Composition of Methionine and Association with Lysine and Tryptophan in Subtropically Adapted Maize Breeding Lines

Background and ObjectivesMaize protein lacks essential amino acids such as methionine, lysine, and tryptophan. Limited information exists on the composition and variation of kernel methionine. This study assessed methionine variability and its relationship with lysine and tryptophan in 48 maize inbreds at three locations.FindingsAnalysis of variance revealed significant variations for kernel methionine (0.031%-0.305%), lysine (0.118%-0.389%), and tryptophan (0.014%-0.090%). CML591 (0.305%), CML596 (0.286%), and CML421 (0.284%) showed the highest methionine content. The average methionine contents were comparable in quality protein maize (0.156%) and normal (0.150%) lines. Methionine showed no correlation with lysine (r = 0.001) and tryptophan (r = 0.032), while lysine and tryptophan showed a strong positive correlation (r = 0.740). CML165 (methionine: 0.272%, lysine: 0.320%, and tryptophan: 0.090%), CML186 (methionine: 0.254%, lysine: 0.389%, and tryptophan: 0.083%), and HKI163 (methionine: 0.252%, lysine: 0.331%, and tryptophan: 0.084%) were promising genotypes considering all three amino acids.ConclusionsMultilocation experiment revealed genetic variation in methionine, lysine, and tryptophan among the 48 inbreds. No negative correlation between the amino acids indicates the possibility of developing cultivars high in methionine, lysine, and tryptophan.Significance and NoveltyIdentified nutrient-rich inbreds will serve as valuable germplasm in maize biofortification programs. This is the first report on methionine variability and its relationship with lysine and tryptophan in subtropical maize.