The composition of high-molecular-weight-glutenin subunits (HMW-GS) is a key determinant of wheat baking properties. These subunits are encoded by the GLU-A1, GLU-B1, and GLU-D1 loci on the long arm of chromosome 1 and consist of x- and y-type subunits. Allelic variations in composition are a major factor influencing bakery quality. Unlike sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) or ultra-performance liquid chromatography (UPLC), which often fail to resolve closely related allelic variants, PCR-based markers allow for clear and definitive discrimination at the DNA level. Building on the results of a previous study that determined the GLU-B1 allele composition, we aimed to confirm—through the use of PCR markers—the allele compositions of GLU-A1 and GLU-D1 in 44 domestic wheat varieties. The results showed that “Jonong” and “Sinmichal1” contained the Glu-A1b (A1x2*) allele rather than Glu-A1a (A1x1) or Glu-A1c (A1x-null). Additionally, “Jonong” and “Sinmichal1” exhibited the allelic composition Glu-D1a (D1x2+D1y12), rather than Glu-D1d (D1x5+D1y10) or Glu-D1f (D1x2.2+D1y12). These results were compared with those obtained by SDS-PAGE and UPLC. The PCR-based markers used to identify GLU-A1 and GLU-D1 alleles in this study will be valuable for determining the allelic composition at the GLU-A1 and GLU-D1 loci in domestic wheat varieties. Furthermore, the re-evaluated genetic composition is expected to improve the precision of assessments related to the baking quality of domestic wheat.

A comprehensive evaluation of 515 Korean wheat germplasms, including cultivars, experimental lines, and landraces, was conducted over 2 years under upland field conditions to characterize major agronomic and grain traits. Allelic variation at 13 key functional loci was assessed using Kompetitive Allele-Specific PCR (KASP) and PCR-based markers. The winter-type vrn-A1 with a single copy (CNV=1; 40.2%) advanced heading by approximately 5 days compared to multiple-copy genotypes, and winter-type vrn-B1 (88.5%) advanced heading by 2 days compared to the spring-type. The photoperiod-insensitive alleles Ppd-B1a (5.6%) and Ppd-D1a (76.3%) advanced heading by 3 and 4 days, respectively, with a combined effect of up to 6 days. Semi-dwarfing alleles Rht-B1b and Rht-D1b showed reduced culm lengths of 2.1 cm and 4.7 cm, respectively, and the Rht-B1a/Rht-D1b genotype was 6 cm shorter than Rht-B1a/Rht-D1a. The Pina-D1a/Pinb-D1a genotype had the lowest kernel hardness value (32.2), whereas Pina-D1b/Pinb-D1a had the highest (60.5). The thousand kernel weight ranged from 36.1 mg to 42.5 mg depending on the allelic combinations of TaCwi-A1, TaGW2-6A, and TaSus2-2B. Cultivars and experimental lines were clearly distinguished from landraces based on phenotype-based clustering, with the majority of cultivars (81.6%) and experimental lines (68.3%) grouped into cluster III. In contrast, landraces were predominantly distributed in clusters I (55.1%) and II (29.2%). Random forest analysis identified four genes, Ppd-D1, Pina-D1, Pinb-D1, and WAPO-A1, as major contributors to cluster classification. Cluster III was highly enriched with alleles favorable for earliness (Ppd-D1a, 98.3%) and grain hardness (Pina-D1b and Pinb-D1b, 57.9%). WAPO-A1b, an allele associated with an increased spikelet number per spike, was more frequently observed in clusters I (94.6%) and II (79.1%) than in cluster III (58.4%).

