The Studies On The Relationship Between The Dose Of Ionizing Radiation And The Variation Effect Of Plant

Ionizing radiation,as an important mean of inducing mutation,has been widely used in the plant mutation breeding,especially crops.A saddle shape relationship between the plant survival rate and radiation dose is found in the mutagenic effect of ionizing radiation on plant.The underlying mechanism of the saddle shape relationship remains unclear.To explore inherent mechanism of the "saddle" survival-dose curve is the certain requirement of development of subject areas and the key problem to be solved in the plant mutation breed.The research work on the relationship between the dose of ionizing radiation and the mutagenic effect of plant consists of two parts of theory and experiment: one is the experimental work of the field traits of maize inbred line radiated the heavy ion completed by the author during the master's course;the second is the theoretical work on the effect-dose relationship of ionization radiation conducted by the author during the doctoral course.And the latter is the core of this study,and make the following main conclusions.1.The ionizing radiation dose,the plant repair and complete randomization were introduced into the Crow-Kimura theory of biological evolution.A parallel evolutionary model suitable for ionizing radiation-induced plant mutagenesis was established and the analytical solution of steady-state distribution was obtained.The internal causes of saddle-shaped experimental curve between ionizing radiation dose and plant variation effect were expounded theoretically for the first time.2.The above theoretical results were applied to the radiation mutagenesis experiments of corn,sweet sorghum and cotton.The results showed that the theoretical survival rates of the three plants were in agreement with the experimental survival rates,and the radiation dose thresholds of the three plants were given.3.The Eigen model was completely randomized.It was shown that the randomization of mutation rate played a dominant role in the broadening effect of the error threshold,and the behavior of the population through the error threshold was the reason of the broadening effect of the error threshold.The study of the Eigen model laid the foundation for the study of the specific mutagenesis theory in which selection coupled with mutation.