Inheritance of seed quality and seed germination in two doubled haploid populations of oilseed rape segregating for acid detergent lignin (ADL) content

The high lignin content of the seed hull of oilseed rape leads to its black seed color compared to yellow seeded soybean. Reducing lignin and increasing oil and protein content is an important breeding aim in oilseed rape. The objective of the present study was to analyze the inheritance of two rapeseed genetic resources with reduced lignin content in the seeds and to elucidate the effects on seed germination and composition. These resources were crossed to black seeded Express 617 and F1 plants were used to develop two doubled haploid (DH) populations. The two DH populations were tested in field experiments in three to five environments. Significant genetic variation for lignin content and bimodal frequency distributions were found in both populations. SNP marker segregation in contrasting bulks revealed for both populations overlapping narrow genomic regions on chromosome C03, responsible for reduced lignin content. The low lignin bulks had a significantly higher percentage of seeds showing bacterial and fungal growth, but germination and vigor was not affected. Non-targeted metabolome analysis of immature green seeds showed exclusively a depletion of metabolites of the proanthocyanidin pathway in DH lines with a reduced lignin content. In these DH lines, a cinnamate-4-hydroxylase gene copy was identified as candidate gene in the overlapping genomic region of both populations. The newly identified QTL for reduced lignin content on chromosome C03 is valuable for studying additive and epistatic effects in combination with other low lignin genotypes.