Pennycress (Thlaspi arvense L.) seed persistence in the field after two years

Concerns regarding long-term seed persistence and weediness represent a major barrier to the widespread adoption of pennycress ( Thlaspi arvense L.) as a commercial oilseed crop in the U.S. Midwest. This study evaluated the long-term survivability and dormancy of a wild-type black-seeded pennycress line and three Transparent Testa 8 gene-edited golden-seeded lines under field burial conditions. Seeds were buried at depths of 2 cm and 15 cm in well-drained and poorly drained soils and exhumed after 2, 4, 6, 12, 18, and 24 months. Germination assays and triphenyltetrazolium chloride staining were used to assess seed viability over time. All golden-seeded gene-edited lines declined to 0% germination by 6 months after burial, with no viable seed remaining by 12 months, whereas the wild-type line retained approximately 60% viability (germinated + triphenyltetrazolium chloride - positive seeds) after 2 years. No triphenyltetrazolium chloride - positive dormant seed was ever recovered from any golden-seeded line. Seed survivability of the wild-type line differed between soil drainage classes, with higher persistence observed under poorly drained conditions, while burial depth influenced viability only in the well-drained soil. These findings demonstrate that Transparent Testa 8 gene-edited golden-seeded pennycress exhibits substantially reduced seed persistence relative to wild pennycress, indicating a lower potential for long-term soil seed bank contribution. Reduced seed survivability supports the agronomic adoption of golden-seeded pennycress as an off-season oilseed crop with diminished risk of increasing weed pressure in subsequent cropping systems. • Introduces new golden colored commercial pennycress lines with TT8 gene edits. • Highlights persistence of commercial and wild pennycress seed in production fields. • Compares seed persistence across well and poorly drained fields over 2 years. • Confirmed lack of any seed persistence in commercial lines with TT8 gene edits after 6 months.