Department of Biology, College of Staten Island, City University of New York, Staten Island, New York 10314, USA.
Am J Bot. 2011 May;98(5):829-38. doi: 10.3732/ajb.1000226.
Endophytic fungi are common inhabitants of cool-season grasses that can affect host growth and reproduction. One prerequisite for the expected coevolution between symbionts is that there exist variable effects of the endosymbiont on its host in different environments. Here, the impact of endophytes ( Neotyphodium lolii ) on survival, growth, and reproduction of wild populations of Lolium perenne from its native range (Italy, Morocco, Turkey, Tunisia) and two United States cultivars was explored.
Two unmanaged, common gardens 30 m apart in New Jersey, USA, were planted with endophyte-infected and uninfected plants of the six populations in August 2008. Plants were scored for tiller number and lengths, and survival in October and December 2008 and May and September 2009; fl owering tillers (spikes) were counted in spring 2009. A greenhouse experiment was designed to assess tiller production and growth of four populations.
There were significant effects of population and garden on tiller number and lengths but no detectable effects of endophytes. Populations from Italy and Morocco and the two US cultivars grew well in one garden, but Tunisian plants grew the least in either garden. Overwinter survival and postfl owering survival were unaffected by endophytes. Spike production was strongly influenced by population. Although populations varied, there were no differences in growth between infected and uninfected plants in the greenhouse.
Due to the absence of unambiguous endophyte-mediated effects on 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.
内生真菌是冷季草的常见居民，它们可以影响宿主的生长和繁殖。共生体之间预期协同进化的一个前提条件是，共生体对其宿主在不同环境中存在可变的影响。在这里，研究了内生真菌（ Neotyphodium lolii ）对其原生范围（意大利、摩洛哥、土耳其、突尼斯）和两个美国品种的野生多年生黑麦草种群的生存、生长和繁殖的影响。
2008 年 8 月，在美国新泽西州相距 30 米的两个无人管理的普通花园中，种植了感染和未感染内生真菌的六个种群的植物。在 2008 年 10 月和 12 月以及 2009 年 5 月和 9 月对植物的分蘖数和长度进行评分；2009 年春季对开花分蘖（穗）进行计数。设计了一个温室实验来评估四个种群的分蘖生产和生长。
种群和花园对分蘖数和长度有显著影响，但内生真菌没有可检测的影响。来自意大利和摩洛哥的种群以及两个美国品种在一个花园中生长良好，但突尼斯植物在两个花园中的生长都最少。越冬后存活率和开花后存活率不受内生真菌的影响。穗产量受种群的强烈影响。尽管种群存在差异，但在温室中，感染和未感染植物之间的生长没有差异。
由于这些分化种群的生长和繁殖没有明显的内生真菌介导效应，因此在这种草 - 内生真菌系统中，内生体与其原生宿主之间的潜在协同进化关系仍然不清楚。
