Metabolic Profiling Provides Unique Insights to Accumulation and Biosynthesis of Key Secondary Metabolites in Annual Pasture Legumes of Mediterranean Origin.

Sajid Latif,Saliya Gurusinghe,Paul A Weston,Russell A Barrow,John W Piltz,Leslie A Weston

doi:10.3390/metabo10070267

Abstract

Annual legumes from the Mediterranean region are receiving attention in Australia as alternatives to traditional pasture species. The current study employed novel metabolic profiling approaches to quantify key secondary metabolites including phytoestrogens to better understand their biosynthetic regulation in a range of field-grown annual pasture legumes. In addition, total polyphenol and proanthocyanidins were quantified using Folin–Ciocalteu and vanillin assays, respectively. Metabolic profiling coupled with biochemical assay results demonstrated marked differences in the abundance of coumestans, flavonoids, polyphenols, and proanthocyanidins in annual pasture legume species. Genetically related pasture legumes segregated similarly from a chemotaxonomic perspective. A strong and positive association was observed between the concentration of phytoestrogens and upregulation of the flavonoid biosynthetic pathway in annual pasture legumes. Our findings suggest that evolutionary differences in metabolic dynamics and biosynthetic regulation of secondary metabolites have logically occurred over time in various species of annual pasture legumes resulting in enhanced plant defense.

Highlights

Broadacre farming frequently occurs with livestock production throughout southeastern Australia, with the pasture phase of crop rotation sustaining both lamb and cattle enterprises [1]
Bladder clover possessed significantly higher concentrations of both coumestrol and 40 -methoxycoumestrol in leaf tissue compared to other pasture legumes (48.4 and 24.8 mg kg−1, respectively) while in stem tissue, bladder clover had the highest concentration of coumestrol (39.6 mg kg−1 )
Lucerne contained the highest concentration of 40 -methoxycoumestrol (27.7 mg kg−1 ) in any tissue of all species, and lucerne inflorescence tissue contained the highest concentrations of coumestrol and 40 -methoxycoumestrol

Summary

Introduction

Broadacre farming frequently occurs with livestock production throughout southeastern Australia, with the pasture phase of crop rotation sustaining both lamb and cattle enterprises [1]. Lamb and beef production account for the majority of livestock-related income in southeastern Australia (AU$22 billion in 2017) and global demand is projected to dramatically increase over the decade Establishment of pasture species that are non-toxic, persistent, and high in nutritional quality is critical for continued improvement of livestock productivity. Subterranean clover (Trifolium subterraneum L.) and lucerne (Medicago sativa L.) are the most widely utilized pasture species in prime lamb, wool, and cattle producing regions across southeastern Australia. Lucerne is a deep-rooted perennial species frequently established across diverse rainfall regions and is suitable for neutral or mildly alkaline soils. Ingestion of lucerne and subterranean clover is associated with metabolic disorders including acute inflammation of both the small and large intestine (red gut), sodium deficiency and pregnancy-related toxemia [5,6,7]

Methods

Results

Discussion

Conclusion