A new procedure for quantification of lignin in soybean (Glycine max (L.) Merrill) seed coat and their relationship with the resistance to mechanical damage

Abstract

The quantitative assay for protein-free lignin measured by thioglycolic acid reaction was applied to soybean (Glycine max L.) seed coat. The lignothioglycolic acid (LTGA) produced by the reaction of thioglycolic and lignin was recorded (at A280 nm) for various dilutions and a wavelength-dependent absorptivity value (e = 17.87 g -1 L cm -1 ) was obtained. Subsequently, the lignin contents of eleven soybean cultivars (Savana, Davis, FT-10, Paranagoina, Bossier, IAC-8, Santa Rosa, Doko, Parana, FT-2 and IAS-5) were determined. The lignin contents correlated with the index of resistance to seed mechanical damage. These results indicate that the LTGA method for lignin quantification can be used for screening genotypes for mechanical damage resistance in a breeding program for soybean seed quality.