A new winter wheat (Triticum aestivum L.) cultivar “Joongmo2015” was developed by the NICS (National Institute of Crop Science), RDA (Rural Development Administration) in 2019. Its heading date was April 20 and its maturity date was June 1, which was similar to Keumkang. “Joongmo2015” had a longer culm length (80 cm), similar spike length (7.8 cm) and spikes per m² (804), lower 1,000-grain weight (43.0 g) than “Keumkang” (78 cm, 7.8 cm, 804 g, 46.3 g, respectively). “Joongmo2015” was showed stronger to winter hardiness than “Keumkang”, and susceptible to fusarium head blight and powdery mildew. The average grain yield in the advanced yield trial (AYT) was 4.97 MT/ha, which were 26% more than “Keumkang” and in the regional yield trial (RYT) was 5.75 MT/ha in upland and 5.27 MT/ha in paddy field, which were 16% and 18% higher than those of “Keumkang” (4.95 MT/ha and 4.46 MT/ha, respectively). “Joongmo2015” showed lower protein content (11.7%), SDS-sedimentation volume (42.8 ml), gluten content (9.0%) and flour lightness(90.76) than “Keumkang” (13.6%, 61.8 ml, 11.4% and 91.50, respectively). “Joongmo2015” showed higher lightness (83.10) of noodle dough sheet than “Keumkang” (82.48). “Joongmo2015” exhibited higher hardness (3.92N) and similar springiness and cohesiveness of cooked noodles (0.94 and 0.60) compared to “Keumkang” (3.65N, 0.93, and 0.59, respectively). High molecular weight gluten subunits (HMW-GS) composition are Glu-D1d (5+10), granule-bound starch synthase (GBSS) composition are Wx-A1a, Wx-B1a, Wx-D1a and composition of puroindolines are Pina-D1a, Pinb-D1a (Registration No. 9790).

In common wheat (Triticum aestivum L.), the protein content and glutenin protein composition are the key quality-determining parameters. Allelic variations, especially in high-molecular-weight glutenin subunits (HMW-GSs), affect bread quality significantly. The HMW-GS Glu-1 locus consists of two tightly linked genes encoding x- and y-type subunits that exhibit highly variable frequencies. In this study, we evaluated Glu-B1 alleles using allele-specific PCR markers in 44 domestic wheat cultivars. The composition of Glu-1Bx7+Glu-1By8 in the 24 cultivars was either Glu-1Bx7+Glu-1By8, Glu-1Bx7*+ Glu-1By8, or Glu-1Bx7*+Glu-1Bx8*. In addition, the two cultivars initially identified Glu- 1Bx7+Glu-1By8* were corrected to Glu-1Bx7*+Glu-1By8*. Seven cultivars previously classified as having Glu-1Bx7+Glu-1By9 composition contained Glu-1Bx7*+ Glu-1Bx9. The allele composition of the cultivar was identified as Glu-1Bx20+Glu-1By20 instead of Glu-1By20. The HMW-GSs of 21 wheat varieties were analyzed using ultra-performance liquid chromatography and sodium dodecyl sulfate-polyacrylamide gel electrophoresis. These results will be helpful for evaluating the composition of Glu-B1 alleles in domestic wheat and accurately assessing the quality of domestic wheat flour.

Fusarium head blight (FHB) causes yield reduction, quality deterioration, and mycotoxin contamination in wheat, highlighting the need for resistant wheat varieties. In this study, we evaluated FHB resistance genes and infection rates in 44 domestic wheat varieties. Among them, 42 had the Type I resistance gene Fhb4, 37 had Fhb5, and 35 possessed both. For Type II resistance, 14 had Fhb1, 11 had Fhb2, and five had both. Twenty cultivars had both type I and type II resistance genes, and among them, Chungkye, Dahong, Gobun, Namhae, and Ol had all of the Fhb1, Fhb2, Fhb4, and Fhb5 genes. The average infection rate over three years was 42.6% in cases with both Type I and Type II resistance genes and 44.3% in cases without Type II resistance genes. The infection rate was very high in 2020 and very low in 2021, complicating the analysis of the three-year average. However, when the infection rate was evenly distributed in 2019, there was a tendency for increased resistance among the varieties carrying Type II resistance genes. This suggested that external factors may influence infection rates, emphasizing the need for a precise evaluation system suitable for selecting additional resistance genes. In addition, it is necessary to develop resistant varieties suited to the domestic environment through additional resistance gene selection and integration of resistance genes. This study contributes to understanding FHB resistance genes in domestic wheat varieties and developing resistant domestic wheat varieties.

