Root imaging showing comparisons in root distribution and ontogeny in novel Festulolium populations and closely related perennial ryegrass varieties

Abstract

The incorporation of new sophisticated phenotyping technologies within a crop improvement program allows for a plant breeding strategy that can include selections for major root traits previously inaccessible due to the challenges in their phenotype assessment. High-throughput precision phenotyping technology is employed to evaluate root ontogeny and progressive changes to root architecture of both novel amphiploid and introgression lines of Festulolium over four consecutive months of the growing season and these compared under the same time frame to that of closely related perennial ryegrass (L. perenne) varieties. Root imaging using conventional photography and assembled multiple merged images was used to compare frequencies in root number, their distribution within 0-20 and 20-40 cm depths within soil columns, and progressive changes over time. The Festulolium hybrids had more extensive root systems in comparison with L. perenne, and this was especially evident at depth. It was shown that the acquisition of extensive root systems in Festulolium hybrids was not dependent on the presence of an entire Festuca genome. On the contrary, the most pronounced effect on root development within the four Festulolium populations studied was observed in the introgression line Bx509, where a single small genome sequence from F. arundinacea had been previously transferred onto its homoeologous site on the long arm of chromosome 3 of an otherwise complete L. perenne genome. This demonstrates that a targeted introgression-breeding approach may be sufficient to confer a significant improvement in the root morphology in Lolium without a significant compromise to its genome integrity. The forage production of Bx509 was either higher (months 1-3) or equivalent to (month 4) that of its L. perenne parent control demonstrating that the enhanced root development achieved by the introgression line was without compromise to its agronomic performance.

A route to decreasing N pollution from livestock: Use of Festulolium hybrids improves efficiency of N flows in rumen simulation fermenters

“…Selective grass breeding has been conducted on LmFg BC 2 introgression lines on the basis of their heat and drought tolerance toward producing a more stress-tolerant and current UK National Listed variety; AberLink (Humphreys, Harper, Armstead, & Humphreys, 2005a;APHA, 2017). Hence, they may be viewed as possible alternatives to the use of seed mixtures, or for a specialist use such as in drought-prone regions or in preventing flooding due to deep rooting, for example, MacLeod et al, (2007); MacLeod et al 2013; Humphreys et al (2018). Theoretically, the hybridization of nutritionally desirable Lolium with stress-tolerant Festuca species would not only help protect the crop in a harsh field environment but could affect the cellular responses on exposure to the adverse conditions of the rumen.…”

“…Grasses were harvested at the same hour (15:00hr) having a target maturity of reproductive stage R1index 3.1 (Moore & Moser, 1995). Selection of these cultivars was based on previous evidence of potential advantages as cultivar or individual genotypes in terms of protein stability and thermotolerance where F. arundinacea var glaucescens had been shown previously to have slower rates of endogenous protein degradation than L. perenne, and F. mairei is one of the most heat tolerant fescues (Humphreys et al, 2014(Humphreys et al, , 2018MacLeod et al, 2013). All cultivars used were 4x as it was shown by Humphreys et al (2014) that a balanced Lolium: Festuca genome was required for expression of the slow proteolysis trait.…”

“…Festuca, Festulolium, Lolium, nitrogen-use efficiency, protein, proteolysis, rumen to be able to provide specialist functions and novel alternatives to existing grass cultivars due to their strong resilience against abiotic or biotic stresses as compared with perennial ryegrass (Ghesquière et al, 2010). As a result, Festulolium varieties have recently gained interest as a source of reliable, productive and nutritive fodder for use in livestock agriculture and for their potential for ecosystem services (Humphreys et al, 2018;MacLeod et al, 2013).…”

Do agricultural grasses bred for improved root systems provide resilience to machinery‐derived soil compaction?

“…Advances in new root screening technologies have provided opportunities for the incorporation of selections for root growth and design in plant breeding strategies. The differences in root architecture and changes in the ontogeny of certain Festulolium cultivars through the growing season have been described elsewhere and compared to currently used perennial ryegrass varieties during equivalent timelines (Macleod et al, 2013 and Humphreys et al, 2018). Humphreys et al (2018) found that certain Festulolium hybrids had more extensive root systems, particularly at depth, when compared to Lolium perenne L. (perennial ryegrass).…”

“…The differences in root architecture and changes in the ontogeny of certain Festulolium cultivars through the growing season have been described elsewhere and compared to currently used perennial ryegrass varieties during equivalent timelines (Macleod et al, 2013 and Humphreys et al, 2018). Humphreys et al (2018) found that certain Festulolium hybrids had more extensive root systems, particularly at depth, when compared to Lolium perenne L. (perennial ryegrass). Such deeper root systems should improve water (Durand et al, 2007) acquisition and aide soil hydrology (MacLeod et al, 2013) and carbon sequestration at depth in soils (Kell, 2011).…”