Cool-season Grasses Research Articles

162 Nutritive value and dry matter yield of stockpiled tall fescue across plant hardiness zones 7 and 8

Abstract Pastures in Tennessee comprise mainly tall fescue [Schedonorus arundinaceus (Schreb.) Dumort.], a cool-season perennial grass. Given that producers in Tennessee feed hay for an average of 143 d per year, there is interest in utilizing the practice of stockpiling to extend the grazing season. Although this practice has been proven to reduce hay needs (Freeman et al., 2019), it is vital to maintain up-to-date recommendations using data from across the southeastern US to inform grazing decisions. The objective of this study was to determine the nutritive value and dry matter yield of stockpiled tall fescue across plant hardiness zones 7 and 8. Fourteen farms across Tennessee and Alabama were identified as sampling sites. In September 2021, three exclusion cages (1.3 m × 1.3 m) were constructed at each site, forage was clipped to a 5-cm height, and plots were fertilized at a rate of 67 kg N/ha. During years 2021-2022 and 2022-2023, samples were clipped at a 5-cm height from a 0.1-m2 quadrat monthly from October through February. Samples were collected from a different location within the plot each month to ensure there was no overlap. Samples were dried and weighed to determine dry matter yield and then ground for NIRS analysis to determine nutritive value. Data were analyzed using PROC GLIMMIX for a completely randomized design. Independent variables were stockpile period length and plant hardiness zone. Results indicate that plant hardiness zone did not have a significant effect on forage yield (P = 0.2098). Dry matter yield increased over the length of the stockpiling period (P < 0.0001) from 2,637 to 4,922 kg DM/ha. Crude protein (CP) and total digestible nutrients (TDN) concentrations decreased (P < 0.0001 and P = 0.0358, respectively) throughout the stockpiling period; however, ranges were still within those needed to support the nutritional needs of a lactating cow with CP ranging from 15 to 17% and TDN ranging from 68 to 70%. As expected, neutral detergent fiber (NDF) and acid detergent fiber (ADF) concentrations increased over the stockpiling period (P = 0.0029 and P = 0.0145, respectively) as plants matures. There were no significant changes in ash and fat concentrations due to stockpiling length. Results from this study conclude that stockpiled tall fescue in plant hardiness zones 7 and 8 can support the nutritional requirements of mature cows at all stages of production through the winter months. Results will be used to inform Extension recommendations to assist producers in making management decisions that increase grazing days and reduce supplemental feed input costs.

163 Growth trends in Bos grunniens raised in pasture-based systems in Eastern Kentucky

Abstract Bos grunniens (yak) are well-adapted to the rugged, high-altitude regions of central Asia where they are utilized for a variety of purposes. While the species is well-researched in its native land, limited research has been conducted in North America. The objective of this on-farm project was to evaluate performance of male and female growing yaks in pasture-based systems over two years. Grazing periods were 138 and 151 d for Yr 1 and Yr 2, respectively. The same plots were grazed both years, and pasture areas were approximately 0.49 ha each with three animals grazing each pasture in Yr 1 and two animals grazing each pasture in Yr 2. Pastures were comprised mostly of cool-season grasses with intermittent legumes and weeds. Yaks were assigned to one of four pastures based on sex with a total of six males (beginning weight 132.8 ± 13.5 kg) and six females (beginning weight 124.3 ± 34.4 kg) being grazed in Yr 1, and four males (beginning weight 157.3 ± 15.0 kg) and four females (beginning weight 160.9 ± 26.4 kg) being grazed in Yr 2. Animals in Yr 1 averaged 432 d of age, and animals in Yr 2 averaged 710 d of age at the start of the respective grazing periods. Pasture samples were collected throughout the study to assess nutritive value; botanical composition, presence of endophyte and concentration of ergovaline were also assessed. Tall fescue (Festuca arundinacea) samples collected at the end of the grazing period in Yr 2 averaged 32.65% infection and 146 ppb ergovaline. Data were analyzed using proc mixed procedure of SAS with sex and year as main effects and pasture as a random effect where α = 0.05. In Yr 1, males gained at a greater rate than females (0.45 kg/d vs. 0.23 kg/d; P = 0.0026). In Yr 2, a similar difference was observed for seasonal gains with males gaining 0.61 kg/d and females gaining 0.25 kg/d (P = 0.0003). A difference was also observed between growth rates of males in Yr 1 compared with males in Yr 2 (0.45 kg/d vs. 0.61 kg/d; P = 0.0024), but this difference was not observed in females. Gender can impact body weight gain in Bos grunniens raised in pasture-based systems with males gaining more rapidly than females.

