Beatriz R. Vázquez-de-Aldana

An Epichloë endophyte affects the competitive ability of Festuca rubra against other grassland species

Background and aimsFestuca rubra plants are asymptomatically infected by the systemic fungal endophyte Epichloë festucae and high infection rates have been found in natural grasslands. Our objective was to determine the effect of endophyte infection on the competitive ability of Festuca rubra in binary mixtures against other grassland species.MethodsIn two glasshouse experiments, endophyte-infected (E+) and non-infected (E−) plants of two half-sib lines (PEN, RAB) of Festuca rubra were grown in monocultures and in binary mixtures against five grassland species: Trifolium repens, Trifolium pratense, Trifolium subterraneum, Lotus corniculatus and Plantago lanceolata.ResultsBiomass production of F.rubra was affected by endophyte infection and plant line but not by competition with T.pratense. In the PEN line E+ plants produced less root biomass than E−; and in the RAB line E+ plants produced less shoot biomass than E−. In spite of these differences shoot and root biomass production of Trifolium pratense were more inhibited when growing with endophyte-infected plants of Festuca rubra than with E− plants, regardless of the plant line. In both F.rubra lines, the endophyte increased the phosphorus concentration in shoots. Regardless of F.rubra plant line, root biomass of the five target species was more inhibited when growing with endophyte-infected than with endophyte-free plants.ConclusionsIrrespective of F.rubra line, endophyte-infected plants had a better competitive ability than non-infected plants, as indicated by the lower relative yield of companion plants when growing in mixture with E+ plants. We suggest an allelopathic effect of E+ red fescue on other grassland species.

Fungal Endophyte (Epichloë festucae) Alters the Nutrient Content of Festuca rubra Regardless of Water Availability

Festuca rubra plants maintain associations with the vertically transmitted fungal endophyte Epichloë festucae. A high prevalence of infected host plants in semiarid grasslands suggests that this association could be mutualistic. We investigated if the Epichloë-endophyte affects the growth and nutrient content of F. rubra plants subjected to drought. Endophyte-infected (E+) and non-infected (E−) plants of two half-sib lines (PEN and RAB) were subjected to three water availability treatments. Shoot and root biomass, nutrient content, proline, phenolic compounds and fungal alkaloids were measured after the treatments. The effect of the endophyte on shoot and root biomass and dead leaves depended on the plant line. In the PEN line, E+ plants had a greater S:R ratio than E-, but the opposite occurred in RAB. In both plant lines and all water treatments, endophyte-infected plants had greater concentrations of N, P and Zn in shoots and Ca, Mg and Zn in roots than E- plants. On average, E+ plants contained in their shoots more P (62%), Zn (58%) and N (19%) than E- plants. While the proline in shoots increased in response to water stress, the endophyte did not affect this response. A multivariate analysis showed that endophyte status and plant line impose stronger differences in the performance of the plants than the water stress treatments. Furthermore, differences between PEN and RAB lines seemed to be greater in E- than in E+ plants, suggesting that E+ plants of both lines are more similar than those of their non-infected version. This is probably due to the endophyte producing a similar effect in both plant lines, such as the increase in N, P and Zn in shoots. The remarkable effect of the endophyte in the nutrient balance of the plants could help to explain the high prevalence of infected plants in natural grasslands.

Interannual variations of above-ground biomass and nutritional quality of Mediterranean grasslands in Western Spain over a 20-year period

The ‘dehesas’ are savannah-like semi-arid grasslands typical of western Spain, which are subject to strong inter-annual variations in biomass production. Over a 20-year period, from 1986 to 2005, above-ground biomass and the nutritional quality of these grasslands in the province of Salamanca (western Spain) were evaluated to determine the relationships between interannual variations in grassland parameters and climate variables (precipitation and temperature). Herbage samples were collected from several sites, along a topographic gradient that differentiated two types of herbaceous communities on the upper and lower part of the slope. Nutritional quality was assessed on the basis of protein, acid detergent fibre, neutral detergent fibre, lignin and digestibility. On both the upper and lower zones, total biomass and biomass of grasses were correlated with annual precipitation calculated from the previous October to the current June. Biomass of legumes and forbs, on the upper zones, was correlated with spring precipitation. Step-wise multiple regression analysis provided different models for grasses, legumes, forbs, and total biomass for the upper and lower zones. Protein concentration was negatively correlated with annual precipitation in both zones of the slope. The number of days in spring with precipitation (≥1 mm or ≥10 mm) was a good predictor of the lignin content and digestibility in both zones of the slope, and of the acid detergent fibre content on the upper zones and the neutral detergent fibre content on the lower zones.

