Transcript Document

Plant-plant interactions
Photo courtesy of Ronald Pierik
© 2013 American Society of Plant Biologists
Plants sense and respond to other
plants植物感知和响应其他植物
Often, but not always,
plants compete with each
other for limiting resources,
such as light and nutrients
通常，但不一定是，植物对有限资源是相
互竞争的，如光和营养。
How do they perceive
competitors?
他们是如何感知竞争对手的？
Are all of their interactions
competitive? 所有植物之间的交
互作用都是竞争性质的吗？
How do interactions
between plants affect
higher organizational levels
(e.g., communities)? 植物之
间的相互作用是如何影响更高水平
的组织结构的？如群落
Photo credit: Tom Donald
© 2013 American Society of Plant Biologists
Outline概要
Key definitions and concepts
关键的定义和概念
Competition竞争
•Competition for light 光
•Competition belowground地下竞争
•Do plants perceive “self” or “kin”?
•植物自我和亲属是怎么感知的？
Cooperation / Facilitation协同和促进
•Environmental modulation环境的调节
•Enhanced nutrient availability提高营养物质
的有效性
•Stress cues胁迫信号
Putting knowledge to work
Photo credit: Mary Williams
© 2013 American Society of Plant Biologists
Key definitions and concepts
Phenotypic plasticity表型可塑性
The capacity of an individual (or a genotype) to exhibit a range of phenotypes in
response to variation in the environment个人的能力,表现出一系列的表型,以应对环境的变化
Low light光
High light
Low Red: 远红
外的比率
High Red: Farred ratio
Low phosphate
High phosphate
Low phosphate
P水平
Polygonum lapathifolium酸膜
Nicotiana tabacum烟
Reprinted by permission from Wiley from Drew, M.C. (1975). Comparison of the effects of a localised supply of phosphate, nitrate and ammonium and potassium on the growth of the seminal root system, and the shoot, in barley. New Phytol. 75:
479-490. Reprinted from Vandenbussche, F., et al. (2005). Reaching out of the shade. Curr. Opin. Plant Biol. 8: 462-468 with permission from Elsevier, Reprinted from Sultan, S.E. (2000). Phenotypic plasticity for plant development, function and
life history. Trends Plant Sci. 5: 537-542 with permission from Elsevier. See also Bradshaw, A. D. (1965). Evolutionary significance of phenotypic plasticity in plants. Adv. Genet. 13: 115–155.
© 2013 American Society of Plant Biologists
Phenotypic plasticity in plants
植物的表型可塑性
Root plasticity in
response to
localized nutrient
availability
Shoot plasticity in response to light光
根可塑性响应局部营养的
可用性
Reprinted by permission from Wiley from Drew, M.C. (1975). Comparison of the effects of a localised supply of phosphate, nitrate and ammonium and potassium on the growth of the seminal root system, and the shoot,
in barley. New Phytol. 75: 479-490. Photo credit Michael Clayton.
© 2013 American Society of Plant Biologists
Signals and cues
Signals and cues convey information
Signals are generally
considered to be an
intended information
broadcast and can include:
hormones, bacterial
metabolites, electrical signals,
light quality, stress signals
Semaphores are
signals
Odors and light can be cues
Cues are considered to be
without intent and can
include:
Nutrient resources, water, light
See for example, Aphalo, P.J. and Ballare, C.L. (1995). On the importance of information-acquiring systems in plant-plant interactions. Funct. Ecol. 9: 5-14. Aphalo,
P.J., Ballaré, C.L. and Scopel, A.L. (1999). Plant-plant signalling, the shade-avoidance response and competition. J. Exp. Bot. 50: 1629-1634. Image from Nesnad.
© 2013 American Society of Plant Biologists
Signals and cues affecting plants
INFORMATION
Internal
Signaling
Primary metabolites
Hormones
Electrical pulses
Some hormones, such
as ethylene and
strigolactones, serve
as communication
vectors both internally
and externally
External
Cueing
Signaling
Abiotic:
Physical and
chemical
environment
atmospheric,
edaphic.
Biotic:
Secretions,
exudates, volatiles
etc
Biotic only
External cueing:
Can be observed
External signaling:
Initially, only a hypothesis.
Whether it is adaptive for the
emitter as well as the receiver
must be determined
© 2013 American Society of Plant Biologists
Cues inform decisions about when
and how to allocate finite resources
Signals and
cues indicate
the “best bet”
Like a poker player, plants
have limited resources.
Gambling on a bad hand,
or expending resources at
the wrong place or time
can be a big mistake
Cues that indicate future
conditions and circumstances
are particularly important.
Plants grow slowly, and can’t
run away, so they have to live
with the consequences of their
behaviors
See for example Shemesh, H, BF Zaitchik, T Acuna, and A Novoplansky (2012) Architectural plasticity in a Mediterranean winter
annual. Plant Signal. Behav. 7:492 – 501 and Shemesh, H. and Novoplansky, A. (2012) Branching the risks: architectural plasticity
and bet-hedging in Mediterranean annuals. Plant Biol., In press. Photo credit Tom Donald.
© 2013 American Society of Plant Biologists
Plant behavior
What a plant does in the course of its lifetime, in
response to an event or change in the environment
Example: Phototropic curvature towards a light source
Images: Wisconsin fast plants, Tangopaso
© 2013 American Society of Plant Biologists
Plant behavior affects morphological
and biochemical phenotypes
Shaded
Full sun
One of the most
studied plastic
responses is
shade-induced
stem elongation
Plants can’t run away – they have
different forms of behavior
The induction of defense responses to
herbivory or pathogens is another type of
phenotypic plasticity. For example, herbivore
attack can induce the synthesis of an antinutritive such as a protease-inhibitor
Franklin, K.A. and Whitelam, G.C. (2005). Phytochromes and shade-avoidance responses in plants. Ann. Bot. 96: 169-175. Ryan, C.A. (1990).
Protease inhibitors in plants: Genes for improving defenses against insects and pathogens. Annu. Rev. Phytopathol. 28: 425-449.
© 2013 American Society of Plant Biologists
Plant behavior is affected by many
environmental parameters
Abiotic
factors:
Light,
moisture,
nutrients, etc.
Biotic
factors:
competitors
symbionts,
pathogens,
herbivores,
etc.
Genome and
epigenome
Phenotypic outcomes:
•Number and length of
root and shoot
•Number, size and
architecture of leaves,
branches and lateral
roots
•Production of
metabolites
•Etc.
Plant behavior is mediated through phenotypic plasticity
© 2013 American Society of Plant Biologists
Case study: Plasticity of leaf
morphology in aquatic plants
Submerged leaf phenotype
Aerial leaf
phenotype
Many species prone to periodic
submergence show phenotypic
plasticity of their leaf forms.
