Sang-Yeol Kim

Use of Pi5(t) markers in marker-assisted selection to screen for cultivars with resistance to Magnaporthe grisea

Identification of the PCR markers tightly linked to genes that encode important agronomic traits is useful for marker-assisted selection (MAS). The rice Pi5(t) locus confers broad-spectrum resistance to Magnaporthe grisea, the causal agent of rice blast disease. It has been hypothesized that the Pi5(t) locus carries the same gene as that encoded by the Pi3(t) and Pii(t) loci. We developed three PCR-based dominant markers (JJ80-T3, JJ81-T3, and JJ113-T3) from three previously identified BIBAC clones—JJ80, JJ81, and JJ113—that are linked to the Pi5(t) locus. PCR analysis of 24 monogenic lines revealed that these markers are present only in lines that carry Pi5(t), Pi3(t), and Pii(t). PCR and DNA gel-blot analysis of candidate resistance lines using JJ80-T3, JJ81-T3, and JJ113-T3 indicated that Tetep is the likely donor of Pi5(t). Of the 184 rice varieties tested, 34 carried the JJ80-T3-, JJ81-T3-, and JJ113-T3-specific bands. Disease evaluation of those 34 varieties revealed that all conferred resistance to PO6-6. The genomic structure of three of these resistant varieties (i.e., IR72, Taebaeg, Jahyangdo) is most similar to that of Pi5(t). Our results demonstrate the usefulness of the JJ80-T3, JJ81-T3, and JJ113-T3 markers for MAS for M. grisea resistance.

Comparative analysis of physicochemicals and antioxidative properties of new giant embryo mutant, YR23517Acp79, in rice (Oryza sativa L.)

Nutritional and physicochemical properties of new giant embryo mutant rice (YR23517Acp79, YR) were analyzed. YR exhibited increased total protein (9.3±0.3%), lipid (3.7±1.1%), amino acid (663.28±1.9 mg/g), and mineral contents (Ca=284.0±6.2, Mg=1417.5±13.6 mg/kg). In YR brown rice four major physicochemicals, including gamma-aminobutyric acid (brown rice= 0.46±0.014 mg/g), γ-oryzanol (0.43±0.021 mg/g), vitamin B1 (6.42±0.3 mg/kg), and tocopherols (alpha= 2.68±0.1, beta=0.11±0.01, gamma=0.05±0.001 mg/100 g) increased in comparison to reported giant embryo (Keunnunbyeo, KB) and normal embryo rice (Ilmibyeo, IB). YR showed higher scavenging activities against 1,1-diphenyl-2-picrylhydrazyl (0.2 g/mL=57.1±2.25) and 2,2′-Azinobis(3-ethylbenzothiazoline-6-sulfonic acid) (0.2 g/mL=50.2±1.45) radicals but also inhibited lipopolysaccharide-induced nitric oxide production without cytotoxicity. These results indicate YR is a high quality functional rice due to its high nutrition content and antioxidant effects of physicochemicals.

A Waxy Black Giant Embryo Earley Maturing Rice Variety ‘Nunkeunheugchal’

Nunkeunheugchal (registration No. 01-0001-2014-4), a black waxy giant embryo rice cultivar, was developed by the rice breeding team of National Institute of Crop Science (NICS), RDA in 2012. This cultivar was derived from the cross between ge and Josaengheugchal in 2004/2005 winter season, and selected by a promising line, YR25277-B-B-314-2, was selected and designated as the line of Milyang263 in 2009. The local adaptability test of Milyang263 was carried out at four locations from 2010 to 2012 and it was named as Nunkeunheugchal. This variety is a early maturity cultivar. It has 65 cm in culm length and 72 spikelets per panicle, and 1,000 grain-weight of brown rice is 17.8 g which is less than that of Josaengheugchal. This variety is resistant to leaf blast, but susceptible to bacterial blight, neck blast, virus disease and insect pest. The yield potential of Nunkeunheugchal was about 3.54 MT/ha as brown rice at ordinary fertilizer level in local adaptability test for three years. Nunkeunheugchal possesses benefits to rice consumers because of high amounts of GABA, anthocyanin, calcium and iron. This variety would be adaptable to the paddy field of middle and southern plain region of Korea.

