## 1 Introduction  
The soybean (_Glycine max_ L.) is a major legume crop that is widely grown for its edible bean. The reproductive period of the soybean has different stages (R1 to R8), from flowering to maturity, and is important in determining the yield, seed quality, and tolerance to various environmental stresses [1]. The time for attaining maturity is a quantitative trait in soybeans that is controlled by multiple genes and quantitative trait loci (QTL), which enable soybean cultivars to adapt to various regions with diverse day lengths [2,3].  
Based on adaptability, soybean varieties are categorized into different maturity groupings (MGs), which facilitate the identification of the optimally adapted soybean cultivar for a particular region, as well as the most suitable time for souring in that region. [PERSON] and [PERSON] [4] delineated the hypothetically optimum MG zones across the United States based on photoperiod sensitivity. The MGs range from MG 000, for the extremely early-maturing varieties, to MG 10, for the latest-maturing varieties [5]. Recently, [PERSON] and [PERSON] [6] re-delineated the optimum MG zones across the United States using the yield data from 2005 to 2015. [PERSON] et al. [7] described a maturity grouping (MG 0 to MG VII) system for 100 Korean soybean cultivars, according to days to maturity (DTM), based on data obtained in 2005-2006 from Miryang, Korea. [PERSON] et al. (2018) used a maturity ecotype based on DTM to evaluate the effects of the growth period and cumulative temperature on the flowering, maturity, and yield of Korean soybean varieties at Suwon.  
Information on soybean maturity, including genetic diversity, maturity locus, and maturity group and ecotype, have been used for the development and breeding of new varieties adapted to a given MG zone (Korea, 2018; Korea, 2018). Moreover, such information can help breeders and genetic researchers to predict combinations that can produce the best offspring. However, to incorporate the maturity trait into breeding programs, QTLs or genetic markers capable of determining the DTM must first be identified. Among the various genetic markers, simple sequence repeats (SSRs) are better suited to analyzing genetic diversity and marker-assisted selection than other types of molecular markers (Korea, 2018; Korea, 2018). However, certain previously developed SSR markers were often found to be less polymorphic and failed to produce the expected PCR products (Korea, 2018; Korea, 2018; Korea, 2018). Furthermore, these molecular markers can differ in their stability, amplification product quality, and equality of amplification loci, while providing less information regarding the genes of interest (Korea, 2018). These disadvantages limit the use and accuracy of SSR markers for genotyping or breeding programs (Korea, 2018). In 2001, [PERSON] et al. (2018) developed a highly informative genotyping set of SSRs for genetic studies of barley that was not limited by these drawbacks. Therefore, we conducted this study to similarly develop SSR markers with high resolution, as well as improved efficiency, precision, and reliability for the genetic study of the soybean pod maturity trait.