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.

The white sesame variety, ‘Kangyou’ (Sesamum indicum L.) with disease resistance and high yield was developed in 2019. It was developed through a cross between ‘China Black’ and ‘SI982849’, in 2006. The ‘Kangyou’ variety has a few branches and triple capsules per node. ‘Kangyou’ exhibited resistance to Phytophthora blight and Fusarium wilt disease in the field. The yield from ‘Kangyou’ was about 1.37 ton per hectare, 13% higher than that of ‘Goenbaek’. ‘Kangyou’ showed a crude fat content of 53% and a lignan content of 4.8 mg/g. This variety will contribute to the increase in sesame production in Korea and will be used in sesame breeding programs.

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.

Potato late blight caused by the fungus Phytophthora infestans is one of the most important diseases worldwide. Developing potatoes with resistance to late blight through breeding programs is a key research interest in Korea. ‘Mangang’ was bred for late blight resistance through a breeding program at the Highland Agriculture Research Institute of National Institute of Crop Science. The population derived from the cross between ‘Atlantic’ as the female parent, which has excellent chipping quality and ‘CIP393371.159’ as the male parent, a late blight-resistant clone introduced from International Potato Center (CIP), was selected. In ‘Mangang’, the plant maturity occurs late and the growth habit is of the erect type. The tuber shape is round and eye-depth is medium. The skin color of ‘Mangang’ is light yellow; however, there are pink spots around the eyes of the tuber, and the flesh color is white. Leaf color is green and flower color is light-purple. ‘Mangang’ exhibits resistance to early blight (Alternaria solani) and leaf roll virus (PLRV). In addition, it has moderate resistance to common scab (Streptomyces scabies). The response to late blight was evaluated in a non-agrochemical treated field for five years between 2012 and 2016; ‘Mangang’ exhibited resistance to late blight. The mean AUDPC (Area Under Disease Progress Curve) values of ‘Mangang’ and ‘Atlantic’ were 165.5 and 795.8, respectively. Total tuber yield from the non-agrochemical application trial at three regions during the five years was 40.3 ton/ha; this was 40.4% higher than that from ‘Atlantic’. The dry matter content of ‘Mangang’ was 21.3%, which was slightly higher than that of ‘Atlantic’. The chip color was 66.5, and the chip processing quality of ‘Mangang’ was at a level similar to that of ‘Atlantic’ (Registration No. 9312).

The rice cultivar ‘Chamdongjin’ was developed to enhance the disease resistance of ‘Sindongjin’. ‘Sindongjin’, developed by the RDA in 1999, is a mega-variety with a unique grain size and excellent taste, and has been cultivated in the largest area in Korea since 2018. As ‘Sindongjin’ has been cultivated in a large area recently, problems such as pest damage are increasing, and the necessity to develop alternative cultivars is emerging. Accordingly, the multiple disease-resistant, mid-late maturing rice cultivar ‘Chamdongjin’, carrying the bacterial blight resistance gene Xa21 into the genetic background of ‘Sindongjin’, was developed. ‘Chamdongjin’ was developed by the backcrossing method using the donor parent ‘HR27195-59-3-5-5’, harboring the bacterial blight resistance genes Xa3+Xa21 and the recurrent parent ‘Sindongjin’. ‘Chamdongjin’ was selected through the pedigree method, yield trials, and local adaptability tests, with a high selection pressure for agronomic trait similarities with ‘Sindongjin’. In order to effectively improve the disease resistance, marker-assisted selection for disease resistance genes and bioassays for bacterial blight, blast, and stripe virus were performed in parallel. ‘Chamdongjin’ was confirmed to have three disease-resistance genes, Xa3+Xa21+Stvb-i. Most of agronomic traits of ‘Chamdongjin’ were similar to ‘Sindongjin’, while ‘Chamdongjin’ showed enhanced disease resistance against bacterial blight and panicle blast compared to ‘Sindongjin’. ‘Chamdongjin’, like ‘Sindongjin’, possessed a grain size-related gene, the gs3 allele, and exhibited larger grains than general Korean japonica cultivars. In addition, ‘Chamdongjin’ showed a similar or higher level of palatability compared to ‘Sindognjin’, indicating the excellent quality characteristics. In the genetic background analysis using 787 KASP markers, ‘Chamdongjin’ showed 96.3% homozygosity with ‘Sindongjin’, indicating that it had a more similar genetic background to ‘Sindongjin’ than to other existing cultivars. ‘Chamgdongjin’ is expected to be widely cultivated as an alternative to ‘Sindongjin’, which could maintain the brand value while preventing the disease damage caused to ‘Sindongjin’ (Registration No. 9310).

