Dynamics of Neotyphodium endophyte infection in ageing seed pools: incidence of differential viability loss of endophyte,infected seed and non-infected seed

Symbiotic associations between grasses and vertically transmitted endophytic fungi are widespread in nature. Within grass populations, changes in the frequency of infected plants are driven by influence of the endophyte on the fitness of their hosts and by the efficiency of endophyte transmission from parent plants to their offspring. During the seed stage, the endophyte might influence the fitness of its host by affecting the rate of seed viability loss, whereas the efficiency of endophyte transmission is affected by losses of viability of the fungus within viable seeds. We assessed the viability losses of Lolium multiflorum seeds with high and low level of infection of the endophyte Neotyphodium occultans, as well as the loss of viability of the fungus itself, under accelerated seed ageing and under field conditions. Starting with high endophyte-infected accessions of L. multiflorum, we produced their low endophyte-infected counterparts by treating seeds with a fungicide, and subsequently multiplying seeds in adjacent plots allowing pollen exchange. In our accelerated ageing experiments, which included three accessions, high endophyte-infected seeds lost viability significantly faster than their low endophyte-infected counterpart, for only one accession. High endophyte-infected seeds of this particular accession absorbed more water than low endophyte-infected seeds. In contrast, the endophyte lost viability within live seeds of all three accessions, as the proportions of viable seeds producing infected seedlings decreased over time. In our field experiment, which included only one accession, high endophyte-infected seed lost viability significantly but only slightly faster than low endophyte-infected seed. In contrast, the loss of viability of the endophyte was substantial as the proportions of viable seeds producing infected seedlings decreased greatly over time. Moving the seeds from the air to the soil surface (simulating seed dispersion off the spikes) decreased substantially the rate of seed viability loss, but increased the rate of endophyte viability loss. Our experiments suggest that, in ageing seed pools, endophyte viability loss and differential seed mortality determine decreases in the proportions of endophyte-infected seeds in L. multiflorum. Endophyte viability loss within live seeds contributes substantially more to infection frequency changes than differential viability losses of infected and non-infected seeds.     

Conspicuous epiphytic growth of an interspecific hybrid Neotyphodium sp. endophyte on distorted host inflorescences

Selected Neotyphodium sp. endophytes are now commonly used to enhance pasture persistence and livestock productivity, with seed of perennial ryegrass and tall fescue cultivars with these selected endophytes being commercially available. In a large population of perennial ryegrass plants infected with a Neotyphodium sp. endophyte that was being grown for seed production a small percentage of inflorescences were distorted and covered with a conspicuous white mycelial growth. Within individual plants only a small number of inflorescences were affected and the amount of distortion differed between affected inflorescences. This Neotyphodium sp. is an interspecific hybrid of Epichloë typhina and Neotyphodium. lolii and like nearly all other Neotyphodium spp is symptomless in host grasses. The fungus isolated from distorted inflorescences had colonies that were identical to those isolated from symptomless inflorescences and these were characteristic of this Neotyphodium sp. This is the first report of distorted inflorescences covered with epiphytic hyphal growth on host grasses infected with an interspecific hybrid Neotyphodium sp.     

Effects of seed hydropriming on growth of Festuca sinensis infected with Neotyphodium endophyte

The interactive effects of a Neotyphodium endophyte and hydropriming on Festuca sinensis seeds were determined within a germination cabinet and under greenhouse conditions. Seed germination was optimized by an imbibition period of 15–30 min. Endophyte combined with hydropriming significantly (P < 0.05) promoted interim germination (at osmotic potentials of ?0.3 to ?0.6 MPa), germination rate (?1.2 MPa), vigor index of seeds (0 to ?1.2 MPa), length of coleoptile and radicle (?0.3 to ?1.2 MPa) and seedling dry weight (0 to ?1.2 MPa). Based on a long-term growth experiment, their interactive effects resulted in significant (P < 0.05) increases of above-ground dry weight, seedling heights during week 7–13 and tiller and leaf number during week 11–13 (P < 0.05), and greatly (P < 0.05) increased leaf elongation during week 7–11. Presence of the Neotyphodium endophyte combined with a seed hydropriming treatment is an effective strategy to improve seed germination and plant growth of F. sinensis.     

