Inheritance of neurotoxin (ODAP) content, flower and seed coat colour in grass pea (Lathyrus sativus L.)

Abstract

A strong epidemiological association is known to exist between the consumption of grass pea and lathyrism. A neurotoxin, β-N-Oxalyl-L-α, β-diaminopropanoic acid (ODAP) has been identified as the causative principle. This study was undertaken to investigate the mode of inheritance of the neurotoxin ODAP, flower and seed coat colour in grass pea. Five grass pea lines with low to high ODAP concentration were inter-crossed in all possible combinations to study the inheritance of the neurotoxin. Parents, F1 and F2 progenies were evaluated under field condition and ODAP analyzed by an ortho-phthalaldehyde spectrophotometric method. Many of the progenies of low x low ODAP crosses were found to be low in ODAP concentration indicating the low ODAP lines shared some genes in common for seed ODAP content. The F1 progenies of the low ODAP x high ODAP crosses were intermediate in ODAP concentration and the F2 progenies segregated covering the entire parental range. This continuous variation, together with very close to normal distribution of the F2 population both of low x low and low x high ODAP crosses indicated that ODAP content was quantitatively inherited. Reciprocal crosses, in some cases, produced different results indicating a maternal effect on ODAP concentration. Blue and white flower coloured lines of grass pea were inter-crossed to study the inheritance of flower colour. Blue flower colour was dominant over the white. The F2 progenies segregated in a 13:3 ratio indicating involvement of two genes with inhibiting gene interactions. The gene symbol LB for blue flower colour and LW for white flower colour is proposed.