You can find more articles by searching the journals with contents on-line,
especially these:
http://www.pnas.org/
[research reports become free usually a few months
after publication]
http://www.sciencemag.org/
[use library terminals for articles less than a year old]
http://www.amjbot.org/
http://www.plantphysiol.org/ ["updates"
(=reviews) and "scientific correspondence"(= short research reports)
are free; longer research reports are not]
http://www.plantcell.org/ [reviews
are usually free; research reports are not]
other free journals
Queens' library has print copies of Science and American Journal of
Botany and other journals (like NATURE)
which may be useful for you. You have to go to a university library to get articles from Plant Physiology, Plant
Cell, and some other sources; but you can find plenty of good stuff in our
own library and the
journals with on-line full content, the links above.
AUXIN
samples of other research reports
involving auxin and its transporters within the last few years:
COP9 signalosome:
- The way auxin works often involves degradation of some proteins so
that other proteins can cause new metabolic and developmental
responses. A protein complex called the COP9 signalosome is required for protein degradation.
http://www.sciencemag.org/cgi/content/full/292/5520/1379
(2001)
- COP9 signalosome and its subunits in animals are involved in the progression of the cell cycle, transcription, thyroid
hormone reception, embryonic and larval development. Thus the COP9 signalosome likely also takes part in numerous regulatory events in
Arabidopsis. http://www.plantphysiol.org/cgi/content/full/124/4/1548
(Dec 2000)
- Lid model of signalosome http://www.plantphysiol.org/cgi/content/full/124/4/1548/F4
- more (2002)In addition to auxin and jasmonic acid, cytokinin,
gibberelic acid (GA), and brassinosteroid (BR) action may all depend on protein degradation
http://www.sciencemag.org/cgi/content/full/297/5582/793/F2
- and (2002) peroxisomes may be involved
http://www.sciencemag.org/cgi/content/full/297/5580/405
- PSK(sulfated peptide phytosulfokine) is secreted from
individual cells in response to changes in the levels of
auxin and cytokinin and that it functions as an autocrine-type growth factor to regulate cellular
dedifferentiation and proliferation in plants. (2002)
http://www.sciencemag.org/cgi/content/full/296/5572/1470
- auxin-binding proteins are degraded very rapidly (2001) http://www.plantcell.org/cgi/content/full/13/10/2161
- apical dominance (2001) http://www.plantphysiol.org/cgi/content/full/127/4/1405/F2
- Auxin and root development: http://www.journals.uchicago.edu/IJPS/journal/issues/v160n3/990050/990050.html
- A natural auxin inhibitor: http://www.journals.uchicago.edu/IJPS/journal/issues/v160n2/990036/990036.html
- Eckardt, Nancy A. 2001. New Insights into Auxin Biosynthesis. Plant Cell
13: 1-3. http://www.plantcell.org/cgi/content/full/13/1/1
- Zhao, Yunde et al. 2001. A Role for Flavin Monooxygenase-Like Enzymes in
Auxin Biosynthesis http://www.sciencemag.org/cgi/content/full/291/5502/306
- Cline, Morris G. 2000. Execution of the auxin replacement apical dominance
experiment in temperate woody species. American Journal of Botany.
87:182-190. http://www.amjbot.org/cgi/content/full/87/2/182
- Harmer, Stacey L., John B. Hogenesch, Marty Straume, Hur-Song Chang, Bin
Han, Tong Zhu, Xun Wang, Joel A. Kreps, and Steve A.
Kay. 2000. Orchestrated Transcription of Key Pathways in Arabidopsis by the Circadian Clock.
Science 290: 2110-2113. http://www.sciencemag.org/cgi/content/full/290/5499/2110
- Becker, D., Hedrich, R. (1999). Auxin-induced K+ channel expression
represents an essential step in coleoptile growth and gravitropism. Proc.
Natl. Acad. Sci. U. S. A. 96: 12186-12191
- Gravitropism in Higher Plants. Plant Physiol. 120: 343-350
- Auxin Is Required for Leaf Vein Pattern in Arabidopsis. Plant Physiol.