To stably produce domestic wheat under water-scarce environmental conditions due to climate change, root characteristics with excellent water utilization rates are crucial. In this study, we analyzed the root and grain phenotypes of 37 domestic wheat varieties over a two-year period by combining the results of genetic mutations related to semi-dwarfing and grain size. Root length was positively correlated with maximum root depth (r=0.76**) and total seminal root length (r=0.54**), whereas it was negatively correlated with the number of roots (r=-0.33**) and root angles (r=-0.51**). The thousand-kernel weight was positively correlated with embryo width (r=0.34**) and embryo area (r=0.33**) but was not correlated with other root traits. Embryo length was positively correlated with the number of roots (r=0.34**) and coleoptile length (r=0.42**). Phenotypic analyses of roots and grains, along with genotypic analyses of semi-dwarfing (Rht-B1 and Rht-D1) and grain size (TaCWI-4A, TaCWI-5D, TaGW2-6A, TaSus2-2B) genes, revealed that the Rht-D1b genotype led to reduced root depth, increased root angles, and reduced coleoptile length. TaCwi-A1, TaCWI-5D, TaSus2-2B, and TaGW2-6A, possessing the alleles TaCwi-A1a, Hap-5D-C, Hap-L, and Hap-6A-G associated with a larger grain size, resulted in an increased number of roots and root depth. Domestic wheat varieties were categorized into three clusters based on root, grain, and coleoptile trait characteristics, with 15 varieties in Cluster I, 9 in Cluster II, and 13 in Cluster III. The results of this study can be utilized in basic research to develop varieties that can produce stable domestic wheat by selecting resources with excellent root growth and seed characteristics.

A new winter wheat (Triticum aestivum L.) cultivar “Hwanggeumal” was developed by the National Institute of Crop Science (NICS) Rular Development Administration (RDA) in 2019. Its heading date was April 20, and its maturity date was June 1, which was similar to that of Jokyung. “Hwanggeumal” had a shorter culm length (75 cm) and spike length (7.1 cm). However, it had lower spikes per m² (699) and 1,000-grain weight (44.2 g) than “Jokyung” (78 cm, 8.2 cm, 776, 46.6 g, respectively). “Hwanggeumal” displayed stronger winter hardiness than “Jokyung”, and was susceptible to powdery mildew (PM) and fusarium head blight (FHB). The average grain yield in the advanced yield trial (AYT) was 6.20 MT/ha, which was 11% more than “Jokyung”. In the regional yield trial (RYT) it was 5.13 MT/ha in upland and 4.77 MT/ha in paddy field, which were 16% and 13% less than “Jokyung”, respectively. “Hwanggeumal”s flour yield (71.4%) and flour lightness (91.82) was similar to that of “Jokyung”, while the protein content (14.0%), gluten content (10.3%), and SDS-sedimentation volume (60.3 ml) were higher than that of “Jokyung”. These results display that the “Hwanggeumal” dough strength of flour is stronger than “Jokyung”. High molecular weight gluten subunit (HMW-GS) composition is Glu-D1d (5+10), the granule-bound starch synthase (GBSS) composition are Wx-A1a, Wx-B1b, and Wx-D1a, and the composition of puroindolines are Pina-D1a and Pinb-D1b (Registration No. 9173).

Powdery mildew (Blumeria graminis f. sp. tritici) significantly affects wheat yield and flour quality. Plant resistance to powdery mildew has been investigated for decades, and numerous resistance genes and quantitative trait loci (QTLs) for molecular markers have been discovered. In Korea, powdery mildew occurs initially in spring, due to frequent rain and low temperatures, becoming severe during the harvest season. In Korea, systematic monitoring and quantitative and qualitative impact assessments of powdery mildew outbreaks have never been conducted properly. Herein, the lifecycle of powdery mildew, resistance genes, QTLs, and selection markers in wheat were examined to elucidate powdery mildew resistance, develop resistant varieties, and genetic markers suitable for the domestic environment.

Fusarium head blight (FHB) is a severe disease of wheat, mainly caused by Fusarium graminearum, which greatly reduces wheat production and directly affects human and animal health due to the mycotoxins produced in wheat grains. To develop high-quality, stable yields, and mycotoxin-free crop, it is essential to first understand the genetic basis of wheat FHB-resistance, and to design molecular markers facilitating the selection of FHB-resistant varieties. However, despite extensive global research efforts, genetic research and marker development for the selection of FHB-resistant varieties, in Korea, are insufficient. Here, we summarize recent studies on FHB-resistance genes, resistance resources, quantitative trait locus analysis, and genome-wide association studies to enhance our understanding of FHB and the breeding of FHB-resistant domestic wheat cultivars.

