Seong-Bum Baek

Proteomic analyses of the interaction between the plant-growth promoting rhizobacterium Paenibacillus polymyxa E681 and Arabidopsis thaliana

Plant growth‐promoting rhizobacteria (PGPR) facilitate the plant growth and enhance their induced systemic resistance (ISR) against a variety of environmental stresses. In this study, we carried out integrative analyses on the proteome, transcriptome, and metabolome to investigate Arabidopsis root and shoot responses to the well‐known PGPR strain Paenibacillus polymyxa (P. polymyxa) E681. Shoot fresh and root dry weights were increased, whereas root length was decreased by treatment with P. polymyxa E681. 2DE approach in conjunction with MALDI‐TOF/TOF analysis revealed a total of 41 (17 spots in root, 24 spots in shoot) that were differentially expressed in response to P. polymyxa E681. Biological process‐ and molecular function‐based bioinformatics analysis resulted in their classification into seven different protein groups. Of these, 36 proteins including amino acid metabolism, antioxidant, defense and stress response, photosynthesis, and plant hormone‐related proteins were up‐regulated, whereas five proteins including three carbohydrate metabolism‐ and one amino acid metabolism‐related, and one unknown protein were down‐regulated, respectively. A good correlation was observed between protein and transcript abundances for the 12 differentially expressed proteins during interactions as determined by qPCR analysis. Metabolite analysis using LC‐MS/MS revealed highly increased levels of tryptophan, indole‐3‐acetonitrile (IAN), indole‐3‐acetic acid (IAA), and camalexin in the treated plants. Arabidopsis plant inoculated P. polymyxa E681 also showed resistance to Botrytis cinerea infection. Taken together these results suggest that P. polymyxa E681 may promote plant growth by induced metabolism and activation of defense‐related proteins against fungal pathogen.

Inheritance of (1–3)(1–4)-beta-D-glucan content in barley ( Hordeum vulgare L.)

Abstractβ-glucan is the soluble dietary fiber component and occurs at its highest in barley. This study aims to evaluate the inheritance of β-glucan content in barley grains and to map quantitative trait loci (QTL) associated with this trait. F5-derived 107 lines from the cross of the six-rowed waxy hulless barley, ‘Yonezawa Mochi’ and the six rowed non-waxy hulless barley,’ Neulssalbori’ were measured for their agronomic traits and β-glucan level at four different environments. These recombinant lines showed significant genotypic variation (P < 0.01) and normal distribution for β-glucan content with a range of 43.6–62.1 g kg−1 across environments. A significant genotype-by-environment interaction was also found. The broad-sense heritability estimates for β-glucan content ranged from 0.42 to 0.82 across environments. Using one-factor analysis and composite interval mapping, a main effect of QTL associated with β-glucan content was identified in the genomic region near waxy gene (wx) and HVM4 on chromosome 7H. The major QTL at this region explained on average 44.4% of the variation for the mean of β-glucan content across environments with LOD values that ranged from 5.7 in Suwon in 2001 to 13.9 in Suwon in 2003. Two minor QTLs were identified but their significance of association with β-glucan content was inconsistent across environments.

Comparison of Growth Characteristics and Yield of Silage Corn Hybrids by Different Planting Dates at Paddy and Upland Field

