Chemical and molecular characteristics of winter oilseed rape (Brassica napus L.) volunteers from the soil seed bank

Oilseed rape (OSR) has one of the highest potential for gene flow through seed and pollen. Volunteer plants are one of the most important sources of contamination of OSR crop of different quality cultivars. The aim of this study was to estimate the abundance of soil seed bank after the harvest of high erucic (HE) cultivar Maplus and to determine biochemical and molecular characteristics of OSR volunteers. The investigation comprised volunteers of oilseed rape obtained from the soil seed bank in two localities in Poland: Dlon and Zielecin (Greater Poland Voivodeship). The seeds of volunteers and reference cultivars were analyzed using biochemical (erucic acid and glucosinolates [GLS]) and molecular biology methods. In seeds of volunteers, erucic acid content ranged from 0 to 57.4% of all fatty acids and glucosinolate content ranged from 5.2 to 105.0 µmol g−1 of seeds. In sowing seeds of the cultivar Maplus, the erucic acid content was 57% and total glucosinolates were 12.6 µmol g−1 of seeds. RAPD markers were used to determine genetic similarity coefficient and relationship between polymorphic RAPD markers and erucic acid and total GLS content. Twenty RAPD markers showed statistically significant association with erucic acid and GLS content in seeds. Volunteers originating from the investigated soil seed bank were characterized by different content of erucic acid and GLS in seeds typical for different types of oilseed rape cultivars: double low (00, canola type), cultivars with zero erucic acid and high GLS content (0HG) and traditional cultivars with high erucic acid and high GLS content (HEHG). The results of this study, especially the presence in soil seed bank the seeds of very old cultivars, confirm that seeds of rapeseed of different origin may persist for a long time at the stage of secondary dormancy.