| Abstract: | Multiple components of leghaemoglobins (Lbs) from several legumespecies have been separated by polyacrylamide gel electrophoresis(PAGE), and identified by densitometry at 405 nm, extractionfrom gels and formation of their respective CO-ferrous complexes.Components were numbered consecutively starting from the anodeside, and their relative concentrations were calculated by densitometryin control and  -treated nodules. The number of Lb components was five in Pisum sativum, four in Glycinemax, at least two in Lupinus luteus and Trifolium repens, andtwo in Vigna radiata and V. unguiculata. Only one componentwas detected in fresh nodules of Phaseolus vulgaris. Nitratesignificantly reduced the total content of Lb in all legumes,except Lupinus, the extent of reduction varying with the species.It also had a major effect on the proportions of components,causing an inversion in the relative abundance of Lb I and LbII of V. radiata: the concentration of Lb I increased from 8%to 81% with application, while total Lb only decreased by 13%. Drastic changes in proportions of Lbcomponents were not artifactual and cannot be attributed exclusivelyto different turnover rates. They should correspond to variationsin biosynthesis of the various components, probably originatingat the genetic level. Key words: Leghaemoglobin components, nitrate, nodule senescence |