Gluten proteins in wheat grains are generally considered one of the most important factors in determining dough properties and bread quality. In this study, wheat protein quality characteristics were investigated in 607 varieties collected from seven countries grown in a South Korean wheat breeding field for two years. The average protein content was 12.2±1.86%, and the sodium dodecyl sulfate-sediment volume (SDSS) was 46.9±8.39 mL. HI-LINE had the highest protein content (18.3±0.35%) and SDSS (76.7±1.98 mL), while both NE 84557 and Iksan 374 showed small deviations in protein content and SDSS. Protein content and SDSS values were higher in Ax2*+By8 and By9+Dy10 combinations at Glu-A, Glu-B1, and Glu-D1 loci of high molecular weight gluten subunit (HMW-GS) than in other combinations. However, no difference in Glu-A3 and Glu-B3 loci in LMW-GS was observed. Furthermore, in HMW-GS, the composition of Glu-D1 Dy10 and Dy12 had a greater effect on protein quality than Glu-B1 By8 and By9 when the allele of Glu-A1 had Ax2*. Significant differences were found between Dy10 and Dy12 genes of the HMW-GS Glu-D1 and between protein content and SDSS, but not among others. These results suggest that Glu-D1 is extremely important for improving protein quality in HMW-GSs. As a result of this study, HMW-GS allele selection using functional markers, protein content, and SDSS investigation are expected to enable the development of varieties with high protein quality that are stable amid various environmental changes.

Low-temperature damage at the seedling stage is one of the most significant natural obstacles to wheat’s growth. In domestic wheat breeding programs, the selection of cold-tolerant varieties is crucial for the development of superior wheat varieties. Traditionally, the extent of damage caused by freezing wheat is estimated through visual observation. In this study, we compared the RGB image analysis method with conventional visual evaluation and chlorophyll content analysis methods to determine if this method could accurately quantify the cold tolerance discrimination of wheat in the field. First, single-leaf-level RGB image analysis revealed a pattern similar to dead leaf ratio and chlorophyll content in three grades of freezing injury. Next, we compared the significance of plant-level RGB image analysis. The greenness index by RGB image analysis showed a higher correlation with dead leaf ratio by visual evaluation. Finally, 40 wheat varieties were planted in the field and wheat canopy images were collected at the seedling stage after wintering. There was a high correlation between the greenness index and the visual evaluation. However, there was no correlation between dead leaf ratio and visual evaluation or greenness index as determined by RGB image analysis. These findings suggest that using RGB image analysis rather than visual evaluation can be useful in assessing freeze damage in wheat fields.

Consumer demand for Triticale cultivars as a winter forage crop in Korea has been increasing because of its ability for high and stable yield. However, more than 10 years are required to develop new varieties with conventional breeding programs. A speed breeding system using long-day photoperiodic treatment has recently been suggested and applied in wheat and barley, but not in the triticale breeding program in Korea. To evaluate the availability of the established speed breeding system for triticale breeding programs in Korea, we used nine domestic triticale cultivars to investigate their growth characteristics under a 22 h photoperiod. The average days to heading (DTH) of the nine cultivars was 38 days, and Gwangyoung and Minpung showed the most delayed DTH at 42 days. Therefore, all nine triticale cultivars were able to shorten the growth duration under the tested photoperiod condition. One productive tiller and more than 10 seeds were obtained from each cultivar. The germination percentage was over 82% when the spikes were harvested 20 days after heading, dried, and chilled for a week to break dormancy. These results suggest that in Korea, the rapid generation advancement system with simple long-day photoperiodic treatment can be applied to triticale breeding programs to reduce the breeding time.