Submerged leaves are often thinner
and without stomata or cuticle.
The hormone ABA is
one signal that
initiates the switch to
the aerial form, and in
this plant, Marsilea
quadrifolia, blue light
is another. The plant
was irradiated with
blue light at the
position indicted by
the arrowhead
Lin, B.-L. and Yang, W.-J. (1999). Blue light and abscisic acid independently induce heterophyllous switch in Marsilea quadrifolia. Plant Physiol. 119: 429-434.
© 2013 American Society of Plant Biologists
Summary: Behavior is the variable
response to the environment
The mechanisms by
which plants perceive
their environment and
integrate information into
a behavioral response
are not well understood,
but under intense
investigation
Plant interactions
involve perception
through cues and
signals, and plastic
behavioral responses
Photo credit: Tom Donald
© 2013 American Society of Plant Biologists
Plants are affected by each other
positively and negatively
Negative
effect:
Competition
for light
Negative
allelopathic effect:
Here, the invasive
species Alliaria
petiolata (garlic
mustard) suppresses
all others
Positive effect:
Nutrient sharing
and suppression
of parasitism
Positive effect:
Stress cues
Victoria Nuzzo, Natural Area Consultants ; Easy Stock Photos; Hassanali, A., Herren, H., Khan, Z.R., Pickett, J.A. and Woodcock, C.M. (2008). Integrated pest management: the
push–pull approach for controlling insect pests and weeds of cereals, and its potential for other agricultural systems including animal husbandry. Phil. Trans. R. Soc. B 363: 611621 copyright 2008 The Royal Society; Karban, R., Baldwin, I.T., Baxter, K.J., Laue, G. and Felton, G.W. (2000). Communication between plants: Induced resistance in wild
tobacco plants following clipping of neighboring sagebrush. Oecologia. 125: 66-71. Max Planck Institute for Chemical Ecology, Jena, Germany / Rayko Halitschke.
© 2013 American Society of Plant Biologists
With similar needs, competition
between plants can be intense
“We can dimly see why the
competition should be most
severe between allied
forms, which fill nearly the
same place in the economy
of nature...”
Charles Darwin, 1859, On the Origin of
Species, Ch 3 Struggle for Existence
© 2013 American Society of Plant Biologists
Light
information
governs
shoot
phenotype,
but also
affects root
development
and
interactions
Nutrient and
water distribution
and various
signals and cues
govern root
phenotype
Plants compete with
themselves and others
Self-shading
Shading by
non-self
Competition
and cues from
non-self
Light can be a limiting resource in
many environments
Trees growing in forests can grow more
than 100 meters high, shading plants
below them, including their own offspring
Photos courtesy Ariel Novoplansky
© 2013 American Society of Plant Biologists
Responses to shading:
confrontation, avoidance, tolerance
Confront
Avoid
Tolerate
Elongation response,
Increased apical dominance
Growing away from
competitors
Light- or fire-dependent
germination
Shade tolerant
morphology and
physiology
Reprinted from Vandenbussche, F., Pierik, R., Millenaar, F.F., Voesenek, L.A.C.J. and Van Der Straeten, D. (2005). Reaching out of the shade. Curr. Opin. Plant Biol. 8: 462-468 with permission
from Elsevier, See also Novoplansky, A. (2009) Picking battles wisely: plant behaviour under competition. Plant Cell Environ. 32: 726-741. Photo credits: Lennart Suselbeek; Ariel Novoplansky
© 2013 American Society of Plant Biologists
Plants perceive light levels and color
(or- light quantity and quality)
Light
© 2013 American Society of Plant Biologists
Detection of light levels and quality
Plants perceive light through
photoreceptors that are sensitive to
light of various wavelengths
Blue light
UV
receptor receptors
Ultraviolet
Short wavelength
High energy
Red / far-red
receptors
Infrared
Long wavelength
Low energy
© 2013 American Society of Plant Biologists
Phytochrome detects the boundary
of photosynthetically active radiance
Action spectrum
for photosynthesis
Photosynthetically
active radiance (PAR)
Cryptochrome
detects blue
(450 nm) light
Absorption
spectra for
chlorophyll and
accessory
pigments
Far- Red light –
too little energy for
photosynthesis
Phytochrome detects both
photosynthetically active
red light (660 nm) and
photosynthetically inactive
far-red (730 nm) light
© 2013 American Society of Plant Biologists
A low ratio of red to far-red light is
indicative of vegetative shading
Red light is depleted as light
passes through the canopy
R
FR
R FR
Shaded
PAR
Green and red light are
not absorbed by the
photosynthetic pigments
– they reflect and pass
through leaves
Full sun
Phytochrome identifies the
ratio of Red to Far-red light
(R:FR), an indicator of
vegetative shading
Reprinted by permission from Macmillan Publishers Ltd from Smith, H. (2000). Phytochromes and light signal perception by plants - an emerging synthesis. Nature. 407:
585-591; Adapted from Jaillais, Y. and Chory, J. (2010). Unraveling the paradoxes of plant hormone signaling integration. Nat. Struct. Mol. Biol. 17: 642-645.
© 2013 American Society of Plant Biologists
Phytochrome’s conformation and
absorption spectra “switch”
Red
Pr
Far-Red
Pfr
Phytochrome changes
conformation when it
absorbs light:
Red light converts it to
the Pfr form, which mainly
absorbs far-red light;
Far-red light converts it to
the Pr form, which mainly
absorbs red light
Reprinted by permission from Macmillan Publishers Ltd from Smith, H. (2000). Phytochromes and light signal perception by plants - an emerging synthesis. Nature. 407: 585-591.
© 2013 American Society of Plant Biologists
Transduction of light information
downstream of photoreceptors
Many of the molecular
events that contribute
to shade avoidance
have been elucidated,
and include effects on
transcription factor
activity and hormone
levels and responses
Reprinted from Gommers, C.M.M., Visser, E.J.W., Onge, K.R.S., Voesenek, L.A.C.J. and Pierik, R. (2013). Shade tolerance: when growing tall is not an option. Trends Plant Sci. 18: 65-71 with permission from Elsevier.
© 2013 American Society of Plant Biologists
Shade avoidance is a collection of
responses to vegetative shading
Light
Vegetative
shading
Delayed or
suppressed
germination
Stem and
hypocotyl
elongation
Petiole elongation,
leaf hyponasty,
narrow leaves
Early
flowering
Reprinted from Casal, J.J. (2012) Shade Avoidance. The Arabidopsis Book 10:e0157. doi:10.1199/tab.0157
© 2013 American Society of Plant Biologists
R FR
Future
Shade?
