Powerful grass hybrids

Perennial ryegrass (Lolium perenne L.) is an economically important forage grass of pastures and cultivated grasslands in temperate regions. Despite the enormous potential hybrid breeding offers to improve biomass yield, its realization in perennial ryegrass is challenging. A prevalent difficulty lies within the lack of genetic structure in breeding populations. Absence of genetic structure or heterotic groups tampers with decisions on potential candidates for crosses and often results in low genetic gains. Resolving this issue without molecular tools is almost impossible, as elite material is phenotypically similar and proven to have overlapping pedigrees. Therefore, we developed a molecular-based strategy to assist breeders in the improvement of structure within their diploid and tetraploid germplasm of perennial ryegrass.

In this study, we characterized the genetic structure of two diploid and two tetraploid parental breeding populations of a cytoplasmic male sterility-based hybrid breeding program using genotyping-by-sequencing. The analysis revealed the existence of sub-populations within the tetraploid breeding material which potentially impedes hybrid breeding.

In addition, 26 hybrids of the tetraploid breeding program were tested for yield performance and compared to synthetic varieties at five sites over four growing seasons. In these extensive yield trials, we could show that – despite the presence of sub-populations – the hybrids significantly outperformed the synthetics by 4.15% on average for total dry matter yield. This yield increase equates to 7-10 years of breeding progress.

In conclusion, we provide a method, which allows breeders to structure their germplasm and develop heterotic groups in order to exploit heterosis more effectively and to further improve the generation of high yielding hybrids of perennial ryegrass. This is an outcome of external page PlantHUB and represents a successful collaboration with Wilbert Luesink from Norddeutsche Pflanzenzucht Hans-Georg Lembke KG and Michael Koch from Deutsche Saatveredelung AG.

Citation:
Vogt M, Yates S, Sykes T, Luesink W, Koch M and Studer B (2020) Developing heterotic groups for successful hybrid breeding in perennial ryegrass. Agronomy 10, 1410
external page https://doi.org/10.3390/agronomy10091410