Nectar composition in moth-pollinated Platanthera bifolia and P. chlorantha and its importance for reproductive success

Abstract

Main conclusion Sugars (glucose, fructose and sucrose), as well as proteogenic and non-proteogenic amino acids, are present in the nectar of Platanthera bifolia and P. chlorantha.

Intraspecific Variation in Nectar Chemistry and Its Implications for Insect Visitors: The Case of the Medicinal Plant, Polemonium Caeruleum L.

“…Most of the 29 AAs that were present in the nectar of P. caeruleum often occur in the nectar of other plant species [ 13 , 15 , 42 , 49 , 50 ]. In addition to AAs common in floral nectar, our analysis also revealed the presence of sarcosine, tryptophan, and norvaline, which have been rarely reported in earlier analyses [ 20 , 50 , 51 ]. However, even the effect of well-known AAs on pollinators is often not known.…”

“…Our analysis revealed that the mean content of AAs in nectar samples was 590.3 ± 1006 pmol/µL and it did not differ among populations. However, despite the lack of significant differences in AA concentration, we found significant variation in nectar AA composition between study populations ( Table 1 , Supplementary Materials Table S3 ), as has been presented for other plant species [ 12 , 13 , 14 , 20 , 46 ]. On the other hand, when considering the differences between the three designated geographical regions, there were no observed trends in the AA profile, despite that the percentage share of glutamine varied significantly.…”

“…Phenylalanine is also considered a phagostimulator for bees [ 57 ]. The functions of norvaline, which have already been recorded in the nectar of some monocotyledons [ 20 , 50 ], remain unclear.…”

“…Earlier studies of nectar diversity have postulated that some nectar features, such as sugar and AA profiles, are species-invariant [ 7 , 9 , 10 , 11 ], and some new analyses support a rather conservative proportion of nectar components, that is sugars, between populations of the same species (e.g., [ 12 ]). However, this notion seems to be the result of technical difficulties associated with early analytical methods [ 3 , 13 ] because many recent studies have reported variation in nectar traits between populations, within populations, within one inflorescence, or even among sexual phases of the same flower [ 8 , 12 , 13 , 14 , 15 , 16 , 17 , 18 , 19 , 20 ]. Such variations are mainly a consequence of environmental factors, such as soil properties, air temperature, and sun exposure [ 1 , 2 , 8 , 13 , 21 ], and, according to the latest study, microorganisms inhabiting nectar [ 22 , 23 ].…”

“…Such variations are mainly a consequence of environmental factors, such as soil properties, air temperature, and sun exposure [ 1 , 2 , 8 , 13 , 21 ], and, according to the latest study, microorganisms inhabiting nectar [ 22 , 23 ]. Importantly, the landscape-scale variability in floral rewards may be correlated with habitat quality and may have a significant effect on the reproductive success of a population [ 13 , 17 , 18 , 20 ]. Unfortunately, this variation in nectar constituents, especially in nectar AAs, is still gravely understudied and poorly understood.…”