inspired by military metaphors. The
American Naturalist, 144(5): 813-832. 1994
Heil, M. and R. Karban. Explaining the evolution of plant communication by airborne signals. Trends in Ecology and Evolution, 25: 137-144. 2010
Karban, R. Communication between sagebrush and wild tobacco in the field. Biochemical Systematics and Ecology, 29: 995-1005. 2001
Karban, R. Plant behaviour and communication. Ecology Letters, 11: 727-739. 2008
Karban, Richard, Anurag A. Agrawal, and Marc Mangel. The benefits of induced defenses against herbivores. Ecology, 78(5): 1351-1355.1997
Karban, R., I.T. Baldwin, K.J. Baxter, G. Laue, and G.W. Felton. Communication between plants: induced resistance in wild tobacco plants following clipping of
neighboring sagebrush. Oecologia, 125: 66-71. 2001
Karban, Richard, Gregory English-Loeb, and David Hougen-Eitzman. Mite vaccinations for sustainable management of spider mites in vineyards. Ecological
Applications. 7(1): 183-193. 1997
Karban, Richard, Gregory English-Loeb and Paul Verdegaal. Vaccinating grapevines against spider mites. California Agriculture, 45(1): 19-21. 1991
Karban, Richard and Judith H. Myers. Induced plant responses to herbivory. Annual Reviews of Ecology and Systematics, 20: 331-348. 1989
Karban, R., J. Maron, G.W. Felton, G. Ervin, and H. Eichenseer. Herbivore damage to sagebrush induces resistance in wild tobacco: evidence for
eavesdropping between plants. Oikos, 100: 325-332. 2003
Karban, R., K. Shiojiri, M. Huntzinger, and A. C. McCall. Damage- induced resistance in sagebrush: volatiles are key to intra- and interplant communication.
Ecology, 87: 922-930. 2006
Karban, R. and K. Shiojiri. Self recognition affects plant communication and defense. Ecology Letters, 12: 502-506. 2009
Thaler, Jennifer S., Michael J. Stout, Richard Karban, and Sean S. Duffey. Exogenous jasmonates simulate insect wounding in tomato plants (Lycopersicon
esculentum) in the laboratory and field. Journal of Chemical Ecology, 22(10): 1767-1781. 1996
Thaler, J.S., M.J. Stout, R. Karban and S.S. Duffey. Jasmonate-mediated induced plant resistance affects a community of herbivores. Ecological Entomology,
26: 312-324. 2001
Thaler, J.S., R. Karban, D.E. Ullman, K. Boege, and R.M. Bostock. Cross-talk between jasmonate and salicylate plant defense pathways: effects on several plant
parasites. Oecologia, 131: 227-235. 2002