Effects of endophyte infection on drought stress tolerance of Lolium perenne accessions from the Mediterranean region

Perennial ryegrass (Lolium perenne) is a cool-season grass species that is often infected by the leaf-inhabiting endophyte Neotyphodium lolii. This particular endophyte is asexual and has the potential to impact host survival, growth and reproduction. The objective was to assess the potential costs or benefits of endophyte infection on drought stress tolerance of native perennial ryegrass accessions originally collected from Italy, Morocco, Tunisia, and Turkey. Sixty infected (E+) individuals from each accession were planted in a greenhouse. Half of these individuals were treated with a systemic fungicide to eliminate the endophyte (E−). For two drought periods water was withheld for 10-14 days and then allowed a one week recovery period following each. In some accessions under drought, E+ plants had more tillers, greater tiller lengths, total dry mass and green shoot mass than E− plants, suggesting a positive effect of endophyte infection on host growth. Total tiller length and the number of tillers showed significant population × treatment × infection interactions for 4 of 6 populations. This work is one of the few that documents the effects of endophyte infection for a common forage grass species from wild populations native to its distributional range. The results demonstrate that endophyte infection can help ameliorate abiotic stress such as drought and there may be a selective advantage for grasses from certain Mediterranean regions.     

Neotyphodium endophyte strain and superoxide dismutase activity in perennial ryegrass plants under water deficit

The presence of Neotyphodium endophyte in forage grass tillers has been associated with increased tolerance of abiotic stresses. The effect of four endophyte treatments (plants with three different strains of Neotyphodium lolii compared with plants without endophyte) on superoxide dismutase (SOD) (EC1.15.1.1) activity in Lolium perenne cv ‘Grasslands Samson’ was measured under high and low dehydration regimes in a glasshouse experiment. SOD activity was assayed by a microplate method utilising the inhibition of reduction of a tetrazolium dye by superoxide radicals. A progressive increase in dehydration over 2 weeks reduced shoot fresh weight, dry weight and shoot water content for high, compared with low, moisture-stressed plants. Mean shoot fresh weight was significantly lower for plants with strain AR37 endophyte than for plants with strain AR1 endophyte, wild-type or endophyte-free plants, but there was no interaction between endophyte treatment and dehydration treatment. There were no differences in mean SOD activity between the dehydration treatments, and the four endophyte treatments at any of the harvests. All harvest mean SOD levels for plants in both stress groups, however, were significantly different from the preceding harvest value. Between the first and second week of moisture stress there was a significant endophyte by harvest interaction for mean percentage change in SOD activity when activity in plants with wild-type strain endophyte increased more rapidly than in AR1, AR37 or endophyte-free plants. The results are in agreement with earlier reports suggesting that Neotyphodium endophytes do not have major effects on the water stress physiology of perennial ryegrass, although water deficits applied were not extreme.     

A fungal endophyte of an annual weed reduces host competitive ability and confers associational protection to wheat

Epichloid fungal endophytes (Epichloë spp., Ascomycota: Clavicipitaceae) inhabit aerial tissues of several cool-season grasses, and enhance host growth and defence against herbivores. The presence of these symbionts can also affect interactions between the host and other non-epichloid plants. The role of an epichloid endophyte on interspecific competition has been tested using perennial grasses with contrasting results, but it has been scarcely tested using annual species in agroecosystems. We evaluated the impact of Epichloë-grass symbiosis on the competitive interaction between a non-host cereal crop (Triticum aestivum, wheat) and a host weed (Lolium multiflorum, ryegrass), growing in the presence of invertebrate herbivores (aphids) under no resource limitation. We conducted an outdoor mesocosm experiment with wheat plants growing in monoculture or in mixture with low or high proportions of ryegrass plants. Ryegrass plants presented either low (E-) or high (E+) incidence of Epichloë occultans (i.e. frequency of epichloid endophytic plants). We measured wheat vegetative and reproductive yield and its natural aphid infestation. Although epichloid endophyte incidence did not affect ryegrass biomass, wheat reproductive yield in mixtures (relative to wheat monocultures) was 45% higher when grown with E+ ryegrass plants than E- conspecific plants. Aphids preferred wheat plants grown with E- plants rather than wheat plants grown with E+ plants, but only in mixtures with high proportion of ryegrass. Our results demonstrate that epichloid endophyte incidence can decrease host competitive ability and confers associational protection to the non-endophytic neighbouring plants. Thus, ryegrass-endophyte symbiosis can increase crop yield by positive neighbourhood effects through different mechanisms probably related to the density of the weed. The benefits of this endosymbiont cannot be considered host-exclusive since they can be disseminated to non-endophytic plants. Furthermore, our results suggest that the epichloid endophyte incidence on annual weeds can contribute to agroecosystem sustainability by influencing pest management and increasing crop yield.     

