Tall Fescue Cultivars Research Articles

Brown Patch Occurrence in a Zoysiagrass-Tall Fescue Polystand Compared with a Tall Fescue Monostand

Core Ideas A polystand mixture of tall fescue and zoysiagrass showed reduced brown patch disease severity compared to a tall fescue monostand. Mixing zoysiagrass with tall fescue improved turfgrass quality during summer months when brown patch was active. In turfgrass systems, creating polystands with comparable color and texture may be a feasible strategy for reducing disease. Tall fescue (Schedonorus arundinaceus Schreb.) is used frequently in Kansas due to its heat and drought tolerance compared with other cool-season grasses. Brown patch caused by the fungus Rhizoctonia solani Kühn AG-2–2 IIIB is the main disease limiting the growth of tall fescue in summer, and brown patch resistance in tall fescue cultivars is limited. Polystands of Japanese lawngrass (Zoysia japonica Steud.), commonly referred to as zoysiagrass, and tall fescue have the potential to provide a lower-input turfgrass sward that has good autumn and early spring color. Our objective was to determine whether a polystand composed of a seeded zoysiagrass (‘Compadre’) and tall fescue (‘Corona’) would reduce brown patch severity compared with a fall fescue monostand while maintaining overall acceptable quality. Studies were established at the Rocky Ford Turfgrass Research Center in Manhattan, KS and Olathe Research Center, Olathe, KS in 2015 and conducted through summer 2017. In the split plot design, natural infection by R. solani or a fungicide-treated control was the whole plot treatment factor, and species (tall fescue monostand and the polystand mixture) were subplots. In both years at Olathe and 2016 in Manhattan, disease severity in the tall fescue monostands was consistently higher than the zoysiagrass–tall fescue polystand during July through September. Turf quality was consistently higher in the polystand compared with the monostand during peak brown patch outbreaks. Use of a zoysiagrass–tall fescue polystand is one option to reduce brown patch in transition zone lawns where the disease is common.

Screening of diverse tall fescue population for salinity tolerance based on SSR marker-physiological trait association

Soil salinity is a notorious abiotic stress which constrains plant growth and limits crop productivity. Recent advances in phytogenetics especially the discovery of marker-trait association have facilitated the efficient selection of stress-tolerant crops. The objective of this study was to evaluate tall fescue (Festuca arundinacea Schreb.) accessions growing under salt stress in order to identify salt-tolerant and salt-sensitive genotypes using physiological and molecular markers. The population consisted of 114 diverse tall fescue accessions which were assessed using 99 simple sequence repeat (SSR) markers and five functional physiological traits i.e., turf quality, leaf water content, chlorophyll content, relative growth rate, and evapotranspiration rate. Salinity stress induced great variations among the functional physiological traits and there were significant correlations among them. The population structure analysis revealed two distinct populations, while association mapping between the SSRs and phenotypic traits identified significant associations. In addition, the accessions that maintained relatively higher physiological traits had a significantly lower accumulation of Na+ and Cl− in the roots compared to those whose functional traits declined. We identified six most salt-tolerant accessions due to their high values of physiological parameters and significantly low accumulation of Na+ and Cl− in the roots. Similarly, we identified six accessions we considered to be most salt-sensitive as observed by high Na+ and Cl− accumulation plus a decline in the physiological activities. Our findings are helpful to tall fescue breeders with a goal of producing tall fescue cultivars with enhanced salt tolerance.