126 Effects of Tall Fescue Seeds and Quercetin on the Meat Quality of Finishing Lambs

Abstract Tall fescue is a major cool-season grass for grazing livestock in North America. However, it is typically infected with endophyte fungus, and the intake of the infected tall fescue was toxic to ruminant animals. Quercetin is one of the natural flavonoids that could increase the anti-inflammatory and antioxidant capacity of an animal. This experiment aims to investigate the effects of infected tall fescue seeds on the carcass characteristics and meat quality of finishing lambs, and also to determine the mitigation effect of quercetin on the toxicity of tall fescue seeds. A total number of 24 lambs were randomly assigned to four groups: 1) Control group (C, n = 6), tall fescue seed group (E+Q-, n = 6, feed with tall fescue seed infected with alkaloid endophyte), tall fescue seed, and quercetin group (E+Q+, n = 6, feed with tall fescue seed infected with alkaloid endophyte), and quercetin group (E-Q+, n = 6, feed with quercetin). All the groups were fed ad libitum for 42 d. The longissimus dorsi muscle of each lamb was collected to analyze the meat quality parameters. The results show that the tall fescue seed decreased the final body weight and the hot carcass weight of finishing lambs (P < 0.05). Intake of tall fescue seed with quercetin increased the meat color parameters (L*, a*, b*, C, and h) significantly (P < 0.05). The tall fescue decreased the intramuscular fat content in the longissimus dorsi muscle and also modulated the fatty acids composition (P < 0.05). In conclusion, infected tall fescue negatively affected the carcass characteristics and intramuscular fat deposition of finishing lambs. However, the quercetin didn’t mitigate the influence of tall fescue seeds on carcass characteristics but increased the meat color characteristics.

Chromosome-scale genome assembly of Poa trivialis and population genomics reveal widespread gene flow in a cool-season grass seed production system.

Poa trivialis (L.) is a cool-season grass species found in various environments worldwide. In addition to being a desired turfgrass species, it is a common weed of agricultural systems and natural areas. As a weed, it is an important contaminant of commercial cool-season grass seed lots, resulting in widespread gene flow facilitated by human activities and causing significant economic losses to farmers. To better understand and manage infestations, we assembled and annotated a haploid genome of P. trivialis and studied troublesome field populations from Oregon, the largest cool-season grass seed producing region in the United States. The genome assembly resulted in 1.35 Gb of DNA sequence distributed among seven chromosome-scale scaffolds, revealing a high content of transposable elements, conserved synteny with Poa annua, and a close relationship with other C3 grasses. A reduced-representation sequencing analysis of field populations revealed limited genetic diversity and suggested potential gene flow and human-assisted dispersal in the region. The genetic resources and insights into P. trivialis provided by this study will improve weed management strategies and enable the development of molecular detection tests for contaminated seed lots to limit seed-mediated gene flow. These resources should also be beneficial for turfgrass breeders seeking to improve desirable traits of commercial P. trivialis varieties and help to guide breeding efforts in other crops to enhance the resiliency of agricultural ecosystems under climate change. Significance Statement: The chromosome-scale assembly of Poa trivialis and population genomic analyses provide crucial insights into the gene flow of weedy populations in agricultural systems and contribute a valuable genomic resource for the plant science community.

Plant-parasitic Nematodes Associated with Grasses Grown for Seed in the Willamette Valley of Oregon.