121: 1179-1190
- Shade Avoidance Responses. Driving Auxin along Lateral Routes. Plant
Physiol. 122:621-626
OTHER HORMONES
links for research
-
2004
http://www.sciencemag.org/cgi/content/full/302/5642/71
Enhanced: Hormones and the Green Revolution
-
2003 auxin effect on root growth involves GA
http://www.biomedcentral.com/news/20030213/04
-
2002 review of plant hormone signalling http://www.plantphysiol.org/cgi/content/full/128/2/363
-
Gibberellin 2002 review of research http://www.plantcell.org/cgi/content/full/14/1/1
-
Ethylene
-
Cytokinins
-
Abscisic acid (ABA) http://www.sciencemag.org/cgi/content/full/287/5451/300
and http://www.sciencemag.org/cgi/content/full/283/5401/537
-
Arabidopsis Basic Leucine Zipper Proteins
That Mediate Stress-Responsive Abscisic Acid
Signaling http://www.plantcell.org/cgi/content/abstract/14/2/343
-
(2002) stomatal closing interaction with
NO
(1) http://www.plantphysiol.org/cgi/content/full/128/3/790
(2) http://www.plantphysiol.org/cgi/content/full/128/1/13
(3) 2003 NO mobilizes intracellular calcium in guard cells, regulates K+ and
Cl- channels in guard cells through a subset of abscisic acid-evoked
signaling pathways [Research
Update Article] Proc Natl
Acad Sci USA 2003
-
(2004) more about NO: BMN.com review of
Bethke et al. Plant Cell 2003 16:332 Bethke and colleagues speculate
that NO may play a role in coordinating the activities of the aleurone
layers with those of the embryo axis or scutellum. Another possibility is
that NO would act as an antimicrobial agent, allowing the embryo to compete
with micro-organism for nutrients once the seed coats are ruptured.
Nitric
oxide (NO) is recognized as an ubiquitous bio-messenger, existing in a wide
variety of organisms. In mammals, endogenous NO is produced by nitric oxide
synthase (NOS). In plants, [snip]. Two unrelated NOS-like enzymes have been
discovered: a pathogen inducible NOS [Chandok, M.R. et al. (2003)
Cell 113] and a hormone-activated NOS [Guo, F-Q. et al. (2003)
Science 302]. Furthermore, NO synthesis is also catalysed by nitrate
reductase, both in vitro and in vivo [Desikan, R. et al.
(2002) PNAS 99]. In a recent Plant Cell paper, Bethke and colleagues
disclose a new fascinating aspect of NO synthesis in plants : they discover
that plant tissues also synthesize NO via the non-enzymatic reduction of
apoplastic nitrite.
First, the authors provide evidences that barley aleurone
layers synthesize NO and that, once produced, NO delays giberellin
(GA)-programmed cell death. [snip] a strong NO signal was observed in
response to abscisic acid (ABA) and GA, two hormones that rapidly acidified
the apoplastic medium to as low as pH 3 to 4.
- Brassinosteroids: "Plant hormones include small peptides, complex chemicals, and steroids known as
brassinosteroids. Brassinosteroids regulate, among other aspects, the plant's response to light conditions, its growth habit, and flowering patterns."
http://www.sciencemag.org/cgi/content/summary/295/5558/1189p
- Pheromones? "When attacked by herbivores, some plants are known to emit volatile compounds that
attract predators of the herbivores. However, these indirect defenses have been demonstrated only in artificial laboratory and agricultural situations. Kessler and Baldwin (p.2141
http://www.sciencemag.org/cgi/content/full/291/5511/2141
[primary research] ; see the Perspective by Sabelis et al. http://www.sciencemag.org/cgi/content/full/291/5511/2104
[enhanced with extra links]) show that such systems also operate under natural conditions. Using plants of Nicotiana attenuata growing in the Great Basin Desert in Utah, they directly manipulated individual components of the suite of volatile organic compounds released after herbivore attack by Manduca caterpillars. They identified compounds that dramatically increased attack by the caterpillar's predators and that also reduced the oviposition rate of the Manduca moth."
