A Simple Approach to Analyze Sugar Nectar Composition in Flowers Using Capillary Electrophoresis and Enzymatic Assays

Dayanne Bordin,John Kalman,Fernando Genta,Lucas Blanes,Graham Pyke,Philip Doble,Samara Latgé

doi:10.21577/0103-5053.20200114

Abstract

Despite the obvious importance of nectar, the composition of this solution remains surprisingly understudied to most of the flowers. Here we describe a simple, low-cost, and reliable methodology to analyze the three main sugars present in 210 nectar samples of Christmas Bellflowers using capillary electrophoresis (CE) and enzymatic assays. CE separation (-16 kV) was made using an electrolyte containing 36 mM NaOH pH 12, 15 mM sorbic acid, 0.5 mM hexadecyl trimethylammonium bromide (CTAB), and indirect UV detection. 72.9% of analyzed nectar samples were sucrose dominant; 13.3% sucrose rich only and 13.8% were fructose rich. The concentrations of fructose and glucose present in most of the samples were very similar, while the amount of sucrose varied considerably. The average amounts of fructose, glucose, sucrose and total sugar were 0.22, 0.21, 0.34 and 0.8 M, respectively. The nectar sample shows a pH average of 5. α-Glucosidase activity was observed in 65% of the samples with an average activity of 0.013 µU µL-1 providing a possible explanation for the similar concentrations of fructose and glucose in the samples. Under our knowledge, this is the first article that shows the analysis of sugars in nectar flowers using CE.

Highlights

The process of pollination is essential for life on Earth, and approximately 90% of all flowering plant species are animal pollinated
In this article we present the validation of a capillary electrophoresis (CE) method for the analysis of sucrose, glucose and fructose in 210 nectar samples of Christmas Bellflowers (Blandfordia grandiflora) as well as the biochemical detection of an α-glucosidase activity on the samples
Higher concentrations of NaOH did not improve the resolution of glucose and fructose peaks, and caused higher currents, resulting in excessive noise due to the Joule heating effect

Summary

Introduction

The process of pollination is essential for life on Earth, and approximately 90% of all flowering plant species are animal pollinated. Floral nectar is an important reward to animals to facilitate pollination, floral nectars remain surprisingly understudied.[1,2] Nectar components, including sugars, amino acids, and other classes of substances are not well characterized and new compounds continue to be discovered.[3] Nectars mainly contain varying proportions of glucose, sucrose, fructose and with smaller quantities of other sugars and organic and inorganic substances.[4]. Nectar characteristics such as concentration, sugar composition, time of nectar secretion, sucrose-hexose. Invertase enzymes, such as transglucosidase and transfructosidase, have been identified in the secretory mechanism, showing essential functions of nectar chemistry.[1] α-Glucosidases may

Methods

Results

Conclusion