Nutraceutical profiling of elite onion germplasm and breeding hybrids with improved nutraceutical quality.

Najma Tabussam,Yongqiang Lu,Muhammad Sheeraz Ahmad,Rashid Mehmood Rana,Muhammad Kausar Nawaz Shah,Muhammad Sajjad,Muhammad Abdul Rehman Rashid

doi:10.1371/journal.pone.0262705

Abstract

Onion (Allium cepa L) is a major reservoir of important nutraceutical ingredients. Herein, nutraceutical profiling of elite germplasm was assessed and hybrids with improved nutraceutical quality were selected. The nutraceutical components were screened through Fourier Transform Infrared Spectroscopy (FTIR) analysis (scan range 4000-400cm-1) followed by spectrophotometric/colorimetric quantification in oven dried bulb samples. Line × Tester (L×T) analysis was used to identify potential hybrids with better nutraceutical quality. Based on common functional groups obtained from FTIR analysis, as well as bulb color, the onion genotypes were categorized into six groups viz., white, yellowish brown, light brown, dark brown, brown and purplish brown. Results indicated that the purplish brown, yellowish brown and dark brown genotypes had maximum concentration of pyruvic acid, total flavonoids and total phenolic content, while vitamin C content showed weak association with color pigmentation. The onion variety ‘Onion Swat’ contained the highest level of pyruvic acid (17.18 μM) and ‘MKS8823GO’ had the highest vitamin C content (13.83mg/100mL). The L×T analysis revealed that out of 35 crosses, ‘MKS-77127 × Onion Swat’ and ‘MKS-77127 × MKS777’ were the best hybrids with improved nutraceutical quality. Further, observations for specific combining ability, general combining ability, genetic versus environmental variance, heritability and heterosis indicated that the studied parameters were genetically inherited and could be improved significantly by adopting an appropriate breeding strategy.

Highlights

Vegetables are important since they contain components of nutritional importance including vitamins, minerals, phytonutrients and fibre as well as provide some carbohydrates
The Fourier Transform Infrared Spectroscopy (FTIR) spectra of onion genotypes were shown in the S1 Fig. The data on peak values and functional groups as analyzed by FTIR showed strong characteristic absorption bands at different wavelengths (Table 1)
Germplasm was screened for nutraceutical contents using FTIR and spectrophotometery/colorimetry

Summary

Introduction

Vegetables are important since they contain components of nutritional importance including vitamins, minerals, phytonutrients and fibre as well as provide some carbohydrates. Amount of pyruvic acid produced during this reaction is best indicator of flavor precursors and has been used to measure onion pungency [4] Phytochemicals such as flavonoids, phenolics and anthocyanins present in onion have therapeutical and pharmaceutical utility [5]. Phytochemicals presence in onion justifies various health benefits associated with onion, for example, it reduces the risk of gastric ulcer by scavenging free oxygen radicals and by inhibiting the development of ulcer forming microorganism. It is used as an antibacterial and antiparasitic agent [6]

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Discussion

Conclusion