“JJ603Balck” is a mid-late maturing high-yielding black rice having multiple-disease resistance. It was developed to increase the yield and disease resistance of Korean black rice. “JJ603Black” was derived from a cross between “Heughyang” and BC₂F₁ plants (Hopum*3/SR30075-1-12-6-1-1-1). “Heughyang” is a mid-late black rice with a short culm, while “Hopum” is a mid-late maturing rice cultivar with high yields and premium quality, and “SR30075” is a pyramid line carrying three bacterial blight resistance genes. “JJ603Black” was selected through the pedigree method, yield trials, and local adaptability tests, with a high selection pressure for black pericarp, resistance to bacterial blight K3a race, and high yield performance. The heading date of “JJ603Black” was August 19, 8 d later than that of “Heugnam,” which is the standard cultivar for black rice. “JJ603Black” is a cultivar tolerant to lodging with erect plant architecture. It showed multiple-disease resistance against bacterial blight and rice stripe virus owing to introgression resistance genes, Xa3+Xa21+Stvb-I; moreover, its yielding performance was high. The average brown rice yield of "JJ603Black" from 2016 to 2018 was 6.02 MT/ha, which was 14% more than that of “Heugnam” (5.30 metric/ha). Further, the anthocyanin content of “JJ603Black” (58 mg/100 g) was higher than that of “Heugnam” (51 mg/100 g). Therefore, “JJ603Black,” a high-yielding black rice cultivar with multiple-disease resistance, can be utilized for enhancing the disease resistance and yield of Korean black rice (Registration No. 7274).

Rice is an important crop used as a staple food in most of the world; however the occurrence of pests is increasing due to climate change. In particular, the brown planthopper (BPH, Nilaparvata lugens stal) is a key cause of rice yield loss. In response to the era of unpredictable climate change in the future, the Plant Molecular Breeding laboratory of the Department of Applied Biosciences, Graduate School, Kyungpook National University, Daegu 41566, Korea bred the ‘Drimi2ho’ strain, which is resistance to BPH or various pests and of excellent eating quality. In order to cultivate ‘Drimi2ho’, ‘Samgang’ and ‘Nagdong’ were crossed and the derived seeds were backcrossed with ‘Junam’, and the pedigree breeding method was applied. During the application of the pedigree method, agricultural characteristics which are investigated in the field were found to be excellent, and the best line for various disease resistance, grain quality, and yield was finally selected as ‘Drimi2ho’. ‘Drimi2ho’ has strong resistance to BPH and its range of resistance to major pests and viral diseases such as blast and bacterial blight on rice is quite wide. In the field, the main agricultural characteristics of ‘Drimi2ho’ were similar to or improved from those of ‘Junam’. ‘Drimi2ho’ is a cultivar with enhanced disease and pest resistance and a wide spectrum while maintaining the good eating quality. ‘Drimi2ho’ yielded 584 kg/10a in ordinary cultivation under normal level of fertilization in south mid-mountainous areas of Korea. Drimi2ho’ can thus be a standard cultivar in Korea due to its varied resistance to multiple diseases and excellent grain quality. (Registration No. 4686).

Brown planthopper (BPH, Nilaparvata lugens Stal) is a major agricultural pest that plays a key role in reducing rice yield. Rapid climate change has emphasized the necessity of cultivating multi-resistant cultivar rather than cultivar with single-resistance to specific pests. Accordingly, the Plant Molecular Breeding Laboratory of the Department of Applied Biosciences, Graduate School, Kyungpook National University, Daegu 41566, Korea developed the ‘Drimi 1ho’ rice cultivar with enhanced resistance to blast and bacterial blight as well as BPH breeding in 2008. In order to breed ‘Drimi 1ho’, ‘Samgang’ and ‘Nagdong’ were crossed and backcrossed with ‘Junam’, after which the pedigree breeding method was applied. Finally, ‘Drimi 1ho’ was selected through analysis of resistance to insect and viral disease, yield, and grain quality. ‘Drimi1ho’ is strongly resistant to BPH and has a wide range of resistance to pests. ‘Drimi 1ho’ is also resistant to blast and bacterial blight (K₁, K₂, K₃), which occurs most frequently and causes serious damage to crops in the Republic of Korea. The agricultural characteristics of 'Drimi 1ho' were similar or improved from 'Junam'. In particular, ‘Junam’ is susceptible to BPH and bacterial blight. ‘Drimi 1ho’ made up for the shortcomings of ‘Junam’ with acquired strong and broad-spectrum resistance. Finally, ‘Drimi 1ho’ had a yield of 563 kg/10 a under normal cultivation and can thus be an adaptable cultivar in south mid-mountainous areas in the Republic of Korea (Registration No. 3685).

