Soybean, the raw material for natto (fermented soybeans), tofu (soybean curd), miso (traditional seasoning), soy sauce and edamame (vegetable soybean), is a very familiar crop to the Japanese people. Globally, it is one of the most economically important crops as it is used as a raw material for cooking oil as well as processed foods, and as livestock feed due to its high protein content. According to the ResourceTrade.Earth dashboard, which deals with commodity trade data, the agricultural products traded in 2019 are grains (507 million tons), oil crops (392 mt), and fruits and vegetables (181 mt) in order of weight rank. However, by commodity, soybeans (239 mt) ranked first in terms of trade volume, surpassing wheat (214 mt). In terms of price, the most traded commodities are fruits and vegetables ($234 bn), oil crops ($188 bn) and grains ($135 bn), and by category, fruits and berries ($122 bn) is followed by soybeans ($99.3 bn) in second place.

Soybeans come in a variety of colors and sizes, each with different uses. The size of soybeans is an important factor in determining yield, and the shape is very important for processing in the food industry. In order to develop soybean varieties with the desired size and shape for different uses, it is necessary to understand the genes that determine these traits. In the development of crop varieties, it is important to understand DNA (deoxyribonucleic acid), a macromolecular biological material responsible for the inheritance and expression of genetic information. The DNA sequence encodes genetic information, and DNA sequencing has been developed as a basic method to analyze such genetic information.

At JIRCAS, we analyzed the DNA sequence variations of soybean varieties with different seed size and shape, as well as their hybrid offsprings, using a next-generation sequencer capable of rapid sequencing, and identified many DNA regions on the chromosomes that control seed size and shape of soybean (quantitative trait loci: QTL). After several years of field experiments, the QTL related to seed shape on chromosome 2 of the 20 soybean chromosomes was validated and its candidate genes were mined. The results of this research will assist in breeding programs to improve seed size and shape traits for the development of new soybean varieties with high yield and suitability for processing. The results are published on April 16, 2021 in Frontiers in Genetics.

Reference
Giriraj Kumawat and Donghe Xu (2021) A Major and Stable Quantitative Trait Locus qSS2 for Seed Size and Shape Traits in a Soybean RIL Population. Front. Genet.
https://doi.org/10.3389/fgene.2021.646102

Contributor: XU Donghe (Biological Resources and Post-harvest Division)