PARENT SESSION
Poster Session 38: Mutualism / Parasitism
Thursday, August 11, 5:00 PM - 6:30 PM, Exhibit Hall 220 A-E, Level 2, Palais des congrès de Montréal

Fungal endophytes affect seedling recruitment of an invasive annual grass.

Omacini, Marina ¹, Chaneton, Enrique ¹, Ghersa, Claudio ¹, bush, Lowell², ¹ IFEVA/CONICET and Facultad de Agronomía, Ciudad de Buenos Aires, Argentina² University of Kentucky, Lexington, Kentucky, USA

ABSTRACT- [:lt]i[:gt]Neotyphodium[:lt]/i[:gt] endophytes (Ascomycota, Clavicipitaceae) infect the leaves and seeds of many temperate grasses. Grass endophytes alter host plant chemistry and ecophysiology usually increasing the host′s resistance to both biotic and abiotic stressors. In addition, litter deposited by endophytic grasses may differentially influence recruitment of infected and noninfected conspecifics in the next generation through effects on microsite conditions. A greenhouse experiment was designed to evaluate endophyte effects on host regeneration from seeds exposed to microhabitats created by different levels of aboveground litter accumulation and soil moisture content. We studied seedling recruitment and herbivory in microcosms sown with endophyte-infected or endophyte-free <i[:gt]Lolium multiflorum</i> seeds under a factorial combination of litter quantity (3 levels), litter quality (produced by infected or uninfected plants), and water addition (2 levels). Sowing infected seeds significatly increased <i[:gt]Lolium</i[:gt] final recruitment, independent of microsite conditions. Water addition and litter quality equally affected infected and uninfected plants recruitment. Both the number of established plants and the proportion of seedlings damaged by leaf-cutting ants were significantly reduced in plots covered by the litter derived from infected plants. Loline-type alkaloids were found only in endophyte-infected seedlings. Intriguingly, the concentration and composition of these alkaloids in seedling tissues were affected by litter quantity, not by the watering regime. Our results suggest that endophytes can mediate plant replacement patterns within a patch through different pathways involving both actual and historical effects.

Key words: Neotyphodium, herbivory, litter, symbiosis