ABSTRACTThis study was conducted to evaluate growth characteristics and yield of silage corn hybrids by different planting dates at paddy and upland field. Days to silking by different planting dates at paddy field were 81 days at planting on April 22, 70 days on May 20 and 62 days on June 10, respectively, and they were getting shorter as planting date delayed. There was no significant difference in days to silking between paddy and upland field. Plant height in paddy field was no significant difference between at planting on April 22 and on May 20, and it was shortened sharply at planting on June 10. There was no significant difference in plant height between paddy and upland field. There was no significant difference in lodging by different planting dates in paddy field. There was significant difference in lodging between paddy and upland field(P<0.05). There was no significant difference in stay-green by different planting dates in paddy field, and no significant difference between paddy and upland field. Ear ratios to total dry matter in paddy field were 43% at planting on April 22, 41% on May 20 and 28% on June 10, respectively, and it was lower as planting date delayed. There was no significant difference in ear ratios to total dry matter between paddy and upland field. Fresh yields in paddy field were lower with 14% at planting on May 20 and 32% on June 10 compared to on April 22 as planting date delayed. There was no significant difference in fresh yield between paddy and upland field. Dry matteryields in paddy field were higher with 9% at planting on May 20 and lower with 24% on June 10 compared to at planting on April 22 as planting date delayed. Dry matter yield in paddy field was lower with 9% compared to 1,931kg/10a at planting on April 22. TDN(Total digestible nutrients) yields in paddy field were higher with 5% at planting on May 20 and lower with 28% on June 10 compared to at planting on April 22 as planting date delayed. TDN yield in paddy field was lower with 11% compared to 1,340kg/10a at planting on April 22. (Key words:Paddy field, Silage corn, Planting date, Yield, Dry matter, TDN)

Optimization of a Virus-Induced Gene Silencing System with Soybean yellow common mosaic virus for Gene Function Studies in Soybeans

Virus-induced gene silencing (VIGS) is an effective tool for the study of soybean gene function. Successful VIGS depends on the interaction between virus spread and plant growth, which can be influenced by environmental conditions. Recently, we developed a new VIGS system derived from the Soybean yellow common mosaic virus (SYCMV). Here, we investigated several environmental and developmental factors to improve the efficiency of a SYCMV-based VIGS system to optimize the functional analysis of the soybean. Following SYCMV: Glycine max-phytoene desaturase (GmPDS) infiltration, we investigated the effect of photoperiod, inoculation time, concentration of Agrobacterium inoculm, and growth temperature on VIGS efficiency. In addition, the relative expression of GmPDS between non-silenced and silenced plants was measured by qRT-PCR. We found that gene silencing efficiency was highest at a photoperiod of 16/8 h (light/dark) at a growth temperature of approximately 27°C following syringe infiltration to unrolled unifoliolate leaves in cotyledon stage with a final SYCMV:GmPDS optimal density (OD)600 of 2.0. Using this optimized protocol, we achieved high efficiency of GmPDS-silencing in various soybean germplasms including cultivated and wild soybeans. We also confirmed that VIGS occurred in the entire plant, including the root, stem, leaves, and flowers, and could transmit GmPDS to other soybean germplasms via mechanical inoculation. This optimized protocol using a SYCMV-based VIGS system in the soybean should provide a fast and effective method to elucidate gene functions and for use in large-scale screening experiments.

Physiological and Protein Profiling Response to Drought Stress in KS141, a Korean Maize Inbred Line

Understanding the complex response mechanism of a crop to drought is the major step in the developing of tolerant genotypes. In our study, to investigate physiological traits and proteome dynamics, an inbred maize (Zea mays L.) line (KS141) was subjected to 10 days of water-withholding at the V5 or V6 leaf stage. The subsequent analysis of their physiological parameters revealed a decreased relative leaf water content, Fv/Fm, stomatal conductance, net CO2 assimilation rate, leaf transpiration, and water use efficiency, resulting in severe growth retardation of leaf area, stem length and width, aerial part, and root dry matter at 3 and 10 days after withholding water. However, aerial part and root dry matter were little changed during drought stress for 3 days. To understand the proteome dynamics during the 10-day drought stress in maize leaves, comparative proteome analysis was carried out between the well-watered and drought-treated leaves. Proteins were extracted using phenol extraction method from leaves with/without drought stress, and then separated by 2-DE. After 2-DE gel analyses, 14 differentially expressed protein spots were identified by MALDITOF mass spectrometry. Out of 14, eleven and three protein spots were found to be up- or down-regulated, respectively. Interestingly, stress-related proteins such as glutathione S-transferase, abscisic stress-ripening proteins, and pathogenesis-related proteins were increased by drought stress. Our study may provide molecular mechanisms and selective markers for drought tolerant maize genotypes.

