ASGSB 1998 Annual Meeting Abstracts

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MICROGRAVITY EFFECTS ON FREE AMINO ACIDS CONTENT IN BRASSICA RAPA.   T. Cherevchenko, and N. Zaimenko, Central Botanical Garden of National Academy of Sciences of Ukraine

As a result of our experiments, we determined that total content of amino acids in plants at 9, 15 and 28 days of development during spaceflight increased 1.4-2.1 times. Important changes in amino acid content were observed at 15 and 28 days of Brassica rapa development. Following growth in microgravity, the average concentration of asparagine in leaves of 15-day-old plants increased 21 times, while threonine, serine, glutaminic acid, alanine and valine increased 1.2-1.8 times. In stems of tested plants, proline content increased 4 times, arginine -7, asparaginic acid -1.8, and threonine -2.1 times. We observed a sharp increase in free arginine in leaves of Brassica rapa 5.5 times, in stems - 25.6 times, and this suggests the lack of phosphate. Accumulation of free amino acids in these plants suggests water stress. We found a negative dependence between intensity of growth processes and increasing of amino acid concentrations in tissues. It must be noted a critical decrease of asparaginic acid concentration in stems of Brassica rapa at 28 days of plant development indicates nitrogen deprivation. Since Brassica rapa is a C3 plant, AMINO ACIDS production in leaves is higher when these plants are cultivated on ammonium compounds. Glutaminic acid concentration after 15-day growth in indicates increasing biosynthesis activity of photosynthetic pigments. We observed a 1.2-1.9 times increase of photosynthetic pigments content in Brassica rapa at 15 day of development and decreasing of their number 2.3-3.7 times at 28 days. Obtained results allow us to improve the technology of plant growth during spaceflight by improving physical and chemical features of soil substitutes and using of balanced fertilizers of prolonged action in response to biological peculiarities of plants.

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