Salinity Tolerance of Turf-type Tall Fescue as Affected by Nitrogen Sources

Tall fescue [Schedonorus arundinaceus (Schreb) Dumort] has potential in cool arid regions, where it is often subject to salinity stress. The objective of this 2-year field study was to investigate the effect of nitrogen sources on tall fescue turf quality under salinity stress in the northern Great Plains of North America. ‘Wolfpack’, ‘Wolfpack II’, ‘Tar Heel’, ‘Tar Heel II’, ‘Jaguar 3’, ‘Jaguar 4G’, and ‘Arid 3’ were treated with NaCl and CaCl2 in equal amounts. Six N sources were used for fertilization: nitrate-N, urea-N, ammonium-N, urea-N/ammonium-N/nitrate-N, urea-N with urase and nitrification inhibitor, and organic N. Salt treatment reduced turf quality of all cultivars. Turf quality was affected differently by N source. Regardless of salt treatments, urea stabilized with a urease inhibitor and a nitrification inhibitor consistently had the best turf quality. Equal amounts of nitrate, ammonium, and urea-N yielded the lowest turf quality. However, there was no interaction between N source and salt treatment. These results were also supported by green density (GD), dark-green color index (DGCI), shoot chlorophyll (Chl) content, and leaf relative water content (RWC). Tall fescue cultivars responded to salinity treatment differently, with ‘Wolfpack II’ being the cultivar ranked consistently at the top and maintained above the acceptable level of visual quality.

Physiological changes and DREB1s expression profiles of tall fescue in response to freezing stress

Tall fescue is a widely used cool season turfgrass. In this study, we screened freezing tolerance of six tall fescue cultivars based on TEL50 (temperature causing 50% electrolyte leakage). We observed that freezing tolerant tall fescue cultivar exhibited lower EL, accumulated higher soluble sugar and proline, and showed higher CAT and SOD activities when compared with freezing intolerant cultivar. Based on bioinformatics analysis, 6 FaDREB1 unigenes were identified from publicly available transcriptomic data. Expression profiles showed that freezing tolerant cultivar only activated specific FaDREB1 unigenes, while freezing intolerant cultivar activated all six FaDREB1s during cold acclimation period. These findings indicated that cold stress modulated diverse physiological process in different tall fescue cultivars and activated various gene networks through regulating different subsets of FaDREB1s.

Bazı Kamışsı Yumak Çeşitlerinin Serin İklim Ekolojik Koşullarında Yeşil Alan Performanslarının Belirlenmesi

This study was conducted to determine the turfgrass performance of newly introduced tall fescue ( Festuca arundinacea Schreb.) cultivars in the ecological conditions of the cool climate. The experiment was carried out in the Plant Cultivation garden of the Parks and Gardens Directorate of Tokat Municipality for 3 years between May 2009 - January 2012. Six different tall fescue cultivars (Apache, Eldorado, Firaces, Merida, SR8600 and Turbo) were used. In the study; turf cover ratio, weed invasion density, turf color, winter endurance and turf quality characteristics were measured with scores between 1-9 point, and turf texture was measured in mm. Study results showed that the highest values were obtained from the Merida and Turbo cultivars and that, generally speaking, the other cultivars could easily be used in turf establishment in the region and in similar ecological conditions.

The effect of grass endophytes on earthworms and slugs under a turf mowing regime

Earthworms are not a direct pest of turf grass but they are considered a problem on many sports fields, disrupting playability and aesthetics due to the castings they deposit on the playing surface. Also, a number of slug species are well-known foliage destroying pests of a number of agriculturally important crop species. Perennial ryegrass and tall fescue cultivars associated with selected Epichloë endophytes, originally developed for bird management at airports, were assessed to determine their deterrent properties towards worms and slugs. Plots sown with endophyte-free ryegrass had significantly higher numbers of worms and slugs than plots containing the same grass cultivar infected with the endophyte strain AR95. Also, plots sown with endophyte-free tall fescue had significantly higher numbers of slugs (but not worms) than plots containing the same grass cultivar infected with the endophyte strain AR601. Although more research is required on the exact mechanism of action, these results suggest selected novel endophyte-infected grass associations, such as those including the endophyte AR95, may substantially reduce populations of worms and slugs in areas where these grasses are sown.