Plants elongate less
when wearing a collar
that filters out far-red
light reflected from
adjacent leaves
Shade
Touch is another cue
that signals future
competition and
stimulates elongation
From Ballaré, C.L., Scopel, A.L. and Sánchez, R.A. (1990). Far-red radiation reflected from adjacent leaves: An early signal of competition in plant canopies. Science. 247:
329-332. reprinted with permission from AAAS, de Wit, M., Kegge, W., Evers, J.B., Vergeer-van Eijk, M.H., Gankema, P., Voesenek, L.A.C.J. and Pierik, R. (2012). Plant
neighbor detection through touching leaf tips precedes phytochrome signals. Proc. Natl. Acad. Sci. USA (2012) 109: 14705-14710.
© 2013 American Society of Plant Biologists
Case study: Portulaca oleracea, light
responses in recumbent plant
Portulaca oleracea grows
and branches in a way that
minimizes self shading
When lower red/far-red
ratios are provided from one
direction, the plant grows
away, suggesting that
phytochrome controls the
growth directionality
Low R:FR light
Growth direction;
probability
Reprinted with permission from Novoplansky, A., Cohen, D., and Sachs, T. (1990) How Portulaca seedlings avoid their neighbours. Oecologia 82: 490-493.
© 2013 American Society of Plant Biologists
Future shade can be more important
than present shade
Filters were set up on opposite sides
of Portulaca seedlings The other side
Little
red
Little
far-red
transmitted
and reflected
more
photosynthetic
light but much
more far-red
than red light
Green
Portulaca grows away from
far-red light, even when it
means that they are growing
towards less light
One side (grey) transmitted
very little photosynthetic
light, equally low in R and FR
Grey
Do the plants grow towards the
side with more light now (green)
or more light later (grey)? The low
R / FR ratio on the “green” side
implies the presence of potential
competitor…
Low R:FR cues indicate the
presence of a competitor, so
growing away from the direction
of such cues might improve the
plant’s fitness
Adapted from Novoplansky, A. (1991). Developmental responses of portulaca seedlings to conflicting spectral signals. Oecologia 88: 138-140.
© 2013 American Society of Plant Biologists
Some plants have evolved to
tolerate shade – life in the dim lane
Shade-tolerant species are adapted
to low light environments
Photos courtesy Tom Donald and Ariel Novoplansky
© 2013 American Society of Plant Biologists
Shade tolerance takes many forms
Full sun
Shade
Long-lived shade-tolerant
plants invest relatively
more resources into
defenses against
herbivores and pathogens
Defenses
Adaptations to maximize light
interception:
Increased leaf area
Leaves oriented to intercept light
Leaves positioned to minimize overlap
High chlorophyll b to a content
Growth rate
Reduced
stemelongation
response
Reprinted with permission from Valladares, F. and Pearcy, R.W. (1998). The functional ecology of shoot architecture in sun and shade plants of Heteromeles arbutifolia M. Roem., a Californian chaparral shrub. Oecologia. 114: 1-10; Coley, P.D.
(1988). Effects of plant growth rate and leaf lifetime on the amount and type of anti-herbivore defense. Oecologia. 74: 531-536.See also Valladares, F. and Niinemets, Ü. (2008). Shade tolerance, a key plant feature of complex nature and
consequences. Annu. Rev. Ecol. Evol. Syst. 39: 237-257 and Gommers, C.M.M., et al. (2013). Shade tolerance: when growing tall is not an option. Trends Plant Sci. 18: 65-71. Photo courtesy of Ronald Pierik
© 2013 American Society of Plant Biologists
10
Light
compensation
point
Typically, shade tolerant plants
have a lower rate of respiration
in the dark, lower light
compensation point, and lower
light saturation point
CO2 assimilation
(μmol/m2/sec)
Energetics of shade tolerance:
max. assimilation, min. expenditure
Sun plant
Shade plant
0
Dark
respiration
Light saturation
point
0
200
400
800
Light intensity
(μmol/m2/sec)
© 2013 American Society of Plant Biologists
Light information: Angle, gradients,
quality, and time of day
Light information is MORE than just quantity and spectrum. It is
likely that plants respond to a richer gamut of light cues
Vertical, mid-day shade (possibly
low R:FR) might indicate a very
tall neighbor – don’t bother
trying to catch up!
Horizontal and late-day low R:FR
cues might indicate similarly-sized
neighbors – go for it!
See for example Sellaro, R., Pacín, M. and Casal, J.J. (2012). Diurnal dependence of growth responses to shade in Arabidopsis: Role of hormone, clock, and light signaling. Mol. Plant. 5: 619-628.
© 2013 American Society of Plant Biologists
Germination plasticity: light and
other cues for seed germination
One of the
most
important
decisions a
plant makes
is when to
germinate
Many seeds germinate in
response to white or red light,
but far-red light is inhibitory
R
FR
Photo credits: Forest & Kim Starr, Starr Environmental; Howard F. Schwartz, Colorado State University, Bugwood.org
© 2013 American Society of Plant Biologists
Fire (heat and smoke) can promote
seed germination
Fire stimulates seed release
or germination in some plants
Banskia spp, before and after fire
Some cones and seed pods
are fire-serotinous, opening
in response to fire
Image sources: pfern, Hesperian, © Kurt Stueber, 2003
© 2013 American Society of Plant Biologists
Karrikins are germination-promoting
compounds found in smoke
Fire-induced germination lets
seedlings become established with
less competition from taller plants.
Karrikins are cues from smoke that
promote germination.
However, following a fire, there can
be increased competition between
similarly-sized seedlings….
Reprinted from Chiwocha, S.D.S., Dixon, K.W., Flematti, G.R., Ghisalberti, E.L., Merritt, D.J., Nelson, D.C., Riseborough, J.-A.M., Smith, S.M. and Stevens, J.C. (2009). Karrikins: A new family of plant growth regulators
in smoke. Plant Science. 177: 252-256 with permission from Elsevier, and see also Flematti, G. R., et al., (2004). A compound from smoke that promotes seed germination. Science 305: 977.
© 2013 American Society of Plant Biologists
Somatic competition: When plants
compete with themselves
Plants produce many
redundant organs that
compete with each other
Somatic competition can
increase plant performance
by putting resources into
more successful organs
Are these branches shedding as a direct result of them growing in low light ? Or is it
a result of competition with other, more successful branches on the same tree?
See Sachs, T. and A. Novoplansky (1995) Tree form: architecture models do not suffice. Israel J. Plant Sci. 43:203-212; Photos courtesy Ariel Novoplansky.
