The isolation and characterisation of a catalase-deficient mutant of barley (Hordeum vulgareL.)

摘要

A mutant line of barley, R(othamsted)-Pr 79/4, has been isolated which grows poorly in natural air, but normally in air enriched to 0.2 CO2. Analysis of the products of14CO2fixation showed that there was no major block in photosynthetic or photorespiratory carbon metabolism in the mutant and that rates of CO2fixation were only slightly lower than those measured in the wild type (c.v. Maris Mink). Leaves of the mutant line contained only 10 of the catalase (EC 1.11.1.6) activity found in the wild type; and the two major bands of catalase activity detected after starch-gel electrophoresis of extracts of normal leaves were missing from similar extracts of RPr 79/4. Peroxisomes isolated from mutant leaves contained negligible catalase activity, but normal levels of other enzymes involved in photorespiration. Genetic analysis has shown that the mutation is recessive and that both air-sensitivity and catalase-deficiency segregate together in F2plants derived from a cross between the mutant and the cultivar Golden Promise. 1-14CGlycollate was not converted to14CO2faster in the mutant leaves than in the normal leaves. Thus there was no evidence that photorespiratory CO2may be obtained by the chemical action of H2O2on glyoxylate or hydroxypyruvate.