Assessment of semen quality and fertility in young growing beef bulls exposed to ergot alkaloids

The objective of this study was to evaluate semen quality and fertility in beef bulls grazing the ergot alkaloid (EA) producing tall fescue cultivar, Kentucky 31 (KY31), compared to a novel endophyte (NE) cultivar lacking EA. Two studies were conducted over a 3-year period. In studies 1 (n = 10; ages ≥ 24 mo) and 2 (n = 53 over two years; ages 12–16 mo), Angus (AN) bulls were stratified by body weight (BW), body condition score (BCS), and scrotal circumference (SC), and then allotted to graze either KY31 or NE for 56 days. Semen samples were collected, and BW, BCS, and SC were evaluated at the start of treatment (TRT) on day (d) 0 and every 28 days to the end of each study. In addition, blood samples were collected on d 0 and every 28 days for assessment of circulating prolactin (PRL) levels in study 2. On d 56, for both studies, semen from bulls (n = 2 per treatment in study 1 and n = 4 per treatment in study 2) with similar and acceptable quality were extended, kept at 19° C, and used for timed artificial insemination (TAI) of primi- and multiparous AN and AN- crossbred females. Pregnancy was evaluated at 35 and 90 days post-TAI via transrectal ultrasonography to determine pregnancy rates. Serum PRL concentrations showed a TRT by d effect (P ≤ 0.05), with values for bulls grazing KY31 decreased on d 28 and d 56 of grazing compared to NE. In studies 1 and 2, bull BW and BCS were affected by d (P ≤ 0.05), but not by TRT. No TRT or TRT by d effect on semen quality was observed in either study; however, d impacted both velocity and concentration in study 2 (P ≤ 0.05). In study 1, TAI pregnancy rates at 35 days post-TAI were lower (P ≤ 0.05) in the group inseminated with semen from bulls grazing KY31; however, in study 2, pregnancy rates did not differ due to treatment 35 post-TAI (P > 0.05). Grazing KY31 negatively impacted serum PRL concentrations, supporting previous observations; however, consumption of KY31 had no effect on growth or semen quality of AN bulls ranging from 12 to ≥24 mo of age. Furthermore, fertility data is inconsistent between studies and requires further investigation.

Determining of Some Quantitative Characteristics of Certain Tall Fescue Cultivars in Cool Season Ecological Conditions

Bu arastirma, yeni uretilen bazi kamissi yumak ( Festuca arundinacea Schreb.) cesitlerinin serin iklim ekolojik kosullarinda bazi kantitatif ozelliklerinin belirlenmesi amaciyla, alti farkli kamissi yumak cesidi (Firaces, Merida, Turbo, Apache, Eldorado ve SR8600) ile Mart 2009 - Ocak 2012 tarihleri arasinda 3 yil sureyle Tokat’ta yurutulmustur. Calismada; surgun sayisi (adet/dm ² ), yesil kutle verimi (g/m²), kuru madde orani (%), kuru madde verimi (g/m ² ), kok kutlesi verimi (g/m ² ) ve kisa dayaniklilik (1-9 puan) ozellikleri incelenmistir. Deneme Tesaduf Bloklari Deneme Deseni’ne gore dort tekrarlamali olarak kurulmustur. Istatistiksel analizler; cesit, yil ve cesit × yil etkilesimlere gore degerlendirilmistir. Arastirma sonunda en yuksek rakamsal veriler Merida ve Turbo cesitlerinden elde edilmis ancak diger cesitlerin de genel anlamda bolgenin ekolojik kosullarina uygun oldugu ve cim alan tesisinde kullanilabilecegi sonucuna varilmistir.