Overseeding endophytic perennial ryegrass into stands of Kentucky bluegrass to manage bluegrass billbug (Coleoptera: Curculionidae)

Studies were conducted to determine the utility of overseeding endophyte enhanced varieties of perennial ryegrass, Lolium perenne L., into existing stands of Kentucky bluegrass, Poa pratensis L., to manage bluegrass billbug, Sphenophorus parvulus Gyllenhal, larval populations and their damage. Two commercial varieties of endophyte enhanced perennial ryegrass (Repell II and Triple Play) were overseeded at two different rates in the field. S. parvulus larval populations, their damage, and turfgrass composition were monitored over the course of 3 yr. Significantly fewer larvae were found in plots overseeded with Repell II, whereas Triple Play had no significant effect on larval population density. Endophyte infection was confirmed in approximately 58% of all Repell II shoots, whereas only approximately 31% of Triple Play shoots were infected. Regression analysis, using a segmented model, demonstrated that larval populations declined as the proportion of endophyte-infected perennial ryegrass increased. However, no additional reductions in larval population density were achieved in stands containing >40% endophyte-infected perennial ryegrass. Visual damage varied with cultivar, seeding rate, and year, but generally decreased as the proportion of endophyte-infected perennial ryegrass increased. Although seeding rate had an initial effect on turfgrass composition, these differences were not detected after the first year of the study. Results indicate overseeding existing stands of Kentucky bluegrass with endophytic varieties of perennial ryegrass can reduce S. parvulus larval populations and their damage. However, plant genetic characteristics (i.e., different cultivars) may be overriding determinants of many aspects of plant performance including establishment, tolerance to insect feeding, and expression of endophyte-mediated resistance.     

Grass species and endophyte effects on survival and development of fall armyworm (Lepidoptera: Noctuidae)

Grass selections including 10 zoysiagrasses, 18 paspalums, 34 Bermuda grasses, tall fescue, creeping red fescue, and perennial ryegrasses with and without endophyte were evaluated for potential resistance to fall armyworm, Spodoptera frugiperda (J. E. Smith), larvae. Laboratory evaluations assessed the degree of antibiosis among >70 grass lines to first-instar fall armvworms. When all parameters measured were considered, the trend in resistance to fall armyworm among endophyte-infected (E+) and endophyte-free (E-) cool season grasses from greatest to least was: 'Dawson' E+ > APR 1234 > 'Dawson' E- > 'Rosalin' E+ > Lp 5425, 'Rosalin' E-, ATF 480 > 'Tulsa' or: E+ slender creeping red fescue > E+ turf- type perennial ryegrass > E- slender creeping red fescue > E+ forage-type perennial ryegrass > E- forage-type perennial ryegrasses, and E+ tall fescue > E- turf-type tall fescue. Among warm season grasses larval weight gain was reduced on all zoysiagrasses. Larval weight gain also was lower on the Bermuda grasses 'Tifsport', 'Tifgreen', 97-4, 97-14, 97-22, 97-28, 97-39, 97-40,97-54, 98-15, 98-30, and 98-45 than when larvae were fed 'Tulsa' tall fescue or the diet control. Only APR1234 and 'Dawson' creeping red fescue reduced larval survival to the same extent that was observed for zoysiagrasses. Survival on Bermuda grasses was least on 97-8. Seashore paspalums were only rarely less susceptible to fall armyworm than tall fescue, although pupal weights were consistently lower on 'Temple 1' and 'Sea Isle 1' paspalums than that on 'Tulsa' tall fescue. Genetic resistance to key grass pests can reduce insecticide use and simplify management of these cultivars.     

