We discuss and comment on the role agriculture will play in the containment of the CO2 problem and address protocols for terraforming the planet Earth.
A model farm template is imagined as the central methodology. A broad range of timely science news and other topics of interest are commented on.
Thursday, May 3, 2012
Shade in Agriculture
Modifying natural shade avoidance is important. Our crops almost always have ample time to
productively mature and thus not reacting to shade becomes useful in producing
a shorter stalk and larger fruit.
Corn does not need to be ten feet high in order to capture the light it
needs to produce two full ears of corn by September. The same is true for most plants and on top
of it, a longer maturing time allows a greater concentration of nutrients.
It is not an obvious problem but it is certainly an issue with
domesticated plants that could be beneficially managed. Wild plants are in not just an arms race for
sunlight but also to get maturity before it is out-competed by others. This is controlled in agriculture.
Salk scientists discover
how plants grow to escape shade
by Staff Writers
La Jolla CA (SPX) Apr 18, 2012
This is Joanne Chory,
Professor and Director, Plant Molecular and Cellular Biology Laboratory.
Credit: Courtesy of the Salk Institute for Biological Studies.
Mild mannered though they
seem, plants are extremely competitive, especially when it comes to getting
their fair share of sunlight. Whether a forest or a farm, where plants grow a
battle wages for the sun's rays.
A plant's primary weapon in
this fight is the ability to grow towards the light, getting just the amount it
needs and shadowing its competition. Now, scientists at the Salk Institute for
Biological Studies have determined precisely how leaves tell stems to grow when
a plant is caught in a shady place.
In a paper published April 15
in Genes and Development, the researchers report that a protein known as
phytochrome interacting factor 7 (PIF7) serves as the key messenger between a
plant's cellular light sensors and the production of auxins, hormones that
stimulate stem growth.
"We knew how leaves
sensed light and that auxins drove growth, but we didn't understand the pathway
that connected these two fundamental systems," says Joanne Chory,
professor and director of the Salk's Plant Biology Laboratory and a Howard
Hughes Medical Institute investigator.
"Now that we know PIF7 is
the relay, we have a new tool to develop crops that optimize field space and
thus produce more food or feedstock for biofuels and biorenewable
Plants gather intelligence
about their light situation - including whether they are surrounded by other
light-thieving plants - through photosensitive molecules in their leaves. These
sensors determine whether a plant is in full sunlight or in the shade of other
plants, based on the wavelength of red light striking the leaves.
If a sun-loving plant, such as
thale cress (Arabidopsis thaliana), the species Chory studies, finds itself in
a shady place, the sensors will tell cells in the stem to elongate, causing the
plant to grow upwards towards sunlight.
When a plant remains in the
shade for a prolonged period, however, it may flower early and produce fewer
seeds in a last ditch effort to help its offspring spread to sunnier real
estate. In agriculture, this response, known as shade avoidance syndrome,
results in loss of crop yield due to closely planted rows of plants that block
each other's light.
Scientists knew that a pigment
found in leaves of thale cress plants, phytochrome B (PHYB), is excited by both
the red wavelengths of light that drive photosynthesis, as well as the near
infrared light that is enriched in shady spots. But no one had found a direct
link between this response to light and the hormone-driven growth response to
In their study, Chory and her
colleagues, including Joseph R. Ecker, a professor in Salk's Plant Molecular and
Cellular Biology Laboratory, used biochemical and genomic analyses to identify
PIF7, as the key molecular link between a plant's light sensors
and production of auxins.
They showed that when a thale
cress plant is placed in shade, a cascade of molecular changes occurs in the
cells of the leaves: the PHYB photoreceptor causes chemical changes in PIF7,
which then activates genes that direct the cell to produce auxin.
"We already knew that
auxin is made in the leaves and travels to the stem to stimulate growth,"
says Chory. "Now we know how shade stimulates the leaves to produce auxin,
and it turns out that it's a remarkably simple pathway to control such an
She added that the findings
may offer new avenues for developing crops with stem architectures better
suited to tightly planted field rows, making them less prone to shade avoidance
syndrome. If successful, such crops would produce higher yields of foods and
biofuels than existing strains.
Other authors on the paper
include: Lin Li, the first author and a former postdoctoral researcher in
Chory's lab; Benjamin J. Cole, Lauren J. Ivans, Ullas V. Pedmale, Hou-Sung Jung
and Robert J. Schmitz of Salk Institute; Karin Ljung, of Swedish University of
Agricultural Sciences; and Ghislain Breton, Chris Cowing-Zitron, Steve Kay and
Jose Pruneda-Paz of University of California at San Diego.