Change of Seed Yield, Germination Rate and Hard Seed Rate with Harvest Time in Hairy Vetch (Vicia villosa Roth)

This experiment was conducted to investigate an optimum harvest time for hairy vetch (HV) seed production. The seeds were harvested at 5 times, 35, 42, 48, 54, and 58 days after flowering (DAF) in 2009 and 2010. In 2011, 3 times of harvest, 39, 49, and 53 DAF were done at Suwon, middle part of Korea. HV plants were harvested and threshed by manually at each time. Seed yield, yield components, germination rate, hard seed rate, and viviparous germination rate were investigated. The highest seed yield represented 54 DAF in 2009, 42 DAF in 2010, and 49 DAF in 2011. When the triticale, HV support plant, comes to early lodging, the time of highest yield was delayed. 1,000-seed weight linearly increased from 35 DAF to 54 DAF. The later harvested seed showed a trend of increasing germination and hard seed ratio. However, viviparous germination had occurred because of in rainy season. In conclusion, it was presumed that an optimum harvest time for safe seed production in HV should be during 42 DAF ~ 54 DAF before the rainy season considering seed yield, 1,000-seed weight and germination.

Estimation of genetic distance and its predictability of F1 hybrid performance in barley

Heterotic performance of hybrids is dependent upon the amount of genetic variability among parents and combining ability of alleles at the loci associated with target traits. This study was carried out to determine if (1) pedigree-based genetic distance could explain molecular levels of genetic diversity, and (2) molecular marker-based genetic distance could predict the degree of hybrid performance in barley. The average value of Random Amplified Polymorphic DNA (RAPD)-based genetic similarity for all 58 genotypes was 0.641. Twenty-two hulless barley and eight malt barley varieties showed low levels of genetic diversity with higher similarity values than the average of all or of the hulled barley variety pool. Coefficients of parentage (COPs) computed for 1,653 pairs of 58 Korean barley varieties ranged from 0 to 0.984 with a mean of 0.048. Correlation between the genealogical and RAPD-based genetic similarity matrices was 0.256 (P < 0.01). Correlation values for the related and for all (related + unrelated) genotype pairs were almost similar to each other, indicating that the unrelated genotypes share a large portion of genomes alike in state, not identical by descent. RAPD-based genetic similarity estimates among parents were poorly correlated with their hybrid performance such as 1,000-grain weight (r = 0.34), biomass yield (r = −0.12), and grain yield (r = −0.04) for 11 genotype pairs of hulled barley. However, correlations between heterozygosity at marker loci and hybrid performance for biomass and grain yield slightly increased when two F1 hybrids were excluded in the analysis due to their low yield.

Response of Growth Characteristics and Yield of Silage Corns at Different Regions

This study was carried out to compare growth characteristics and yield of silage corn hybrids at four different regions (Hwaseong, Dangjin, Gochang and Pyeongchang). Two domestic corn hybrids, `Kwangpyeongok` and `Gangdaok`, and two imported corn hybrids, `P3394` and `32P75` were used in this study. Plant height and ear height ratio were not significantly different among corn hybrids. `Kwangpyeongok` was the strongest of all corn hybrids for lodging. The others except `Kwangpyeongok` were similar to lodging. All corn hybrids were excellent to stay-green. Incidence of southern corn leaf blight (Bipolaris maydis) was low at all corn hybrids. `32P75` was 10.1%, the most of all corn hybrids for incidence of BSDV (black streaked dwarf virus). `Kwangpyeongok` and `Gangdaok` were stronger than `32P75` for BSDV. Fresh yield of `Kwangpyeongok` and `Gangdaok` were the most of all corn hybrids as 74.85 and 76.68 ton/ha and `P3394` was the least of all corn hybrids as 64.97 ton/ha. Dry matter yield as 18.83~21.92ton/ha and TDN yield as 12.73~14.52 ton/ha were not significantly different among corn hybrids.