© 2013 American Society of Plant Biologists
Branch autonomy may vary
according to circumstances
L
R
Growth rate
Full sun
L
R
Full shade
L
There is experimental
evidence to support
all three types of
responses between
shoots: independent,
competitive and
cooperative
R
Partial shade
L
R
Independent
L
R
Competitive
L
R
Cooperative
Adapted from Kawamura, K. (2010). A conceptual framework for the study of modular responses to local environmental heterogeneity within the plant crown and a review of related concepts. Ecological Research. 25: 733-744.
© 2013 American Society of Plant Biologists
Case study: Two-shoot peas and
correlative inhibition
“Two-shoot pea”
5-day
old pea
Two shoot peas
Removing the shoot from a
pea seedling causes two
shoots to regenerate – a
good system to study
somatic competition!
Shoot
removal
5 days
Two equal shoots can co-exist,
but very often one becomes
dominant and the other dies
Why does the smaller shoot die?
See Novoplansky, A., Cohen, D., and Sachs, T. (1989) Ecological implications of correlative inhibition between plant shoots. Physiol. Plant. 77: 136-140; Snow, R. (1931). Experiments on
growth and inhibition. Part II. New phenomona on inhibition. Proc. Roy. Soc. B. 108: 305-316. Sachs, T. and A. Novoplansky (1997) What does a clonal organization suggest concerning
clonal plants? in de Kroon, H. and J. van Groenendael (eds.) The Ecology and Evolution of Clonal Growth in Plants, pp. 55-78, SPB Academic Publishing, Leiden, The Netherlands.
© 2013 American Society of Plant Biologists
Case study: Two-shoot peas and
correlative inhibition
A. Dark only:
100% survival of
dark shoot
B. One dark and one
light shoot: 20%
survival of dark shoot
A shoot in the dark can survive 10
days (using nutrient reserves), but in
competition with a more successful
shoot in the light, the darkened shoot
dies. The plant selectively allocates
reserves to the stronger shoot….
A. Dark only
B. One dark and
one light shoot
Model: Resources are allocated to the
best option. In A, the best (only) option is
the shoot in the dark. In B, resources are
allocated to the shoot in the light, at the
expense of the other shoot.
Redrawn with permission from Novoplansky, A., Cohen, D., and Sachs, T. (1989) Ecological implications of correlative inhibition between plan
shoots. Physiol. Plant. 77: 136-140; Snow, R. (1931). Experiments on growth and inhibition. Part II. New phenomona on inhibition. Proc. Roy. Soc. B. 108: 305-316.
© 2013 American Society of Plant Biologists
Within and between trees, branches
in the best conditions prevail
Less successful branches, e.g.
shaded by neighbors or self are
discriminated against and shed
Photo credit: Tom Donald
© 2013 American Society of Plant Biologists
Summary: Perception of and
response to vegetative shading
Light is a resource and also a source of
information that affects plant behavior
Adaptive responses to competition for
light can be architectural (shoot
position, size and number),
morphological (stem elongation,
increased leaf area), physiological
(amount of chlorophyll or Rubisco), etc.
Photo credits: Ariel Novoplansky; Reprinted from Vandenbussche, F., et al. (2005). Reaching out of the shade. Curr. Opin. Plant Biol. 8: 462-468 with permission from Elsevier
© 2013 American Society of Plant Biologists
Competition belowground: Root
growth is extremely plastic
When soil resources are
abundant, plants allocate less
biomass to their roots
When nutrient
distribution is patchy,
roots proliferate in the
nutrient rich patches
Reprinted by permission from Wiley from Drew, M.C. (1975). Comparison of the effects of a localised supply of phosphate, nitrate and ammonium and potassium on the growth of the seminal root
system, and the shoot, in barley. New Phytol. 75: 479-490.. Reprinted from Bouguyon, E., Gojon, A. and Nacry, P. (2012). Nitrate sensing and signaling in plants. Sem. Cell Devel. Biol. 23: 648654, with permission from Elsevier. See also Gersani, M. and Sachs, T. (1992). Development correlations between roots in heterogeneous environments. Plant Cell Environ. 15: 463-469.
© 2013 American Society of Plant Biologists
Competition belowground: Root
growth is extremely plastic
Roots respond
to other roots
Many studies have found that
roots have a tendency to grow
away from each other
Reprinted with permission from Fang, S., Clark, R.T., Zheng, Y., Iyer-Pascuzzi, A.S., Weitz, J.S., Kochian, L.V., Edelsbrunner, H., Liao, H. and Benfey, P.N. (2013). Genotypic recognition and spatial responses by rice
roots. Proc. Natl. Acad. Sci. USA 110: 2670-2675. Muller, C.H. (1946) Root development and ecological relations of Guayule. USDA Technical Bulletin 923, see also Schenk et al., 1999, Adv. Ecol. Res 28: 145–180,
and Gersani, M. and Sachs, T. (1992). Development correlations between roots in heterogeneous environments. Plant Cell Environ. 15: 463-469.
© 2013 American Society of Plant Biologists
Belowground competition:
Cues, signals and responses
Resource
limitation
Confront
(overproliferate)
Root-exuded
chemicals
Avoid
(underproliferate)
Other
Tolerate
© 2013 American Society of Plant Biologists
Plants compete for nutrients, which
are frequently limiting for growth
This map shows the difference
between actual vegetation
productivity and maximum
theoretical productivity based
on availability of water and
sunlight; the difference is
attributed to nutrient limitation
Fisher, J.B., Badgley, G. and Blyth, E. (2012). Global nutrient limitation in terrestrial vegetation. Global Biogeochemical Cycles. 26: GB3007. Credit: NASA JPL/Caltech.
© 2013 American Society of Plant Biologists
Most plants enhance nutrient uptake through
associations with mycorrhizal fungi or nitrogenfixing bacteria大多数植物提高养分吸收通过对菌根真菌或固氮细菌
Some plants
Nitrogenfixing
bacteria
Bacteria in nodules
produce reduce
atmospheric nitrogen
Most
plants
Mycorrhizal
fungi
Fungus
inside
plant root
Extensive
fungal surface
area facilitates
nutrient and
water uptake
Photo credits: Gerald Holmes, Valent USA Corporation, Ulrike Mathesius, Bugwood.org, Sara Wright, USDA; Kristine Nichols, USDA
© 2013 American Society of Plant Biologists
In some cases, roots avoid contact
or proximity to other roots
How do roots respond to the
roots of another plant?
