Relative quantification of gene expression levels associated with lignin biosynthesis in soybean seed coat

There is genetic variability among soybean genotypes for seed quality, which may be related to seed coat characteristics. An example of this is the variable lignin content in the seed coat, a trait associated with tolerance to mechanical damage and to deterioration caused by high relative humidity. The aim of this study was to evaluate soybean seed quality and determine the relative expression of genes associated with lignin biosynthesis in soybean seed coats. Two soybean cultivars differing with respect to lignin content in the seed coat, Doko (high) and Savana (low) were studied. Evaluations were carried out on seeds of four different sizes, representing the development stages of the seeds. Seed quality was evaluated by germination, accelerated ageing and electrical conductivity tests. Through real-time PCR, relative quantification (Doko/Savana) of the genes that encode PAL, C4H, 4CL, HCT, CCoAOMT, CCR, COMT and CAD enzymes was carried out, using the β-Actin gene as an endogenous control. According to the results of the electrical conductivity test, Doko cultivar with high lignin content has the best seed coat structure. PAL, CCoA, 4Cl and CCR genes were upregulated in Doko cultivar relative to the Savana cultivar.