ABSTRACT
Corn DNA was introduced into dry seeds of rice (cv. 'YuJing-6') by ion beam irradiation. Proteinase activities in rice seedling roots were subsequently analyzed by renaturation electrophoresis at pH 4.5, 7.0, and 8.5. Proteinase activity was more pronounced on gels at higher pH. Irradiation of rice seedling roots caused the loss of some proteinase bands at all pH conditions although a novel 50-kDa band was found at both pH 7.0 and 8.5. No new proteinase activity was detected at pH 4.5. However, novel bands and bands showing stronger activity were observed at pH 7.0 and 8.5. The data indicate that the expression of proteinases in rice seedling roots was altered following low energy ion beam mediated transformation with corn DNA.
Subject(s)
DNA, Plant/genetics , Oryza/genetics , Peptide Hydrolases/metabolism , Plant Proteins/metabolism , Seeds/genetics , Transformation, Genetic , Zea mays/chemistry , Electrophoresis, Polyacrylamide Gel , Enzyme Assays , Gene Expression , Hydrogen-Ion Concentration , Ions , Kinetics , Nitrogen/chemistry , Oryza/enzymology , Peptide Hydrolases/genetics , Plant Proteins/genetics , Plant Roots/enzymology , Plant Roots/genetics , Radiation, Nonionizing , Seedlings/enzymology , Seedlings/genetics , Seeds/enzymologyABSTRACT
Rice variation induced by the introduction of exogenous DNA has become an important method of improving rice varieties and creating new germplasms. In this study, we transferred maize genomic DNA fragments to the receptor of Nipponbare rice using a modified "pollen-tube pathway" method. Material from mutant rice B1 and B2 were acquired and 14 specific bands were obtained from the material using amplified fragment length polymorphism analysis. From the 14 specific sequences obtained, there were 3791 bp, including 144 base mutations with a base mutation rate of 3.80%. Specific bands resulted from base mutation of selective bases or restriction endonuclease recognition sequences, or insertion or deletion of DNA fragments. The frequency of single-base mutations was significantly higher than that of double-base mutations, three-sequential base mutations, and multiple-sequential base mutations. The site frequency of base substitution (87.04%) was significantly higher than that of base insertion (3.70%) or deletion (9.26%). In all cases of base substitution, the frequency of transition (76.47%) was significantly higher than transversion (23.53%). The above results indicate that transferring foreign-species DNA into rice cells can induce base mutations in the receptor, with base substitutions occurring at the highest frequency, and the dominant type of base substitutions being transition. Preliminary analysis reveals that the molecular mechanism of transferring exogenous DNA into rice causes mutations, which provides theoretical data on biological mutagenesis for further research.