This study was conducted to investigate the effect of starch properties on the texture of cooked noodles from Korean wheat. The genetic composition of GBSS I (granule bound starch synthase I, called waxy protein) and puroindoline, which affect the amylose content and kernel hardness, was also evaluated. Waxy wheats carrying Wx-1 null alleles showed clearly different starch properties, high swelling power, pasting viscosity, breakdown and paste clarity, unsuitable texture of cooked noodles, and low hardness and springiness. Two partial waxy soft wheats carrying single or double null alleles at the Wx-1 locus gene, and Pina-D1a and Pinb-D1a alleles exhibited a softer and higher elasticity texture of the cooked noodles than Korean wheats carrying wild-type Wx-1 null alleles. There were no significant differences in the starch properties and texture of cooked noodles according to the puroindoline composition. A principal component analysis showed a strong negative relationship between the amylose content and starch swelling power, and these traits also improved the springiness and cohesiveness of the cooked noodles prepared from non-waxy Korean wheat. Joongmo2012, a double null partial waxy wheat, showed higher starch swelling power and springiness of the cooked noodles than other non-waxy Korean wheats.

A new winter wheat (Triticum aestivum L.) cultivar ‘Baekkang’ was developed by the National Institute of Crop Science (NICS) and Rular Development Administration (RDA) in 2015. Its heading date was April 23, and its maturity date was June 3, similar to that of ‘Keumkang’. ‘Baekkang’ had a shorter culm length (75 cm), longer spike length (8.0 cm), more spikes per m² (703), and more 1,000-grain weight (47.5 g) than those of ‘Keumkang’, which were 76 cm, 7.6 cm, 631, 46.4 g, respectively. ‘Baekkang’ was not a winter hardy crop and is susceptible to powdery mildew. However, it has moderate resistance to fusarium head blight. The average grain yield in the advanced yield trial was 5.5 MT/ha, 20% more than ‘Keumkang’. In the regional yield trial, this average yield was 5.1 MT/ha upland and 5.2 MT/ha in the paddy field, which were 10% and 18% more than that of ‘Keumkang’, respectively. Baekkang’s flour yield (71.2%) and flour lightness (92.40) showed similarities to those of ‘Jokyung’. ‘Baekkang’ also showed a higher protein content (12.4%), gluten content (10.1%), and SDS-sedimentation volume (60.0 ml). These results showed that the ‘Baekkang’ flour’s dough strength was greater than that of ‘Jokyung’. Baekkang’s high molecular weight gluten subunits composition was Glu-D1 (5+10), granule-bound starch synthase composition was Wx-A1 (a), Wx-B1 (a), and Wx-D1 (a), and puroindoline composition was Pina-D1(a) and Pinb-D1(b) (Registration No. 6966).

This study was performed to evaluate the characteristics of wheat flour and sourdough bread quality of five Korean bread wheat cultivars, hard red winter wheat (HRW), and T55 (a French commercial wheat flour). Among the cultivars assessed, the protein and gluten contents and SDS-sedimentation values of Joongmo2008 were the highest, Keumkang were similar to those of HRW, and those of the Baekkang, Jokyung, and Hwanggeum were similar to those of T55. Joongmo 2008 and Keumkang had glutenin contents similar to those of HRW and T55, whereas Baekkang and Hwanggeum had higher HMW-GS (high molecular weight-glutenin subunit) and lower LMW-GS (low molecular weight-glutenin subunit) contents than HRW and T55. The α+β gliadin contents of Jungmo2008 and Keumkang were higher than those of other varieties and similar to those of HRW, whereas the γ- and ω-gliadin contents of Baekkang and Hwanggeum were similar to those of T55. Mixolab analysis revealed that Joongmo2008 and Keumkang had water absorption and kneading characteristics similar to those of HRW, and that Baekkang, Hwanngeum, and Jokyung showed characteristics similar to those of T55. Campagne and baguettes prepared using Korean wheat flour were similar in appearance to those prepared using T55 or HRW, the bread volume of campagne bread was smaller than that of T55, and the volume of baguettes were similar to that of T55. Joongmo2008 showed a higher bread volume than other Korean wheat cultivars, which was similar to that of HRW. The quality of sourdough bread prepared from Korean wheat flour was similar to that made with commercial flour, although the bread prepared using Joongmo2008 was found to be superior to that prepared using the flour of other Korean wheat cultivars.

