Influence of mutations in pea symbiotic Sym33 and Sym40 genes on leghemoglobin content and metleghemoglobin reductase activity in nodules

Leghemoglobin content and metleghemoglobin reductase activity were determin ed in root nodules of the original pea line SGE and mutants SGEFix(-)-1 (ge ne Sym40) and SGEFix(-)-2 (gene Sym33) that produce ineffective nodules wit h defects of infection thread formation and bacteroid differentiation. The content of leghemoglobin in root nodules of SGEFix(-)-2 and SGEFix(-)-1 mut ants was 5 and 150 times lower than in the original pea line. The activity of metleghemoglobin reductase was similar in nodules of all lines tested. T he data are discussed in relation to the ultrastructural analysis of nodule s and classification of mutants.