Response of Tall Fescue and Kentucky Bluegrass Mixtures to Wear

Tall fescue (TF) [Schedonorus arundinaceus (Schreb.) Dumort.] and Kentucky bluegrass (KBG) Poa pratensis L.) are often seeded as mixtures in temperate and transition climates. This study assessed the performance and species composition of TF and KBG mixtures containing newer cultivars that were subjected to wear. Individual plots of TF cultivars were established in 2010 on a loam along with 16 mixtures of TF and KBG (TF 90/KBG 10; w/w). Wear was applied during autumn 2011, 2012, and 2013. Plots were evaluated for turfgrass quality, brown patch disease (caused by Rhizoctonia solani), and species composition. Data were analyzed using a 5 × 4 × 2 factorial of KBG (none, ‘Midnight II’, ‘Blue Note’, A05–361, A05–361), TF (‘Falcon V’, ‘Mustang 4’, ‘Justice’, ‘Greenkeeper’), and wear (no wear and wear) arranged in a strip plot design with three replications. Wear reduced quality but had no effect on species composition. Mixing KBG with Falcon V or Mustang 4 TF had no effect on quality after wear compared with either TF alone; however, the quality of Greenkeeper TF was better when mixed with Midnight II or Blue Note KBG, whereas mixing with A05–361 and A05–344 KBG had no effect on quality. Kentucky bluegrass selection had a much greater influence on species composition compared with TF selection. Tall fescue composition was influenced by KBG cultivar and ranged from 37 to 79%. Brown patch severity was decreased in TF mixtures with KBG and was more strongly influenced by KBG cultivar than TF cultivar. Our data indicate that KBG cultivars can dramatically affect TF composition of mixes and brown patch severity, whereas autumn wear does not.

483 Vasoconstrictive responses of the carotid artery in pregnant ewes to ergot alkaloid exposure

Color Doppler ultrasonography was used to assess ergot alkaloid-induced vasoconstriction in pregnant ewes (Ovis aries) that were fed diets with or without toxic endophyte-infected seed of tall fescue (Lolium arundinaceum). A fungal endophyte (Epicloë coenophialia)that infects most plants of the standard cultivar of tall fescue, ‘Kentucky 31,’ produces ergot alkaloids that can cause a persistent constriction of blood flow in grazing ruminants, which incapacitates the animal's ability to thermo-regulate core body temperature. Suffolk ewes were stratified by BCS for random assignment to four treatment groups (n = 15/treatment). Either endophyte-free (E-) or endophyte-infected (E+) tall fescue seed were fed in similar diet concentrations such that the daily consumption of ergovaline and ergovalanine for E+ was 1,772 µg/ewe/d mixed in a TMR (corn, soybean meal, and cottonseed hulls). The ewes were fed the TMR without seed for the first 35 d. On day 35, ewes were fed endophyte-free (E-) or endophyte-infected (E+) seed, and on day 86, half of each group was switched to the opposite treatment (E-E+ or E+E-) and half remained on the same treatment (E-E- or E+E+ ) to parturition. Ultrasound imaging of left carotid artery was done at the start of lambing and the range in days on fed seed ranged from 50 to 106 days. Color Doppler ultrasonography was performed using a Classic Medical TeraVet 3000 Ultrasound Unit (Classic Universal Ultrasound, Tequesta, FL) with a 12L5-VET (12 MHz) linear array transducer. Cross-sectional area of the left carotid artery was measured for each ewe to determine luminal area, and a Power Doppler image was collected for measuring peak systolic and end diastolic velocities, heart rate, and pulsatility and resistance indices. Luminal areas were similar (P > 0.5) between E-E- (28.8 ± 1.98 mm2) and E+E- (30 ± 1/85 mm2) treatments, and between E+E+ (17.0 ± 2.06 mm2) and E-E+ (17.5 ± 2.06 mm2). Carotid arteries with E-E- and E+E- treatments were relaxed (P < 0.001) in comparison to those with the E+E+ and E-E+ treatments. Although there were no treatment effects (P > 0.10) on peak systolic and end diastolic velocities or heart rate, pulsatility and resistance indices were greater (P < 0.05) for E+E+ and E-E+ than for E-E- and E+E- treatments. Results indicated a vasoconstrictive response of the carotid arteries in pregnant ewes exposed to ergot alkaloids, but vascular recovery was demonstrated for sheep that had been switched from E+ to E- diets.

