Soybean [Glycine max (L.) Merr.] is a major agricultural crop widely used for providing human and animal food owing to its high protein and oil content. For this reason, they have been consumed in Asia and world greatly and demand is ever increasing. Soybean is classified as a moderately salt-sensitive crop and its production is greatly affected due to increasing salinity stress. About 8 % of the world’s total land is salt-affected. In Korea, around 9 % of total agricultural land (approximately 130,000ha) was reclaimed since 1960's. In order to meet the demand for soybean and to solve arable land shortage problem, it is unavoidable to cultivate soybean in salt-affected soils. Fortunately, soybean germplasm has been shown to have salt-tolerant phenotypes, which have been used to identify the salt-tolerant genes. GmCHX1, a novel ion transporter, is one of the genes known to confer salt tolerance in soybeans. Present study was conducted to understand the effects of sequence variations of GmCHX1, on salt tolerance in wild and cultivated soybeans. A total of 1026 (301 lines of G. max and 725 lines of G. soja) lines were phenotyped for salt tolerance in greenhouse conditions. At the V1-V2 growth stage, the plants were treated with 100mM NaCl solution for two weeks and thereafter the response was measured depending on leaf scorch score (1-health, 3-mid, 5-dead). About 20 lines found to show tolerance to saline conditions and were selected for sequence analysis of GmCHX1. Most of the haplotypes detected in this study corresponded with the haplotype patterns in previous studies. However, several lines showed different patterns of polymorphism in the coding region, suggesting that sequencing of more lines and analysis for the polymorphism in GmCHX1 is needed in order to identify new haplotypes that could confer greater salt tolerance.

Soybean has around 20% oil in total seed compound. Fatty acid concentration of soybean oil is about 12% palmitic acid, 4% stearic acid, 23% oleic acid (ω-9), 54% linoleic acid(ω-6) 54% and 8% linolenic acid(ω-3). To improve oxidative stability and quality of oil, the breeding programs mainly focused on reducing saturated fatty acids, increasing oleic acid and reducing linolenic acid in soybean oil. In plant oil, an essential fatty acid omega-3 fatty acid is in the form of α-linolenic acid (ALA) therefore, increasing ALA in soybean oil became one of the breeding goals for human health. In our research group, we have two breeding programs for concentration of ALA in soybean oil. Wild soybeans have almost twice ALA than that in cultivated soybeans. Introgression of alleles from wild soybean to cultivated soybean may lead to the increase of ALA in soybean seed oil for various applications. We developed several backcross populations by elite cultivars x wild soybean to select high ALA with good agronomic traits. In the case of low linolenic acid program, we developed an EMS (ethyl methane sulfonate) mutation population to select low ALA concentration line and found a mutant line with low ALA in seed oil. The scheme for developing high ALA concentration from wild soybean and molecular characterization for low ALA line will be discussed.

The THO/TREX complex mediates the transport of nascent mRNAs from the nucleus towards the cytoplasm in animals, and it has a role in small RNA-dependent processes in plants. Here we describe five mutant alleles of Arabidopsis thaliana THO2, whichencodes a core subunit of the plant THO/TREX complex. tho2 mutants present strong developmental defects resembling those in plants compromised in microRNA (miRNA) activity. In agreement, not only the levels of siRNAs, but also of mature miRNAs were reduced in tho2 mutants. As a consequence miRNA target mRNAs accumulated to higher levels than in wild type. Yeast two hybrid experiments showed that THO2 does not seem to interact with any of the known miRNA biogenesis components, implying a more indirect role of THOs in small RNA biogenesis. We also detected alterations in the splicing pattern of genes encoding Serine/Arginine-rich proteins in tho2 mutants, suggesting a previously unappreciated role of the THO/TREX complex in alternative splicing.

Ubiquitin is a small polypeptide (10kDa) and ubiquitination is one of the post-translational modifications (PTMs) by ubiquitin protein, resulting in degradation of the target proteins by 26S proteasome complex. Here, we found that E3 ubiquitin ligase SINAT5, an Arabidopsis homolog of the Drosophila SINA RING-finger protein, directly interacts with LHY (late elongated hypocotyls), a component of the circadian oscillator, and DET1 (De-etiolated 1), a negative regulator of light-regulated gene expression. In addition, we also found that SINAT5 has an E3 ubiquitination activity for LHY but not for DET1. Interestingly, LHY ubiquitination by SINAT5 was inhibited by DET1, suggesting that flowering time through regulation of LHY stability by SINAT5 may be controlled by DET1. We are now investigating whether DET1 indeed involves in the regulation of the proteolytic turnover of the LHY by SINAT5 in vivo.