Plant-parasitic nematodes (PPN) are an understudied pathogen group in the Oregon cool-season grass seed cropping system. In this survey, the PPN associated with annual ryegrass, bentgrass, fine fescue, orchardgrass, perennial ryegrass, and tall fescue were determined. Thirty-seven fields were sampled in the 2022 or 2023 growing season by collecting 10 soil cores in each of six 100-m transects for nematode extraction and visual identification. PerMANOVA testing indicated significant differences in PPN community composition across grass host and sampling time. Pratylenchus and Meloidogyne were the most commonly encountered nematodes, with maximum population densities of 1,984 and 2,496 nematodes/100 g soil, respectively. Sequencing of the COX1 gene region indicated the presence of P. crenatus, P. fallax, P. neglectus, P. penetrans, and P. thornei, with some of these species being detected for the first time on these grass hosts. The only Meloidogyne sp. found in these grasses was M. nassi, based upon sequencing of the ITS gene region. This first-of-its-kind survey indicates the need for further assessment of the impact of these PPNs on yield and stand longevity in cool-season grass seed fields in Oregon.

Effects of combined extreme cold and drought stress on growth, photosynthesis, and physiological characteristics of cool-season grasses

Abiotic stress is an important factor affecting turf establishment and limiting the sustainability of the turf industry. To alleviate the effects of combined cold and drought stress in cold- and drought-prone regions, it is essential to select and introduce turfgrass germplasms that are suitable for these conditions for successful turf establishment. Thus, we evaluated the effects of combined extreme cold and drought stress on the morphological, plant leaf functional, photosynthetic, and physiological and biochemical traits of 16 wild annual bluegrass (Poa annua) germplasms. We found that there were significant differences (P < 0.05) among different provenances, combined cold and drought stress, and the main interaction factors. Combined cold and drought stress altered the morphological characteristics of the 16 germplasms to varying degrees. Furthermore, combined cold and drought stress significantly reduced the net photosynthetic rate (Pn), stomatal conductance (gs), transpiration rate (Tr), instantaneous water use efficiency (WUE), chlorophyll content, chlorophyll fluorescence parameters, accumulated intercellular CO2 concentration (Ci), and relative electrical conductivity (REC) and malondialdehyde (MDA), proline (Pro), soluble protein (SP), soluble sugar (SS), superoxide anion (O2.-), hydrogen peroxide (H2O2), and hydroxyl radical (·OH) and other active oxygen, and increased the superoxide dismutase activity (SOD), peroxidase activity (POD), catalase activity (CAT), ascorbate peroxidase activity (APX) and glutathione reductase (GR) activities. Comprehensive evaluation using principal component analysis (PCA), membership function analysis, and clustered heatmaps indicated that the ‘HZ’ germplasm had stronger combined cold and drought tolerance, whereas the ‘ZQ’ germplasm was more sensitive to combined cold and drought, which was roughly consistent with the order of morphological damage symptoms. Therefore, it is recommended to use the ‘HZ’ germplasm for planting projects in cold- and drought-prone areas, while the ‘ZQ’ germplasm is more suitable for use under warmer and non-water-deficient conditions.

Response to Waterlogging Stress in Wild and Domesticated Accessions of Timothy (Phleum pratense) and Its Relatives P. alpinum and P. nodosum

Timothy (Phleum pratense) is a cool-season perennial forage grass widely grown for silage and hay production in northern regions. Climate change scenarios predict an increase in extreme weather events with fluctuating periods of high rainfall, requiring new varieties adapted to waterlogging (WL). Wild accessions could serve as germplasm for breeding, and we evaluated the responses of 11 wild and 8 domesticated accessions of timothy, P. nodosum and P. alpinum from different locations in northern Europe. Young plants at tillering stage were exposed to WL for 21 days in a greenhouse, and responses in growth allocation and root anatomy were studied. All accessions produced adventitious roots and changed allocation of growth between shoot and root as a response to WL, but the magnitude of these responses varied among species and among accessions. P. pratense responded less in these traits in response to WL than the other two species. The ability to form aerenchyma in the root cortex in response to WL was found for all species and also varied among species and among accessions, with the highest induction in P. pratense. Interestingly, some accessions were able to maintain and even increase root growth, producing more leaves and tillers, while others showed a reduction in the root system. Shoot dry weight (SDW) was not significantly affected by WL, but some accessions showed different and significant responses in the rate of production of leaves and tillers. Overall correlations between SDW and aerenchyma and between SDW and adventitious root formation were found. This study identified two wild timothy accessions and one wild P. nodosum accession based on shoot and root system growth, aerenchyma formation and having a root anatomy considered to be favorable for WL tolerance. These accessions are interesting genetic resources and candidates for development of climate-resilient timothy varieties.

