Proteomic insights into synthesis of isoflavonoids in soybean seeds

Abstract

Soybean seeds are the major human dietary source of isoflavonoids, a class of plant natural products almost entirely exclusive to legumes. Isoflavonoids reduce the risk of a number of chronic human illnesses. Biosynthesis and accumulation of this class of compounds is a multigenic and complex trait, with a great deal of variability among soybean cultivars and with respect to the environment. There is a wealth of genomic, transcriptomic, and metabolomics data regarding isoflavonoid biosynthesis, but the connection between multigene families and their cognate proteins is a missing link that could provide us with a great deal of functional information. The changing proteome of the developing seed can shed light on the correlative increase in isoflavonoids, while the maternal seed coat proteome can provide the link with inherited metabolic and signaling machinery. In this effort, 'seed-filling' proteomics has revealed key secondary metabolite enzymes that quantitatively vary throughout seed development. Seed coat proteomics has revealed the existence of metabolic apparatus specific to isoflavonoid biosynthesis (isoflavonoid reductase) that could potentially influence the chemical content of this organ. The future of proteomic analysis of isoflavonoid biosynthesis should be centered on the development of quantitative, tissue-specific proteomes that emphasize low-abundance metabolic proteins to extract the whole suite of factors involved.

Twin anchors of the soybean isoflavonoid metabolon: evidence for tethering of the complex to the endoplasmic reticulum by IFS and C4H

“…The rapid induction of isoflavonoid biosynthesis in response to stress in legume plants is one of the major pieces of evidence supporting the existence of a metabolon. Research into the protein profiles of soybean tissue before and after inoculation has added to our understanding of this plant response (Dastmalchi and Dhaubhadel, ). Infection of soybean root hairs by Bradyrhizobium japonicum causes increased expression of GmPAL and GmCHI, two proteins implicated in the isoflavonoid metabolon, the former through interaction with the C4H anchor and the latter through interaction with both IFS and C4H (Wan et al ., ; Nguyen et al ., ).…”

“…Sample extraction and preparation are crucial for the analysis of low‐abundance proteins, such as those involved in specialized metabolism. Unfortunately, these proteins are often masked in the LC‐MS/MS method by highly abundant proteins of the translation machinery, and other key cellular processes (Dastmalchi and Dhaubhadel, ). It is also evident from the distribution of unique peptides associated with the list of 244 candidates that those of specialized metabolism have low coverage.…”

Identification and Characterization of Flavonoid Biosynthetic Enzyme Genes in Salvia miltiorrhiza (Lamiaceae)

“…The biosynthetic pathway of flavonoids has been generally elucidated from studies in numerous plant species ( Figure 1 ). Thus, enzymes catalyzing flavonoid biosynthesis have been analyzed in various plant species, such as Arabidopsis thaliana [ 4 ], Glycine max [ 5 ], and Vitis vinifera [ 3 ]. Chalcone synthase (CHS, EC 2.3.1.74) acts in the first step of the flavonoid biosynthetic pathway.…”

Transcriptomic evidence for the control of soybean root isoflavonoid content by regulation of overlapping phenylpropanoid pathways

“…There are at least nine CHS genes in soybean ( GmCHS1-GmCHS9 ) that share 89.43 to 99.48% sequence identity at the amino acid level [6]. Members of the CHS gene family are differentially expressed, respond to different stimuli, and have shown functional divergence.…”