Effect of microgravity on rhizosphere and endophytic microorganisms- A review

Abstract

Outer space agriculture and planetary colonization are two major goals in space science as well as in agriculture in the future world. It is not an easy task that cultivate crop plants in outer space with limited resources as well as under several abiotic stresses. For cultivate crops in outer space, it is essential to take a better understanding about the behavioral differences as well as physical and chemical compositional changes in the plants as well as the microbiomes that related to the plant root system and some plant tissues such as leaves. Usually many microorganisms that related to the plant rhizosphere and endophytes behave in different way under the microgravity conditions that has been created within the laboratory conditions for demonstrate the conditions which the earth gravity is not affecting to plant growth and development. As an example, that has been observed, Pseudochrobacterium kiredjianiae, a type of microorganism that inhabited the rhizosphere stimulating the growth of wheat (Triticum aestivum L.) by increasing the root length and biomass accumulation. Under the earth’s gravity this P. kiredjaniae also behaving in the same manner. But specially under the microgravity conditions, their activities have been enhanced. Unlike Pseudochrobacterium kiredjianiae there is a possibility of some strains of microorganisms that can be inhabited in plants caused the negative effects on the cultivations such as by decreasing the growth rate of the plant. Because of that, the understanding regarding the behavioral changes of the rhizosphere and endophytic microorganisms will be definitely helpful for the future agriculture in space and the colonization programs that based on some other planets such as Mars. Ultimately, studies regarding the studies of microgravity on rhizosphere and endophytic microorganisms will open a new chapter of agriculture in the future generations.