Influence of fungal endophyte infection on nutrient element content of tall fescue

Abstract Fungal endophytes infect several grass species. The fungus can alter the growth, and physiological and morphological characteristics of the infected plant. A greenhouse experiment was designed to determine the effect of the fungal endophyte Neotyphodium coenophialum on the nutrient element content of a selected ecotype of tall fescue (Festuca arundinacea), when growing at two nutrient element supply levels. Stem dry matter, averaged over all harvests and nutrient element supply treatments, was higher in non‐infected (E‐) than in endophyte infected (E+) plants. We found a significant interaction between endophyte infection and nutrient element supply level and/or harvest date on the nitrogen (N), phosphorus (P), calcium (Ca), and magnesium (Mg) plant tissue concentrations. Only for Ca leaf concentrations the effect of infection status was not influenced by harvest date or nutrient element supply treatment and Ca concentration was higher in E‐ than in E+ plants. Differences between E+ and E‐ plants...

Epichloë endophytes affect the nutrient and fiber content of Lolium perenne regardless of plant genotype

Background and AimsEpichloë endophytes inhabit aerial grass tissues but they can modify belowground processes that might affect host nutrient balance. We aimed to determine the effects of endophyte status (E+=endophyte-infected; E−=non-infected) and three Epichloë morphotypes (M1,M2,M3) on growth and nutrient content of a heterogeneous set of naturally infected asymptomatic plants of Lolium perenne. In addition, plant parameters were compared between asymptomatic E+ and plants with choke disease.MethodsA field experiment was conducted with 194 plants obtained from six natural populations (97E+, 97E−). For each E+ plant, the endophyte morphotype it hosted was known.ResultsEndophyte-infected plants had significantly lower P, Ca, S, B, neutral detergent fiber and lignin contents, and higher Mn and digestibility than E−, independently of plant origin. Biomass production was affected by plant origin but not by endophytes. No effect of Epichloë morphotypes in any parameter was found. However, asymptomatic E+ and choke diseased plants differed in nutrients, fibers, and digestibility.ConclusionsAn endophyte effect was detected in nutrient and fiber content, in spite of the heterogeneous constitution of the plant and fungal material used. The results obtained indicate that Epichloë may affect above and possibly underground processes involved in nutrient absorption, as well as plant quality, what may potentially affect litter decomposition processes.

A spectroscopy approach to the study of virus infection in the endophytic fungus Epichloë festucae

BackgroundIn this work we propose a rapid method based on visible and near-infrared (Vis-NIR) spectroscopy to determine the occurrence of double-stranded RNA (dsRNA) viruses in Epichloë festucae strains isolated from Festuca rubra plants. In addition, we examined the incidence of infections by E. festucae in populations of F. rubra collected in natural grasslands of Western Spain.MethodsVis-NIR spectra (400-2498 nm) from 124 virus-infected and virus-free E. festucae isolates were recorded directly from ground and freeze-dried mycelium. To estimate how well the spectra for uninfected and infected fungal samples could be differentiated, we used partial least-squares discriminant analysis (PLS1-DA) and several data pre-treatments to develop calibration models.ResultsApplying the best regression model, obtained with two sampling years and using standard normal variate (SNV) combined with first derivative transformation to a new validating data set (42 samples), we obtained a correct classification for 75% of the uninfected isolates and up to 86% of the infected isolates.ConclusionsThe results obtained suggest that Vis-NIR spectroscopy is a promising technology for detection of viral infections in fungal samples when an alternative faster approach is desirable. It provides a tool adequately exact and more time- and cost-saving than the conventional reference analysis.