Relative tolerance to aluminium and manganese toxicities of Phalaris, cocksfoot, and tall fescue genotypes developed for low rainfall environments

ABSTRACTNew breeding lines of Phalaris (Phalaris aquatica), cocksfoot (Dactylis glomerata) and tall fescue (Festuca arundinacea = syn. Lolium arundinaceum) are currently under evaluation for the selection of new cultivars for low rainfall environments. The aim was to test the relative tolerance of six elite genotypes of Phalaris, cocksfoot and tall fescue to aluminium and manganese toxicities in solution culture. Two solution culture experiments were conducted at aluminium concentrations of 0, 50, 100, 200 and 300 µM, or manganese (Mn) concentrations of 0, 2, 4, 6 and 8 mM in a basal nutrient solution at pH 4.5. Elite genotypes of cocksfoot, AVH48 Selection and Moroccan Fine, exist with improved tolerance to aluminium and Mn toxicities. Elite genotypes of Phalaris, particularly Northern Retainer, were superior to Sirolan at moderate to high aluminium concentrations in solution. There was little difference in the tolerance to aluminium and manganese toxicities between the elite genotypes and existing cultivars of tall fescue.

Forage grasses with lower uptake of caesium and strontium could provide 'safer' crops for radiologically contaminated areas.

Substitution of a species or cultivar with higher uptake of an element by one with lower uptake has been proposed as a remediation strategy following accidental releases of radioactivity. However, despite the importance of pasture systems for radiological dose, species/cultivar substitution has not been thoroughly investigated for forage grasses. 397 cultivars from four forage grass species; hybrid ryegrass (Lolium perenne L. x Lolium multiflorum Lam.), perennial ryegrass (Lolium perenne L.), Italian ryegrass (Lolium multiflorum Lam.) and tall fescue (Festuca arundinacea Shreb.); were sampled from 19 field-based breeding experiments in Aberystwyth and Edinburgh (UK) in spring 2013 and analysed for caesium (Cs) and strontium (Sr) concentrations. In order to calculate concentration ratios (CRs; the concentration of an element in a plant in relation to the concentration in the soil), soils from the experiments were also analysed to calculate extractable concentrations of Cs and Sr. To test if cultivars have consistently low Cs and Sr concentration ratios, 17 hybrid ryegrass cultivars were sampled from both sites again in summer 2013 and spring and summer 2014. Tall fescue cultivars had lower Cs and Sr CRs than the other species. Three of the selected 17 hybrid ryegrass cultivars had consistently low Cs CRs, two had consistently low Sr CRs and one had consistently low Cs and Sr CRs. Cultivar substitution could reduce Cs CRs by up to 14-fold and Sr CRs by 4-fold in hybrid ryegrass. The identification of species and cultivars with consistently low CRs suggests that species or cultivar substitution could be an effective remediation strategy for contaminated areas.

Transcriptome profilings of two tall fescue (Festuca arundinacea) cultivars in response to lead (Pb) stress

BackgroundLead (Pb) is one of the most toxic heavy metal environmental pollutants. Tall fescue is an important cold season turf grass which can tolerate and accumulate substantial amount of Pb. To estimate genes related to Pb response and the molecular mechanism associated with Pb tolerance and accumulation, we analyzed the transcriptome of tall fescue in response to Pb treatment.ResultsRNA-sequencing was performed in two tall fescue cultivars, Pb tolerant Silverado and Pb sensitive AST7001. A total of 810,146 assembled unique transcripts representing 25,415 unigenes were obtained from the tall fescue leaves. Among the panel, 3,696 differentially expressed genes (DEGs) were detected between the Pb treated (1000 mg/L) and untreated samples. Gene ontology (GO) and pathway enrichment analysis demonstrated that the DEGs were mainly implicated in energy metabolism, metabolism of terpenoids and polyketides, and carbohydrate metabolism related pathways. The expression patterns of 16 randomly selected genes were in consistent with that from the Solexa analysis using quantitative reverse-transcription PCR. In addition, compared to the common transcriptional response to Pb stress in both cultivars, the regulation of numerous genes including those involved in zeatin biosynthesis, limonene and pinene degradation, phagosome was exclusive to one cultivar.ConclusionsThe tall fescue assembled transcriptome provided substantial molecular resources for further genomics analysis of turfgrass in response to heavy metal stress. The significant expression difference of specific unigenes may account for Pb tolerance or accumulation in two different tall fescue cultivars. This study provided new insights for the investigation of the molecular basis of Pb tolerance and accumulation in tall fescue as well as other related turf grass species.