Plexiglass boxes were set up
to record root responses…
Control roots without contact or
with a physical barrier
Plants exposed to the chemical
exudates of another root system
decreased their rate of root growth
Reprinted with permission from Mahall, B.E. and Callaway, R.M. (1991). Root communication among desert shrubs. Proc. Natl. Acad. Sci. USA 88: 874-876.
© 2013 American Society of Plant Biologists
Plants integrate information about
nutrients and neighbors
Plants were
planted alone or
with a neighbor, in
uniform soil or soil
with nutrient rich
patches (shaded
bar), and root
distribution
analyzed
In uniform soil, roots
avoided each other
But they proliferate in a
nutrient-rich patch, in
spite of their neighbor
Reprinted from Cahill, J.F., McNickle, G.G., Haag, J.J., Lamb, E.G., Nyanumba, S.M. and St. Clair, C.C. (2010). Plants integrate information about nutrients and neighbors. Science. 328: 1657 with permission from AAAS.
© 2013 American Society of Plant Biologists
Many plants make allelochemicals
that deter competitors
Allelopathic chemicals
(allelochemicals) interfere
with growth of nearby plants
Juglone is an allelochemical
produced by black walnut
(Juglans nigra)
Sorgoleone is produced in Sorghum
bicolor root hairs and exuded as oily
drops. It accumulates in the soil and acts
as a pre-emergence herbicide affecting
photosynthesis in very young seedlings
Reprinted from Dayan, F.E., Howell, J.L. and Weidenhamer, J.D. (2009). Dynamic root exudation of sorgoleone and its in planta mechanism of
action. J. Exp. Bot. 60: 2107-2117 with permission of Oxford University Press; Howard F. Schwartz, Colorado State University.
© 2013 American Society of Plant Biologists
Allelochemicals can suppress plant
growth directly or indirectly
m-tyrosine is a nonprotein
amino acid from fescue
(Festuca spp) roots, that
inhibits plant growth directly
Alliaria petiolata (garlic mustard) is an invasive plant in
the US that indirectly suppresses plant growth through
the inhibition of their mycorrhizal fungal symbionts
Reprinted with permission from Bertin, C., Weston, L.A., Huang, T., Jander, G., Owens, T., Meinwald, J. and Schroeder, F.C. (2007). Grass roots chemistry: meta-Tyrosine, an herbicidal
nonprotein amino acid. Proc. Natl. Acad. Sci. USA 104: 16964-16969, copyright National Academy of Sciences.; Victoria Nuzzo, Natural Area Consultants, Jil Swearingen, USDI National Park
Service, Bugwood.org; See also Callaway, R.M., et al., (2008). Novel weapons: Invasive plant suppresses fungal mutualists in America but not in its native Europe. Ecology. 89: 1043-1055.
© 2013 American Society of Plant Biologists
Summary: Plants compete
belowground
Besides resource
competition, the best
understood form of
belowground competition
is the production of toxic
or inhibitory
allelochemicals
The Monterey manzanita (Arctostaphylos montereyensis)
suppresses competitors through allelopathy
Additional cues likely
contribute to belowground
interactions
©2011 David Graber
© 2013 American Society of Plant Biologists
Plants can respond differently to
self, kin and alien
Is that me?
You seem
familiar…
Photo credits: Tom Donald
© 2013 American Society of Plant Biologists
Do plants respond differently to
relatives and unrelated plants?
YES- This study showed that roots tend to
avoid roots of plants that are not related
Same genotype: More overlap
Different genotype:
Less overlap - avoidance
Reprinted with permission from Fang, S., Clark, R.T., Zheng, Y., Iyer-Pascuzzi, A.S., Weitz, J.S., Kochian, L.V., Edelsbrunner, H., Liao, H.
and Benfey, P.N. (2013). Genotypic recognition and spatial responses by rice roots. Proc. Natl. Acad. Sci. USA 110: 2670-2675.
© 2013 American Society of Plant Biologists
Do roots discriminate self from nonself?
A
B
Yes, plants discriminate self from nonself. Plant B, competing with non-self,
makes ~50% more root mass than
plant A, competing only with self
Yes, When cuttings that originate from the
very same node are separated, they become
progressively alienated from each other and
relate to each other as genetically alien plants
These studies showed more root growth in the presence of “other”
than “self”. What cues and signals are involved?
Reprinted with permmission from Falik, O., Reides, P., Gersani, M. and Novoplansky, A. (2003). Self/non-self discrimination in roots. J.Ecology. 91: 525-531. Reprinted with permission from
Gruntman, M. and Novoplansky, A. (2004). Physiologically mediated self/non-self discrimination in roots. Proc. Natl. Acad. Sci. USA 101: 3863-3867 copyright National Academy of Sciences USA.
© 2013 American Society of Plant Biologists
S/NS may rely on self recognition,
rather than on NS discrimination
“Double plants” were
produced with two shoots
and two roots. Some
double plants were split,
to make “twins”. Some of
the split plants were
paired up with an
unrelated alien. Does a
plant recognize self
without a physiological
connection?
INTACT
TWINS
ALIEN
Split pea “Twins”
and alien make
more roots than
intact peas,
indicating that
physiological
connections are
important for
recognizing “self”
Spatially, intact peas produced more roots toward
nonself than toward self roots. Pairs of severed
plants developed similarly towards their neighbors,
regardless of whether these neighbors were their
own twins or alien
Reprinted with permission from Falik, O., Reides, P., Gersani, M. and Novoplansky, A. (2003). Self/non-self discrimination in roots. J. Ecol. 91: 525-531.
© 2013 American Society of Plant Biologists
Case study: Parasitic plants are
extreme competitors
Parasitic
Striga
infestation
•Parasitic plants cost approximately
10 billion USD in crop losses
annually
Heavy
Moderate
Light
•They infest major cereal crops
including corn, sorghum, millet and
rice, in over 70 million hectares
•Food production for 300 million
people is affected
•No effective control measure has
been developed
Striga hermonthica
Striga asiatica
Adapted from Ejeta, G. and Gressel, J. (eds) (2007) Integrating new technologies for striga control: towards
ending the witch-hunt. World Scientific Publishing, Singapore; Image sources: USDA APHIS PPQ Archive,
Florida Division of Plant Industry Archive, Dept Agriculture and Consumer Services.
© 2013 American Society of Plant Biologists
Parasitic plants perceive their hosts
through chemical cues
Cuscuta pentagona
(dodder) uses tropisms,
touch and volatile cues,
to locate its hosts
Host root
Host-exuded
strigolactones and
flavonoids promote
germination and
attachment of Striga and
other parasitic plants
Striga
Reprinted from Runyon, J.B., Mescher, M.C. and De Moraes, C.M. (2006). Volatile chemical cues guide host location and host selection by parasitic plants. Science. 313: 1964-1967 with permission from AAAS.
