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

Also see:AeAeroponic Wheat Test Results