Paleobiology of Pleistocene large land mammals from the Brazilian Pampa

The southern Brazilian Pleistocene fauna exhibited a rich diversity of large mammalian herbivores, which are now extinct or locally extinct. In this study, we employed stable isotope analysis to investigate the past ecology of these animals. Specifically, we examined the carbonate fraction of bones and teeth and utilized compiled carbon and oxygen isotopic ratios from previous research publications. The δ13C values indicated that most specimens inhabited grassland environments, which aligns with environmental reconstructions based on pollen records of the “Campos” region. The dominant food resource for these herbivores consisted of C3 photosynthesizers, mainly cool-season grasses. This preference can be attributed to the higher abundance and nutritional quality of cool-season grasses compared with warm-season grasses employing C4 photosynthesis. The variability in δ18O values within and between taxa may suggest a seasonal climate. Based on these findings, we conclude that the environmental changes during the Pleistocene-Holocene transition were detrimental to the survival of these large herbivores.

Fructan Catabolism by Rumen Microbiota of Cattle and Sheep

Fructans serve as the primary form of storage carbohydrate in cool-season grasses, but little is known about potential differences in ruminal fermentation of fructans between cattle and sheep. An ex vivo study was conducted to evaluate species differences in fructan catabolism. Buffered media containing ground orchardgrass (Dactylis glomerata L.) substrate was inoculated with uncultivated rumen microbiota obtained from cattle and sheep (n = 4 species−1). Fructan profiles were monitored over the incubation period (8 h; 39 °C) using high-performance anion-exchange chromatography coupled to pulsed amperometric detection (HPAEC-PAD). In both species, disappearance of long-chain fructans (degree of polymerization [DP] &gt; 8) was evident by 2 h of incubation (p &lt; 0.01), whereas short-chain fructans (DP 4–8) increased from 0 to 2 h prior to subsequent degradation (p &lt; 0.01). However, the overall rate of long-chain fructan catabolism was greater in bovine versus ovine fermentations, particularly between 2 and 4 h (p &lt; 0.01). Additionally, rapid utilization of short-chain fructans occurred from 2 to 4 h in bovine fermentations, but was delayed in ovine fermentations, with substantial degradation occurring only after 4 h of incubation (p &lt; 0.01). These results indicate that rumen microbiota of cattle may have a greater capacity for fructan degradation.

Draft Genome Sequences of 11 Isolates of Ophiosphaerella spp., the Causal Agents of Several Turfgrass Diseases Including Spring Dead Spot of Bermudagrass and Necrotic Ring Spot of Kentucky Bluegrass

Ophiosphaerella herpotricha, O. korrae, and O. narmari are the causal agents of spring dead spot of warm-season grasses worldwide, and O. korrae is the causal agent of necrotic ring spot of cool-season grasses that primarily occurs in North and South America. All three species are considered important pathogens of turfgrasses, and there is limited genomic information about these ectotrophic, root-infecting fungi. Herein are reported the draft genome sequences of three isolates of O. herpotricha, five O. korrae, and three O. narmari isolates, furthering the knowledge about these three important turfgrass disease-causing species. [Formula: see text] Copyright © 2024 The Author(s). This is an open access article distributed under the CC BY-NC-ND 4.0 International license .

