Molecular Analysis of Stable Mutagenesis Rice Cultivar Induced by High Hydrostatic Pressure

By using high hydrostatic pressure treatment, two genetically stable rice lines were obtained from the japonica rice cultivar Bijing 38. Mutant 1 is characterized by its lower segregation frequency and 20 d less of maturation period than the original cultivar. Mutant 2 is characterized by its significantly increased height, increased tillering efficiency and elongated kernels which is similar to what has been seen for indica rice. ISSR and RAPD analyses of these two mutants and the original cultivar revealed that there exists significant genetic variation between the two mutants and the original cultivar, each with 28.57% and 45.98% polymorphic bands respectively. The genetic diversity in Mutant 2 is significantly higher than in Mutant 1. ISSR analysis indicated that the mean absolute distance coefficient between the original cultivar and the Mutant 1 is 0.030 3, while that between the original cultivar and the Mutant 2 is 0.261 3. RAPD analysis demonstrated that the mean absolute distance coefficient between the original cultivar and the Mutant 1 is 0.084 5, while that between the original cultivar and the Mutant 2 is 0.416 7. These studies have provided strong evidence that high hydrostatic pressure could induce mutagenesis during seed germination and the phenotypes, and genetic traits can be stably passed on to the progeny. This is the first time we have shown at molecular level that treatment by high hydrostatic pressure can induce genetically stable mutations in higher plants. In addition to a variety of chemical and X-ray mutagenic methods, high hydrostatic pressure might as well be proven as another efficient method for mutagenesis.