Umehara, M., Hanada, A., Yoshida, S., Akiyama, K., Arite, T., Takeda-Kamiya, N., Magome, H., Kamiya, Y., Shirasu, K., Yoneyama, K., Kyozuka, J., and Yamaguchi, S. (2008). Inhibition of shoot branching by new
terpenoid plant hormones. Nature 455: 195-200 Dörr, I. (1997). How Striga parasitizes its host: a TEM and SEM study. Ann. Bot. 79: 463-472, by permission of Oxford University Press.
© 2013 American Society of Plant Biologists
Facilitative behaviors: Plants
benefitting from their neighbors
Tempering of
harsh abiotic
environments
Stress cues
can induce
anticipatory
responses
Enhancing nutrient
uptake
Walder, F., Niemann, H., Natarajan, M., Lehmann, M.F., Boller, T. and Wiemken, A. (2012). Mycorrhizal networks: common goods of plants shared under unequal terms of trade. Plant Physiol. 159: 789-797.
© 2013 American Society of Plant Biologists
Benefit from others is commonly
higher in harsher environments
In harsher, high-elevation
environment, plants whose
neighbors were removed
fared relatively poorly,
indicating that they benefited
from their neighbors
Reprinted by permission from Macmillan Publishers Ltd from Callaway, R.M., Brooker, R.W., Choler, P., Kikvidze, Z., Lortie, C.J., Michalet, R., Paolini, L., Pugnaire, F.I.,
Newingham, B., Aschehoug, E.T., Armas, C., Kikodze, D. and Cook, B.J. (2002). Positive interactions among alpine plants increase with stress. Nature. 417: 844-848.
© 2013 American Society of Plant Biologists
Plants can protect others from harsh
abiotic and biotic environments
High Andes
Buffered
substrate and air
temperature,
enhanced soil
moisture and
nutrient content
Southern
France
Protection from
browsing
Semi-arid
plains of
Spain
Semi arid
environment,
Jordan
Protection
from drought
Protection from
browsing and
drought
Images used by permission of Lohengrin A. Cavieres, Fernando T. Maestre, Pierre Liancourt, and Georges Kunstler. See
Brooker, R.W et al. . (2008). Facilitation in plant communities: the past, the present, and the future. J. Ecol. 96: 18-34,.
© 2013 American Society of Plant Biologists
Plants can benefit from amelioration
of abiotic stresses by their
Wind breaking
neighbors
•
• Increased retention of soil
moisture
• Improved physical
characteristics of soil
• Increased soil
oxygenation in waterlogged environments
• Increased nutrients
• Decreased evaporation
and soil salinity
Palo verde (Parkinsonia spp) can act as a
“nurse plant” for saguaro cactus (Carnegiea
gigantean). Tiny cactus seedlings need
shade to get established. Often, though, the
cactus later outcompetes its nurse plant
Photo credits: Tom Donald, Joy Viola, Northeastern University, Bugwood.org
© 2013 American Society of Plant Biologists
Intercropping and crop rotation
confer many benefits
The total yields of fields grown with two or more species at the time or in
alternating years can be higher than the most productive monocultures
Different crown
heights can
accommodate
different light
requirements
Legumes
increase
nitrogen content
of soil
Rotating crops
reduces pest
populations
Ground-hugging
plants can
suppress weeds
Different root
distributions can
minimize
competition for
nutrients
See Horton, J.L. and Hart, S.C. (1998). Hydraulic lift: a potentially important ecosystem process. Trends Ecol. Evol. 13: 232-235. Lee, J.-E., Oliveira,
R.S., Dawson, T.E. and Fung, I. (2005). Root functioning modifies seasonal climate. Proc. Natl. Acad. Sci. USA. 102: 17576-17581.
© 2013 American Society of Plant Biologists
A common mycorrhizal network can
facilitate resource sharing
Intercropping with sorghum drastically enhanced flax’s
growth (+46% increase). Nutrient uptake was
facilitated via the common mycorrhizal network (CMN)
Flax
Mixed
Sorghum
Walder, F., Niemann, H., Natarajan, M., Lehmann, M.F., Boller, T. and Wiemken, A. (2012). Mycorrhizal networks: common goods of plants shared under unequal terms of trade. Plant Physiol. 159: 789-797.
© 2013 American Society of Plant Biologists
Case study: Community-level effects
of phenotypic plasticity
How does
phenotypic
plasticity and
facilitation affect
other community
members?
Variation in root
architecture affects
the plant
communities
associated with
Quercus douglasii;
only shallow-rooted
trees compete with
grasses
Republished with permission of Ecological Society of America from Callaway, R.M., Pennings, S.C. and Richards, C.L. (2003). Phenotypic plasticity and interactions among plants. Ecology. 84: 1115-1128; See
also Callaway, R.M., Nadkarni, N.M. and Mahall, B.E. (1991). Facilitation and interference of Quercus douglasii on understory productivity in central California. Ecology. 72: 1484-1499.
© 2013 American Society of Plant Biologists
Cues from other plants can prime
plants for defense or tolerance
Alarm signals are well
described in social animals.
Stressed plants may emit
cues to which other plants
respond
Be
prepared
cues
cues
Reprinted from Glinwood, R., Ninkovic, V. and Pettersson, J. (2011). Chemical interaction between undamaged plants – Effects on herbivores and natural
enemies. Phytochemistry. 72: 1683-1689 with permission from Elsevier. Photo credits: Snowmanradio, Justin Johnsen, D. Gordon E. Robertson
© 2013 American Society of Plant Biologists
Perception of and responses to
stress and stress cues
Induction and
priming of defense
responses
Mechanical damage
Herbivore-derived
chemicals
Pathogens
Volatile
compounds
Volatile emission
Root
exudates
Stomatal closure
Other?
Drought or UV light
Genomic instability
© 2013 American Society of Plant Biologists
Volatile compounds from damaged
plants can initiate defenses in others
The signal(s) travel through air
Sagebrush
(Artemisia
tridentata)
When nearby sagebrush was
mechanically damaged, wild
tobacco increased production of
defense compounds (PPO) and
suffered less herbivore damage
Wild tobacco
(Nicotiana
attenuata)
Volatile compounds
emitted by damaged
plants can induce
defenses in their
neighbors
Karban, R., Baldwin, I.T., Baxter, K.J., Laue, G. and Felton, G.W. (2000). Communication between plants: Induced resistance in wild tobacco plants following clipping of neighboring
sagebrush. Oecologia. 125: 66-71. see also Kessler, A., Halitschke, R., Diezel, C. and Baldwin, I. (2006). Priming of plant defense responses in nature by airborne signaling between Artemisia
tridentata and Nicotiana attenuata. Oecologia. 148: 280-292. Photo courtesy Ian Baldwin Copyright Max Planck Institute for Chemical Ecology, Jena, Germany / Rayko Halitschke
© 2013 American Society of Plant Biologists
What are the active compounds and
how far do they spread?
methacrolein
cis-3-hexenal
trans-2-hexenal
cineole
MeJA
Reprinted from Baldwin, I.T., Halitschke, R., Paschold, A., von Dahl, C.C. and Preston, C.A. (2006). Volatile signaling in
plant-plant interactions: "Talking Trees" in the genomics era. Science. 311: 812-815 with permission from AAAS.