Dig up tall fescue plastid genomes for the identification of morphotype-specific DNA variants

BackgroundTall fescue (Festuca arundinacea Schreb.) is an important cool-season perennial grass species. Hexaploid tall fescue has three distinct morphotypes used either as forage or turf purposes. Its chloroplast genome is conserved due to it being maternally inherited to the next generation progenies. To identify morphotype-specific DNA markers and the genetic variations, plastid genomes of all three tall fescue morphotypes, i.e., Continental cv. Texoma MaxQ II, Rhizomatous cv. Torpedo, and Mediterranean cv. Resolute, have been sequenced using Illumina MiSeq sequencing platform.ResultsThe plastid genomes of Continental-, Rhizomatous-, and Mediterranean tall fescue were assembled into circular master molecules of 135,283 bp, 135,336 bp, and 135,324 bp, respectively. The tall fescue plastid genome of all morphotypes contained 77 protein-coding, 20 tRNAs, four rRNAs, two pseudo protein-coding, and three hypothetical protein-coding genes. We identified 630 SNPs and 124 InDels between Continental and Mediterranean, 62 SNPs and 20 InDels between Continental and Rhizomatous, and 635 SNPs and 123 InDels between Rhizomatous and Mediterranean tall fescue. Only four InDels in four genes (ccsA, rps18, accD, and ndhH-p) were identified, which discriminated Continental and Rhizomatous plastid genomes from the Mediterranean plastid genome. Here, we identified and reported eight InDel markers (NRITCHL18, NRITCHL35, NRITCHL43, NRITCHL65, NRITCHL72, NRITCHL101, NRITCHL104, and NRITCHL110) from the intergenic regions that can successfully discriminate tall fescue morphotypes. Divergence time estimation revealed that Mediterranean tall fescue evolved approximately 7.09 Mya, whereas the divergence between Continental- and Rhizomatous tall fescue occurred about 0.6 Mya.ConclusionsTo our knowledge, this is the first report of the assembled plastid genomes of Rhizomatous and Mediterranean tall fescue. Our results will help to identify tall fescue morphotypes at the time of pre-breeding and will contribute to the development of lawn and forage types of commercial varieties.

Synthetic auxin herbicides do not injure intermediate wheatgrass or affect grain yield

AbstractIntermediate wheatgrass (IWG) is a cool-season perennial grass developed as a dual-purpose grain and forage crop. One barrier to adopting this crop is a lack of information on the effects of herbicides on IWG for grain production. An experiment was conducted to evaluate herbicide effects on IWG grain yield, crop injury, and weed control over 2 yr (2019 to 2021) at sites in Wisconsin, Minnesota, New York, and North Dakota. This evaluation included broadleaf herbicides registered for use on wheat: 2,4-D amine, clopyralid, MCPA, and a mixture of clopyralid + MCPA (all are categorized as Group 4 herbicides by the Weed Science Society of America). Each herbicide or mixture was applied at 1× and 2× the labeled wheat application rate to newly planted and established (1- to 5-yr-old) IWG stands in the fall or spring. Herbicides were applied during IWG tillering or jointing stages in the fall or during the jointing stage in the spring. Across site years, application timing, herbicide, and application rate showed no effect on IWG grain yield or plant injury. Broadleaf weed control ranged from 71% to 92% across herbicide treatments relative to the nontreated check at the Wisconsin site, whereas weed control at the Minnesota site was variable among treatments. At the New York site, herbicides were equally effective for broadleaf weed suppression, whereas weed pressure was very low at the North Dakota site and treatments did not affect weed cover. The results show that newly planted and established stands of IWG are tolerant to the synthetic auxin herbicides 2,4-D amine, clopyralid, and MCPA when applied during tillering or jointing in the fall or during jointing in the spring. Synthetic auxins represent a potentially useful tool for weed control in IWG cropping systems, especially for problematic broadleaf weed species.

Methylome changes in Lolium perenne associated with long-term colonisation by the endophytic fungus Epichloë sp. LpTG-3 strain AR37.

