Man-Soo Choi

Expression of BrD1, a plant defensin from Brassica rapa, confers resistance against brown planthopper (Nilaparvata lugens) in transgenic rices.

Plant defensins are small (5-10 kDa) basic peptides thought to be an important component of the defense pathway against fungal and/or bacterial pathogens. To understand the role of plant defensins in protecting plants against the brown planthopper, a type of insect herbivore, we isolated the Brassica rapa Defensin 1 (BrD1) gene and introduced it into rice (Oryza sativa L.) to produce stable transgenic plants. The BrD1 protein is homologous to other plant defensins and contains both an N-terminal endoplasmic reticulum signal sequence and a defensin domain, which are highly conserved in all plant defensins. Based on a phylogenetic analysis of the defensin domain of various plant defensins, we established that BrD1 belongs to a distinct subgroup of plant defensins. Relative to the wild type, transgenic rices expressing BrD1 exhibit strong resistance to brown planthopper nymphs and female adults. These results suggest that BrD1 exhibits insecticidal activity, and might be useful for developing cereal crop plants resistant to sap-sucking insects, such as the brown planthopper.

Suppression of NS3 and MP is important for the stable inheritance of RNAi-mediated Rice Stripe Virus (RSV) resistance obtained by targeting the fully complementary RSV-CP gene

Rice stripe virus (RSV) is a viral disease that seriously impacts rice production in East Asia, most notably in Korea, China, and Japan. Highly RSV-resistant transgenic japonica rice plants were generated using a dsRNAi construct designed to silence the entire sequence region of the RSV-CP gene. Transgenic rice plants were inoculated with a population of viruliferous insects, small brown planthoppers (SBPH), and their resistance was evaluated using ELISA and an infection rate assay. A correlation between the expression of the RSV-CP homologous small RNAs and the RSV resistance of the transgenic rice lines was discovered. These plants were also analyzed by comparing the expression pattern of invading viral genes, small RNA production and the stable transmission of the RSV resistance trait to the T3 generation. Furthermore, the agronomic trait was stably transmitted to the T4 generation of transgenic plants.

Development of Low Gly m Bd 30K (P34) Allergen Breeding Lines Using Molecular Marker in Soybean [ Glycine max (L.) Merr.]

An increasing production of soybean (Glycine max (L.) Merr.)-based food products may limit dietary choices for soy-allergic individuals. Gly m Bd 30K (P34) is the main seed allergen causing implications in soybean-sensitive patients. The objective of this research was to develop low allergenic soybean lines with molecular marker. The soybean genome assembly specifies that three copy genes of P34 exist in soybean genome. These are Glyma08g12270, which is expressed at significantly higher level over the other two, Glyma08g12280 and Glyma05g29130. Glyma08g12270 was found inactive and was not expressed in low P34 germplasm accessions. Using a co-dominant marker and a polyclonal antibody, polymorphisms and the quantity of protein produced by Glyma08g12270 were analyzed in the F2 and F3 generations obtained by crossing PI567476 and the Korean cultivar Hwanggum. The molecular marker and polyclonal antibody developed in this study could therefore be effectively used for selecting lines that express P34 at low levels. Selected lines could further be used to cross with other null allergenic soybean accessions to breed low allergenic soybean variety.

An assessment of the interactions between climatic conditions and genetic characteristic on the agricultural performance of soybeans grown in Northeast Asia

Glycine max, commonly known as soybean or soya bean, is a species of legume native to East Asia. The interactions between climatic conditions and genetic characteristic affect the agricultural performance of soybean. Therefore, an investigation to identify the main elements affecting the agricultural performances of 11 soybeans was conducted in Northeast Asia, China [Harbin (45°12′N) Yanji (42°53′N) Dalian (39°30′N) Qingdao (36°26′N)] Republic of Korea [Suwon (37°16′N) and Jeonju (35°49′N)]. The days to flowering (DTF) of soybeans with the e1-nf and e1-as alleles and the E1e2e3e4 genotype, except Keumgangkong, Tawonkong, and Duyoukong, was relatively short compared to soybeans with other alleles. Although DTF of the soybeans was highly correlated to all climatic conditions, days to maturity (DTM) and 100-seed weight (HSW) of the soybeans showed no significant correlation with any climatic conditions. The soybeans with a dominant Dt1 allele, except Tawonkong, had the longest stem length (STL). Moreover, the STL of the soybeans grown at the test fields showed a positive correlation with only day length (DL) although the results of our chamber test showed that STL of soybean was positively affected by average temperature (AVT) and DL. Soybean yield (YLD) showed positive correlations with latitude and DL (except L62-667, OT89-5, and OT89-6) although the response of YLD to the climatic conditions was cultivar-specific. Our results show that DTF and STL of soybeans grown in Northeast Asia are highly affected by DL although AVT and genetic characteristic also affect DTF and STL. Along with these results, we confirmed that the DTM, HSW, and YLD of the soybeans vary in relation to their genetic characteristic.