Effects of the Neotyphodium endophyte fungus on dormancy and germination rate of Lolium multiflorum seeds

Abstract Neotyphodium frequently occurs as an endophyte in grasses. Evidence shows enhanced fitness of endophyte infected grasses relative to non‐infected ones. Some studies of seed germination show endophyte enhancement of plant fitness in various environments, but inconsistent results indicate that further studies are needed. So far, experiments have failed to separate the confounded effects of population origin and seed management. For this reason, we evaluated the effects of endophyte infection on seed dormancy and germination in Lolium multiflorum using an experimental design controlling these factors. Depending on the year of seed production, endophyte infection modified seed response to light quality, affecting predominantly seed dormancy levels. Nevertheless, the endophyte did not affect base temperature or thermal time of germination. We concluded that endophytes were not a strong influence on germination behaviour. We speculate from our results that the presence of the endophyte changes germination by an indirect effect, in extending growth of the maternal plant during seed development and ripening. The direct effect of hyphae in the seed on seed behaviour was disregarded, because the difference between infected and non‐infected seed varied within the year of seed production. Future experiments should focus on effects of the endophyte on the canopy of parent plants during seed production and ripening, and, hence, on subsequent dormancy and germination of the seeds.     

醉马草内生真菌共生体研究进展

有关醉马草(Achnatherum inebrians)内生真菌(Epichloë gansuensis, E. inebrians)共生体的研究, 代表了我国禾草内生真菌研究领域的重要方向, 使中国的醉马草-内生真菌与美国的苇状羊茅(Festuca arundinacea)-内生真菌(E. coenophiana)和新西兰的多年生黑麦草(Lolium perenne)-内生真菌(E. festucae var. lolii)成为禾草内生真菌国际三大研究分支。该文综述了近30年来对醉马草内生真菌共生体的系统研究, 包括: 内生真菌的分布、带菌率、检测方法、多样性, 内生真菌提高宿主的抗旱、耐寒、耐盐碱、耐重金属、抗虫、抗病等抗逆性及其机理, 共生体产生的生物碱等次生代谢物, 对草食动物的毒性, 及其在草地生态系统中的作用等。研究者实验证实了醉马草本身无毒, 只有当内生真菌与醉马草共生并产生麦角新碱和麦角酰胺等麦角类生物碱后才能导致采食醉马草家畜中毒。文章展望了醉马草内生真菌基因组学和功能分析, 利用杀菌剂杀死内生真菌进行醉马草脱毒, 利用无毒内生真菌菌株进行饲用醉马草新品种选育, 利用有毒醉马草内生真菌共生体进行抗虫防鸟的机场绿化新品种选育及生物源农药与医药开发等。     

Possible involvement of aquaporins in water uptake by pea seeds differing in quality

Using the method of room temperature phosphorescence (RTP), we divided air-dry pea (Pisum sativum L.) seeds subjected to accelerated ageing (40°C, 85% relative humidity) into three fractions: (I) high-quality seeds, (II) weakened seeds, and (III) dead seeds. In the process of ageing, seed germinability firstly decreased and then increased due to so-called “improved” seeds of fraction II, which returned to fraction I as judged from the RTP level; the germinability of these seeds became equal to that of fraction I seeds. Seeds capable of germination (fractions I and II) differed in the rates of imbibition, which depended on plasma membrane permeability (opened or closed water channels) but not on the presence of the seed coat. A low activation energy of seed imbibition in fraction II (less than 5 kcal/mol) indicates that water channels are open. A mercury-containing compound (5 μM p-chloromercuribenzoate (PCMB) reduced the rate of water uptake by these seeds, and dithiothreitol restored it. A high activation energy of fraction I seed imbibition (more than 12 kcal/mol) corresponded to the water uptake mainly across the lipid bilayer when water channels are closed. PCMB did not affect the rate of fraction I seed imbibition. We supposed that mature air-dry pea seeds had open water channels. During the first stages of fraction I seed imbibition, these channels were closed, limiting water uptake. NaF (100 μM), an inhibitor of phosphatase, prevented channel closing and accelerated the imbibition of fraction I seeds. It did not affect the imbibition rate of fraction II seeds, indicating their water channels to be opened. However, NaF did not affect the water uptake of “improved” fraction II seeds as well. It seems likely that their channels were closed during accelerated ageing but otherwise than via dephosphorylation. The results obtained indicate the possibility of water inflow regulation in the weakened seeds via the state of aquaporins, which form water channels in the membranes.     

