Incidence and Diversity of Neotyphodium Fungal Endophytes in Tall Fescue from Morocco, Tunisia, and Sardinia

Abstract

There is a premium on having Neotyphodium germplasm available for temperate grass improvement programs because these fungal endophytes present opportunities for developing new grass–endophyte combinations for enhanced tolerance to abiotic and biotic stresses. Unfortunately, surveys have revealed a low incidence of Neotyphodium fungi in grass germplasm collections. This research surveyed tall fescue (Festuca arundinacea Schreb.) accessions from a 1994 Australian–U.S. plant‐collection trip to Morocco, Tunisia, and Italy (Sardinia) for viable Neotyphodium fungi and determined whether infected accessions harbor different Neotyphodium genotypes. Conidial measurements of isolates cultured on agar and bioassays of the differential survival of bird cherry‐oat aphid [Rhopalosiphum padi (L.)] on infected accessions were used to characterize Neotyphodium diversity. A secondary objective determined the consistency of a polymerase chain reaction (PCR) method to detect Neotyphodium fungi in tall fescue. Neotyphodium was detected in 336 of 439 plants (76.5%) distributed among 104 accessions, of which 99 were endophyte‐infected. Mean conidial lengths of 42 isolates ranged from 3.91 to 9.91 μm. Most of the isolates (71.4%) had conidia with mean lengths smaller than the lower limit (6.5 μm) characteristic of the tall fescue endophyte N. coenophialum (Morgan‐Jones and Gams) Glenn, Bacon, and Hanlin. In aphid assays, all endophyte‐free plants were susceptible to R. padi and all but two infected plants were resistant to this aphid. Thus, a Mediterranean plant‐collection trip secured diverse Neotyphodium endophytes in tall fescue for storage in seed banks, and a PCR assay detected Neotyphodium in tall fescue plants of diverse geographical origin.

Genotypic and Chemotypic Diversity of Neotyphodium Endophytes in Tall Fescue from Greece

“…Previous studies of endophytes from tall fescue populations have relied heavily on phenotypic data such as conidium length, isozyme analyses, and alkaloid production to classify individual isolates as N. coenophialum or FaTG-2 or -3 (Festuca arundinaceum endophyte taxonomic groups 2 and 3, respectively) (12,14,31,41,42). In this study, we combined phylogenetic analyses of housekeeping genes tubB and tefA with a PCR-based alkaloid gene profiling approach and chemical analyses to comprehensively characterize five distinct endophyte morphotypes from a representative tall fescue collection from Greece.…”

“…FaTG-2 (see Table S2 in the supplemental material). For the sake of clarity, where necessary, gene copies are amended with a prefix referring to the isolate or species, followed by the gene name, with a suffix that reflects the phylogenetic heritance of the gene; e.g., Nco-tefA-Efe refers to the N. coenophialum tefA gene copy inherited from the E. festucae progenitor (14).…”

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

“…The infection frequency of native accessions of summer-dormant tall fescue is usually high (Clement et al 2001;Piano et al 2005;Pecetti et al 2007), suggesting an important ecological role similar to that in continental tall fescue ecotypes. In fact, some of the benefits of endophyte infection are similar for both fescue types, i.e.…”

“…Indeed, DNA sequence analysis grouped tall fescue into the southern ecotypes (originating from North Africa, Western Mediterranean, Iberia and southern Italy, bounded in the north by the Pyrenees and the Alps) and northern ecotypes originating from northern Europe into Iberia, Morocco and northern Italy (Craven et al 2005). Both tall fescue groups harbour the endophytes; however, the endophytes (designated FaTG-2 and FaTG-3) in some of the southern ecotypes of tall fescue (from southern Spain, Algeria and Sardinia) are genetically, biochemically and morphologically different from E. coenophiala (Christensen et al 1993;Clement et al 2000;Piano et al 2005). E. coenophiala is commonly found in northern tall fescue and in those tall fescue lineages introduced from northern Europe into North America, Australia and New Zealand (Craven et al 2009).…”

Variable Effects of Grass-Neotyphodium Associations on Cereal Leaf Beetle (Coleoptera: Chrysomelidae) Feeding, Development and Survival

“…The first was fungal isolation on potato dextrose agar supplemented with streptomycin sulfate and tetracycline hydrochloride (50 g each per ml) for suppression of bacteria. Following procedures in Clement et al (2001), basal stem sections (~1 cm in length) from 1-2 tillers per plant were surface-disinfected and placed on potato dextrose agar in sealed polystyrene Petri dishes and incubated in a laboratory (complete darkness, room temperature). Petri dishes were examined for mycelial growth from plant tissue at 2-3 day intervals for 45 days.…”