- Arabidopsis in space: http://www.journals.uchicago.edu/IJPS/journal/issues/v161n1/000001/000001.html
-
A receptor for salicylic acid signaling in plant disease
resistance
High-affinity salicylic
acid-binding protein 2 is required for plant innate immunity and has
salicylic acid-stimulated lipase activity. Kumar, D. and
Klessig, D.F. Proc Natl Acad Sci USA E-publication ahead of print
Commentary from bmn.com by Richard C Staples : Salicyclic acid
(SA) is an important regulator of plant disease responses.
Increases in SA levels correlate with resistance of tobacco to infection
by tobacco mosaic virus and induction of the hypersensitive
response (HR), and a variety of Arabidopsis mutants impaired in
resistance against bacterial and fungal pathogens show defects in SA
synthesis or accumulation. Furthermore, these local defense responses
frequently are accompanied by the subsequent induction of systemic
acquired resistance (SAR), a resistance that provides protection
throughout the plant against a broad spectrum of pathogens. they have
isolated the SABP2 protein and shown that it is an SA-stimulated lipase.
[snip] they have proposed that SABP2 belongs to a large class of ligand-stimulated
hydrolases involved in stress hormone-mediated signal transduction.
There is growing evidence that lipids play an important role in
signaling disease resistance. [snip]
| HORMONE |
FUNCTIONS, MECHANISMS, ETC. |
CHEMISTRY |
LOCATIONS |
| auxin (IAA)
[2,4-D, agent Orange) |
elongation in general:
(explain)_______________ phototropism: (explain)_______________________
geotropism: (explain)_________________________
branch root formation
differentiation of vascular tissue
(ripening). Herbicidal: _______________________
lateral inhibition = apical dorminance with high conc.? (be able to explain bud
inhibition)
sometimes flowering, fruiting, other signs of maturation |
tryptophan derivative (=a modified
amino acid). Requires receptors. Ca-dependent for some actions |
synthesized in young tissues,
polar transport = moves down, then outward within roots, requires active transporters |
| gibberellins, GA, gibberellic acids |
mitosis, elongation, germination,
bolting, sometimes flowering. Activates enzymes and probably genes |
resembles a steroid |
plastids in roots |
| abscisic acid, ABA |
inhibition of germination &
elongation Stress coping: inhibitory metabolism, closes stomata |
a 6-carbon ring Ca-dependent? |
plastids in any tissue? |
| cytokinins (zeatin, kinetin) |
promotes cell division anti-senescent
metabolism
germination, root and branch formation, etc: a "permissive" or synergistic
function, maybe counteracting inhibitors |
adenine derivative (= a modified
DNA base) => ___? Ca-dependent? |
roots |
| ethylene |
ripening (put green fruit in bags
or warehouse with ethylene) abscission and short stems
sometimes sex changes |
small gas |
any part with high O2
and low CO2 |
| systemin |
induces proteinase inhibitors
& phytoalexins (anti-herbivore and anti-fungal compounds) |
short peptide |
injured tissues----->
throughout |
| others? |
|
|
|
TROPISMS
RECENT RESEARCH
- A pollen-specific calmodulin-binding protein in Arabidopsis sheds
light on how Ca2+ signalling is mediated in pollen tube growth in
PNAS Sept 2003
- Flower power may have helped give rise to brainpower during evolutionary
development, according to University of Chicago scientists who found that
plant reproduction is triggered by the same chemical that helps build
brains.
- The chemical, a neurotransmitter called GABA
(gamma-amino butyric acid) acts as a signal to guide pollen sperm to the
eggs of a flower, which then produce seeds, they reported in the current
issue of the journal Cell.
Research by other scientists has shown that GABA also plays a crucial
role in brain development by guiding newly formed neurons to their
proper places in the brain. GABA, one of the brain's most important
neurotransmitters, is also involved in building connections between
brain cells and in maintaining their orderly performance.
