Seed coat composition in black and white soybean seeds with differential water permeability

Abstract

The seed coat composition of white (JS 335) and black (Bhatt) soybean (Glycine max (L.) Merr) having different water permeability was studied. Phenols, tannins and proteins were measured, as well as trace elements and metabolites in the seed coats. The seed coat of Bhatt was impermeable and imposed dormancy, while that of JS 335 was permeable and seeds exhibited imbibitional injury. Bhatt seed coats contained comparatively higher concentrations of phenols, tannins, proteins, Fe and Cu than those of JS 335. Metabolites of seed coats of both genotypes contained 164 compounds, among which only 14 were common to both cultivars, while the remaining 79 and 71 compounds were unique to JS 331 and Bhatt, respectively. Phenols are the main compounds responsible for seed coat impermeability and accumulate in palisade cells of Bhatt, providing impermeability and strength to the seed coat. JS 335 had more cracked seed coats, mainly due to their lower tannin content. Alkanes, esters, carboxylic acids and alcohols were common to both genotypes, while cyclic thiocarbamate (1.07%), monoterpene alcohols (1.07%), nitric esters (1.07%), phenoxazine (1.07%) and sulphoxide (1.07%) compounds were unique to the JS 335 seed coat, while aldehydes (2.35%), amides (1.17%), azoles (1.17%) and sugar moieties (1.17%) were unique to Bhatt seed coats. This study provides a platform for isolation and understanding of each identified compound for its function in seed coat permeability.

Research advances on the hard seededness trait of soybean and the underlying regulatory mechanisms

“…Three major phenolics, namely epicatechin, cyanidin-3-O-glucoside, and delphinidin-3-O-glucoside, were isolated from wild soybean seed coats, and the changes in epicatechin content were significantly positively correlated with the HS trait under different water conditions during seed development and under different gas conditions during seed storage (Zhou et al, 2010). Similarly, Vijayan et al (2023) measured the phenols, tannins, proteins, trace elements, and metabolites in the seed coats of two soybean cultivars exhibiting different levels of water permeability. They found that phenols are the main compounds responsible for seed coat impermeability, which may provide strength to the seed coat.…”