Epichloë spp. often form mutualistic interactions with cool-season grasses, such as Lolium perenne. However, the molecular mechanisms underlying this interaction remain poorly understood. In this study, we employed reduced representation bisulfite sequencing method (epiGBS) to investigate the impact of the Epichloë sp. LpTG-3 strain AR37 on the methylome of L. perenne across multiple grass generations and under drought stress conditions. Our results showed that the presence of the endophyte leads to a decrease in DNA methylation across genomic features, with differentially methylated regions primarily located in intergenic regions and CHH contexts. The presence of the endophyte was consistently associated with hypomethylation in plants across generations. This research sheds new light on the molecular mechanisms governing the mutualistic interaction between Epichloë sp. LpTG-3 strain AR37 and L. perenne. It underscores the role of methylation changes associated with endophyte infection and suggests that the observed global DNA hypomethylation in L. perenne may be influenced by factors such as the duration of the endophyte-plant association and the accumulation of genetic and epigenetic changes over time.

Long term study of cell wall saccharification and high added value phenolic acids production from Phalaris aquatica L. energy crop

Phalaris aquatica L. is a cool-season perennial grass of the Mediterranean that has been used for forage production, while recently was identified as a novel candidate for sustainable second-generation bioethanol production. This study provides for the first time evidence about this energy crop long-term performance (five years of growth), the cell wall saccharification efficiency and the production of high added value compounds during this period. High biomass production was recorded constantly after the first year of plant growth, with a maximum of 22.4 ± 0.5 t of dry mass (DM) per ha and stable structural polysaccharides concentration 68.8% ± 0.8 w/w DM from the third year on. Independently from crop age, dilute acid pretreatment (120 °C, 1.5% H2SO4, 45 min) promoted the subsequent enzymatic hydrolysis of P. aquatica L. biomass. The dilute acid pre-treatment positive effect is attributed both to the hemicellulose solubilization and the breakage of intermolecular bonds between polysaccharides and phenolic acids, as supported by the present study results These combined acid/enzymatic hydrolysis processes were able to convert more than 80% of cell wall polysaccharides into fermentable sugars, releasing simultaneously a substantial amount of phenolic acids of 2.16% ± 0.48 w/w DM. The ratio of ferulic to p-coumaric acid in the acid hydrolysate can be used for the prediction of the subsequent cellulose enzymatic saccharification efficiency, by the model described here. The protocatechuic acid, which can find many technological applications, was the main bioactive polyphenol in the final hydrolysate with concentration ∼1% w/w DM. These results are supportive of Phalaris aquatica L. suitability as a sustainable biorefinery crop, under the semi-arid Mediterranean climatic conditions contributing to this region biodiversity and prosperity.

Trojan Horse on the Great Plains: Landowner Thresholds, Coping Capacity, and Management of Kentucky Bluegrass

Kentucky bluegrass, an invasive cool-season grass in the US northern Great Plains, embodies the Greek story of the Trojan horse in which an apparent gift initially seems to bestow benefits but ultimately becomes harmful and subversive.Its competitive nature and early spring growth give it an advantage over native cool season grasses. This early and prolific growth provides forage for livestock but eventually leads to a decrease in other plant species and to negative impacts to multiple ecosystem services. Developing effective landscape-scale management techniques for invasives like Kentucky bluegrass depends on understanding the perceptions, coping capacity, and management abilities of private landowners. Through a mail survey conducted in North Dakota, this research provides insight into the cognitive processes that motivate agricultural landowners to manage Kentucky bluegrass and investigates psychological factors that constrain or enable the implementation of management behaviors. The results showed that less than half of the landowners surveyed had a management goal for Kentucky bluegrass, and among those with such goals, the perceived capacity to cope with the species was moderate to low. The majority of landowners who wanted to decrease the abundance of Kentucky bluegrass on their rangelands did not believe they could effectively do so. This highlights the need for the rangeland science and extension community to develop effective and feasible management techniques and conservation programs that integrate research findings to provide viable solutions. Participatory processes that include diverse interested and affected parties and rights holders can provide social learning environments conducive to the joint exploration of problems and refinement of actionable solutions. Through the focus on Kentucky bluegrass in the northern Great Plains, our research approach and recommendations also provide transferable insights for invasive species management and conservation in other social-ecological systems.