In 2018, a new potato variety, ‘Arirang-2’, was released by the Highland Agriculture Research Institute in Pyeongchang, Korea. To create new varieties with better tuber formation at high temperature under long day, a cross was performed between high-temperature tolerant ‘Eigenheimer’ and drought tolerant ‘Daegwan 1-116’ in 2011. The shoot (57.9 cm) of ‘Arirang-2’ was taller than ‘Superior’ and ‘Sante’, and its tuber skin and flesh were red and light-yellow colored, respectively. Average number of tubers per plant of ‘Arirang-2’ was 9.1 while ‘Superior’ and ‘Sante’ had 5.4 and 14.1 tubers, respectively. Average weight of tuber of ‘Arirang-2’ was 98.1 g, which was slightly heavier than that of ‘Superior’ (90.0 g), and much heavier than that of ‘Sante’ (38.9 g). Total weight of tuber per plant of ‘Arirang-2’ was 892 g, which was remarkably higher than that of ‘Superior’ (486 g) and ‘Sante’ (549 g). Total yield (TY) of ‘Arirang-2’ measured in Gangwon-Do, Korea was around 5,022 kg/10a while that of ‘Superior’ was 3,036 kg/10a. In Kazahstan, total yield of ‘Arirang-2’ was 4,657 kg/10a and that of ‘Sante’ was 4,155 kg/10a. Marketable tuber yield (MTY) of ‘Arirang-2’ was 3,119 kg/10a in Gangwon-Do, Korea while that of ‘Superior’ was only 2,147 kg/10a. In Kazahstan, MTY of ‘Arirang-2’ was 3,162 kg/10a, which was 60% higher than that of ‘Sante’ (1,974 kg/10a). ‘Arirang-2’ is resistant to early blight (Alternaria solani) and late blight (Phytophthora infestans) compared to ‘Superior’ and ‘Sante’, and it shows tolerance to drought or high temperature. ‘Arirang-2’ was approved as a new potato cultivar by The Korea Seed and Varieties Service on March 3, 2021 (Registration No. 8444).

The cultivation of early maturing rice in the plain areas in Korea is increasingly diversifying its cropping systems. Early maturing rice cultivars are usually vulnerable to bacterial blight (BB) and rice stripe virus (RSV) compared to mid- and mid-late maturing rice cultivars. To enhance the resistance of early maturing rice against BB and RSV, ‘IS592BB’ was developed by introgression of resistance genes, Xa3, Xa21, and Stvb-i into the genetic background of ‘Unkwang’, an early maturing rice cultivar with excellent agronomic characteristics. ‘IS592BB’ was derived from a backcross between ‘Unkwang’ and the F1 cross between ‘Unkwang’ and ‘SR31206-12’ (‘Unkwang’/‘SR30075’) and selected through the pedigree method, yield trials, and local adaptability tests. Using bioassay and marker-assisted selection to BB and RSV, Xa3, Xa21, and Stvb-i were pyramided in ‘IS592BB’. ‘IS592BB’ exhibited high-level and broad-spectrum resistance against BB, including the K3a race, the most virulent race in Korea, and also showed a resistance reaction to RSV. ‘IS592BB’ was found to be an early maturing rice cultivar with similar agronomic characteristics to ‘Unkwang’ such as early maturing, lodging tolerance with short culm, erect plant architecture, blast resistance, and high-yielding performance. In the genetic background analysis using 771 KASP (Kompetitive Allele-Specific PCR) markers, ‘IS592BB’ was confirmed to be the near-isogenic line (NIL) of ‘Unkwang’ with a 93.6% recovery rate. ‘IS592BB’ was successfully introgressed with the Xa3+Xa21+Stvb-i genes into ‘Unkwang’ without linkage drag negatively affecting its agronomic characteristics. ‘IS592BB’ would enhance the adaptability of early maturing rice in the plain area through its multiple disease resistance (Registration No. 7648).

