Studies On The Spatio-temporal Features And Regulation Of Polyamine Oxidase During Peanut (Arachis Hypogaea L.) Seed Germination And Growth

Peanut (Arachis hypogaea L.) was chosen as the experimental material in this thesis. The changes of polyamine oxdiase (PAO) activity and its distribution during the seed germination and seedling growth were studied. The relationship between PAO activity and seed vigor among 5 peanut cultivars was investigated. The cell localization of PAO in roots, embryonic axes and leaves of primary seedlings was conducted by using the Cerium method. In addition, the effects of light, putrescine (Put), cadaverine (Cad), spermine (Spm), Cu2+ and Ca2+ on the seed germination and the PAO activity were investigated.1. Distribution and changes of PAO activity during peanut seedgermination and the early period of seedling growthNo PAO activity was detected in soaked and ungerminated peanut seeds till germinated for 24h, and then the PAO activity increased quickly. The PAO activity in radicles reached to the peak just at the time of germination for 24h and declined afterwards. The PAO activity in embryonic axes and primary leaves reached to the peak at the time of germination for 120h and then began to slow down. A significant correlation between PAO activity and seed vigor wasobserved among 5 peanut cultivars, namely the higher PAO activity, the higher seed vigor, vice versa.2 . Cell localization of PAO in peanut primary seedingsIt was found that the PAO in primary leaves of peanut seedlings is located at cell wall of mesophyll parenchyma, intercellular spaces and vacuole membrane, especially the localization at vacuole membrane. PAO of cortical parenchyma cells in embryonic axes and roots was mainly located at the middle of cell wall and intercellular spaces.3 . Regulation of light on peanut seed germination and PAO activityIt was observed that peanut seeds can germinate normally whether in the light or in the dark. However, the PAO activity in radicles or embryonic axes of the germinating peanut seeds (Yueyou 79 and Zhanqiu 48) was higher in the dark than that in the light. Red or far-red light treatment for a short time (5min) had significantly effect on PAO activity. PAO activity was inhibited by red light pulse, while it was promoted by far-red light treatment. The inhibitive effect was reversible when a saturating pulse of far-red light was given immediately after the red light pulse. Additionally, the effect of red light and far-red light treated alternatively on the seed germination weakened with the increase of treatment times.4. The effects of Put, Cad, Spm, Cu2+ and Ca2+ on peanut seedgermination and PAO activityThe germination of peanut seeds was promoted by soaking with a moderate concention of Put or Spm, but the inhibitive effect of Cad treatment with every concentration in this experiment was seen. However, soaking with a moderate concention of Put, Spm or Cad all increased the PAO activity of the germinating seeds. Moreover, soaking with a moderate concention of CuS04 or CaCl2 could promote the germination of peanut seeds and enhance the PAO activity.In conclusion, above results of the spatio-temporal features and regulation of polyamine oxidase during peanut seed germination and growth are helpful toelucidate the physiolgical functions and the regulative mechanism of polyamine oxidation metabolism during seed germination and seedling growth. Besides, the present study may have some practical purposes in the application of polyamines to improve the quality of seed germination and establishment during peanut production.