Polyploidy induction is recognized as one of the major evolutionary processes that presents a variety of remarkable morphological, physiological, and genetic variations in plants [
1,
2,
3]. In Fabaceous crops such as soybean, also known as soja bean or soya bean, Kim
et al. [
1] reported a paleopolypoidy history that dates back to approximately 56.5 million years ago, which is similar to that of common bean and other
Glycine specific polyploids. Such history on evolution and diversification of plant species also drove soybean domestication, and the improvement of its agronomic, as well as nutritional characteristics [
4]. Both soybean’s evolutionary information and domestication made this crop to become one of the current major sources of dietary carbohydrates, fibre, minerals, oil, proteins and vitamins for human and animal consumption [
5]. Generally, plant polyploidization is comprised of the multiplication of a complete set of chromosomes that co-exist within a single cell nucleus. Progenies, subsequently leading to the formation of diversified species’ mutant varieties [
6], can stably inherit these newly formed genomic features. In leguminous plants, likewise in non-leguminous species like rice, wheat, tomato, cutleaf groundcherry etc., polyploidization has been widely tested using chemicals such as colchicine [
7], epoxomicin [
8], sodium azide [
9], oryzalin [
10], nitroxide [
11] and ethyl methanesulfonate [
12], some of which are illustrated below in
Figure 1. These chemical compounds cause numerous genetic mutations that result in significant changes on the plant’s nuclear and proteome systems. Although, the induced mutations can cause genetic defects, and undesirable deformities that could be easily identified through phenotypic evaluations, changes incurred also serve as alternative means of achieving genetic variations, which contribute to the much needed species diversity. Mastuti et al. [
13] reported variations in growth response characteristics of the different types of explants treated with 0.1% colchicine solution for 0, 24, 48 and 72 hours in
Physalis angulate. In specifically targeting the proteasome using epoxomicin, van der Hoorn et al. [
14] demonstrated unexpected changes in
Arabidopsis’ protein activities during defense and stress response. Even though, epoxomicin has been widely reported mainly as an antitumoral natural product inhibiting primarily chymotrypsin-like activity [
15]. Mutagenesis studies in
Saccharomyces cerevisiae and other organisms, in combination with proteomics, revealed that this chemical indirectly induces irreversible mutations.
This chemical influences proteolytic systems in the cytosol and nucleus to alter cell growth and gene expression regulations in living cells [
16,
17,
18,
19]. However, nitroxide regulates plant morphogenesis and development through post-translational protein modifications, calcium pump, hormonal regulations, and reduction of reactive oxygen species (ROS) activity [
18]. Meanwhile, other studies show that oryzalin induced polyploidy in plants by disrupting microtubule formations, similar to the preventative anisotropic growth effects of colchicine [
20]. Interestingly, for proper plant growth, vegetative development and reproduction under high salt concentrations, mutagenic chemicals could also be used to enhance morpho-physiological and biochemical adaptive response mechanisms of plants. The ability of plants to respond and survive under salinity stress remains a priority as this abiotic condition essentially reduces cell water potential causing dehydration and ion cytotoxicity. This stress, resulting from the combinational effects of over-irrigation and poor soil drainage, disrupted soybean growth like many other plants by hindering seed germination, seedling development, flowering and fruiting [
11,
20,
21,
22,
23].
This review, therefore, describes the role of synthetic polyploid plant production in soybean for the mitigation against high soil salt stress levels, and then briefly discusses how this evolving approach could be used to further enhance the nutritional, pharmaceutical and economic value of this and other leguminous crops, including addressing challenges involved during the polyploidization process under both in vivo and in vitro conditions.