© 2013 American Society of Plant Biologists
Why do plants emit volatile signals?
• Volatile signals may have
evolved for intra-plant
communication
• Having defensive neighbors
can enhance the emitter’s
fitness
• Some volatiles are also
inhibitory allelochemicals
that reduce competition
• Some volatiles promote
indirect defenses by acting
as signals to attract
predatory arthropods
Reprinted from Arimura, G.-i., Shiojiri, K., and Karban, R. (2010). Acquired immunity to herbivory and allelopathy caused by airborne plant emissions. Phytochemistry 71:
1642-1649 with permission from Elsevier, see also Heil M, Karban R (2010) Explaining evolution of plant communication by airborne signals. Trend Ecol Evol 25: 137–144.
© 2013 American Society of Plant Biologists
Case study: Plants may also
communicate drought stress
Oblivious
Stressed
Drought,
high salt
Can other
stresses be
communicated
between plants?
Can unstressed
plants respond
to stress cues
emitted from
their stressed
neighbors?
?
Novoplansky, A. (2012) Learning plant learning.
© 2013 American Society of Plant Biologists
Testing for root-to-root and relay
communication
Novoplansky, A. (2012) Learning plant learning.
© 2013 American Society of Plant Biologists
Stress cue moves from the stressed
plant via the roots
Stomatal aperture was measured in plants
without a soil connection and plants whose
roots share soil with the induced (IND) plant
Before
treatment all
the plants
had the
No response in plants that
same
did not share their rooting
stomatal
volume
width
After treatment,
stomatal
aperture was
reduced in
plants whose
roots were in
contact (directly
or indirectly)
with the
stressed plant
Falik O, Mordoch Y, Quansah L, Fait A, Novoplansky A (2011) Rumor has it…: Relay communication of stress cues in plants. PLoS ONE 6(11): e23625. See also Falik,
O., Mordoch, Y., Ben-Natan, D., Vanunu, M., Goldstein, O. and Ariel Novoplansky (2012) Plant responsiveness to root-root communication of stress cues, Ann. Bot., 110: 271-280.
© 2013 American Society of Plant Biologists
Summary: Cooperative and
facilitative behaviors
Plants can benefit from other plants, which can
• Modulate the abiotic environment,
• Facilitate nutrient uptake, and
• Emit cues that prime for stress
Like competition,
facilitative encounters
occur between and
within species
Photo credit: Tom Donald
© 2013 American Society of Plant Biologists
Putting knowledge to work
Understanding plant
behavioral responses
can contribute to
combatting highly
competitive invasive
species…
Leafy spurge
(Euphorbia esula)
Water hyacinth (Eichhornia crassipes)
And to developing novel crop
combinations, such as the
intercropping of dry beans, coffee
and papaya near Palmira,
Colombia
Kudzu
(Pueraria montana var. lobata)
Photo credits: Ted Center, USDA; William M. Ciesla, Forest Health Management International; John D. Byrd, Mississippi State University; Howard F. Schwartz, Colorado State University,
© 2013 American Society of Plant Biologists
Do invasive plants have shared
phenotypes?
Some invasive plants
show greater than
average phenotypic
plasticity, but many do
not.
A
B
C
D
E
Are invasive plants more
plastic, and so more able
to succeed in diverse
environments?
Kudzu (Pueraria lobata),
also known as “The vine
that ate the South”
Some invasive plants
succeed by making lots
of small seeds, growing
very quickly, producing
allelochemicals, or
competing effectively for
water or nutrients
Davidson, A.M., Jennions, M. and Nicotra, A.B. (2011). Do invasive species show higher phenotypic plasticity than native species and, if so, is it adaptive? A meta-analysis. Ecolo.Lett. 14: 419-431. Godoy, O., Valladares,
F. and Castro-Díez, P. (2011). Multispecies comparison reveals that invasive and native plants differ in their traits but not in their plasticity. Funct. Ecol. 25: 1248-1259. Jil Swearingen, USDI National Park Service,
© 2013 American Society of Plant Biologists
Case study: Knotweed, “from prizewinners to pariahs”
Prize-winners
In 1847, the
Society of
Agriculture &
Horticulture
awarded a gold
medal to Fallopia
japonica, “for the
most interesting
new ornamental
plant of the year”
Pariahs
Now they are one of the
most aggressive plant
invaders, and cause
considerable economic
and ecological damage.
Allelochemical production
and rapid growth rate
contribute to their
ecosystem dominance
Knotweed shows a highly
plastic response to salt,
which allows it to succeed
in salty environments
See Bailey, J. P., and Conolly, A. P. (2000). Prize-winners to pariahs - a history of Japanese knotweed s.l. (Polygonaceae) in the British Isles. Watsonia 23: 93-110; Murrell, C., Gerber, E., Krebs, C., Parepa, M.,
Schaffner, U. and Bossdorf, O. (2011). Invasive knotweed affects native plants through allelopathy. Am. J. Bot. 98: 38-43, Richards, C.L., et al., (2008). Plasticity in salt tolerance traits allows for invasion of novel
habitat by Japanese knotweed s. l. (Fallopia japonica and F.×bohemica, Polygonaceae). Am. J. Bot. 95: 931-942. Photo credit Fallopia japonica MdE 2.jpg, © MdE at Wikimedia Commons, CC-BY-SA 3.0 German.
© 2013 American Society of Plant Biologists
Case study: Backfiring biocontrol of
invasive knapweed?
Spotted knapweed (Centaurea stobe ssp.
micranthos / Centaurea maculosa) was
introduced into North America in the 1890s. It
is a “noxious weed” that competes very
effectively with native plants
Agapeta zoegana
Starting in the
1980s, the specific
herbivore knapweed
root moth has been
introduced as a
biocontrol agent,
with mixed results
Herbivory may
induce allelochemical
production, further
harming native plants
– a case of biocontrol
backfiring!