A new double cropping potato variety, ‘Gangseon’, was bred by the Highland Agriculture Research Institute, National Institute of Crop Science (NICS), RDA, Korea, in 2016. ‘Gangseon’ was obtained from the cross between ‘Daegwan1-83’ and ‘Chubaek’ in 2006. Seedling and line selection was performed from 2008 to 2009, and preliminary and advanced yield trials were carried out with ‘Gangseon’ from 2010 to 2013 in Gangneung city. The regional yield trials were conducted in Gangneung, Muan, and Jeju from 2014 to 2016. ‘Gangseon’ has light purple flowers, green narrow leaflets and petioles with medium anthocyanin coloration, round tubers with yellow russet skin, and yellow flesh. The dormancy of ‘Gangseon’ stored in 20 ℃ was 60-70 days after harvesting, which is longer than those of ‘Dejima’ and ‘Chubaek’, but shorter than that of ‘Superior’. The average yields of tubers in the spring and fall seasons were 36.6 and 21.2 ton⋅ha^-1, respectively, in the regional yield trials. It is susceptible to common scab and potato virus Y, but has high resistance to potato leaf roll virus, potato virus X, early blight, and late blight. The dry matter contents were 22.1% in spring and 19.8% in autumn. The adaptation area of ‘Gangseon’ is the southern coastal area, including Jeju Island, Korea. The plant variety protection right of ‘Gangseon’ was registered in April 2020, and its grant number is 8081.

Chlorophyll is an essential pigment involved in light absorption and electron transfer in photosynthesis, a photochemical process that is indispensable for plant growth and development. The biosynthesis of chlorophyll occurs in plastids and shares a common biosynthetic pathway with other tetrapyrroles. The chlorophyll metabolic pathway is divided into four distinct components: the common pathway, chlorophyll-specific biosynthetic pathway, chlorophyll cycle, and chlorophyll degradation pathway, which are regulated in developmental- and environmental-specific manners. During the early stages of plant growth, the expression of most chlorophyll biosynthetic genes is induced by light, resulting in an increase in chlorophyll accumulation, induction of high photosynthetic activity, and continuous plant growth. In contrast, during plant maturation, the expression of most of these genes is gradually downregulated, whereas genes involved in chlorophyll degradation are upregulated during leaf senescence. Chlorophyll biosynthesis is directly or indirectly regulated by the members of various transcription factor families. In this review, we describe representative mechanisms of transcription factor-mediated activation and repression of chlorophyll biosynthesis in response to light treatment. We also present an overview of recent studies that have examined all the enzymatic steps involved in chlorophyll metabolic pathways and their gene regulation at the transcriptional level, which will enable readers to gain a better understanding of chlorophyll metabolism.

‘Sinjinbaek’ is a bacterial blight (BB)-resistant, mid-late maturing rice cultivar with high grain quality. To diversify the resistance genes and enhance the resistance of Korean rice cultivars against BB, ‘Sinjinbaek’ was developed from a cross between ‘Iksan493’ (cultivar name ‘Jinbaek’) and the F₁ cross between ‘Hopum’ and ‘HR24670-9-2-1’ (‘HR24670’). ‘Jinbaek’ is a BB-resistant cultivar with two BB resistance genes, Xa3 and xa5. ‘Hopum’ is a high grain quality cultivar with the Xa3 resistance gene. ‘HR24670’ is a near-isogenic line that carries the Xa21 gene, a resistance gene inherited from a wild rice species O. longistaminata, in the genetic background of japonica elite rice line ‘Suweon345’. ‘Sinjinbaek’ was selected through the pedigree method, yield trials, and local adaptability tests. Using bioassay for BB races and DNA markers for resistance genes, three resistance genes, Xa3, xa5, and Xa21, were pyramided in the ‘Sinjinbaek’ cultivar. ‘Sinjinbaek’ exhibited high-level and broad-spectrum resistance against BB, including the K3a race, the most virulent race in Korea. ‘Sinjinbaek’ is a mid-late maturing rice cultivar tolerant to lodging. It has multiple disease resistance against BB, rice blast, and stripe virus. The yield of ‘Sinjinbaek’ was similar to that of ‘Nampyeong’. ‘Sinjinbaek’ showed excellent grain appearance, good taste of cooked rice, and enhanced milling performance, and we concluded that it could contribute to improving the quality of BB-resistant cultivars. ‘Sinjinbaek’ was successfully introgressed with the Xa21 gene without the linkage drag negatively affecting its agronomic characteristics. ‘Sinjinbaek’ improved the resistance of Korean rice cultivars against BB by introgression of a new resistance gene, Xa21, as well as by pyramiding three resistance genes, Xa3, xa5, and Xa21. ‘Sinjinbaek’ would be suitable for the cultivation in BB-prone areas since it has been used in breeding programs for enhancing plants’ resistance to BB (Registration No. 7273).

