Some Biological Effects On Soybean Seedlings By Ar~+ Laser Irradiation

The germinating germ of soybean with high isoflavone content were irradiated by 5.7mW/mm2 Ar+ laser with wavelenth of 457,465,472,477,488,496,502,514 nm for different times of 1,3,5 and 7 minute(s). By comparing the differences of their biological characteristics between the experimental group (L) and the control (ck), such as seedling cotyledon and leaf photosynthesis, protein metabolism, isoflavone content and antioxidation, some systematic studies had been done about the biological effects before and after the irradiation. The aim was to fully understand biological stimulation mechanism of the low-power Ar+ laser irradiated on biomass and to provide some theoretical and experimental basis on breeding soybean with high isoflavone content by way of laser irradiation. Completed work includes the following main aspects:1. Study on correlations between isoflavones content and quality of soybeanIsoflavone components (genistein, genistin, daidzein, daidzin, glycitein and glycitin), proteins (albumin, glutelin, globulin, gliadin,7S globulin,11S globulin and total protein), crude fat and five fatty acids (palmitic acid, stearic acid, oleic acid, linoleic acid and linolenic acid) in seven different soybean germplasms were used for quantitative analysis. The results showed that:there were different correlations between isoflavone content and protein content and oil content in different soybean germplasms. Among them, (1) the six isoflavone components content had different significant positive correlations with the content of albumin, 11S globulin, total protein, total fat, and negative correlations with the content of glutelin, globulin, gliadin respectively. (2) the six soybean isoflavone components were positively correlated with linoleic acid and linolenic acid significantly, especially linoleic acid. (3) genistein, genistin were negatively correlated with soybean fat, while daidzein, daidzin, glycitein and glycitin had some positive correlations with soybean fat. After quality analysis of seven different soybean germplasms, Jinong 19, in which the total content of six isoflavones were 2437.28μg/g, was selected as an experimental material for the study of biological effects with Ar+ laser irradiation on soybean seedlings.2. Effect of Ar+ laser irradiation on the soybean seedlings in physiological and biochemical propertiesWhen the germ of the soybean seed (named as Jinong 19) were being irradiated by a low-power Ar+ laser, its conductivity of the soaking solution, moisture content, plant height, carbonic anhydrase (CA) activity, chlorophyll, photoassimilate, endogenous protease activity, soluble protein, the heat-stable protein, total free amino acids content behaved remarkable difference from the control group (ck). Laser irradiation could affect the plasma membrane, plant height and photosynthetic assimilation, protein metabolism. The results showed that: 457-502nm laser irradiation could effectively repair the plasma membrane injuries of soybean seeds under water stress, reduce the outflow of intracellular material. And among 32 sets of laser irradiation groups (L), laser irradiation with 502nm for 5 minutes could be effectively in promoting chlorophyll synthesis (10.09%), raising the Chla/Chlb ratio (16.78%), CA activity (118.25%), heat-stable protein content (47.47%) and total free amino acids content (12.33%), while reducing the endogenous protease activity (34.85%) and plant height (1.43%). Laser irradiation accelerates the product of soybean seedling photoassimilate, protein metabolism, at the same time, accelerates the process of metabolism of the seedlings.3. Effect of Ar+ laser irradiation on soybean seedlings in isoflavones metabolismHPLC method was applied in the measure of content of the six kinds of isofavone: genistein, genistin, daidzein, daidzin, glycitein, glycitin in the soybean seedlings cotyledons and leaves after Ar+ laser irradiation. The results showed that:among 32 irradiation groups, the content of 6 isoflavone components in seedling cotyledons and in leaves were 50% and 15.6% higher than that in ck respectively. The irradiation with 502nm for 3 minutes could be effective in promoting 6 isoflavone synthesis in soybean seedling cotyledons and leaves. And the increase rates were 44.06% and 117.46% respectively. There were certain constraints between biosynthesis system of the glycitein and glycitin, The activity of PAL, C4H,4CL, SIF and Phe content in soybean seedlings were the influencing factors of the level of the isoflavone content, while laser irradiation could change the content of Phe, which was the precursors substance of isoflavone, and the activity of related enzymes in biosynthesis. The impact differs from the laser wavelength and irradiation time. Phe level is the main factor, while the PAL, C4H,4CL, SIF activity have positive correlations with isoflavone content.4. Effect of Ar+ laser irradiation on soybean seedlings in antioxidationThe activity of super oxide dismutase (SOD), peroxidase (POD), catalase (CAT), the content of ascorbic acid (AsA), carotenoids (Car), proline(Pro), UV-absorbing compounds, glutathione(GSH) and malondialdehyde (MDA) in cotyledons and leaves of Jinong 19 seedlings were different from the control group (ck) after the germinating soybean seeds germ were irradiated by Ar+ laser. Antioxidant enzyme activity and non-enzyme antioxidant content of soybean seedlings changed evidently. The results showed that:the activity of SOD, CAT, POD and the content of AsA, Car, Pro, and UV-absorbing compounds in soybean seedlings were significantly increased. The content of GSH in leaves, Pro in cotyledons were reduced, while the content of GSH in cotyledons, Pro in leaves increased. Laser wavelength and irradiation time were two main factors which could affect antioxidant capacity. Laser wavelength of 477,488,496 and 502nm and the laser irradiation time of 5,7 minutes could reduce the peroxidation of seedlings. Therefore, antioxidation of soybean seedling could be improved by Ar+ laser irradiation on seed germ.