The potential of novel Festulolium (2n = 4x = 28) hybrids as productive, nutrient‐use‐efficient fodder for ruminants

Markku S Farrell,Alan P Gay,Alison H Kingston‐Smith,Mike W Humphreys,Sally A O'Donovan

doi:10.1002/fes3.50

Abstract

AbstractThe field performance and potential future use of F1 Lolium multiflorum and Lolium perenne × Festuca arundinacea var. glaucescens and Festuca mairei hybrids (2n = 4x = 28) are described. Foliar trait expression in the hybrids was largely determined by the Lolium rather than their Festuca parent ensuring maintenance of high‐forage quality. All four Festulolium populations comprised high‐yielding genotypes, but the L. multiflorum populations were particularly erect and tall, while the L. perenne populations had significantly higher numbers of tillers and were prostrate. Forage yields of the Festulolium populations assessed in field plot trials were either not significantly different from, or were superior to leading L. multiflorum and L. perenne cultivars used as controls. Endogenous plant proteases contribute to excessive proteolysis in the rumen which causes environmental N pollution. Protein degradation due to plant‐mediated proteolysis was assessed by in vitro exposure of leaves to the environmental conditions of the rumen (39°C, anaerobic) and calculated based on the time taken for protein levels to be reduced to half their original levels (t½). Leaf proteins were significantly more stable in L. multiflorum × F. arundinacea var. glaucescens and L. perenne × F. arundinacea var. glaucescens F1 hybrids (t½ 18–21 h) than in their respective Lolium parental genotypes (t½ 4–5 h), and there was a highly significant genome interaction. The t½ in the majority of the L. multiflorum × F. arundinacea var. glaucescens F1 hybrids studied often exceeded 24 h, whereas t½ of their Lolium and Festuca parents was consistently <14 h. Although inferior to the F1, F. arundinacea var. glaucescens genotypes tested had significantly greater t½ than L. perenne under rumen‐simulated conditions. Significant variation in protein stability was apparent within the F1 and their respective parent species' groups. The initial protein content of the F1 hybrids was lower than their respective parents, but following 24‐h exposure to anoxia at 39°C, the protein content of both parent and hybrid genotypes was similar. The differences in protein stability between parental and hybrid genotypes was due to the greater rate of protein decline observed in the Lolium genotypes. Hence, uptake of these Festulolium hybrids as forage crops has potential to directly mitigate environmental impact of livestock farming without affecting production capacity.

Highlights

In mild temperate climates such as that found in the UK ryegrass (Lolium spp.) is often the forage grass of choice due to its high yield and nutritious value
The IBERS-bred variety AberNiche, the first Festulolium to gain entry onto the UK National Recommended List is an example of an introgression form and is around 75% Italian ryegrass (L. multiflorum) and 25% meadow fescue (Festuca pratensis) (Cernoch and Kopecky, pers. comm.) while the French variety Lueur is an example of the amphiploid type with a more balanced ryegrass: fescue genome complement (Ghesquière et al 2010)
Fertility in the LmFg, LpFg, L. multiflorum × F. mairei (LmFm), and L. perenne × F. mairei (LpFm) F1 genotypes employed as parents in their respective polycross combinations was high and more than sufficient to provide seed for the four plant populations used in the initial field study

Summary

Introduction

In mild temperate climates such as that found in the UK ryegrass (Lolium spp.) is often the forage grass of choice due to its high yield and nutritious value. Festulolium varieties may be either amphiploids with combined genome sets of ryegrass and fescue chromosomes, or they may be introgressive forms. In the latter, a limited number of donor gene sequences, most frequently derived from a fescue species, are incorporated into the recipient (ryegrass) genome through a backcross breeding program (Humphreys et al 2003; Ghesquière et al 2010). This has been achieved through targeted markerassisted transfers of a single small genome sequence of F. arundinacea var. Glaucescens onto a terminal location of chromosome 3 (Humphreys et al 2005) This fescue sequence has subsequently been transferred into breeders’ lines of both Italian and perennial ryegrass (Humphreys et al 2012)

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Conclusion