A single recessive gene, rxp, controls bacterial leaf pustule (BLP) resistance in a soybean. The Rxp locus appears to be linked to the malate dehydrogenase (Mdh) locus and Satt372 on linkage group (LG) D2. Around the Rxp locus, four bacterial artificial chromosome (BAC) clones are anchored by Satt486, Satt498, BARC-022037-04263, and BARC-040963-07870. Using these BAC clone sequences, possible orthologous region of Rxp locus was identified: Medicago truncatula contig 962 at chromosome 3 and contig 283 and contig 1108 at chromosome 8. Sequence analysis of contig 962 had revealed microsynteny with three soybean BAC clones on LG A1, which are duplicated with other two soybean BAC clones anchored by Satt486 and Satt498. After BLAST search was performed with M. truncatula contig 962 against soybean ESTs, several soybean ESTs were identified. With developed single nucleotide polymorphism (SNP) markers and the RIL population from the cross of Pureunkong and Jinpumkong 2, SNP genotyping was able to locate twos oybean ESTs: CO979743 at 1 cM away from Satt195 on LG C1 and BE021935 at 5 cM away from Satt363 on LG C2. Thus, our results indicate that structure of soybean genome around Rxp locus is very complicated.

A new black seed coat soybean variety, “Socheong” was developed at the Yeongnam Agricultural Research Institute (YARI) in 2006. The goal to breed the black seed coat soybean is to develop the cultivar with high yield, lodging tolerance, resistant to disease such as soybean mosaic virus (SMV), and bacterial pustule and seed size. Socheong was selected from the cross between Milyang 78, which was late maturing, susceptible to lodging and SMV and with large seed size and green cotyledon, and Peking which was tolerant to lodging and with small seed size. The preliminary, advanced and regional yield trials for evaluation and selection of this variety were carried out from 2002 to 2006. It has determinate growth habit, white flower, brown pubescence, brown pod color, black seed coat, green cotyledon, elongated flattened seed shape, oval leaf shape and small seed size (15.7 grams per 100 seeds), and it was 3 days later in maturity than the check cultivar Cheongjakong. Socheong was higher, in the seed quality of sucrose and total sugar contents (6.8 and 8.2%) and isoflavone contents (1,754 ㎍/g) than the check cultivar. Futhermore, it has good characteristics for mechanical harvest, such as lodging tolerance, pod shattering and stem diameter. It also has been identified to have resistance to soybean mosaic virus symptom which was the troublesome soybean diseases. The average yield of Socheong was 2.21 ton per hectare in the regional yield trials carried out in four locations of Korea among seven locations from 2004 to 2006, which was 5 percent lower than the check cultivar Cheongjakong.

A new black seed coat soybean cultivar, “Heugmi” was developed at the Yeongnam Agricultural Research Institute (YARI) in 2006. The goal to breed the black seed coat soybean is to develop the cultivar with high yield, lodging tolerance, resistant to disease such as soybean mosaic virus (SMV), and bacterial pustule and seed size. Heugmi was selected from the cross between Milyang 78, which was late maturing, susceptible to lodging and SMV and with large seed size and green cotyledon, and Milyang 68, which was middle maturing, resistant to lodging and SMV and with middle seed size and yellow cotyledon. The preliminary, advanced and regional yield trials for evaluation and selection of this cultivar were carried out from 2001 to 2006. It has determinate growth habit, purple flower, brown pubescence, black pod color, black seed coat, green cotyledon, spherical seed shape, oval leaf shape and middle seed size (24.8 grams per 100 seeds), and it was 2 days earlier in maturity than the check cultivar Cheongjakong. Heugmi was better in the seed quality of crude protein contents, sucrose and total sugar contents than the check cultivar. It also has been identified to have resistance to SMV which was the troublesome soybean diseases. The average yield of Heugmi was 2.53 ton per hectare in the regional yield trials carried out in seven locations of Korea from 2004 to 2006, which was 8 percent higher than the check cultivar Cheongjakong.

A new sprout-soybean cultivar, “Wonhwang” was developed at the Honam Agricultural Research Institute (HARI) in 2005. Wonhwang was selected from a cross between Camp and Myeongjunamulkong. The preliminary, advanced, and regional yield trials for evaluation and selection of Iksan45 were carried out from 2001 to 2005. This cultivar has a determinate growth habit with purple flower, grayish brown pubescence, grayish brow hilum, lanceolate leaflet shape and small seed size (10.0 grams per 100 seeds). The maturity date of Wonhwang is 7 days earlier than that of the check variety, Pungsan. It has good seed quality for soybean-sprout, and resistance to lodging. It has also been identified to have resistance to soybean mosaic virus (SMV) and necrotic symptom(SMV-N). The average yield of “Wonhwang” was 2.80MT/ha, which was higher by 4% than “Pungsannamulkong” at the regional yield trials.