Differential Tolerance of Rice Cultivars to Mesotrione-Contained Herbicides

Greenhouse experiment was conducted to evaluate tolerance of six rice cultivars, three IndicaJaponica rice (long grain, cv. Dasanbyeo, Segejinmi and Hanareumbyeo) and three Japonica rice (short grain, Nampyung, Ilpumbyeo and Junamjosaeng) cultivars, to mesotrione+pretilachlor (MP) and bensulfuron-methyl+mesotrione+pretilachlor+pyriftalid (BMPP) in transplanting rice. Two herbicides were applied at 90 g and 180 g a.i. to three to four leaf stage rice at 5 and 15 days after transplanting, respectively. Related study was also conducted to compare for IndicaJaponica and Japonica rice cultivars at different MP rates. Response to two herbicides varied with respect to rice cultivars and herbicide rates. All IndicaJaponica rice cultivars exhibited susceptible to both MP and BMPP as reflected by increased visual injury, shorter plant height and higher plant dry matter reduction when compared with nontreated rice cutlivars. The degree of foliar chlorosis by MP at 90 g a.i. was 5~6 at 7 days after treatment(DAT) but it was decreased to 3~6 at 14DAT. The degree of leaf chlorosis treated with 180 g a.i. MP was 6~7 at 7DAT and it was also decreased to 3~8 at 14 DAT. The plant hight of IndicaJaponica rices was inhibited by 18~43% at application of 90 g a.i. MP and 30~50% at 180 g a.i. MP. The dry matter reduction was greater than that of plant height inhibition, showing 46~73% at 90 g a.i. MP and 65~82% at 180 g a.i. MP. Similar leaf chlorosis injury and growth inhibition of rice cultivars was observed in the BMPP treatment. The injury and growth inhibition by MP and BMPP increased with increase in herbicide rate from 90 g a.i. to 180 g a.i. . However, most of the Japonica cultivars are tolerant to MP and BMPP at both rates. There was no visible leaf chlorosis but plant height and dry matter production were slightly reduced at 180 g a.i. . Based on value determined in reduction of shoot dry weight for MP, the IndicaJaponica rice showed 12.9 fold lower compared with the Japonica rice. The result indicates that rice cultivars vary in tolerance to herbicides of MP and BMPP and IndicaJaponica rices were more susceptible than the Japonica rices to the MP and BMPP.

Comparative studies on major nutritional components of black waxy rice with giant embryos and its rice bran

The concentration of nutrients in brown rice is mainly associated with embryo size. Various beneficial components have been purified from rice bran. Recently developed black waxy rice with a giant embryo (‘Milyang 263’, BGE), which is the get mutant of the GE gene, was selected and analyzed to produce high quality nutritional components. γ-Aminobutyric acid (GABA) content in BGE rice bran, one of the most important nutritional compounds in rice, showed a 10.6-fold increase (2.66±0.48 mg/g) compared to that of BGE brown rice (0.25±0.01 mg/g). In addition, brown rice and BGE rice bran showed enriched amylopectin (94.5±0.5 and 97.0±0.0%) and bioactive anthocyanin [Cy-3-G: 75.15±4.18 (brown rice), 82.97±0.81 (rice bran) and Pn-3-G: 1.52±0.50 (brown rice), 4.33±0.20 (rice bran); mg/100 g] contents. These results suggest that BGE rice bran can be used as an excellent raw material to efficiently produce high quality essential amino acids, cyanidin-3 glycoside-enriched anthocyanins, and GABA.

Effect of light on endogenous levels of gibberellin and abscisic acid in seed germination of photoblastic weedy rice (Oryza sativa L.)

The effect of red (R) and R/far-red (FR) lights on endogenous gibberellin (GA) and abscisic acid (ABA) content was first investigated during the germination of photoblastic black-hulled weedy rice (PBWR) seeds. The R light-treated PBWR seeds germinated after 36–48 h and germination was increased to 63% at 72 h. However, the FR light-treated seeds after R light treatment, suppressed the R light effect showing only 11% germination even at 72 h after the light treatment. The PBWR seed treated with R light rapidly increased the endogenous level of GA1 to about 200 times at 12 h before seed germination as compared with R/FR (control) which suppressed the effect of R light. The contents of other GAs like GA12, GA53, GA19, GA20, and GA8 were not affected by the R light irradiation. These results showed that the major biosynthetic pathway of GAs in PBWR seeds is the early 13-hydroxylation pathway leading to GA1, which was suggested to be physiologically active in the PBWR seed germination. The decrease in the level of ABA in the R light-treated seeds was greater than the R/FR light-treated seeds, indicating that the balance of endogenous GA1 and ABA is responsible for the induction of germination in the PBWR seed.