The regeneration rate of plantlets cultivated via tissue culture is an important factor for wheat transformation. Similar to other monocotyledons, the most efficient tissue culture materials for wheat are immature embryos. However, stable year-round production of immature embryos is not possible in the field where various stress factors co-exist. In this study, we investigated the generation and subsequent plantlet incident rates of callus induced from immature embryos obtained from different sowing times in 2020 and compared these among wheat cultivars. We found that the rates of regeneration and plantlet incidence obtained using immature embryos of the Ariheuk cultivar were higher than those of other domestic cultivars, and that the tissue culture efficiency was similar to that of Bobwhite, which has been established as a cultivar with excellent transformation efficiency. Furthermore, the Baekkang cultivar showed high tissue culture efficiency only when sown from early to mid-March, whereas Keumkang showed higher tissue cultivation efficiency only by sowing in mid- and late February. Among the five cultivars assessed in this study, Jopum showed the lowest tissue culture efficiency. It is anticipated that the findings of this study will contribute to enhancing the transformation efficiency of domestic wheat varieties.

Kernel weight is a vital trait for selecting high-yielding wheat in breeding programs. We evaluated the thousand-kernel weight (TKW), test weight (TW), grain length (GL), grain width (GW), grain thickness (GT), and grain roundness (GR) of 41 Korean winter wheat cultivars over a period of 4 years. Correlation analyses revealed that TKW was positively correlated with GL (r=0.76***), GW (r=0.85***), and GT (r=0.84***), whereas TW was negatively correlated with GL (r=-0.38*) and GT (r=-0.31*). Allelic variation was analyzed for 13 kernel weight-related genes/loci (TaCwi-A1, TaCWI-4A, TaCWI-5D, TaGW2-6A, TaTGW6-A1, TaTGW-7A, TaGS1a, TaSus1-7A, TaSus1-7B, TaSus2-2B, TaCKX6-D1, TaCKX6a02-D1, and TaSnRk2.3). Significant associations between the allelic variation and kernel traits were identified in TaCWI-4A (TW, GL, and GR), TaCWI-5D (TKW), TaGW2-6A (TKW, GL, GW, and GT), TaSus2-2B (TKW, GL, GW, and GT), and TaGS1a (TW). In contrast, we detected no significant association between the allelic variation of TaCwi-A1, TaTGW6-A1, TaSus1-7A, and TaSus1-7B and variations in kernel traits. Also, TaTGW-7A, TaCKX6-D1, TaCKX6a02-D1, and TaSnRK2.3 were found to be monomorphic. The four loci TaCWI-4A, TaCWI-5D, TaGW2-6A, and TaSus2-2B showed significant phenotypic differences, a totalof 10 different haplotypes (AC1-AC10) were observed at four loci among the Korean wheat cultivars. Cultivars with the AC1 haplotype exhibited significantly higher TKW than those with the AC8 haplotype, which comprises alleles for high TKW at all four loci, indicating that additional loci controlling kernel weight might be present in the high TKW cultivars.

AbstractStem rust is a major wheat disease caused by the fungus Puccinia graminis f. sp. tritici (Pgt). Occurring mainly in warm and humid climates, stem rust has generally been considered less prevalent than leaf rust (P. triticina) and stripe rust (P. striiformis f. sp. tritici). However, a highly virulent stem rust race, Ug99, appeared in Uganda in 1998 and has devastated wheat production throughout Africa and the Middle East. As damage caused by the Ug99 lineage and other newly diverging stem rust races continues to increase, extensive research on wheat breeding and genetics to enhance stem rust resistance has been conducted internationally. Among the 60 stem rust resistance genes reported thus far, 11 (Sr13, Sr21, Sr22, Sr33, Sr35, Sr45, Sr46, Sr50, Sr55, Sr57, and Sr60) have been cloned. New resistance sources have been sought by screening diverse wheat germplasms through international collaborations. Such efforts are urgently required in Korea to address the increasing threat of stem rust epidemics. Furthermore, major Pgt races in the Korean peninsula need to be pathotyped. This information can be used to screen major wheat cultivars, breeding lines, and landraces to identify effective resistance sources. Previously reported stem rust resistance genes should also be introduced and pyramided into the genetic background of Korean wheat breeding populations via available molecular markers. Finally, research capacity in molecular genetics and genomics needs to be strengthened to enable the identification of new stem rust resistance genes and the development of precise molecular markers.

