Two flavonoid-deficient mutants, designated as fldL-1 and fldL-2, were isolated in EMS-mutagenized (0.15, 10h) M2 progeny of grass pea (Lathyrus sativus L.). Both the mutants contained total leaf flavonoid content only 20 of their mother varieties. Genetic analysis revealed monogenic recessive inheritance of the trait, controlled by two different nonallelic loci. The two mutants differed significantly in banding patterns of leaf aconitase (ACO) and S-nitrosoglutathione reductase (GSNOR) isozymes, possessing unique bands in Aco 1, Aco 2, and Gsnor 2 loci. Isozyme loci inherited monogenically showing codominant expression in F2 (1:2:1) and backcross (1:1) segregations. Linkage studies and primary trisomic analysis mapped Aco 1 and fld 1 loci on extra chromosome of trisomic-I and Aco 2, fld 2, and Gsnor 2 on extra chromosome of trisomic-IV in linked associations. © 2012 Dibyendu Talukdar.