Comparative Pathogenicity of Fusarium graminearum Isolates from Wheat Kernels in Korea.

Fusarium head blight (FHB) caused by Fusarium species is a major disease of wheat and barley around the world. FHB causes yield reductions and contamination of grains with trichothecene mycotoxins including; nivalenol (NIV), deoxynivalenol (DON), 3-acetyldeoxynivalenol (3-ADON), and 15-acetylde-oxynivalenol (15-ADON). The objectives of this study were to identify strains of F. graminearum isolated in Korea from 2012-harvested wheat grain and to test the pathogenicity of these NIV- and DON-producing isolates. Three hundred and four samples of wheat grain, harvested in 2012 in Chungnam, Chungbuk, Gyeongnam, Jeonbuk, Jeonnam, and Gangwon provinces were collected. We recovered 44 isolates from the 304 samples, based on the PCR amplification of internal transcribed spacer (ITS) rRNA region and sequencing. Our findings indicate that F. asiaticum was the predominant (95% of all isolates) species in Korea. We recovered both F. asiaticum and F. graminearum from samples collected in Chungnam province. Of the 44 isolates recovered, 36 isolates had a NIV genotype while 8 isolates belonged to the DON genotype (3-ADON and 15-ADON). In order to characterize the pathogenicity of the strains collected, disease severity was assessed visually on various greenhouse-grown wheat cultivars inoculated using both NIV- and DON-producing isolates. Our results suggest that Korean F. graminearum isolates from wheat belong to F. asiaticum producing NIV, and both F. graminearum and F. asiaticum are not significantly different on virulence in wheat cultivars.

Enhanced anthocyanin accumulation confers increased growth performance in plants under low nitrate and high salt stress conditions owing to active modulation of nitrate metabolism.

Plants require nitrogen (N) for growth and development. However, they are frequently exposed to conditions of nitrogen deficiency. In addition, anthocyanin accumulation is induced under salt stress and nitrate deficiency. To date, most studies have revealed that nitrate deficiency under high sucrose levels induce high levels of anthocyanin accumulation in plants. However, the underlying mechanisms remain unclear. Under nitrate-starved conditions, plant growth rapidly worsens and cells eventually die. In addition, plants are severely affected by salt exposure. Therefore, in this study, we determined whether increased levels of anthocyanin could improve plant growth under salt stress and nitrate-starved conditions. We used PAP1-D/fls1ko and ttg1 plants which have a perturbed anthocyanin biosynthesis pathway to explore the role of anthocyanin in plant adaptation to nitrate-deficient conditions and salt stress. Our results demonstrate that high anthocyanin accumulation in PAP1-D/fls1ko plants confers enhanced tolerance to nitrate-deficient conditions combined with high salinity. PAP1-D/fls1ko plants appeared to use absorbed nitrate efficiently during the nitrate reduction process. In addition, nitrate-related genes such as NRT1.1, NiA1 and NiA2 were upregulated in the PAP1-D/fls1ko plants. On the basis of these findings, it can be concluded that high anthocyanin accumulation helps plants to cope with salt stress under nitrate-deficient conditions via the effective utilization of nitrate metabolism.

Evaluation of a Rapid Method for Screening Heat Stress Tolerance Using Three Korean Wheat (Triticum aestivum L.) Cultivars.

Thermotolerance in plants is a topic of concern given the current trends in global warming. Here, we aimed to develop a rapid and reproducible screening method for selection of heat stress-tolerant wheat varieties to expedite the breeding process. We tested the robustness of the screen in three Korean wheat cultivars, "BackJung", "KeumKang", and "ChoKyeong". We showed that 4-day-old seedlings of "KeumKang" had the highest survival rates after a 45 °C treatment for 20 h. Moreover, the ability to retain chlorophyll and antioxidant activity was also highest in "KeumKang". The increase in malondialdehyde content in "ChoKyeong" indicated that this cultivar showed the greatest damage after heat stress. Collectively, our results showed that "KeumKang" is the most heat-tolerant cultivar of the three examined. In conclusion, the most reliable and rapid screening method in our investigation was survival rate examined at lethal temperature.

Hydration and Pasting Properties of Oat (Avena sativa) Flour.

Three oat cultivars and one oat breeding line were evaluated for chemical, hydration and pasting properties. Protein, starch and ß-glucan levels ranged 11.13∼14.37, 56.37∼64.86 and 3.44∼4.76%, respectively. The oat cultivars Daeyang and Seonyang contained higher ß-glucan levels of 4.76 and 4.35%. The Daeyang variety had a higher water absorption index (WAI) of 2.83∼3.35 (g/g), but a lower water solubility index (WSI) of 8.67 ∼11.08%. Daeyang and Seonyang cultivars showed higher peak and trough viscosity, but lower breakdown and setback, indicating that they easily swell, and thus could possibly provide the desirable viscosity of an oat product. The ß-glucan levels were correlated positively with WAI, peak and trough viscosity, and negatively to WSI, breakdown and setback viscosity.

Substituting normal and waxy-type whole wheat flour on dough and baking properties.

Normal (cv. Keumkang, KK) and waxy-type (cv. Shinmichal, SMC) whole wheat flour was substituted at 20 and 40% for white wheat flour (WF) during bread dough formulation. The flour blends were subjected to dough and baking property measurement in terms of particle size distribution, dough mixing, bread loaf volume and crumb firmness. The particle size of white wheat flour was the finest, with increasing coarseness as the level of whole wheat flour increased. Substitution of whole wheat flour decreased pasting viscosity, showing all RVA parameters were the lowest in SMC40 composite flour. Water absorption was slightly higher with 40% whole wheat flour regardless of whether the wheat was normal or waxy. An increased mixing time was observed when higher levels of KK flour were substituted, but the opposite reaction occurred when SMC flour was substituted at the same levels. Bread loaf volume was lower in breads containing a whole wheat flour substitution compared to bread containing only white wheat flour. No significant difference in bread loaf volume was observed between normal and waxy whole flour, but the bread crumb firmness was significantly lower in breads containing waxy flour. The results of these studies indicate that up to 40% whole wheat flour substitution could be considered a practical option with respect to functional qualities. Also, replacing waxy whole flour has a positive effect on bread formulation over normal whole wheat flour in terms of improving softness and glutinous texture.

The cancer preventive seed peptide lunasin from rye is bioavailable and bioactive.

Lunasin is a unique 43-amino acid peptide that has been shown to be chemopreventive in mammalian cells and in a skin cancer mouse model against oncogenes and chemical carcinogens. In search for new sources of lunasin and to better understand the role of cereals in cancer prevention, we report here the properties of lunasin from rye. The stability and bioavailability were measured by in vitro digestibility assay using pepsin and pancreatin and feeding rats with lunasin-enriched rye (LER). Inhibition of histone acetyl transferase (HAT) and nuclear localization in mammalian cells were used to measure lunasin bioactivity. Lunasin is present in 15 out of 21 cultivars of rye analyzed. Lunasin present in rye crude protein preparation is stable to pepsin and pancreatin in in vitro digestion. The liver, kidney, and blood of rats fed LER show the presence of lunasin in Western blot. Lunasin extracted from these tissues inhibits the activities of HATs, confirming that the peptide is intact and bioactive. Lunasin purified from rye internalizes in the nuclei of mouse fibroblast cells. We conclude that lunasin in rye is bioavailable and bioactive and that consumption of rye may play an important role of cancer prevention in rye-consuming populations.