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Epichloe endophytes are symbiotic fungi which unlike mycorrhiza grow within aerial parts of host plants. The fungi may increase host tolerance to both biotic and abiotic stresses. In this study, the effect of endophyte infection on growth and tolerance, carbohydrate contents and ABC (ABC transporter) and MET (metallothionein) expression in the leaves of tall fescue ( Festuca arundinacea ) plants cultivated in Ni polluted soil were evaluated. The endophyte infected (E+) and non-infected (E−) fescue plants were cultivated in soil under different Ni concentrations (30, 90 and 180 mg kg −1 ). Growth parameters including root, shoot, total biomass, tiller number and total chlorophyll content of plants and H 2 O 2 content of shoots were measured at the end of experiment. Ni translocation to the shoots, carbohydrate contents in roots and expression of ABC and MET of the leaves were also measured after 10 weeks of growth. Results demonstrated the beneficial effect of endophyte association on growth and Ni tolerance of tall fescue under Ni stress through an avoidance mechanism (reduction of Ni accumulation and translocation to the shoots). Endophyte infected plants showed less ABC and MET expression compared to the endophyte free plants. In endophyte free plants, H 2 O 2 production had a significant positive correlation with genes expression, indicating that an increase in H 2 O 2 might be involved in the up-regulation of ABC and MET under Ni stress. [ABSTRACT FROM AUTHOR]

Tall fescue ( Festuca arundinacea Schreb. subsp. arundinacea) is one of the most economically important forage grasses in cold and temperate regions of the world. In this study, we have assessed the genetic diversity and structure of wild Iranian tall fescue populations. Thirty-seven individuals from nine natural populations from northern, western, and southern Iranian mountain ranges were analyzed using six genomic-SSRs and five EST-SSRs primer pairs. Our analysis has demonstrated that transcribed EST-SSR regions showed levels of polymorphism similar to genomic-SSR regions. UPGMA, repeated bisection, and model-based Bayesian STRUCTURE clustering methods coupled with neighbor-net network were used to establish six divergent groups of individuals. FST estimates among clusters showed moderate to low genetic structure. Within-group genetic diversity estimate H and partial correlations between genetic and geographic distances among populations suggested that western Zagros population was related to the rest of the Iranian individuals. The isolation-by-distance hypothesis was not supported by SSR data and the present geographical sampling. [ABSTRACT FROM AUTHOR]

Soil pollution with heavy metals is an important environmental problem which affects human and food health. Neotyphodium endophytes are a group of fungi which have their entire life cycle within the aerial parts of many cool-season grasses without any negative symptoms, and increase host tolerance to biotic and abiotic stresses. In this study, four groups of endophyte-host combinations including two genotypes of tall fescue either infected or non-infected by endophyte (75B E+, 75B E-, 75C E+ and 75C E-) were cultivated by using 10 equal sized tillers in each plastic pot containing Ni contaminated soil at concentrations of 30, 90 and 180 mg Ni per kg in 3 replicates. Growth parameters including root and shoot dry weight, tiller number of plants and chlorophyll and carotenoid content of shoots were measured at the end of the experiment. Antioxidant enzymes (CAT, SOD, APX, GPX, GR and GST) activities, total content of phenolic compounds and Ni accumulation in the roots and shoots after 10 weeks of growth was also determined. Results demonstrated that endophyte infection had a benefit to the plant growth and Ni tolerance in genotype 75B by improving the antioxidative system and by a reduction of Ni accumulation in the shoots. In genotype 75C, in contrast, the E- plants showed more tolerance to Ni stress compared to the E+ counterparts. It was revealed that the effect of endophyte infection on Festuca plants as the host may be dependent on the host genotype and endophyte*host interaction. [ABSTRACT FROM AUTHOR]