Single Cross Maize Hybrid for Silage with Lodging Tolerance and High Yield, 'Dacheongok'

Dacheongok’, a new maize F1 hybrid (Zea mays L.), is developed by the maize breeding team at the National Institute of Crop Science (NICS), RDA in 2016. The high-yielding hybrid, named ‘Dacheongok’ was bred by crossing between two inbred lines, ‘KS197’ and ‘KS202’. It is a yellow dent maize hybrid. After advanced yield trial of ‘Dacheongok’ in Suwon for one year, regional yield trial was subsequently carried out for evaluation of its growth and yield at four different locations from 2014 to 2016. The days to silking of ‘Dacheongok’ are 80, similar to ‘Kwangpyeongok’. The plant height of ‘Dacheongok’ is 267 cm, similar to ‘Kwangpyeongok’, and its ear height ratio is 51%, similar with that of ‘Kwangpyeongok’. It has resistance to lodging. The stay-green of ‘Dacheongok’ is not different with that of ‘Kwangpyeongok’. The number of ear per 100 plants of ‘Dacheongok’ is 95, similar to ‘Kwangpyeongok’. The ear length of ‘Dacheongok’ is 18.6 cm, longer than that of ‘Kwangpyeongok’. The weight of 100 seeds of ‘Dacheongok’ is 29.8 g, similar to that of ‘Kwangpyeongok’. It has moderate resistance to southern leaf blight (Bipolaris maydis). It has moderate resistance to European Corn Borer (Ostrinia nubilalis). The dry matter yield (23.69 ton/ha) of ‘Dacheongok’ was 10% higher than that of ‘Kwangpyeongok’. The TDN (Total Digestible Nutrients) yield (16.11 ton/ha) of ‘Dacheongok’ was 7% higher than that of ‘Kwangpyeongok’. The seed production of ‘Dacheongok’ was acceptable due to a good synchronization of flowering period during crossing between the seed parent, KS197, and the pollen parent, KS202, in Yeongwol and F1 seed yield was 2.46 ton/ha. ‘Dacheongok’ would be a suitable cultivar to all plain area in Korea. (Variety registration No. 7054)

Covered Barley(Hordeum vulgare L.) Variety, ‘Hyeyang’ with BaYMV Resistance, High Yield and Good Malt Quality

Improvement of winter hardiness, lodging resistance and good quality have been recently received more attention by covered barley(Hordeum vulgare L.) breeders than ever in Korea. ‘Hyeyang’, a new covered barley cultivar with early maturing and high yield was developed by the National Institute of Crop Science, RDA in 2010. It was derived from the cross between‘Milyang87’and‘Wolsung8120’with good quality. The initial cross was done in 1999 and the selected line, ‘Iksan432’ (YB4494-B-B-21-2), showed high yield and good quality characteristics under yield trial test from 2008 to 2010. The following is the characteristics of‘Hyeyang’that is characterized as the vernalization of I, green leaf, compact spike and long rough awns. The heading date of‘Hyeyang’were similar to‘Olbori’. The culm length was 82 cm which was 6 cm shorter than‘Olbori’. It showed the spike length of 4.3 cm, 798 spikes / m 2 , 56 grains / spike and 26.7 g for 1,000 grains weight. It showed similar winter hardiness and stronger resistance to barley yellow mosaic virus (BaYMV) compare to‘Olbori’. It showed higher diastatic power 235DP than that of check cultivar, ‘Olbori’. Average yield of ‘Hyeyang’ was 4.44 MT/ha in the regional yield trials carried out in four location at double cropping system in Korea from 2008 to 2010, which was 8 percent higher than ‘Olbori’. ‘Hyeyang’would be suitable for the area above –8°C of daily minimum temperature in January in Korean peninsula.