AbstractExtensive research has been conducted in wheat to improve genetic resistance to rust, a major disease that deteriorates wheat yield and quality worldwide. Leaf rust caused by Puccinia triticina is the most prevalent among the three major wheat rust diseases (leaf, stripe, and stem rust) globally and is adapted to a wide range of climates. Approximately 80 genes for leaf rust resistance have been reported, and six (Lr1, Lr10, Lr21, Lr22a, Lr34, and Lr67) have been cloned. Among these cloned genes, Lr34/Yr18/Sr57/Pm38 and Lr67/Yr46/Sr55/Pm46 are of special interest for breeding programs, as they provide pleiotropic resistance to stripe rust, stem rust, and powdery mildew as well as leaf rust. In Korea, knowledge on wheat breeding and genetics for rust resistance is insufficient, as agronomic measures have mainly been used to avoid rust. Therefore, an extensive research program to address the increasing threat of rust epidemics due to climate change is urgently required. Major Korean wheat cultivars, breeding lines, and landraces should be screened for leaf rust resistance. Diverse germplasms also need be introduced through international collaborations to broaden the genetic background for resistance. It is equally important to characterize the distribution of different leaf rust races in Korea and respond to changes in pathogen populations by using effective resistance genes in breeding programs. Research on molecular genetics and genomics needs to be furthered to identify new leaf rust resistance genes and develop efficient molecular markers.

Stripe rust (or yellow rust) caused by Puccinia striiformis f. sp. tritici is the major wheat disease responsible for deteriorating global wheat yield and quality. Although stripe rust appears to be prevalent mainly in temperate areas, new races adapting to high temperature have recently appeared in warmer areas, such as Australia, the Middle East, and Africa, increasing the threat to global food security. Among the approximately 80 reported genes for stripe rust resistance, six (Yr5, Yr7, Yr15, Yr18, Yr36, Yr46) have been cloned. Stripe rust resistance genes are generally classified into race-specific (or all-stage) and non-race-specific (or high temperature adult plant) resistance genes. While resistance conferred by most race-specific genes are overcome by the appearance of new pathogen races within few years, non-race-specific genes, such as Yr18, Yr36, and Yr46, provide more durable resistance and are often stable for several decades. Yr18/Lr34/Sr57/Pm38 and Yr46/Lr67/Sr55/Pm46 are especially useful in breeding as they confer resistance to leaf rust, stem rust, and powdery mildew as well as stripe rust. Unlike the extensive global research efforts, few studies have been conducted in Korea regarding breeding and genetics for stripe rust resistance. To prevent damage by stripe rust in advance, it is important to monitor the changes in major pathogen races in Korea, evaluate major wheat breeding lines and landraces for stripe rust resistance by establishing an efficient screening system, and introduce new germplasm with various resistance genes. Reinforcing wheat molecular genetics and genomics capacity is also important to enable identification of new stripe rust resistance genes and efficient transfer of the novel genes into elite wheat cultivars using molecular markers.

Barley and wheat are a major food crop of humans, along with rice, soybean and corn. A systematic breeding program for Korean barley began in 1906 with selection and introduction breeding. In 1908, landrace barley was collected, and breeding focused on selection and introduction for high yielding varieties until the 1970s. In the 1980s and 1990s, breeding was carried out for diversity; thereafter, we aimed to improve quality, productivity and lodging tolerance that can be applied to the paddy field in Korea. Since 2010, the major result of breeding was shortening cultivation to approximately 6–12 days, making a double cropping system possible in the paddy field in Korea. Yield has increased by 1.2 times from 438 kg/10 a in the 1960s to 536 kg/10 a in the 2010s, and farm yield has increased by 1.7 times. In addition, as cultivation safety has been enhanced, the varieties have also improved, such as the covered barley used in making tea and other processing products. In case of wheat, up to now forty cultivars have been developed in Korea. In the early stage, we developed a domestic wheat variety that was early maturing and high yielding. As a result, the maturation time of wheat planted in the 1970s to 2010 was shortened (from 13 to 30 days), while productivity increased by 30% from 408 kg/10 a in the 1970s to 532 kg/10 a in 2010. In recent years, there have been remarkable efforts for a more stable production by focusing on increasing disaster and pest resistance due to climate change. In addition, a wheat variety discrimination marker was developed using a variety-specific marker, and selection was made using a trait-specific marker at the early stage of breeding to enhance breeding efficiency. In the 2000s, winter cereals for forage have been promoted to expand forage production and to replace imported feed grains. Therefore, winter cereal that is useful for feed, such as rye, oat, and triticale, have had various varieties and safe production techniques developed. Currently, our research goal for winter cereals for feed is to develop a double-cropping adaptation and abiotic stress tolerance cultivar, and safe production in paddy field. Hence, aggressive action is needed to support the strategic survival of the Korean wheat and barley industry. Barley is a health food that requires a multifaceted effort to improve breeding efficiency, develop varieties that contain large amounts of functional components and are more resistant to stronger biotic and abiotic stresses in response to climate change. It is necessary to recognize the role of wheat and barley as the second main crop after rice, and to improve the self-sufficiency rate of these crops for the health and food industry crisis of Korea.