"This is an example of something that nature found works well and
then reused it over and over again," said U. of C. geneticist
Daphne Preuss, who headed the study.
"We were kind of surprised to find GABA involved in plant
fertilization, but it was exciting," said Preuss, an investigator
in the Howard Hughes Medical Institute. "It tells us that a
signaling molecule that's important for how nerve cells might grow and
talk to each other is the same kind of molecule used in a very different
biology in a plant system."
The findings may help unravel a long-standing mystery of plant
reproduction. Although nearly 80 percent of the world's food begins as
seeds, such as corn, rice and wheat, scientists know little about the
actual mechanism of fertilization.
A better understanding of how pollen can travel as much as several
inches after landing on plants to reach their eggs could lead to
improved crop production.
Learning how these signaling molecules work could also shed light on how
newly minted brain cells know where to go during fetal development, a
time when 100 billion neurons are being created.
"When a pollen grain is deposited on the surface of a flower, it's
like a speck of dust landing on the skin," Preuss said. The pollen
grain has to somehow grow a tube from where it lands on a flower's
stigma, usually rodlike structures in the center of the blossom, and
burrow all the way down to where the eggs are.
The U. of C. scientists found that GABA acts like a beacon to direct the
burrowing tube directly to the eggs.
Pollen sense the presence of GABA and begin extruding a tube that drills
through the cells of the stigma, using the cellular debris as building
blocks for the tube. The tube heads toward the increasing concentrations
of GABA until it reaches an egg.
"It's almost like drilling an oil well in the sense that you have a
drill but behind it you've got tubing, and sperm are riding down that
tube," Preuss said.
GABA's role was discovered when co-author Laura Brass examined the genes
of a mutant infertile plant. The plant, Arabidopsis, is a member of the
mustard family that includes radishes and cabbages.
- Copyright (c) 2003, Chicago Tribune
- thigmotropism GOOD Review 2002 http://www.amjbot.org/cgi/content/full/89/3/375
- guard cells "that flank the stomatal pores of leaves and stems must integrate and
respond appropriately to a multitude of instantaneously varying stimuli. In addition to a
background circadian rhythmicity, the principle physiological determinants of stomatal
aperture are the respective levels of blue light, CO2, and the stress-induced hormone
abscisic acid (ABA). The 1990s witnessed a blossoming in our understanding of how
guard cells work, largely because of the advent of patch-clamp recording techniques, new
ways to measure cytoplasmic free Ca2+ and the adoption of Arabidopsis as a
model organism. This month's [May 2001] The Hot and the Classic presents a brief synopsis of the
most cited guard cell research contribution for each year of the 1990s."
http://www.plantphysiol.org/cgi/content/full/126/1/23
-
- LIGHT/photobiology
-
- pollen tube growth 2001
CHART for TROPISMS, NASTIC MOVEMENTS, SEASONAL RESPONSES, ETC.
| TYPE |
What happens? |
Why? (What is the selective advantage of
this adaptation?) |
How does it work? (Explain the
"known" mechanisms as simply as possible) |
Examples |
| *Phototropism |
|
|
|
|
*Gravitropism
=Geotropism |
|
|
|
|
| thigmotropism |
|
|
|
twining of tendrils and vines |
| Chemotropism |
|
|
|
Pollen tube grows toward/into ovule |
| stomatal closing |
|
|
|
|
| Seismonasty |
reversible response to touch |
|
|
Venus fly trap. |
| thermonasty |
reversible response to temperature |
|
--- |
cold causes Rhododendron leaves to droop |
| Circadian rhythms |
|
|
|
|
| circadian nyctinasty |
|
|
|
leaves close at night; open at dawn |
| solar tracking= circadian heliotropism |
|
|
|
leaves face east before dawn, then…. |
| Thigmomorpho- Genesis |
repeated touching or vibration causes plant to
grow "stockier." |
|
|
|
| ____-tropism? |
|
|
|
(U find it) |
| * Photoperiodism |
|
|
|
|
| Vernalization (and
other cold treatments like stratifying seeds) |
|
|
|
|
| Senescence |
|
|
|
soybeans die before end of summer. |
| Dormancy |
|
|
|
|
| ?? |
|
|
|
|
SEASONAL RESPONSES
See
chart above, also
- Read about vernalization and other temperature responses in http://www.cnr.vt.edu/dendro/forestbiology/htmltext/chapter6.htm
- Read about photoperiods, phytochrome, and long-day = short-night plants,
etc., in any biology textbook or online "textbook" like this: http://www.hcs.ohio-state.edu/hcs300/devel2.htm
- RESEARCH REPORTS
-
http://www.sciencemag.org/cgi/content/full/303/5660/1003 Photoreceptor
Regulation of CONSTANS Protein in Photoperiodic Flowering (Federico Valverde,1
Aidyn Mouradov,1* Wim Soppe,1* Dean
Ravenscroft,1 Alon Samach,2 George Coupland1
 ) Many plants flower in response to seasonal fluctuations in day
length. The CONSTANS (CO) gene of Arabidopsis promotes flowering in long days.