Rhizobacteria-enhanced drought tolerance and post-drought recovery of creeping bentgrass involving differential modulation of leaf and root metabolism.

Rhizobacteria that produce 1-aminocyclopropane-1-carboxylic acid (ACC) deaminase (ACCd) that inhibits ethylene production may mitigate stress damages. The objectives of this study were to examine whether a novel strain of ACCd-producing bacteria, Paraburkholderia aspalathi "WSF23," promotes plant tolerance to drought stress and post-stress recovery and determine changes in metabolic profiles in leaves and roots associated with the positive ACCd-bacteria effects in cool-season perennial grass species. Creeping bentgrass (Agrostis Stolonifera L. cv. "Penncross") plants were inoculated with P. aspalathi "WSF23" and exposed to drought by withholding irrigation for 35 days, followed by re-watering for 15 days in growth chambers. Inoculated plants demonstrated increased turf quality, canopy density, and root growth during drought stress and more rapid re-growth upon re-watering. Metabolomic analysis demonstrated that inoculation with P. aspalathi "WSF 23" increased the content of metabolites in the metabolic pathways related to stress defense, including osmoregulation, cell wall stability, and antioxidant protection in both leaves and roots, as well as nitrogen metabolism in roots of creeping bentgrass exposed to drought stress. The promotion of post-stress recovery by P. aspalathi "WSF 23" was mainly associated with enhanced carbohydrate and pyrimidine metabolism and zeatin biosynthesis pathways in leaves and increased carbohydrates, biosynthesis of DNA and proteins, cellular metabolism, and TCA cycle activity in roots. These results provide insights into the metabolic pathways regulated by "WSF23," with the PGPR conferring improvements in drought stress tolerance and post-drought recovery in a perennial grass species.

Rotational Grazing Strategies Minimally Impact Soil Microbial Communities and Carbon Dynamics—A Texas Case Study

The goal of our study was to evaluate the long-term (&gt;12 years) influence of stocking density and herd rotation frequency on plant and soil microbial community and carbon dynamics in three working ranches in Texas. One ranch utilized a high stocking density and high-frequency (HIGH) rotation where cattle were moved multiple times each day; the second ranch used a medium stocking density and rotation frequency (MED) where herds were moved every 2–3 weeks; and the third ranch used a low stocking density with continuous grazing (LOW). Neither plant nor microbial diversity measures differed between the ranches, but plant functional and microbial community compositions differentiated management strategies. The MED ranch was characterized by a plant community dominated by little bluestem (Schizachyrium scoparium) and had the greatest soil organic matter content (2.8%) and soil respiration rates compared to the LOW (SOM = 2.2%) and HIGH (SOM = 2.1%) ranches. The HIGH ranch had a relatively high abundance and diversity of forbs and introduced grasses, and the LOW ranch had an even mixture of tall, introduced, and cool-season grasses. All three ranches had relatively high levels of Gram-positive bacteria (&gt;70%) with MED having a higher relative abundance of bacteria important for carbon cycling. Furthermore, network analyses suggest that soil microbial communities at all ranches were highly synergistic and exhibited well-defined ecological niches. Differences in soil properties between ranches tended to be minor and suggest that grazing strategies can differ without any substantial shifts in soil and microbial function.