A winter wheat (Triticum aestivum L.) cultivar, ‘Taejoong’, was developed by the National Institute of Crop Science, Rural Development Administration in 2016. It was derived from a cross between ‘Xian83(104).11’ and ‘Keumkang’ in 2005. It was generated through the bulk and pedigree methods for six years, and then designated as ‘Iksan370’ after a two-year advanced yield trial test. This variety was designated the name ‘Taejoong’ after a regional yield trial test in eight locations throughout Korea for three years from 2014 to 2016. Its heading date was April 27 in upland and paddy filed conditions, and its maturity date was June 7 in uplands and June 4 in paddy fields, which were late compared to that of ‘Keumkang’. ‘Taejoong’ had 417 spikes per m², which was 300 less than that of ‘Keumkang’. However, the spike length was 13.4 cm and the number of kernel per one spike was 48, which was 5.8 cm longer and 19 higher than those of ‘Keumkang’, respectively. ‘Taejoong’ showed strong resistance to lodging and moderate resistance to Fusarium head blight, but was susceptible to powdery mildew. ‘Taejoong’ flour yield (71.8%) and flour lightness (91.90) were similar to those of ‘Keumkang’, but its protein content (11.1%), gluten content (8.8%), and sodium dodecyl sulfate-sedimentation volume (34.2 ml) were lower. These result showed that the flour dough strength of ‘Taejoong’ was weaker than that of ‘Keumkang’. The high-molecular-weight gluten subunit compositions of ‘Taejoong’ were Glu-A1 (N), Glu-B1 (7+9), and Glu-D1 (2+12). The granule-bound starch synthase compositions were Wx-A1, Wx-B1, and Wx-D1. The puroindoline compositions were Pina-D1 (a type) and Pinb-D1 (b type). The average grain yield of ‘Taejoong’ in a regional yield trial was 5.3 ton/ha in uplands and 4.6 ton/ha in paddy fields, which were 21% and 13% higher than that of the reference cultivar, ‘Keumkang’, respectively. (Registration No. 7378).

Association analysis was conducted to identify quantitative trait locus (QTL) of yield potential traits, days to heading date, culm length, spike length and kernels per spike in the genetic mapping population (94 F₁₀ recombinant inbred line) produced from a cross between two Korean wheat cultivars, Taejoong which has a large kernel number line, a longer spike length, and a higher kernel number per spike and Keumkang. Yield potential traits, days to heading date, culm length, spike length and kernels per spike were evaluated in 2017 and 2018 under upland conditions. Days to heading date were biased toward late heading date (skewness=-0.3), and spike length was biased toward short spike length (skewness=0.7). A genetic map was constructed with 57 microsatellite marker loci and two QTLs were detected for spike length. The first QTL on chromosome 2A, qSL-1 was detected by Xcfd5 and Xpsp3050 and explained 20.7% of phenotypic variation. The second QTL on chromosome 5B, qSL-2 was detected by Xwmc656 and Xwmc415 and explained 40.8% of phenotypic variation. These QTLs were applied to validate the relationships between genotypes of QTLs and 29 Korean wheat cultivars cultivated for nine years, from 2010 to 2018. The Korean wheat cultivars were classified into 6 types according to the genotypes of Xcfd5-Xpsp3050 and Xwmc656-Xwmc415. The same genotypes as Keumkang showed a higher frequency and shorter spike length than that of Taejoong in Korean wheat cultivars.