Studies On Screening Of Nitrogen Nutrition Mutant And Its Nitrogen Nutrition Mechanism

T1 generation mutants from Zhonghua 11 of rice (Oryza sativa L.) caused by T-DNA insertion by Aagrobacterium tumefaciens-mediated transformation, were used to screen the nitrogen nutrition mutants under solution culture, according to the growth character and PCR detecting, the co-segregate mutants were used to study the nitrogen nutrition and root characters. The main results as follows:1 Among 2173 mutant lines there were 152 mutant lines were detected, which accounted for 6.99% in all of the screening population. The mutant lines were divided into five types: mutant in sufficient of nitrogen, mutant in root, mutant in albino, mutant in etiolated maize leaves and mutant in plants dwarfish, and the mutant ratios were 1.24%, 0.33%, 4.23%, 0.87% and 0.33%, respectively.2 The PCR detection results showed that there were 14 lines co-segregated among the 27 nitrogen mutants. The features of nitrogen mutant lines were as follows: dwarfish plants, short and chlorate symptom, slowly growth of roots, bad development of fine roots and root hairs, more yellow roots and bad development of white roots.3 T1 and T2 generation of the 12 co-segregated lines were cultured under different concentrations of nitrogen. The results showed that 955 lines in the experiment had the same co-segregated features in different concentrations of nitrogen in T1 and T2 generation, and it indicated that mutants were directly related to the T-DNA insertion. Further genetic analyses on the 955th line showed that the mutant segregation ratio conformed to Mendelian Laws in T1 and T2 generation, and the mutant character may be caused by some gene mutant and it was recessive mutant.4 The roots characters and difference in nitrogen metabolism of 955 lines in T2 generation were studied. As the reduction of the absorption rate of nitrate and ammonium, the nitrogen concentration, the activity of nitrate reductase and the capacity of nitrogen assimilation were all decreased which effected the root growth and development, and it indicated roots became shorter, root volume and active area lessened, plant height and SPAD value of chlorophyll decreased.