Productivity in simulated drought and post-drought recovery of eight ryegrass cultivars and a tall fescue cultivar with and without Epichloë endophyte

Many ryegrass cultivars are available on the market, but little research information exists on their comparative drought tolerance or the role of their commercially associated Epichloë endophytes in drought tolerance. Cloned plants of seven perennial ryegrass (Lolium perenne L.) cultivars (Grasslands Commando, Ceres One50, Banquet II, Alto, Bealey, Trojan and Avalon) and an unreleased elite line (URL) and one Mediterranean tall fescue (Festuca arundinacea Schreb.) cultivar (Grasslands Flecha), in all cases both endophyte-free (E–) and -infected (E+) plants, were subjected to a cycle of summer drought and rehydration from December 2012 to May 2013. Other clones of the same plants were irrigated. Insecticide was used to protect plants from insect attack. We report data for shoot dry matter (DM), tiller survival rate (TSR) and reproductive development assessed approximately monthly during the experiment. In the second month of drought, only Banquet II and Grasslands Flecha showed no significant shoot DM reduction under water deficit. After 3 months of drought, shoot DM was reduced by 43% (Flecha) to 85% (URL) compared with irrigated plants. For Banquet II, Avalon and Grasslands Flecha, TSR was not significantly reduced by water deficit. During rehydration, growth of previously non-irrigated plants typically exceeded growth of irrigated clones across all cultivars. Banquet II and Grasslands Flecha were drought-tolerant in the sense that they showed a lower percentage yield reduction under drought than other cultivars tested; this was in part because they were not among the highest yielding under irrigation. Irrespective of irrigation treatment, the shoot DM of E+ plants of ryegrasses URL (with AR37 endophyte) and One50 (with AR1 endophyte) was reduced by almost 50% relative to their E– counterparts in each harvest from December to May, whereas the other six ryegrass varieties generally showed a small trend towards reduced shoot DM as E+ plants. This indicates that some novel cultivar–endophyte associations can incur a yield disadvantage compared with E– plants when protected from insect pressure.

Assessment of germination and endophyte viability in perennial ryegrass and tall fescue seeds following accelerated ageing treatment

Temperate pasture grasses form symbiotic associations with asexual fungal endophytes of the genus Epichloe. Viabilities of both seed and endophyte were assessed in cultivars of perennial ryegrass and tall fescue following different accelerated ageing (AA) treatments based on variations of relative humidity (RH) (80-100%) and duration at elevated temperature (42 degrees C), to identify particularly stable and compatible host-endophyte associations. The cultivars were inoculated with three endophytes (NEA10, NEA11 and NEA12) isolated from perennial ryegrass and belonging to distinct taxa (E. festucae var. lolii, LpTG-2 and LpTG-3, respectively), and two endophytes isolated from tall fescue (belonging to the taxon E. coenophiala). Consistent with previous studies, endophyte viability following AA treatment was inversely correlated with both increasing RH and duration of treatment in both species. Significant interaction effects between cultivar variety, endophyte genotype, humidity level and treatment duration were observed for both seed germination and endophyte viability. NEA12 consistently displayed higher viability following AA treatment than NEA10 and NEA1 1 in each of the perennial ryegrass cultivars. Stable host-endophyte combinations were observed for 'Alto'-NEA10, 'Bealey'-NEAll and 'Trojan'-NEA12, 'Bronsyn' being the least compatible host population. The applicability of AA for selecting stable host-endophyte associations, or to identify and eliminate unstable associations, is discussed.

