Light converts endosymbiotic fungus to pathogen, influencing seedling survival and niche-space filling of a common tropical tree, Iriartea deltoidea.
Light converts endosymbiotic fungus to pathogen, influencing seedling survival and niche-space filling of a common tropical tree, Iriartea deltoidea.
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DOI：
10.1371/journal.pone.0016386
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发表时间：
2011-01-31
期刊：
影响因子：
3.7
通讯作者：
Gil N
中科院分区：
文献类型：
--
作者：
Álvarez-Loayza P;White JF Jr;Torres MS;Balslev H;Kristiansen T;Svenning JC;Gil N
病原体被认为在维持热带森林植物物种丰富度中起着重要作用。值得注意的是，寄主种群与病原菌的相互作用可能导致生态位空间不完全填充，从而促进物种丰富度的提高。一组潜在的重要病原体是内生真菌，它们无症状地定殖植物，在热带生态系统中种类繁多。内生菌可以改变寄主个体的竞争能力，提高寄主在逆境下的适应性，但也可能具有致病性。关于内生菌对寄主生态位空间填充的影响，目前所知甚少。在这里，我们评估了感染普通热带棕榈的广泛真菌内生菌如何影响其在自然生态系统中的招募和生存，以及这种影响是否受到非生物环境的调节，潜在地限制了宿主生态位空间的填充。伊里亚特三角洲在许多潮湿的低地新热带森林中占优势。残双plodia是成熟植物中一种常见的无症状内生菌；然而，它会导致一些幼苗生病。我们研究了光效对残蝇病表达的影响。我们发现，在阴凉条件下，三角花幼苗优先生长。相应地，我们还发现强光会触发内生菌的致病性，而弱光则有利于内生共生的发展，通过降低幼苗在直射光下的存活率，限制了内生菌侵染的幼苗向遮荫林下的招募。强光下的致病性被认为是由于真菌在光诱导下产生H2O2，引发掌部的超敏反应、细胞死亡和组织坏死。这是第一个研究表明，内生菌响应非生物因素影响植物在自然生态系统中的分布；也是第一个发现光是影响内生菌在内生菌-病原体连续体中的位置的因素。我们的研究结果表明，病原体确实可以限制其他成功的热带植物物种的生态位空间填充，为其他物种提供未被占用的生态位空间。
Pathogens are hypothesized to play an important role in the maintenance of tropical forest plant species richness. Notably, species richness may be promoted by incomplete filling of niche space due interactions of host populations with their pathogens. A potentially important group of pathogens are endophytic fungi, which asymptomatically colonize plants and are diverse and abundant in tropical ecosystems. Endophytes may alter competitive abilities of host individuals and improve host fitness under stress, but may also become pathogenic. Little is known of the impacts of endophytes on niche-space filling of their hosts. Here we evaluate how a widespread fungal endophyte infecting a common tropical palm influences its recruitment and survival in natural ecosystems, and whether this impact is modulated by the abiotic environment, potentially constraining host niche-space filling. Iriartea deltoidea dominates many wet lowland Neotropical forests. Diplodia mutila is a common asymptomatic endophyte in mature plants; however, it causes disease in some seedlings. We investigated the effects of light availability on D. mutila disease expression. We found I. deltoidea seedlings to preferentially occur under shady conditions. Correspondingly, we also found that high light triggers endophyte pathogenicity, while low light favors endosymbiotic development, constraining recruitment of endophyte-infested seedlings to shaded understory by reducing seedling survival in direct light. Pathogenicity of D. mutila under high light is proposed to result from light-induced production of H2O2 by the fungus, triggering hypersensitivity, cell death, and tissue necrosis in the palm. This is the first study to demonstrate that endophytes respond to abiotic factors to influence plant distributions in natural ecosystems; and the first to identify light as a factor influencing where an endophyte is placed on the endosymbiont–pathogen continuum. Our findings show that pathogens can indeed constrain niche-space filling of otherwise successful tropical plant species, providing unoccupied niche space for other species.
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影响因子：
16.5
作者：
Crous PW;Slippers B;Wingfield MJ;Rheeder J;Marasas WF;Philips AJ;Alves A;Burgess T;Barber P;Groenewald JZ
通讯作者：
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DOI：
10.1073/pnas.2533483100
发表时间：
2003-12-23
影响因子：
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作者：
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影响因子：
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作者：
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影响因子：
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作者：
Clay, K;Holah, J
通讯作者：
Holah, J