Root knot nematode species, such as Meloidogyne hapla, M. incognita, M. arenaria and M. javanica are economically most notorious nematode pests, causing serious damage to the various crops throughout world. In this study, DNA sequence analyses of the D1-D3 expansion segments of the 28S gene in the ribosomal DNA were conducted to characterize genetic variation of the four Meloidogyne species obtained from Korea and United States. PCR-RFLP (Polymerase Chain Reaction-Restriction Fragment Length Polymorphism), SCAR (Sequence Characterized Amplified Region) marker and RAPD (Random Amplification of Polymorphic DNA) also were used to develop the methods for exact and rapid species identification. In the sequence analysis of the D1-D3 expansion segments, only a few nucleotide sequence variation were detected among M. incognita, M. arenaria, and M. javanica, except for M. hapla. The PCR-RFLP analysis that involves amplification of the mitochondrial COII and lrRNA region yielded one distinct amplicon for M. hapla at 500 bp, enabling us to distinguish M. hapla from M. incognita, M. arenaria, M. javanica reproduced by obligate mitotic parthenogenesis. SCAR markers successfully identified the four root knot nematode species tested. We are under development of RAPD primers specific to the three root knot nematodes found in Korea.

Fermented soybean food is one of most economical and health food due to its valuable nutritional and medicinal attributes and have been consumed for centuries as flavoring ingredient in Korea. On fermented soybean food such as doenjang, aroma compounds are important property because they determine taste and grade of fermentation. This study investigated variety of aroma compounds of doenjang made from different soybean genotypes. Aroma compounds in twelve different doenjang made from two cultivar (Daewon and Taekwang) and ten elite lines were extracted by steam distillation extraction (SDE) method and analyzed by gas chromatography/mass spectrometry (GC/MS). Aroma compound were detected over 80 kinds in eight samples (Daewon, Taekwang, MY177, MY187, MY189, MY192, MY204 and MY205) and under 70 kinds in four samples (yeonchun1, MY188, MY203 and MY206). Among the detected aroma components, 47 compounds were assigned as aromatic compounds (21), long chain fatty acid (13), short chain fatty acid (5) and others (8) by the computer library (Wiley 7n program). The major aroma compounds in twelve different doenjang were benzaldehyde, benzeneacetaldehyde, 2-methoxy-4-vinylphenol, pyrazine type compounds, cysteaminesulfonic acid, palmitic acid, oleic acid and linoleic acid. Each doenjang made by same condition (microbe, temperature, aging time and etc) had a difference in ratio and variety of aroma compounds due to different components having soybean genotype.