Report to NASA
by BioServe
(located on the campus of the University of Colorado, Boulder, CO)
Report Date: 7/31/98
Mission Report: NASA 6 / Mir Space Station
Subject: Anti-fungal properties of ODC
I. Background
Aeroponics International, formerly EnviroGen, Inc., of Berthoud, Colorado,
has been exploring the elicitation of a plant’s own natural defense systems
to fend off fungal pathogen attacks. They place the plant in contact
with a naturally occurring compound that elicits the production of fungal
fighting compounds within the plant. BioServe has been involved in
plant growth experiments in space almost since the Center’s inception in
1987. Research conducted by BioServe researchers may indicate that seedlings
grown in space develop fewer lignified vascular elements and less lignin
overall (Campbell et al. 1996). Previous research on mung bean sprouts
demonstrated similar results (Cowles et al. 1994). This research indicates
a shift in the plants metabolic pathways. This could be a result
of a number of factors including influences on environmental parameters
induced by the experimental hardware, or potentially part of the gravitropic
sensory and response mechanisms, or, most intriguing, a decrease in mechanical
loading due to the microgravity environment. Based on these and other initial
studies, Aeroponics International is interested how the hypothesized shift
in metabolic pathways would affect the elicitation of the antifungal response
during space flight. This interest is both to better understand the
underlying mechanisms of the elicitation as well as the applicability of
this technology for use in future advanced life support food production
systems for long term space missions.
II. Objective / Hypothesis
The objective of this experiment was to determine whether or not the
antifungal response of the plants was maintained during spaceflight. Of
even greater interest is whether or not Aeroponic International’s elicitor
induced the same response on plants grown in space as it did for plants
on the ground. The hypothesis is that plants grown in space, with and without
the elicitor’s influence, will show greater production of antifungal compounds.
III. Results
Along with the experiments that were conducted aboard Mir during NASA
6, concurrent ground control experiments were conducted at SpaceHab in
Cape Canaveral, Florida. Adzuki beans were selected as the test subject
due to slower growth characteristics than Mung beans providing higher mission
success probability in the event of return mission delays. The experiment
included untreated controls as well as the treated experiments with varying
elicitor levels to investigate dose responses of the plants in the two
different gravitational environments. Most of the seedlings were returned
alive to Earth and have undergone biochemical assay to determine the extent
of the elicitation. One set of seedlings was fixed on orbit and is undergoing
further analysis to determine differences in plant structure and the effect
of low gravity on the gravisensing cells (statocytes) of the treated and
control seedlings.
In general the seeds sprouted quite well both on Earth and onboard Mir.
The Mir-grown seedlings tended to exhibit more growth than those grown
on Earth. Though no fungal challenge was intentionally introduced
into the plants, we did see fungal infection of several of the seedlings.
Preliminary visual analysis indicated that the seedlings that were pretreated
with the elicitor exhibited less fungal infection than the untreated seeds.
This was true for both flight and ground experiments. Biochemical
analysis has supported this finding and has further shown these plants
have retained their fungal fighting abilities and the elicitor has maintained
its effectiveness in microgravity. Further analysis is still being
performed on the fixed samples to determine structural differences in the
seedlings.
IV. Conclusions
This experiment suggests that plants can retain their fungal fighting
abilities during growth in microgravity. Further, the elicitation
of antifungal compounds by Aeroponics International’s proprietary
elicitor and delivery system exhibits the same dose response both on the
ground and during space flight.
V. Terrestrial applications of the findings
There is tremendous terrestrial application of this technology.
Fungal pathogen infection is a major cause of crop failure around the world.
Widespread use of pesticides raises crop production costs and has potentially
dramatic health concerns. Aeroponics International’s elicitor technology
with their unique, patented delivery system can improve food safety and
ground-water quality, as well as reduce farming cost.
This and future studies will help the company perfect its delivery system
for a variety of crops including potatoes, wheat, barley, tomatoes, rice
and soybeans. These experiments are also a potentially important part of
NASA’s search for viable strategies to grow food plants on long term space
flights or on future bases on other planets or moons.
VI. Photos
Photos from the Mir Space Station/Kennedy Space Center ODC
Tests
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