‘Haepum’ is a bacterial blight-resistant, medium maturing rice cultivar with high grain quality. It was derived from a cross between ‘Iksan493’ (cultivar name ‘Jinbaek’) and the F₁ cross between ‘Iksan495’ (‘Dacheong’) and ‘Iksan496’ (‘Jungmo1005’). Of these three cultivars, ‘Jinbaek’ is a bacterial blight-resistant mid-late maturing rice cultivar with high grain quality, ‘Dacheong’ is a mid-late maturing rice cultivar with multiple resistance to disease and insects, and ‘Jungmo1005’ is a mid-late maturing rice cultivar with lodging tolerance. To develop fixed lines, the anther culture method was applied to F₁ plants. The cultivar ‘Haepum’ was selected using the pedigree method, yield trials, and local adaptability tests. The heading date of ‘Haepum’ was August 11^th, three days earlier than that of ‘Nampyeong’ cultivar. Haepum’ is a cultivar tolerant to lodging and it has short culms. Due to its low rate of viviparous germination, ‘Haepum’ could be useful for preventing pre-harvest sprouting in cultivation of medium maturing rice in the southern plain area of Korea. ‘Haepum’ carries two bacterial blight resistance genes (Xa3 and xa5), and in our study, it exhibited high-level and broad-spectrum resistance against bacterial blight, including K3a, the most virulent race in Korea. ‘Haepum’ is also resistant to the rice stripe virus and moderately resistant to rice blast. The yield of ‘Haepum’ was similar to that of ‘Nampyeong’. ‘Haepum’ showed excellent grain appearance and good taste of cooked rice, and therefore it could contribute to the development of bacterial blight-resistant rice cultivars of improved quality. ‘Haepum’ would be suitable for cultivation in the southern plain area of Korea as well as in bacterial blight-prone areas. (Registration No. 6068)

Watermelon (Citrullus lanatus) is an economically important vegetable crop all over the world, which has functional compounds such as lycopene and citrulline. Gummy stem blight caused by Didymella bryoniae is one of the most devastative diseases in watermelon. Single nucleotide polymorphisms (SNPs), which are genetic variations occurring between individuals with respect to a single base, were often used to construct genetic linkage maps and develop molecular markers linked to a variety of horticultural traits and resistance to several diseases. In this study, we developed high-resolution melting (HRM) markers based on SNPs generated from NGS resequencing of two parents in watermelon. Plant materials were C. lanatus ‘920533’ (female and susceptible parent), C. amarus ‘PI 189225’ (male and resistant parent), and their F₁ and F₂ progenies. A total of 13.6 Gbp (‘920533’) and 13.1 Gbp (‘PI 189225’) of genomic sequences were obtained using NGS analysis. A total of 6.09 million SNPs between ‘920533’ and ‘PI 189225’ were detected, and 354,860 SNPs were identified as potential HRM primer sets. From these, a total of 330 primer sets for HRM analysis were designed. As a result, a total of 61 HRM markers that have polymorphic melting curves were developed. These HRM markers can be used for the construction of SNP-based linkage maps and for the analysis of quantitative trait loci (QTLs) related to gummy stem blight resistance.

‘Manbaek’ is a bacterial blight resistant mid-late maturing rice cultivar with high grain quality. ‘Manbeak’ was derived from anther culture using the backcross combination, Hopum*2/SR30075. ‘Hopum’ is a mid-late maturing rice cultivar with high grain quality and ‘SR30075’ is a pyramid line carrying three bacterial blight resistance genes. ‘Manbaek’ was selected through the pedigree method, yield trials, and local adaptability tests. ‘Manbeak’ carrying two bacterial blight resistance gene Xa3 and xa5 showed high-level and broad-spectrum resistance against bacterial blight. ‘Manbaek’ was resistant to K3a, mostly virulent race in Korea, and exhibited resistance reaction against 16 Korean bacterial blight isolates. ‘Manbaek’ was a mid-late maturing rice. The heading date of ‘Manbaek’ was August 19th, which was 5 days later than that of ‘Nampyeong’. Manbaek’ was a lodging-tolerant rice with short culm and dark green leaf. Due to the low viviparous germination, ‘Manbaek’ could be a useful material to prevent pre-harvest sprouting. ‘Mabeak’ was resistant to bacterial blight and rice stripe virus, but susceptible to other virus diseases and insect pests. The yield of ‘Manbaek’ was similar to ‘Nampyeong’. ‘Manbaek’ showed excellent grain appearance and good tastes of cooked rice, so that it could contribute to improving the quality of bacterial blight resistant cultivars. ‘Manbaek’, bacterial blight resistant cultivar with high grain quality, is suitable for the cultivation at bacterial blight prone area and has been utilized in the breeding programs for enhancing the resistance against bacterial blight (Registration No. 6069).