Advances in research of Achnatherum inebrians-Epichloë endophyte symbionts

有关醉马草(Achnatherum inebrians)内生真菌(Epichloë gansuensis, E. inebrians)共生体的研究, 代表了我国禾草内生真菌研究领域的重要方向, 使中国的醉马草-内生真菌与美国的苇状羊茅(Festuca arundinacea)-内生真菌(E. coenophiana)和新西兰的多年生黑麦草(Lolium perenne)-内生真菌(E. festucae var. lolii)成为禾草内生真菌国际三大研究分支。该文综述了近30年来对醉马草内生真菌共生体的系统研究, 包括: 内生真菌的分布、带菌率、检测方法、多样性, 内生真菌提高宿主的抗旱、耐寒、耐盐碱、耐重金属、抗虫、抗病等抗逆性及其机理, 共生体产生的生物碱等次生代谢物, 对草食动物的毒性, 及其在草地生态系统中的作用等。研究者实验证实了醉马草本身无毒, 只有当内生真菌与醉马草共生并产生麦角新碱和麦角酰胺等麦角类生物碱后才能导致采食醉马草家畜中毒。文章展望了醉马草内生真菌基因组学和功能分析, 利用杀菌剂杀死内生真菌进行醉马草脱毒, 利用无毒内生真菌菌株进行饲用醉马草新品种选育, 利用有毒醉马草内生真菌共生体进行抗虫防鸟的机场绿化新品种选育及生物源农药与医药开发等。     

Influence of nutrient availability and tree wildling density on nutrient uptake by Oxalis acetosella and Acer saccharum

The different weight-number strategies of seed production displayed by individuals of a Mediterranean fire-prone plant species (Cistus ladanifer) were investigated in relation to seed germination responses to pre-germination heating. A control (no heating), a high temperature during a short exposure time (100 degrees C during 5 min) and a high temperature during a long exposure time (100 degrees C during 15 min) were applied to seeds from different individual plants with different mean seed weight. These pre-germination treatments resemble natural germination scenarios for the studied species, absence of fire, typical Mediterranean shrub fire, and severe fire with high fuel load. Seed germination was related to heat treatments and seed mass. Seed heating increased the proportion of seeds germinating compared with the control treatment. Mean seed weight was positively correlated to the proportion of germinated seeds but only within heat treatments. These results suggest that in periods without fire, the relative contributions to the population dynamics are equal for all seeds, regardless of their mass, whereas heavier seeds would be the main contribution after wildfire events. Since lighter seeds can be produced in higher quantities than heavier ones within a given fruit, the number of seedlings produced per fruit depended strongly on the germination conditions. In the absence of wildfire, fruits producing lighter seeds gave rise to more seedlings; nevertheless, they were numerically exceeded by those producing heavy seeds after a wildfire. The implications of these results are discussed in relation to their consequences on the population dynamics of this species, considering also additional information on stand flammability and changes in seed mass with plant age.     