Flowering is induced when CO messenger RNA expression coincides with the
exposure of plants to light. However, how this promotes CO activity is
unknown. We show that light stabilizes nuclear CO protein in the evening,
whereas in the morning or in darkness the protein is degraded by the
proteasome. Photoreceptors regulate CO stability and act antagonistically to
generate daily rhythms in CO abundance. This layer of regulation refines the
circadian rhythm in CO messenger RNA and is central to the mechanism by which
day length controls flowering.
- new http://www.nmnh.si.edu/botany/projects/dcflora/springfloweringrecords.htm
- photoperiodism Arabidopsis http://www.biomedcentral.com/news/20031120/01
- FKF1 is essential for photoperiodic-specific
light signalling in Arabidopsis 302
TAKATO IMAIZUMI, HIEN G. TRAN,
TREVOR E. SWARTZ, WINSLOW R. BRIGGS & STEVE A. KAY
doi:10.1038/nature02090
First paragraph
|
Full Text
- 500-year-old sacred Lotus seeds will germinate but the seedlings appear to
be damaged, probably because of natural soil radiation effects on auxin (2002)
http://www.amjbot.org/cgi/content/full/89/2/236
- Arabidopsis dormancy involves abscisic acid because vivipary can be
induced before the seed matures
http://www.amjbot.org/cgi/content/full/89/5/766
- warm stratification and seed dormancy 2002 http://www.amjbot.org/cgi/content/full/89/3/486
- The effect of maternal photoperiod on seasonal dormancy in Arabidopsis http://www.amjbot.org/cgi/content/full/88/7/1240
2001
- phytochromes affect floral phenotypes (shapes & proportions in
flowers) http://www.amjbot.org/cgi/content/full/89/2/230
(2002)
- phytochrome moves to nucleus to activate genes: http://www.sciencemag.org/cgi/content/full/288/5467/821
- phytochrome review http://www.plantcell.org/cgi/content/full/13/9/1983
- ENHANCED latest on circadian rhythm:
http://www.sciencemag.org/cgi/content/full/288/5465/451
- the very old Beal experiments http://www.sciencemag.org/cgi/content/full/291/5510/1884
- GOOD Review of summer 2001 photobiology research meetings,
perspective and links to phytochrome, cryptochrome and other light receptor
molecules and their genes http://www.plantcell.org/cgi/content/full/13/8/1704
- new 2002: Arabidopsis, the Rosetta Stone of Flowering Time? (a
review with good diagrams) http://www.sciencemag.org/cgi/content/full/296/5566/285
and
Multiple Roles of Arabidopsis VRN1 in Vernalization and Flowering Time Control http://www.sciencemag.org/cgi/content/full/297/5579/243
(very tech) explained here:
"In one talk, Richard Amasino, a biochemist at the University of
Wisconsin, Madison, described the emerging molecular mechanics behind "vernalization":
a biennial plant's use of the cold season as a time-out, a transition from
growing leaves and shoots to preparing for a burst of spring flowering.
