The screening and preliminary construction of quality mutant population for cultivar "Nipponbare" in japonica rice (Oryza sativa)

Progenies of Oryza sativa cv. Nipponbare induced with 0.4% ethyl methane sulphonate (EMS) were screened for quality mutants and the preliminary quality mutant population was constructed in present experiment. A total of 2210 materials were first screened using near infrared reflectance spectroscopy (NIRS) from which 208 quality mutants were obtained for a second screening and then yielded 73 quality mutants including amylase content (AC), gel consistency (GC), gelatinization temperature (GT), protein content (PC), rapid viscosity analysis (RVA) parameters and amino acid contents. The screening yielded 11 PC mutants with a mutation frequency of 4.98aEuro degrees, followed by 7 rice floury viscosity mutants (3.17aEuro degrees), 5 AC mutants (2.26aEuro degrees), 4 chalky mutants, GT and GC mutants (1.81aEuro degrees), and 2 ASV mutants (0.9aEuro degrees). The relative contents of 17 kinds of amino acid mutations, including 7 kinds for essential amino acids and 10 kinds for nonessential amino acids were identified. With the variation of 10% as the screening standard, mutants were obtained for lysine and leucine at 0.45aEuro degrees and for valine at 4.98aEuro degrees, but no mutants were found for isoleucine, phenylalanine, threonine. For nonessential amino acids, mutants of glutamic (0.45aEuro degrees), arginine (3.62aEuro degrees), alanine (3.17aEuro degrees), serine (0.45aEuro degrees), glycine (0.45aEuro degrees), tyrosine (1.81aEuro degrees), proline (2.71aEuro degrees), and histidine (0.45aEuro degrees) were obtained, but none was found for aspartic, phenylalanine nor threonine. At 100% as the screening standard for methionine and cysteines, the mutation frequency of these two amino acid mutants were 0.9aEuro degrees and 4.98aEuro degrees respectively. Quality mutants in this preliminary library of rice could play important role in gene function and breeding of rice quality.