Influence of long term exposure to space flight on tomato seeds

Effects of long term exposure to physical factors of space flight on dormant seeds were studied on plants derived from tomato seeds flown for 6 years on board of the space station MIR. Upon return to the Earth, the seeds were germinated and grown to maturity (first generation). A second generation of plants was grown from seeds collected from these plants. Samples from both generations of plants were compared to plants from parallel ground-based controls, and significant differences in growth and development were observed between these groups. The test plants exhibited higher variability in yield than control ones. Some of the test plants were infertile. Various differences in cell walls, chloroplasts and mitochondria were observed with an electron microscope. The results obtained point out to significant changes occurring on the molecular level in tomato plants. The leaves of the first generation plants were used for random amplified polymorphic DNA analysis. Among 40 random primers used in this experiment, 31 primers generated the same DNA bands type, and nine primers generated a different DNA band type. Two hundred and sixty-nine DNA bands were produced, among which 29 DNA bands were polymorphic with the percentage of polymorphism being 10.8%. Considering the specificity of the examined organelles, their sensitivity to environmental factors and dynamics, it can be assumed that these changes are an adaptive response of cells to alterations in their environment. These changes should be taken into consideration in developing and modifying life-support systems involving higher plants for long-functioning interplanetary stations.