"These plants have evolved a way to measure winter and wait until it's been
cold enough, long enough, to signify spring," Amasino says.
In the past few years, Amasino; Caroline Dean, associate research
director at the John Innes Centre in Norwich, U.K.; and others have been
unraveling the biochemistry that causes Arabidopsis to overwinter
and delay flowering. The researchers have found that as cold sets in, a gene
dubbed FRIGIDA promotes the buildup of the flowering locus C (FLC)
transcript, a repressor protein that blocks genes for flowering. After a
period of cold, the plant's FLC levels drop, allowing flowers to emerge when
temperatures warm.
By creating Arabidopsis mutants that flower off schedule, the
team has found a handful of additional vernalization genes. Dean's lab last
month reported finding the gene VRN1, which helps shut down FLC so
spring flowers can bloom (Science, 12 July, p.
243).
Dean says that Arabidopsis likely bears a key set of floral
genes that, when activated, switch on flowering. Vernalization proteins
represent just one biochemical pathway that can activate those flowering
genes, she says. Other pathways, lined with proteins that sense the day's
length (photoperiod), for instance, or developmental changes can also
trigger those same genes. "My view is these sets of pathways have somewhat
overlapping functions to reinforce each other," Dean says. "So the plant
says, 'I've had longer days and enough cold, so I'm doubly sure it's
O.K.--it's spring, it's time to flower.' "
The emerging research could help plant breeders improve yields of
biennial crops such as alfalfa and sugar beets, adds Jan Zeevaart, a
botanist at Michigan State University in East Lansing. With molecular tools
in hand, the science should blossom".
http://www.sciencemag.org/cgi/content/full/297/5585/1267
- new 2002: genes for dormancy in Arabidopsis http://www.amjbot.org/cgi/content/full/89/5/766
- NEW other resources new
Bibliography of References Related to Seed Dormancy and/or Germination
in Higher Plants http://library.usask.ca/dbs/seed.html (look up Amen)
PHOTOSYNTHESIS
OVERVIEW CHART (fill in the details yourself)
| |
light reactions |
Calvin Cycle |
| also called |
photochemical reactions |
|
| main purpose |
convert light energy to potential
energy stored in the chemical bonds of ATP and NADPH (energy to run two endergonic
reactions in Calvin cycle) |
make C6H12O6 by transferring energy from ATP and NADPH to organic acids and other Calvin cycle
intermediary metabolites. |
| location (intracellular) |
chloroplast thylakoids |
|
| input (main initial
reactants) |
photons, ADP, NADP, H2O,
Pi |
CO2, RUBP, ATP,
NADPH |
| output (main products) |
|
|
| key processes |
photoexcitation electron
transport and NADP reduction
chemiosmotic phosphorylation (ATP synthesis) |
initial carbon fixation reduction
of PGA to PGAL |
| summary reaction |
|
|
DETAILS OF PHOTOSYNTHESIS
Use these resources:
Examples of Current Photosynthesis Research
POSTER TOPICS:
- 2003"Multicellular organisms need to control the proliferation of
pluripotent stem cells, also referred to as meristematic cells in the apices,
cambium, and pericycle of flowering plants. Because organ differentiation of
plants is predominantly postembryonic and does not involve cell migration,
plant stem cells need to be controlled by short- and long-distance signals to
achieve equilibrium between cell proliferation and differentiation. The role
of short-distance signaling in plant development has been more extensively
researched, and some of the key genes involved have been identified" but we're
still pretty far from understanding how it all fits together
http://www.sciencemag.org/cgi/content/full/299/5603/109
-
You can find more articles by searching the journals with contents on-line,
especially these:
Queens' library has print copies of Science and American Journal of
Botany and other journals (like NATURE)
which may be useful for you. You have to go to a university library to get articles from Plant Physiology, Plant
Cell, and some other sources; but you can find plenty of good stuff in our
own library and the
journals with on-line full content, the links above.
|
421, 740 - 743 (13 Feb
2003)