See Callaway, R.M., DeLuca, T.H. and Belliveau, W.M. (1999). Biological-control of herbivores may increase competitive ability of the noxious weed Centaurea maculosa. Ecology. 80:
1196-1201; Knochel, D.G. and Seastedt, T.R. (2010). Reconciling contradictory findings of herbivore impacts on spotted knapweed (Centaurea stoebe) growth and reproduction. Ecol.
Appl. 20: 1903-1912.Photo credits: L.L. Berry, Bugwood.org; USDA Agricultural Research Service Archive, Bugwood.org; Steve Dewey, Utah State University, Bugwood.org
© 2013 American Society of Plant Biologists
Case study: Maize, bean, squash –
the three sisters
Archeological records show that Native
Americans have grown corn, beans and
squash together for millennia
The corn provides a structure for the climbing
bean vines, and the ground-covering squash
maintains soil moisture and suppress weeds
Maize
Bean
Squash
A recent study found that the root systems
of the three plants are complementary,
minimizing belowground competition
Photo credit: Howard F. Schwartz, Colorado State University, Bugwood.org; Reprinted from Postma, J.A. and Lynch, J.P. (2012). Complementarity in root
architecture for nutrient uptake in ancient maize/bean and maize/bean/squash polycultures. Ann Bot. 110: 521-534 by permission of Oxford University Press.
© 2013 American Society of Plant Biologists
Case study: Push-pull planting
systems to enhance productivity
Pests are a particular problem in
tropical agriculture. An agronomic
system called push-pull was
developed to protect corn crops
from stem borer caterpillars
Maize
This involves intercropping
maize with a legume
Desmodium, in a field
surrounded by Napier grass
(Pennisetum purpureum)
Desmodium
Napier grass
See Hassanali, A., Herren, H., Khan, Z.R., Pickett, J.A. and Woodcock, C.M. (2008). Integrated pest management: the push–pull approach for controlling insect pests
and weeds of cereals, and its potential for other agricultural systems including animal husbandry. Phil. Trans. R. Soc. B 363: 611-621; Pickett, J.A., Hamilton, M.L.,
Hooper, A.M., Khan, Z.R. and Midega, C.A.O. (2010). Companion Cropping to Manage Parasitic Plants. Annu. Rev. Phytopath. 48: 161-177. Push-pull.net
© 2013 American Society of Plant Biologists
Case study: Push-pull planting
systems to enhance productivity
Desmodium PUSHES away
the insects by producing
repellent volatile chemicals
Napier grass PULLS away the
insects by producing
attractive volatile chemicals
Desmodium also
produces allelochemicals
that interfere with Striga
parasitism, protecting the
crop from yet another pest
Reprinted from Khan, Z.R., Midega, C.A.O., Bruce, T.J.A., Hooper, A.M. and Pickett, J.A. (2010). Exploiting phytochemicals for developing a
‘push–pull’ crop protection strategy for cereal farmers in Africa. J. Exp. Bot. 61: 4185-4196, by permission of Oxford University Press.
© 2013 American Society of Plant Biologists
Case study: Allelopathic rice plants
Momilactone B
Momilactones are allelopathic
compounds produced by rice
that interfere with the growth of
a common paddy weed,
barnyard grass (Echinochloa
crus-galli)
Efforts are underway to increase momilactone production
in cultivated rice varieties, to reduce the need for herbicide
use and mechanical weed removal
Image source: IRRI. Belz, R.G. (2007). See also Allelopathy in crop/weed interactions — an update. Pest Management Science. 63: 308-326.
© 2013 American Society of Plant Biologists
Case study: Exploiting light-response
plasticity for increased productivity
Greenhouse covers, including a
fluorescent pigment that absorbs some of
the blue and green sunlight and emits
additional red light, increases the ratio
between RED and FAR-RED light.
In response to such spectral cues,
some plants reduce their allocation to
competitive organs and increase
allocation to agriculturally-important
organs such as flowers and fruits.
LEDs can produce similar effects.
Novoplansky, A., T. Sachs, D. Cohen, R. Bar, J. Budenheimer and R. Reisfeld (1990) Increasing plant productivity by changing the solar spectrum. Solar
Energy Materials 21: 17-23. See also Stamps, R.H. (2009). Use of colored shade netting in horticulture. HortScience. 44: 239-241..
© 2013 American Society of Plant Biologists
Summary of plant-plant interactions
Local
conditions
Cues from
other plants
Interactions
with other
plants
Genotype
Plasticity
A plant’s phenotype depends on its genotype
and environment, and relies on its plasticity.
The environment includes cues from and
interactions with other plants, many of which
we are just beginning to understand, and which
continue to be very active research areas
Biodiversity
Stochasticity
Fixed
development
Phenotype
Ecological
interactions
Ecosystem
functioning
Plant
production and
agriculture
Evolution
Partially adapted from Cahill, J.F. and McNickle, G.G. (2011). The behavioral ecology of nutrient foraging by plants. Annu. Rev. Ecol. Evol. System. 42: 289-311.
© 2013 American Society of Plant Biologists
Summary of plant-plant interactions
Plants perceive other
plants through changes
in the light spectrum,
volatile and rootexuded chemicals,
effects on nutrients,
water and soil
microbes, and other
unknown signals
Their responses
depend on their
age, genotype and
other endogenous
and exogenous
factors, and may
include
confrontation,
avoidance or
tolerance
Reprinted from Kegge, W. and Pierik, R. (2010). Biogenic volatile organic compounds and plant competition. Trends Plant Sci. 15: 126-132 with permission from Elsevier.
© 2013 American Society of Plant Biologists
Future directions (1)
Can fragile ecosystems and
biological diversity be protected
by better understanding plant –
plant interactions?
Japanese knotweed
(Fallopia japonica )
Aggressive aliens, moved by
human actions, damage
ecosystems
Giant hogweed
(Heracleum mantegazzianum)
Photo credits: Fallopia japonica MdE 2.jpg, © MdE at Wikimedia Commons,
CC-BY-SA 3.0 German. Randy Westbrooks, U.S. Geological Survey
© 2013 American Society of Plant Biologists
Future directions (2)
Can food yields be increased by suppressing
competition and competitive responses,
enhancing facilitation and increasing production
of desired organs?
• Human population
growth demands more
food production, and
higher crop yields
• Plant-plant interactions
can decrease yields, but
these effects can be
ameliorated
David Nance USDA ARS Bugwood.org
© 2013 American Society of Plant Biologists
Future directions (3)
Can crop yields be increased, especially in
marginal agricultural land, by inducing and
priming plants to better fit their particular
expected growth conditions, forthcoming
opportunities and stresses?
J.S. Quick, Bugwood.org
© 2013 American Society of Plant Biologists