Species and functional diversity of cool-season pastures are influenced by warm-season grazing management

CONTEXTIn southern Brazil, livestock producers often overseed cool-season annual grasses into warm-season perennial pastures to extend the grazing season and improve animal performance. However, the effects of warm-season pasture management on the subsequent cool-season pasture are poorly understood. OBJECTIVEWe aimed to evaluate how grazing height and nitrogen (N) fertilization applied to a mixed-species pasture during the warm season affect forage accumulation and diversity in the cool-season pastures. METHODSThe experiment was conducted in a subtropical climate and consisted of two phases: warm season (November/December – April/May) and cool season (May – October/November). During the warm season, we applied a factorial combination of two pre-grazing heights (0.17 and 0.23 m) and three N rates (50, 150, and 250 kg N ha−1) to a mixed-species pasture. During the cool season, we managed all plots equally and measured forage accumulation and diversity using Simpson's and Rao's indices. RESULTS AND CONCLUSIONSWe found that warm-season N fertilization had no residual effect on cool-season pasture responses, but grazing at 0.17 m height during the warm season resulted in higher forage accumulation during the cool season than grazing at 0.23 m height (5100 vs. 4780 kg DM ha−1). However, grazing at 0.23 m height during the warm season increased species diversity (Simpson's index of 0.49 vs. 0.40) and functional diversity (Rao's index of 0.33 vs. 0.29) during the cool season compared to grazing at 0.17 m height. SIGNIFICANCEThis study provides novel insights into the long-term effects of warm-season pasture management on cool-season pasture diversity and productivity in a subtropical climate. It shows that grazing at a height close to the critical leaf area index during the warm season can increase legume proportion and functional diversity in the cool season, which can improve pasture resilience and sustainability. While this study offers valuable insights, it is important to acknowledge its restriction to a single location, and the need to assess the hypothesis raised here to other sites and conditions.

Host Genetic Background Effect on Vertical Seed Transmission of Epichloë Endophyte Strains in Tall Fescue.

Tall fescue (Lolium arundinaceum (Schreb.) Darbysh.) is a cool-season perennial grass widely grown for forage and turf. Tall fescue lives in association with a fungal endophyte that helps the grass overcome abiotic and biotic stressors. The endophyte is asexual and transmits vertically from the tall fescue plant to the next generation through the seed. Producers of endophyte-infected tall fescue must have endophyte infection in at least 70% of their seed. Therefore, endophyte seed transmission is vital in breeding and seed production. Transfer of endophytes from their native host to different backgrounds of elite tall fescue cultivars can lead to a low seed transmission of the endophyte to the seed. This study screened 23 previously uncharacterized endophyte strains for transmissibility when artificially inoculated into continental and Mediterranean-type host tall fescue. We found no correlation between the rate of successful inoculation and the seed transmission rate of the endophyte in the new host. Nor did the seed transmission rate of the endophyte strains in their native host correlate with the seed transmission rate of the endophyte in the new host. Five strains exhibited seed transmission above 70% in both Mediterranean and Continental host backgrounds and will be characterized further for potential use in cultivar development.

Combined genomic and transcriptomic analysis reveals the contribution of tandem duplication genes to low-temperature adaptation in perennial ryegrass.

Perennial ryegrass (Lolium perenne L.) is an agronomically important cool-season grass species that is widely used as forage for ruminant animal production and cultivated in temperate regions for the establishment of lawns. However, the underlying genetic mechanism of the response of L. perenne to low temperature is still unclear. In the present study, we performed a comprehensive study and identified 3,770 tandem duplication genes (TDGs) in L. perenne, and evolutionary analysis revealed that L. perenne might have undergone a duplication event approximately 7.69 Mya. GO and KEGG pathway functional analyses revealed that these TDGs were mainly enriched in photosynthesis, hormone-mediated signaling pathways and responses to various stresses, suggesting that TDGs contribute to the environmental adaptability of L. perenne. In addition, the expression profile analysis revealed that the expression levels of TDGs were highly conserved and significantly lower than those of all genes in different tissues, while the frequency of differentially expressed genes (DEGs) from TDGs was much higher than that of DEGs from all genes in response to low-temperature stress. Finally, in-depth analysis of the important and expanded gene family indicated that the members of the ELIP subfamily could rapidly respond to low temperature and persistently maintain higher expression levels during all low temperature stress time points, suggesting that ELIPs most likely mediate low temperature responses and help to facilitate adaptation to low temperature in L. perenne. Our results provide evidence for the genetic underpinning of low-temperature adaptation and valuable resources for practical application and genetic improvement for stress resistance in L. perenne.