Earth and Life Institute-Agronomy, UCLouvain, Louvain-la-Neuve, Belgium.
CEFE, CNRS, Université de Montpellier, EPHE, IRD, Montpellier, France.
PLoS One. 2022 Aug 2;17(8):e0269992. doi: 10.1371/journal.pone.0269992. eCollection 2022.
For pollinators such as bees, nectar mainly provides carbohydrates and pollen provides proteins, amino acids, and lipids to cover their nutritional needs. Here, to examine differences in pollinator resources, we compared the amino acid profiles and total amino acid contents of pollen from 32 common entomophilous plants in seven families. Our results showed that the amino acid profiles and contents in pollen samples differed according to the plant family and the chromatography method used, i.e., high-performance liquid chromatography (HPLC) versus ion exchange chromatography (IEX). Pollen from Boraginaceae species had the highest total amino acid contents (361.2-504 μg/mg) whereas pollen from the Malvaceae family had the lowest total amino acid contents (136-243.1 μg/mg). Calculating an amino acid score (AAS) that reflects pollen nutritional quality showed that slightly less than half of the species (19 out of 32) had the maximum nutritional score (AAS = 1) and offered high nutritional quality pollen amino acids for bee pollinators. Though they had high total amino acid contents, the amino acid composition of the studied Boraginaceae species and several members of the Fabaceae was not optimal, as their pollen was deficient in some essential amino acids, resulting in suboptimal amino acid scores (AAS < 0.7). Except for cysteine, the measured amino acid contents were higher using IEX chromatography than using HPLC. IEX chromatography is more robust and is to be preferred over HPLC in future amino acid analyses. Moreover, our observations show that some bee-pollinated species fail to provide complete amino acid resources for their pollinators. Although the implications for pollinator behavior remain to be studied, these deficiencies may force pollinators to forage from different species to obtain all nutritionial requirements.
对于传粉者(如蜜蜂)来说,花蜜主要提供碳水化合物,花粉则提供蛋白质、氨基酸和脂质,以满足其营养需求。在这里,为了研究传粉者资源的差异,我们比较了来自 7 个科的 32 种常见虫媒植物的花粉中的氨基酸图谱和总氨基酸含量。我们的结果表明,花粉样本中的氨基酸图谱和含量因植物科和所用的色谱方法(高效液相色谱法[HPLC]与离子交换色谱法[IEX])而异。滨藜科植物的花粉总氨基酸含量最高(361.2-504μg/mg),而锦葵科植物的花粉总氨基酸含量最低(136-243.1μg/mg)。计算反映花粉营养质量的氨基酸评分(AAS)表明,略少于一半的物种(32 种中的 19 种)具有最大的营养评分(AAS=1),并为蜜蜂传粉者提供了高营养价值的花粉氨基酸。尽管这些滨藜科植物和几种豆科植物的花粉总氨基酸含量较高,但氨基酸组成并不理想,因为它们的花粉缺乏一些必需氨基酸,导致氨基酸评分(AAS<0.7)不理想。除了半胱氨酸外,使用 IEX 色谱法测量的氨基酸含量高于使用 HPLC 法。在未来的氨基酸分析中,IEX 色谱法比 HPLC 更稳健,应优先选用。此外,我们的观察表明,一些被蜜蜂授粉的物种无法为其传粉者提供完整的氨基酸资源。虽然传粉者行为的影响仍有待研究,但这些不足可能迫使传粉者从不同的物种中觅食以获得所有的营养需求。