Imperfect Vertical Transmission of the Endophyte Neotyphodium in Exotic Grasses in Grasslands of the Flooding Pampa
Imperfect Vertical Transmission of the Endophyte Neotyphodium in Exotic Grasses in Grasslands of the Flooding Pampa
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DOI：
10.1007/s00248-008-9447-y
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发表时间：
2009-05-01
影响因子：
3.6
通讯作者：
Omacini, Marina
中科院分区：
文献类型：
--
作者：
Gundel, Pedro E.;Garibaldi, Lucas A.;Omacini, Marina
冷季型牧草与自然界中广泛存在的垂直传播的新伤寒霉内生真菌建立共生关系。封闭种群(即非迁徙种群)中内生真菌感染植株的频率取决于感染和未感染植株之间的差异适合度和内生真菌传播效率。大多数研究都集中在第一种机制上，而忽视了第二种机制。调查了两种牧草的侵染频率和内生真菌从营养组织到种子的传播，这些牧草生长在不同的洪水和放牧制度以及土壤盐分的植被单元中。高羊茅的传播效率和侵染频率差异不显著，分别为0.98和1.00。多花黑麦草在湿润草原的传播效率和感染频率分别为0.88和0.57，在其他植被单元分别为0.96和0.96。只有在湿润的中生草甸，观察到的格局与食草动物的存在与否无关。我们的结果表明，两个物种对内生菌感染的选择力量是不同的。只有在高羊茅中，通过增加受感染植物的适合度，才能补偿不完全的传播。考虑到内生菌的传播可能是不完美的和可变的，仅从不同的适应度来解释感染频率的变化可能会产生误导。因此，这项研究突出了衡量传输效率的重要性。
Cool-season grasses establish symbioses with vertically transmitted Neotyphodium endophytes widespread in nature. The frequency of endophyte-infected plants in closed populations (i.e., without migrations) depends on both the differential fitness between infected and non-infected plants, and the endophyte-transmission efficiency. Most studies have been focused on the first mechanism ignoring the second. Infection frequency and endophyte transmission from vegetative tissues to seeds were surveyed in two grasses growing in vegetation units that differ in flood and grazing regimes, and soil salinity. Transmission efficiency and infection frequency for tall fescue did not vary significantly and were 0.98 and 1.00, respectively. For Italian ryegrass, transmission efficiency and infection frequency were 0.88 and 0.57 in humid prairies, and 0.96 and 0.96 in the other vegetation units. Only in humid mesophytic meadows, the observed pattern was irrespective of the presence or absence of grazers. Our results suggest that selection forces for endophyte infection are different for both species. Imperfect transmission was only compensated in tall fescue through an increased fitness of infected plants. Interpreting variations of infection frequency only in terms of differential fitness can be misleading, considering that endophyte transmission can be imperfect and variable in nature. Therefore, this study highlights the importance of measuring transmission efficiency.