Publicly available maize (Zea mays L.) inbred lines with expired Plant Variety Protection certificates (ex-PVP) constitute the elite germplasm used in hybrids grown by North American farmers during the past half century. A set of 329 ex-PVP inbreds and eight public reference inbreds was evaluated for genetic diversity using molecular marker and pedigree-based relationships. The majority of inbreds originated from Dekalb Genetics Corporation, Holden's Foundation Seed, Pioneer Hi-Bred International, and Syngenta via Novartis and Northrup King. Flowering ranged from 968–1806 growing degree days to anthesis, supporting that these inbreds represent adaptation across the range of North American production environments. Admixture analysis supported eight subgroups (B14, B37, B73, Oh43, Iodent, Iodent-Lancaster, Lancaster, and Flint), reflecting heterotic patterns and company of origin. Five diallel-cross experiments identified primary yield heterotic patterns within early-, intermediate-, and late-maturity groups. Parental pedigree information was compiled for 2392 Plant Variety Protection and/or utility patented inbreds through 2017, allowing for multigenerational analysis of progenitors and the eight heterotic subgroups across current proprietary breeding programs. Key progenitors were identified for recently merged companies, Bayer Crop Science and Corteva Agriscience. The results of this study strengthen the value of the ex-PVP inbreds as a source of elite and relevant germplasm for breeders and researchers to exploit. This study provides information that will be logistically useful to researchers who use ex-PVP inbreds and adds to our understanding of heterotic grouping within North American proprietary germplasm.
ASJC Scopus subject areas
- Agronomy and Crop Science