Agronomic and molecular evaluation of cocksfoot and tall fescue cultivars for adaptation to an Algerian drought-prone environment

A prime objective for improving perennial grasses for Mediterranean environments is the identification and selection of genotypes well adapted to semi-arid conditions. This study was conducted at an experimental site in Algeria over three consecutive seasons, with the aim of evaluating the agronomic performance and genetic diversity of 13 cultivars of two species of perennial grasses: six cocksfoot (Dactylis glomerata L.) and seven tall fescue (Festuca arundinacea Schreb. = syn.Lolium arundinaceum (Schreb.) Darbysh.) cultivars. Variation was found in both species for dry-matter yield, sward recovery, heading date, water-use efficiency (WUE), and summer senescence. Tall fescue cultivars gave greater yield in spring, with earlier heading date and higher WUE than cocksfoot, with no differences for the other traits. Among the genotypes, ‘Flecha’ was the most promising, together with ‘E-542’, ‘Fraydo’ and ‘Centurion’, all of which are tall fescue cultivars. Principal component analysis indicated that persistence of grass cover is relatively independent from dry-matter yield and water-use efficiency. The level of genetic diversity within each species was assessed using AFLP markers, and the molecular variation was analysed together with agronomic trait variation, with identification of molecular markers potentially associated with the relevant traits.

Insight into the genetic variability analysis and cultivar identification of tall fescue by using SSR markers.

BackgroundGenetic diversity of 19 forage-type and 2 turf-type cultivars of tall fescue (Festuca arundinacea Schreb.) was revealed using SSR markers in an attempt to explore the genetic relationships among them, and examine potential use of SSR markers to identify cultivars by bulked samples.ResultsA total of 227 clear band was scored with 14 SSR primers and out of which 201 (88.6 %) were found polymorphic. The percentage of polymorphic bands (PPB) per primer pair varied from 62.5 to 100 % with an average of 86.9 %. The polymorphism information content (PIC) value ranged from 0.116 to 0.347 with an average of 0.257 and the highest PIC value (0.347) was noticed for primer NFA040 followed by NFA113 (0.346) whereas the highest discriminating power (D) of 1 was shown in NFA037 and LMgSSR02-01C. A Neighbor-joining dendrogram and the principal component analysis identified six major clusters and grouped the cultivars in agreement with their breeding histories. STRUCTURE analysis divided these cultivars into 3 sub-clades which correspond to distance based groupings.ConclusionThese findings indicates that SSR markers by bulking strategy are a useful tool to measure genetic diversity among tall fescue cultivars and could be used to supplement morphological data for plant variety protection.

Fungal endophyte and tall fescue cultivar interact to differentially affect bulk and rhizosphere soil processes governing C and N cycling

Tall fescue (Lolium arundinaceum (Schreb.)) is a cool-season perennial grass within which can live a fungal endophyte (Epichloë coenophiala) thought to provide enhanced edaphic and climactic stress tolerance to the host compared to non-infected individuals. Our prior research demonstrated that a variety of root exudate compounds released from tall fescue were differentially affected by tall fescue cultivar, endophyte genotype and their interaction. Changes in root exudates and associated microbial communities could influence soil processes, including carbon and nitrogen cycling, but these effects may differ depending on fescue and endophyte genetics. To test this, we collected rhizosphere and bulk soil samples from six year old field plots located in Lexington, KY planted with two different tall fescue cultivars (PDF and 97TF1), each containing four endophyte treatments [endophyte-free (E−) or infected with one of three strains of E. coenophiala (common toxic, novel AR542E+ and novel AR584E+)]. The influence of fescue cultivar, endophyte strain, and soil sample location (rhizosphere vs. bulk) were assessed for soil organic carbon, soil organic nitrogen, particulate and non-particulate organic matter (POM and n-POM, respectively) - C and – N, and dissolved organic carbon and nitrogen (DOC, DON) pools. Soil functional aspects were evaluated by measuring soil respiration and the activity of seven different soil enzymes related to C, N and P cycling. We found that rhizosphere soils had greater microbial biomass, potential enzyme activity, and oxygen utilization, but lesser POM-N concentrations than bulk soils. In rhizosphere soils, tall fescue cultivar had the greatest influence on soil microbial community structure, while endophyte genotype had a stronger influence on soil C fractions (notably POM-C). Changes in root system architecture, biomass, and tissue composition, together with root exudate chemistry, which we have shown in previous studies to be affected by endophyte infection and fescue cultivar, likely explain these findings. There was greater POM-N in bulk soils which was influenced by the interaction of endophyte and cultivar potentially due to differences in the chemical composition of the tissues brought about by this interaction. Our results support current observations that tall fescue cultivar and fungal endophyte strain influence soil C and N cycling and, by analyzing bulk and rhizosphere soils separately, go further to show the level of influence cultivar and endophyte have within each of these compartments.