Effect of post-irradiation ageing on onion seeds

Seeds of onion (Allium cepa) cv. Ailsa Craig were exposed to various doses of gamma radiation (0, 10, 20, 40, 80 and 100 krad) and subjected to accelerated ageing (RH 100%, 42°C) for 12 h. Radiation doses significantly affected the percentage of normal seedlings, abnormality types (%) and seedling growth. Seed viability, conductivities of seed leachates, final germination (%), germination speed and time to reach 50% germination (T ₅₀) were not affected by the seed irradiation. Accelerated ageing after irradiation had significant influence on seed viability, conductivities of seed leachates, final germination (%) and percentage of normal seedlings. Germination speed, T ₅₀ and seedling growth were not affected by the accelerated ageing. However, all the parameters studied were significantly influenced by the interaction of radiation doses and accelerated ageing. Accelerated ageing generally enhanced the damaging effects of irradiation on seeds. Therefore, it was concluded that onion seeds should not be exposed to adverse environmental conditions after irradiation.     

Bimodal changes in germinability of pea seeds under the influence of low doses of gamma-radiation

Pea seeds (cv. 'Nemchinovskii-85', harvest of 2002, 80%-germination percentage) were exposed to gamma-radiation with doses ranging from 19 cGy to 100 Gy. One week after the irradiation with doses of 19 cGy and 3 Gy. the germination percentage decreased to 58 and 45%, respectively; at doses of 7 and 10 Gy it was 73 and 70% respectively. At greater doses (25, 50, and 100 Gy), germination percentage decreased in proportion. Anomalous changes in seed germination percentage (as a function of irradiation dose) were caused by the redistribution of irradiated seeds between fractions I and II. The measurements of room temperature phosphorescence in air-dry seeds and the phosphorescence of endogenous porphyrines of imbibing seeds showen that the germination decrease after the irradiation with low doses (19 cGy and 3 Gy) was caused by the increase in the number of weak seeds of fraction II, which had high rates of water uptake and suffered from hypoxia under seed coat. Some of these seeds suffocated from hypoxia, and other seeds produced seedlings with morphological defects (such seeds were considered incapable of germination). During storage of seeds irradiated at doses 19 cGy-10 Gy, the recovery of germination percentage (after its initial decrease) was caused by the decrease in seed number in fraction II. The subsequent germination decrease was caused by seed death. The higher was the irradiation dose, the faster were changes in germination percentage during storage of irradiated seeds. Bimodal changes in pea seed germination with the increase of y-irradiation dose has apparently the same origin as the changes in seed germination during accelerated ageing.     

Lipid peroxidation and peroxide-scavenging enzymes associated with accelerated aging of peanut seed

Accelerated aging is known to reduce seed viability and vigor in many crop species. The phenomenon is due in part to aging-induced lipid peroxidation, which has the potential to damage membranes of the seed tissues. This study was undertaken to evaluate the effect of accelerated aging on germinability and several physiological characteristics related to peroxidation in the seed of two peanut cultivars. Accelerated aging was achieved by incubating seed at 45°C and 79% relative humidity in a closed chamber for 3, 6, or 9 days. The results indicate that accelerated aging inhibited seed germination and seedling growth. Enhanced lipid peroxidation and increased peroxide accumulation were observed in the axis and cotyledons of aged seed. Accelerated aging also inhibited the activity of superoxide dismutase, peroxidase, ascorbate peroxidase, and lipoxygenase. Seed axes appeared to be more susceptible to aging than cotyledons. The changes in germination and physiological activities, expressed as a function of aging duration, were similar in the two cultivars, despite differences in their seed weight.     

High nitrogen supply and carbohydrate content reduce fungal endophyte and alkaloid concentration in Lolium perenne

The relationship between cool-season grasses and fungal endophytes is widely regarded as mutualistic, but there is growing uncertainty about whether changes in resource supply and environment benefit both organisms to a similar extent. Here, we infected two perennial ryegrass (Lolium perenne) cultivars (AberDove, Fennema) that differ in carbohydrate content with three strains of Neotyphodium lolii (AR1, AR37, common strain) that differ intrinsically in alkaloid profile. We grew endophyte-free and infected plants under high and low nitrogen (N) supply and used quantitative PCR (qPCR) to estimate endophyte concentrations in harvested leaf tissues. Endophyte concentration was reduced by 40% under high N supply, and by 50% in the higher sugar cultivar. These two effects were additive (together resulting in 75% reduction). Alkaloid production was also reduced under both increased N supply and high sugar cultivar, and for three of the four alkaloids quantified, concentrations were linearly related to endophyte concentration. The results stress the need for wider quantification of fungal endophytes in the grassland-foliar endophyte context, and have implications for how introducing new cultivars, novel endophytes or increasing N inputs affect the role of endophytes in grassland ecosystems.     

