Symbioses: Plant, Animal, and Microbe Interactions
Cheplick, Gregory .
Endophytic fungi and population differentiation in wild and cultivated Lolium perenne (Poaceae).
Endophytic fungi are common leaf inhabitants of cool-season grasses. An important prerequisite to the expected coevolution between the symbionts is that there exist variable effects of the endosymbiont on its host in different environments. The impact of endophytes (Neotyphodium lolii) on survival, growth, and reproduction of diverse populations of Lolium perenne from its native range (Italy, Morocco, Turkey, Tunisia) and two United States cultivars was explored in two unmanaged, common gardens 30 m apart in New Jersey, USA. Some plants were treated with a systemic fungicide (benomyl) prior to planting to eliminate endophyte infection. Gardens were established in late August 2008 and were not weeded to provide a quasi-natural environment where competition with herbaceous species was likely. All plants were scored for tiller number and total tiller length in October and December, 2008 and in May 2009; flowering in spring 2009 was assessed by counting flowering tillers (spikes). There were highly significant effects of population and garden on tiller number and lengths but no detectable effects of endophyte infection. Populations from Italy and Morocco and the two US cultivars grew well in one garden with high soil moisture availability, but plants from Tunisia showed the least growth in either garden. Both overwinter survival and post-flowering survival were unaffected by endophytes. Spike production mostly occurred in the garden with greater soil moisture and was strongly influenced by population. A few populations made more spikes when endophyte-infected, but the proportion of plants that flowered was not coupled to infection. Seed production was low and did not differ between infected and uninfected plants.
Due to the absence of consistent endophyte-mediated effects on the growth and reproduction of these differentiated populations, putative coevolutionary relations between the endosymbiont and its native host species remain obscure in this grass-endophyte system. Sweeping assumptions regarding mutualisms in grass-endophyte interactions should not be made in the absence of experimental evidence.
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1 - City University of New York, College of Staten Island, Department Of Biology, Staten Island, New York, 10314, USA
common garden study
Presentation Type: Poster:Posters for Topics
Location: Hall A/Convention Center
Date: Monday, August 2nd, 2010
Time: 5:30 PM