Gibberellin-Regulation and Genetic Variations in Leaf Elongation for Tall Fescue in Association with Differential Gene Expression Controlling Cell Expansion.

Leaf elongation rate (LER) is an important factor controlling plant growth and productivity. The objective of this study was to determine whether genetic variation in LER for a fast-growing (‘K-31’), and a dwarf cultivar (‘Bonsai’) of tall fescue (Festuca arundinacea) and gibberellic acid (GA) regulation of LER were associated with differential expression of cell-expansion genes. Plants were treated with GA3, trinexapac-ethyl (TE) (GA inhibitor), or water (untreated control) in a hydroponic system. LER of ‘K-31’ was 63% greater than that of ‘Bonsai’, which corresponded with 32% higher endogenous GA4 content in leaf and greater cell elongation and production rates under the untreated control condition. Exogenous application of GA3 significantly enhanced LER while TE treatment inhibited leaf elongation due to GA3-stimulation or TE-inhibition of cell elongation and production rate in leaves for both cultivars. Real-time quantitative polymerase chain reaction analysis revealed that three α-expansins, one β-expansin, and three xyloglucan endotransglycosylase (XET) genes were associated with GA-stimulation of leaf elongation, of which, the differential expression of EXPA4 and EXPA7 was related to the genotypic variation in LER of two cultivars. Those differentially-expressed expansin and XET genes could play major roles in genetic variation and GA-regulated leaf elongation in tall fescue.

Plant drought survival under climate change and strategies to improve perennial grasses. A review

The three cool-season perennial forage grasses cocksfoot/orchardgrass, Dactylis glomerata L., tall fescue, Festuca arundinacea Schreb. syn. Lolium arundinaceum (Schreb.) Darbysh., and phalaris/harding grass, Phalaris aquatica L., are of major economic and ecological importance in regions with summer-dry environments. This review considers the constraints that these species are likely to experience under current and predicted increase of droughts due to climate change scenarios in south-eastern Australia, the southern Great Plains of USA and the Western Mediterranean Basin. The review identifies research required to maximise the development and use of C3 cool-season grasses with enhanced resilience to drought while considering the concern of some regulators that these grasses may be potential weeds. The state of knowledge of factors influencing plant drought survival and therefore recovery after stress and long-term persistence is discussed in the light of adaptive strategies. The major research needs identified to enhance traits conferring drought survival include (1) increasing the depth and density of grass root systems to strengthen dehydration avoidance; (2) exploring the biochemical, molecular and hydraulic bases of dehydration tolerance and improving techniques to measure this trait; (3) breaking the trade-off between summer dormancy and forage yield potential and improving understanding of environmental, biochemical and genetic controls over summer dormancy; (4) identifying non-toxic endophyte strains compatible with summer-dormant cultivars of tall fescue to enhance drought survival; and (5) enhancing seed production capability of new cultivars as well as the development of agronomic management packages for promoting stable mixtures combining perennial grasses and legumes. The weed potential of newly introduced summer-dormant cultivars is concluded to be minor. The research directions proposed here should improve pasture grass resilience and forage crop sustainability in Mediterranean and temperate summer-dry environments under the future drier and warmer conditions associated with climate change.