Contrasting effects of yeasts and bacteria on floral nectar traits
Contrasting effects of yeasts and bacteria on floral nectar traits
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DOI：
10.1093/aob/mcy032
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发表时间：
2018-06
期刊：
影响因子：
4.2
通讯作者：
R. Vannette;T. Fukami
中科院分区：
文献类型：
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作者：
R. Vannette;T. Fukami
背景和目的花蜜的体积和化学成分可能有很大的变化，即使在同一植物中也是如此，但这种变化的原因尚不完全清楚。一个潜在的原因是定植花蜜的细菌和酵母菌，但很大程度上缺乏分离它们对野花影响的实验测试。这项研究考察了酵母菌和细菌的优势物种对加州蜂鸟授粉灌木Mimulus aurantiacus的影响。方法野花接种与田间滴度相关的酵母Metschnikowia reukaufii或细菌Neokomagataea sp.。(前身为Gluconbacter sp.)，均分离自橙花蜜。将新开的花朵套袋，接种，3d后采收，分析微生物丰度、花蜜体积、糖和氨基酸的浓度和组成。关键结果：接种酵母菌降低了花蜜中的氨基酸浓度，改变了氨基酸组成，但对蜜汁体积和糖类组成无显著影响。相反，接种细菌增加了氨基酸浓度，增加了由单糖组成的蜜糖比例，减少了蜜汁体积。结论研究结果表明，花蜜中的微生物群落通过酵母菌和细菌对花蜜化学和有效性的不同影响，可能改变了植物-传粉者之间的相互作用，从而使花蜜特性在不同的花朵之间发生了变化。
Background and Aims Flowers can be highly variable in nectar volume and chemical composition, even within the same plant, but the causes of this variation are not fully understood. One potential cause is nectar-colonizing bacteria and yeasts, but experimental tests isolating their effects on wildflowers are largely lacking. This study examines the effects of dominant species of yeasts and bacteria on the hummingbird-pollinated shrub, Mimulus aurantiacus, in California. Methods Wildflowers were inoculated with field-relevant titres of either the yeast Metschnikowia reukaufii or the bacterium Neokomagataea sp. (formerly Gluconobacter sp.), both isolated from M. aurantiacus nectar. Newly opened flowers were bagged, inoculated, harvested after 3 d and analysed for microbial abundance, nectar volume, and sugar and amino acid concentration and composition. Key Results Yeast inoculation reduced amino acid concentration and altered amino acid composition, but had no significant effect on nectar volume or sugar composition. In contrast, bacterial inoculation increased amino acid concentration, enhanced the proportion of nectar sugars comprised by monosaccharides, and reduced nectar volume. Conclusions The results presented suggest that microbial inhabitants of floral nectar can make nectar characteristics variable among flowers through divergent effects of yeasts and bacteria on nectar chemistry and availability, probably modifying plant-pollinator interactions.