| This thesis contains two parts. The first part is about abiotic formation of organic molecules under super high-pressure hydrothermal system, which simulates the chemical evolution of origin of life, and the second is the research on the genetic variation of spermatophyte by induced of high hydrostatic pressure.Part I: Synthesis of prebiotic molecules at the chemical evolution of origin of life.From ancient times, origin of life on earth is a fascinating and elusive topic, and there has been several hypotheses including creationism theory, autogenetic theory, biogenesis theory, and cosmogony theory. Up to now, the theory of chemical evolution is generally accepted by majority of scientists. On original earth, inorganic compounds can be transformed into organic matter, and organic matter can be developed into biological macromolecules and multi-cellular system, until the primitive life forms. After the discovery of deep-sea hydrothermal vents, scientists have considered the origin of life may be related to hydrothermal vent ecosystems. John Corliss was the first one who originated the hydrothermal origin of life model; he thought life matter could be obtained under high pressure and high temperature environment of hot spring.In order to study submarine hydrothermal theory of the origin of life, a high pressure hydrothermal system was established to simulate the environment of hot spring, which includes wide range of temperature (room temperature-350℃), pressure (0.1-10MPa). Inorganic compounds(such as CO2, NH3 and H2O)were used to synthesize organic molecules with transition metal catalyst. The experimental result could provide clues to verify the submarine hydrothermal theory.First of all, two inorganic systems (NH3-CO2-H2O & CO2-H2O) were used to generate ethanol, acetic acid, propionic acid, isobutyric acid and acetamide, which were identified by GC-MS. According to our experimental results,we propose a possible reaction mechanism based on Fischer–Tropsch Type synthesis, which includes the surface carbide mechanism, oxygenate mechanism, and CO inserting mechanism. The thermodynamic analysis and the effect of catalyst were investigated to understand the mechanism of the organic reaction. The abiotic synthesis of propionic acid and isobutyric acid are rarely reported.(1) The isobutyric acid was obtained under the super high pressure hydrothermal conditions of 7.64-7.69MPa and 350℃. The yield of isobutyric acid was 2.40% (mole percentage), which was very low compare to that of other organic synthesis, but it was reasonable to simulate the original earth hydrothermal environments. It cannot only provide a prehistoric clue of CO2 activation, but also provides strong scientific evidence for the origin of life. The branched-chain compounds play a key role in the origin of life, but it is very difficult to synthesize from inorganic compounds due to its complex formation mechanism. Take nature amino acid as example,α-amino acid is the main type, so the position of branch is very essential. The origin of chiral molecules in the biochemical is related to the structure of branched-chain compounds. Therefore, the synthesis of isobutyric acid can help us to explain the chirality origin of life, and provide the foundation for understanding the complex process of origins of life.(2) The propionic acid was obtained under the super high pressure hydrothermal conditions of 8.84-9.45MPa and 300℃. The yield of propionic acid was 0.48%. The prebiotic synthesis organic acids, which contain more than three carbons, are rarely reported. In order to study the carbon-chain growth mechanism, long-chain carboxylic acid even carboxylate should be synthesized. Then the research may be go into a biological macromolecules stage on the origin of life, because carboxylate is the main component of cell membrane.Second, phthalimide, which is the precursor compounds of amino acid and is important at evolutionary stage of the chemical origin of life, was obtained under the super high pressure hydrothermal conditions of 7.82-9.32MPa and 300℃, which simulated submarine hydrothermal environments. The simple inorganic molecules (NH3, CO2, H2O) were used as starting materials. The reaction mechanism is very complicated, which contains carbide mechanism of Fischer-Tropsch synthesis, rearrangement and chemical adsorption, desorption process. Because phthalimide is the important intermediate compound of fine chemicals and the raw material for synthesis of amino acid, the synthesis of phthalimide brought us another way to the study of the origin of life.At last, NH3-CO2-H2O system was adopted to synthesize amino acid. In the presence of NH3, it is easier to synthesize amino acid using two different temperature steps because amino acid decomposed at the temperature higher than 200℃. At last, glycine and D, L-alanine was synthesized from inorganic compound NH4HCO3 in the presence of iron powder and magnetite assemblage catalyst under hydrothermal conditions. And our result provides a new route for synthesis of amino acid under the hydrothermal condition.Thus, the conversion of simple inorganic compounds to the important prebiotic organic molecules was successful under the super high pressure hydrothermal conditions which simulated submarine environment, and provided strong evidence to verify the hydrothermal theory of the origin of life.Part II: Research on the genetic variation of spermatophyte induced by high hydrostatic pressure.High pressure biology is to study the biological effects under the pressure, which can reveal the impact of pressure on the general rules and disciplines of biological systems. Under the pressure, many results were obtained from the research on the protein structure and function, gene expression, metabolism and other biological processes. Therefore, the high-pressure biology can help us to understand the phenomena of life better.Plant mutagenesis was commonly used in crop breeding in order to obtain superior varieties in recent years. Development of high pressure bioscience allows people to use hydrostatic pressurization as a novel approach to breed new plant varieties. To our knowledge, this is the first time to show at molecular level that high hydrostatic pressure mutagenesis could result in stable genomic mutations in cucumber cultivar. The results obtained from this study provide potential molecular mechanisms that cause morphological variation after mutagenesis with hydrostatic pressure.Two mutant cucumber lines were obtained from the Tianjin cucumber cultivar S9925-3 after treatment with high hydrostatic pressure. DNA fingerprint analysis was performed for the two mutant and their parental wild-type cucumber cultivars by amplified fragments length polymorphism (AFLP) analysis. A total of 30 randomly selected primer pairs were used for AFLP. Six specific different bands between the mutant and the wild-type cucumber cultivars were excised from the polyacrylamide gel for DNA sequencing. Alignment of the obtained DNA sequences with NCBI database identified the mutation sites in cucumber genome, which may be the reason of phenotypic changes of the mutant cucumbers.This is the first time we showed at molecular level that treatment with high hydrostatic pressure resulted in stable mutations in cucumber cultivar. Our results indicated that high hydrostatic pressure-induced mutational breeding can be used as an effective approach for the crop improvement.
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