It has been commonly accepted that soybean domestication originated in East Asia. Although East Asia has the historical merit in soybean production, the USA has become the top soybean producer in the world since 1950s. Following that, Brazil and Argentina have been the major soybean producers since 1970s and 1990s, respectively. China has once been the exporter of soybean to Japan before 1990s, yet she became a net soybean importer as Japan and the Republic of Korea do. Furthermore, the soybean yield per unit area in East Asia has stagnated during the past decade. To improve soybean production and enhance food security in these East Asian countries, much investment has been made, especially in the breeding of better performing soybean germplasms. As a result, China, Japan, and the Republic of Korea have become three important centers for soybean genomic research. With new technologies, the rate and precision of the identification of important genomic loci associated with desired traits from germplasm collections or mutants have increased significantly. Genome editing on soybean is also becoming more established. The year 2019 marked a new era for crop genome editing in the commercialization of the first genome-edited plant product, which is a high-oleic-acid soybean oil. In this review, we have summarized the latest developments in soybean breeding technologies and the remarkable progress in soybean breeding-related research in China, Japan, and the Republic of Korea.

Soybean is an important and valuable crop for global food and feed supply, providing high-quality nutrition. Globally, five countries—namely Brazil, the USA, Argentina, China and India—have dominated soybean production for many years. The intention of this paper is to review the reasons for their dominance, starting with seeds. High-quality seeds enable stress-free, high-density and even planting of soybean in the field. Seed quality assurance is essential for the successful expansion of soybean cultivation. The aim of this review is to compare and contrast the factors impacting soybean seed production in these top five soybean-producing countries, including the situations at different stages of the supply chain; research and development on new soybean varieties; and regulations, rules and quality assurance systems (seed testing, certification and labeling). Since the soybean supply chain involves many different operating parties, principles and practices, efforts on different fronts need to be well coordinated by a central authority to ensure successful production. Recently, China has implemented a revised national “Seed Law”. The possible impacts of this new legal framework on soybean seed development and trading in China are also discussed. The strengthened China Seed law to protect resources and encourage variety innovation, as well as the clearer China GM soybean commercial release policy, implies future soybean cultivation expansion with elite varieties. A continuous global production increase will require every party’s compliance to the sustainability principles.

Key message: The QTLs and candidate genes governing the multifoliolate phenotype were identified by combining linkage mapping with BSR-seq, revealing a possible interplay between genetics and the environment in soybean leaf development. Soybean, as a legume, is typified by trifoliolate leaves. Although multifoliolate leaves (compound leaves with more than three leaflets each) have been reported in soybean, including sporadic appearances in the first compound leaves in a recombinant inbred line (RIL) population from a cross between cultivated soybean C08 and wild soybean W05 from this study, the genetic basis of this phenomenon is still unclear. Here, we integrated quantitative trait locus (QTL) mapping with bulked segregant RNA sequencing (BSR-seq) to identify the genetic loci associated with the multifoliolate phenotype in soybean. Using linkage mapping, ten QTLs related to the multifoliolate trait were identified. Among these, a significant and major QTL, qMF-2-1 on chromosome 2 and consistently detected across biological replicates, explained more than 10% of the phenotypic variation. Together with BSR-seq analyses, which analyzed the RILs with the highest multifoliolate frequencies and those with the lowest frequencies as two distinct bulks, two candidate genes were identified: Glyma.06G204300 encoding the transcription factor TCP5, and Glyma.06G204400 encoding LONGIFOLIA 2 (LNG2). Transcriptome analyses revealed that stress-responsive genes were significantly differentially expressed between high-multifoliolate occurrence lines and low occurrence ones, indicating environmental factors probably influence the appearance of multifoliolate leaves in soybean through stress-responsive genes. Hence, this study offers new insights into the genetic mechanism behind the multifoliolate phenotype in soybean.

Soybean (Glycine max L.) is gaining in importance due to its many uses, including as a food crop and a source of industrial products, among others. Increasing efforts are made to accelerate soybean research and develop new soybean varieties to meet global demands. Soybean research, breeding, identification, and variety protection all rely on precise genomic information. While DNA markers are invaluable tools for these purposes, the older generations, especially those developed before the advent of genome sequencing, lack precision and specificity. Thankfully, advancements in genome sequencing technologies have generated vast amounts of sequence data over the past decade, allowing precise and high-resolution analyses. However, making sense of the genomic information requires a certain level of professional training and computational power, which are not universally available to researchers. To address this, we generated a set of PCR-based DNA markers out of the existing genomic data from 228 popular soybean varieties that offer precise, unambiguous genomic information and can be easily adapted in various applications. A standard operating procedure (SOP) was also designed for these markers and validated on diverse soybean varieties to ensure their reproducibility. This user-friendly universal panel of DNA markers, along with the SOP, will facilitate soybean research and breeding programs through simple applications.