This study was conducted to develop the early maturing rice lines with genes conferring resistance to bacterial blight and rice stripe virus to enhance the adaptability in plain area. Unkwang carrying Xa3 was used as a recurrent parent and SR30075 carrying Xa4+xa5+Xa21+Stvb-i was used as a donor parent. RL1(Resistant Line, BC₁F₇), RL2, RL3, RL4, and RL5(BC₂F₆) were bred through bio-assay of K3a race inoculation and phenotypic selection of agronomic traits. The presence of introduced genes was confirmed by testing the resistance levels against bacterial blight and rice stripe virus and then double-checked by using DNA marker. RL1 has all target genes, Xa3+xa5+Xa21+Stvb-i. RL2, RL3, and RL5 have Xa3+Xa21+Stvb-i whereas RL4 has only Xa21. Rice lines carrying Stvb-i showed resistance reaction to rice stripe virus. The combinations of bacterial blight resistant genes(Xa3+xa5+Xa21 and Xa3+Xa21) were found to be promising, as the rice lines carrying these genes enhanced a strong resistant reaction against 16 bacterial blight isolates. Also, the inoculation of K3a race did not alter the brown rice yield, ripened grain ratio and kernel quality of brown rice compared to control. Although RL1 containing all the target resistance genes showed excellent resistance performance, it is not suitable to cultivate in plain area due to instability to lodging, 80% yield level than Unkwang, and low grain quality. RL5 backcrossed twice with Unkwang was found to be a promising line due to its effective resistance gene combination, Xa3+Xa21+Stvb-i and good agronomic traits such as stability to lodging, higher yield and quality compared to Unkwang.

‘Huimangchan’ is a new japonica rice variety developed and registered by the rice breeding team of Department of Rice and Winter Cereal Crop, NICS, RDA in 2011. This variety was derived from the three-way cross of ‘Milyang165’, ‘Shindongjin’ and ‘YR19105-Acp222’. This variety has about 126 days of growth duration from transplanting to harvesting in Honam and Youngnam plain of Korea. It is about 91 cm in culm length and tolerance to lodging. In reaction to biotic stresses, it shows moderate resistance to blast, resistance to bacterial blight pathogen races from K1 to K3, and rice stripe virus, but susceptible to other major diseases and insect pests. The milled rice of ‘Huimangchan’ has high quality, midium short grain. The milled rice yield of this variety is about 6.18 T/ha in local adaptability test for three years. ‘Huymangchan’ would be adaptable to Middle plain, Honam plain and Youngnam plain area of Korea.

This study was conducted to develop breeding lines carrying bacterial blight resistance genes, Xa2, Xa3, xa5, and Xa21 for enhancing the resistance of early maturing glutinous japonica rice. Resistant lines were developed by backcrossing into early maturing glutinous elite cultivar, Sangjuchalbyeo and phenotypic selection for bacterial blight resistance and agronomic traits. Selected lines were confirmed the incorporation of the resistance genes using DNA markers and evaluated the resistance reaction against four Korean and eleven Philippine bacterial bight races. HR24465 line carrying Xa2 was resistant to Korean races K1, K2, and Philippine race 9a. HR24666 line carrying Xa3 was moderately resistant or resistant to races except for Korean race K3a and Philippine race 6. Resistant lines carrying xa5 were resistant to all races except for Philippine race 6. HR24669 line carrying Xa21 was moderately resistant or resistant to races except for Korean race K1 and Philippine race 10. Yield-related traits of breeding lines exhibited similar characteristics to Sangjuchalbyeo. These resistant lines could be useful breeding materials for improving the resistance of early maturing glutinous japonica rice against Xanthomonas oryzae pv. oryzae.