Gravity plays a crucial part in the growth of plants, especially in the early phase. This was amply demonstrated in the seedlings of cucumber analyzed for gravity-related changes in growth.
Plants carry specialized cells that perceive gravity and distribute the growth hormone auxin to develop their vital features.
Japanese researchers examined cucumber seedlings germinated at the International Space Station, where microgravity conditions prevailed. The results of the study were reported in the journal Nature Microgravity.
Experiments On Cucumber
The reason for choosing cucumber was the opportunity to observe the growth of protuberances which are influenced by gravity during formation.
These "pegs" help seedlings to liberate from the coat of seeds and place themselves in the soil when roots are formed.
In the experiment, seedlings placed vertically prior to germination, or had budding roots that were under microgravity conditions, showed a skewed origination of pegs.
Hideyuki Takahashi, a scholar at the Space and Adaption Biology Laboratory at Tohoku University, said peg formation on the upper side of horizontally placed seedlings was suppressed as a reaction to the poor gravity conditions.
The pegs, however, developed well on the lower side of the transition zone between hypocotyl and root that held the seed coat. The hypocotyl expanded well to pull out the plumule and cotyledons from the seed coat.
Auxin Depression Verified
The study pin-pointed the role of CsPIN1 protein in the peg growth process. The protein is vital in transporting growth hormones.
To draw more conclusions, the researchers loaded cucumber seeds into special canisters after irrigating the plastic foam of the container.
The germinating seedlings were then let to grow in a microgravity compartment for 24 hours. Two conditions followed:
- Cucumber seedlings were maintained in microgravity
- Gravi-stimulation applied using a 1g centrifugal force.
With staining technique, the researchers marked changes from enforced gravi-stimulation. They tested seedlings sections and found CsPIN1 protein's positions were shifting under the influence of gravity.
That was apparent in the transition area where cucumber seedling developed pegs. This led to the assumption that a cellular canal transports growth hormones from one part to another.
"This result helps explains the gravity-regulated decrease in auxin level and thereby suppression of peg formation on the upper side of horizontally growing cucumber seedlings," added Takahashi.
Boost For Plant Life In Space
Meanwhile, Zero Gravity Solutions based in Boca Raton has developed a technology for boosting plant life both on earth and space.
It is already working with NASA for growing food for Mars Mission where the space agency is mounting a human mission in 2030.
The company has vowed to save Earth from food shortages and make Mars habitable for human life.
Harvey Kaye, chairman of Zero Gravity Solutions, set up the company in 2012 after acquiring intellectual property from John Wayne Kennedy, who is now chief science officer at Zero Gravity. Kennedy got a U.S. patent for methods seeking to deposit minerals directly into a living plant.
According to Andrew Koopman, CEO of Zero Gravity Life Sciences, the world needs to produce more crops on less land.
The NASA-Ames Research Center agreement stipulates Zero Gravity must fund research on food in lieu of access to NASA resources and the International Space Station.
