Molecular characterisation and interpretation of genetic diversity within globally distributed germplasm collections of tall fescue (Festuca arundinacea Schreb.) and meadow fescue (F. pratensis Huds.)

Abstract

Allohexaploid tall fescue (Festuca arundinacea Schreb. syn. Lolium arundinaceum [Schreb.] Darbysh.) is an agriculturally important grass cultivated for pasture and turf world-wide. Genetic improvement of tall fescue could benefit from the use of non-domesticated germplasm to diversify breeding populations through the incorporation of novel and superior allele content. However, such potential germplasm must first be characterised, as three major morphotypes (Continental, Mediterranean and rhizomatous) with varying degrees of hybrid interfertility are commonly described within this species. As hexaploid tall fescue is also a member of a polyploid species complex that contains tetraploid, octoploid and decaploid taxa, it is also possible that germplasm collections may have inadvertently sampled some of these sub-species. In this study, 1,040 accessions from the publicly available United States Department of Agriculture tall fescue and meadow fescue germplasm collections were investigated. Sequence of the chloroplast genome-located matK gene and the nuclear ribosomal DNA internal transcribed spacer (rDNA ITS) permitted attribution of accessions to the three previously known morphotypes and also revealed the presence of tall fescue sub-species of varying ploidy levels, as well as other closely related species. The majority of accessions were, however, identified as Continental hexaploid tall fescue. Analysis using 34 simple sequence repeat markers was able to further investigate the level of genetic diversity within each hexaploid tall fescue morphotype group. At least two genetically distinct sub-groups of Continental hexaploid tall fescue were identified which are probably associated with palaeogeographic range expansion of this morphotype. This work has comprehensively characterised a large and complex germplasm collection and has identified genetically diverse accessions which may potentially contribute valuable alleles at agronomic loci for tall fescue cultivar improvement programs.

Genotypic and Chemotypic Diversity of Neotyphodium Endophytes in Tall Fescue from Greece

“…FaTG-2 isolates and Mediterranean-type tall fescue have been reported previously (12,14,42,49), but this is the first tall fescue endophyte population study to observe this correlation on a larger scale. Our findings, together with tall fescue interfertility data and cladogenic segregation based on grass gene sequences (26,27,30,50), suggest that these tall fescue races are likely different species. Furthermore, the mixture of both tall fescue races identified in this study suggests that Greece, particularly Crete, is a region with overlapping Continental and Mediterranean tall fescue populations and may be a region of considerable biodiversity for both plant and fungal germplasms.…”

“…S1 in the supplemental material). The tall fescue race (Continental, Mediterranean, or rhizomatous) and ploidy status of each line were determined through sequence analysis of chloroplast matK as described by Hand et al (27). Four endophyte-infected (E ϩ ) seedlings per line were maintained in the greenhouse (24°C during days [15 h] and 20°C during nights).…”

“…Three different races of tall fescue have been recognized (rhizomatous, Continental, and Mediterranean), each with distinctive physiological and morphological traits, geographical distributions, and population structures (27). Rhizomatous tall fescue originates from the Iberian Peninsula and is the target of turf breeding programs due to longer, more prevalent rhizomes (27,56). Summer-active Continental tall fescue is prevalent in northern Europe and is the primary cultivated germplasm used in temperate regions for animal forage.…”

“…Summer-dormant Mediterranean tall fescue has been collected from northern Africa and Mediterranean regions and has recently become the focus of grass breeders looking to expand the agronomic range of tall fescue to more arid regions (39,60). Both Continental and Mediterranean tall fescue germplasm has been collected from Sardinia, indicating that the natural distributions of the two races overlap in the Mediterranean basin (27). However, crosses between Mediterranean germplasm and the other tall fescue races result in F 1 hybrids with low fertility (30,56), and phylogenetic analyses indicate that Mediterranean tall fescue is genetically distinct from Continental and rhizomatous races, possibly from an independent polyploid origin (26,50).…”

Molecular Mapping and Breeding of Physiological Traits

“…Further, the markers could directly characterize the genome of organism. The microsatellites or simple sequence repeats (SSRs) are now favoured at length for diversity analysis due to their simplicity, repeatability, and high polymorphism levels [115][116][117][118][119][120] among the various PCR-based markers available for genetic characterization. Molecular markers detected the entire genome as a substitute of only the regions responsible for the manifestation of the traits of interest [121].…”