Does endophyte symbiosis resist allelopathic effects of an invasive plant in degraded grassland?

Allelopathic effects and plant associated systemic endophytic fungi are often thought to play a role in the invasion of exotic plant species. Here, we tested the inhibitory effects of the aqueous extracts of the hemiparasitic weed Pedicularis kansuensis on seed germination and seedling growth of endophyte-free (E−) and -infected (E+) grass species, Stipa purpurea and Elymus tangutorum. The weed extracts significantly inhibited both seed germination and seedling growth of the target grass species. Extracts from the inflorescences gave greater inhibition than those from the stems or roots, while the concentration of the extract had a direct effect on the extent of inhibition. The E+ target plants were less susceptible to the extracts than their E-counterparts. Our results suggest that the allelopathic potential of P. kansuensis will lead to increased frequencies of endophyte infected plants in grass populations.     

Fungal endophyte infection changes growth attributes in Lolium multiflorum Lam

Abstract Lolium multiflorum is a successful invader of postagricultural succession in the Inland Pampa grasslands in Argentina, becoming a dominant species in the plant community. Individual plants of this annual species are naturally highly infected with fungal endophytes (Neotyphodium sp.) from early successional stages. We assessed the effect of Neotyphodium infection on the biology of L. multiflorum. We evaluated growth attributes between endophyte infected (E+) and uninfected (E–) plants under non‐competitive conditions during the normal growing season. E+ plants produced significantly more vegetative tillers and allocated more biomass to roots and seeds. Although seed germination rates were greater in endophyte free plants, the rate of emergence and the final proportion of emerged seedlings were similar between the biotypes. The greater production of vegetative tillers, and the greater resource allocation to roots and seeds are likely to confer an ecological advantage to E+ plants, thus enabling their dominance over the E– individuals in natural grasslands.     

Fungal endophytes of a forage grass reduce faecal degradation rates

Mutualisms between fungal endophytes and forage grasses can exert broad-reaching effects on grassland communities and ecosystem processes. We hypothesised that endophytes of grasses would retard the process of faecal degradation since grazing animals consume primarily live plant material and excrete a large portion of the herbage they consume as faeces. We examined the degradation rates of faeces from sheep that had consumed pure swards of perennial ryegrass containing a range of unique strains (AR1, AR37, or Wild type) of the fungal endophyte, Neotyphodium lolii, or no endophyte. Ultimately, the presence of endophytes in perennial ryegrass resulted in slower faecal decay rates compared to the nil endophyte treatment, although only consistently for the C concentration decay rates that were approximately 2× to 4× slower in the endophyte-derived faecal matter. The decay rate of dry matter content was significantly slower (ca. 1.5×) in the novel endophyte-derived faeces (AR1 and AR37) compared to the nil endophyte-derived faeces. The N decay rates differed significantly only in the AR1 treatment that was approximately 4× slower than the nil endophyte group. The reduced decay rates are attributed to the presence of endophyte-derived alkaloids in the faeces, and a greater proportion of more easily degraded hemicellulose in faeces from sheep that consumed the endophyte-free grass. There were no significant differences in the faecal carbon and nitrogen decay rates among the three endophyte strain treatments. This suggests that all the strain-specific alkaloids might have similar effects, or that N. lolii has a general effect that is not strain-specific, such as altered fibre composition, as reported here. This is the first report of a fungal endophyte affecting the rate of faecal degradation, and the first report of the alkaloids peramine, lolitrem B and epoxy–janthitrems in faecal matter. This study shows that a common agronomic grass–endophyte mutualism can have effects on ecosystem processes that have not previously been considered.