Qualitative and quantitative analysis of endophyte alkaloids in perennial ryegrass using near-infrared spectroscopy: NIRS to detect Epichloë alkaloids in ryegrass

BACKGROUND Near-infrared reflectance spectroscopy (NIRS) has been widely used in forage quality control because it is faster, cleaner and less expensive than conventional chemical procedures. In Lolium perenne (perennial ryegrass), one of the most important forage grasses, the infection by asymptomatic Epichloë fungal endophytes alters the plant nutritional quality due to the production of alkaloids. In this research, we developed a rapid method based on NIRS to detect and quantify endophyte alkaloids (peramine, lolitrem B and ergovaline) using a heterogeneous set of L. perenne plants obtained from wild grasslands and cultivars. RESULTS NIR spectra from dried grass samples were recorded and classified according to the absence or presence of alkaloids, based on reference methods. The best discriminant equations for detection of alkaloids classified correctly 94.4%, 87.5% and 92.9% of plants containing peramine, lolitrem B and ergovaline, respectively. The quantitative NIR equations obtained by modified partial least squares (MPLS) algorithm had coefficients of correlation of 0.93, 0.41, and 0.76 for peramine, lolitrem B and ergovaline respectively. CONCLUSION NIRS is a suitable tool for qualitative analysis of endophyte alkaloids in grasses and for the accurate quantification of peramine and ergovaline.

Quantitative Analysis of Chlorophyll and Protein in Alfalfa Leaves Using Fiber‐Optic Near‐Infrared Spectroscopy

The performance of near‐infrared (NIR) spectroscopy as a rapid technique for the estimation of chlorophyll and protein contents in alfalfa (Medicago sativa L.) was investigated. A fiber‐optic probe was employed directly on a total of 198 fresh leaves to measure spectra between 1100 and 2200 nm. Partial least squares (PLS) regression models were developed with a calibration set of 120 samples spanning a concentration range of 5.20–158.5 for the chlorophyll content index (CCI), 0.39–4.60 mg g−1 (fresh weight) for the chlorophyll extracted with dimethylsulfoxide (DMSO), and 9.92–45.32% (dry matter) for protein content. The models obtained were validated with 78 independent samples. Standard errors of prediction of 12.49 were obtained for the CCI, 0.24 mg g−1 for DMSO‐extracted chlorophyll, and 3.27% for the protein content. These results support the use of NIRS equipped with a fiber‐optic probe to monitor and assess the composition and quality of forages in a nondestructive way.

Near-infrared spectroscopy allows detection and species identification of Epichloë endophytes in Lolium perenne : Detection of endophytes in ryegrass by NIRS

BACKGROUND Perennial ryegrass (Lolium perenne) is systemically infected by seed-transmitted fungal endophytes (Epichloë sp.). The presence of Epichloë endophytes alters the nutritive quality of its hosts by modifying several plant traits. The aim of this research was to develop a fast method based on near-infrared reflectance spectroscopy (NIRS) to discriminate between perennial ryegrass plants infected (E+) or not infected (E-) with two endophyte species, Epichloë festucae var. lolii, and Epichloë typhina, using a heterogonous set of perennial ryegrass samples collected from wild grasslands and cultivars. Epichloë festucae var. lolii cultures show two morphotypes, M1 and M3, and Epichloë typhina cultures have a different M2 morphotype. RESULTS Near-infrared reflectance spectra from E+ and E- ryegrass plants were recorded. Applying the best NIRS model for the detection of Epichloë, 93.3% of E+ plants were classified correctly. The NIRS morphotype classification was correct for 92.9% of M1 morphotype and 100% of M2 morphotypes. The NIRS classification of M3 morphotypes was not as accurate, but it was in accordance with the fungal species classification, identifying some M3 as M1 morphotypes. CONCLUSION Near-infrared reflectance spectroscopy can detect the presence of Epichloë fungal endophytes directly in samples of perennial ryegrass, and it is adequate for discriminating among fungal species.