Simulated folivory increases vertical transmission of fungal endophytes that deter herbivores and alter tolerance to herbivory in Poa autumnalis
Simulated folivory increases vertical transmission of fungal endophytes that deter herbivores and alter tolerance to herbivory in Poa autumnalis
复制标题
模拟叶面取食增加了内生真菌的垂直传播，从而阻止了草食动物并改变了早熟禾对草食动物的耐受性
DOI：
10.1093/aob/mcaa021
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发表时间：
2020-05-08
期刊：
影响因子：
4.2
通讯作者：
Rudgers, Jennifer A.
中科院分区：
文献类型：
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作者：
Gundel, Pedro E.;Sun, Prudence;Rudgers, Jennifer A.
背景和目的：维持寄主种群中共生流行率变化的过程尚不清楚。虽然已经清楚地表明，共生的健康益处驱动了共生患病率的变化，但对传播率的研究却很少。许多草寄主共生真菌（Epichloe spp.），它可以垂直传播到种子或通过孢子水平传播。这些共生体可以通过产生生物碱或增加对损害的耐受性来保护植物免受食草动物的侵害。因此，食草性可能是一个关键的生态因素，通过影响共生体对宿主适应性的益处或共生体的传播率来改变共生体在宿主种群中的流行。在这里，我们解决了以下问题：共生体的存在是否调节植物对草食的耐受性？folivory是否增加了共生体向种子的垂直传播或幼苗中的菌丝密度？具有共生体水平传播的植物是否比没有水平传播的植物具有更低的垂直传播率？方法：对秋草及其共生真菌进行研究。我们测量了植物的适应性（存活率，生长）。在3年的普通园林试验中，模拟叶面后的繁殖和共生传播到种子，并调查了不同共生传播方式的自然种群。【关键词】秋牡丹寄主有两个epiichloe类群。一种未描述的垂直传播的Epichloe sp. patg -1和E. typhina亚sp。具有垂直和水平传输的Poae。模拟叶面降低了植物的存活率，但内生菌的存在增加了对损害的耐受性并提高了适应性。叶分增加了幼苗内的垂直传播和菌丝密度，表明对受损植株后代的诱导保护。在自然种群中，垂直传播的流行与共生体流行无关，也与传播方式无关。结论：草食性不仅介导了共生的生殖适宜性效益，而且通过增加真菌向下一代的垂直传播促进了共生的盛行。我们的研究结果揭示了一种新的机制，通过这种机制，食草动物可以影响宿主种群中微生物共生体的流行。
Background and Aims: The processes that maintain variation in the prevalence of symbioses within host populations are not well understood. While the fitness benefits of symbiosis have clearly been shown to drive changes in symbiont prevalence, the rate of transmission has been less well studied. Many grasses host symbiotic fungi (Epichloe spp.), which can be transmitted vertically to seeds or horizontally via spores. These symbionts may protect plants against herbivores by producing alkaloids or by increasing tolerance to damage. Therefore, herbivory may be a key ecological factor that alters symbiont prevalence within host populations by affecting either symbiont benefits to host fitness or the symbiont transmission rate. Here, we addressed the following questions: Does symbiont presence modulate plant tolerance to herbivory? Does folivory increase symbiont vertical transmission to seeds or hyphal density in seedlings? Do plants with symbiont horizontal transmission have lower rates of vertical transmission than plants lacking horizontal transmission?Methods: We studied the grass Poa autumnalis and its symbiotic fungi in the genus Epichloe. We measured plant fitness (survival, growth. reproduction) and symbiont transmission to seeds following simulated folivory in a 3-year common garden experiment and surveyed natural populations that varied in mode of symbiont transmission.Key Results: Poa autumnalis hosted two Epichloe taxa. an undescribed vertically transmitted Epichloe sp. PauTG-1 and E. typhina subsp. poae with both vertical and horizontal transmission. Simulated folivory reduced plant survival, but endophyte presence increased tolerance to damage and boosted fitness. Folivoiy increased vertical transmission and hyphal density within seedlings, suggesting induced protection for progeny of damaged plants. Across natural populations, the prevalence of vertical transmission did not correlate with symbiont prevalence or differ with mode of transmission.Conclusions: Herbivory not only mediated the reproductive fitness benefits of symbiosis, but also promoted symbiosis prevalence by increasing vertical transmission of the fungus to the next generation. Our results reveal a new mechanism by which herbivores could influence the prevalence of microbial symbionts in host populations.