Variation of Agronomic Traits of Rice Mutant Lines Induced by Sodium Azide

Abstract

To investigate the mutagenecity of sodium azide (SA) and to select mutants having various agronomic characteristics in rice (Oryza sativa L. ssp. japonica), dry seeds of rice variety ‘Suweon 472’ were treated with 0, 0.5, 1.0, 2.0, and 4.0 mM SA solutions prepared in 0.1 M phosphate buffer (pH 3.0). Germination rate, seedling height and sterility were investigated in M1 generation and chlorophyll mutations were observed in M3 generation. Germination rate and seedling height decreased as the increase of SA concentration in M1 generation, the maximum seed sterility (40.8%) was found at 4.0 mM SA concentration. Chlorophyll mutants were occurred in M3 generation and the frequency calculated on a line basis was 13.5% at the same treatment. Many kinds of mutations for morphological and agronomic characters were observed and mutations with short culm and glabrous leaf were frequently found in M3 generation. Interestingly, five mutant lines resistant to blast or bacterial blight (BB) were selected and evaluated with several isolates in M3 generation although Suweon 472 has been known to be susceptible to blast and BB. These mutants showed all resistance to seven isolates of blast and a total of 76 lines among 2,567 lines evaluated showed resistant to race K1 of bacterial blight. Two mutant lines (440172 and 41272) showed different reaction to BB isolates from the other resistant mutants. A few kinds of endosperm mutants were also identified and most of them were waxy mutants.