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Recently, crossbreeding between Asian rice (O. sativa) and African rice (O. glaberrima) has become an important solution for hunger refugees and food problems in Africa by improving grain yield. O. glaberrima exhibits important traits such as stress tolerance, and genetic diversity evaluation and structural analysis of agronomic traits have been conducted. In this study, 11 yield-related agricultural traits were analyzed in 45 lines of O. sativa and 28 lines of O. glaberrima under Korean climatic conditions. Through cluster analysis using the investigated yield-related traits, O. sativa and O. glaberrima were grouped into clusters by characterizing the remaining traits, except for the number of spikelets, grain width, and grain thickness. The number of spikelets was highly influenced by the environment and had the greatest variation, whereas grain width showed the least variation. In addition, rice yield components are quantitative traits, and in breeding to improve yield, it is important to analyze the interaction of agricultural traits and the influence of the environment to maintain an optimal balance and improve plant potential. Although O. sativa was found to exhibit different agricultural traits depending on its ecotype, it still belonged to the same group when clustered. The results of this study provide basic information on the yield-related agronomic characteristics of O. sativa and O. glaberrima under Korean climatic conditions, suggesting that O. glaberrima can be used as breeding material to diversify Korean rice genetic resources. [ABSTRACT FROM AUTHOR]

The cultivated area of glutinous rice in the Homan Plain of Korea is increasing to diversify the cropping system. Depending on the time of transplanting, glutinous rice can be divided into early, ordinary, and late cultivation. Eight glutinous rice cultivars (Baegseolchal, Baekogchal, Boramchal, Boseogchal, Dongjinchal, JJ644wx, Nunbora, and Sinseonchal) were used to evaluate yield, pasting properties, and texture according to cultivation time and to analyze the genotype-environment relationship. There were nine yield-related, six pasting-related, and four texture-related traits studied. Heading date and culm length were shortened as cultivation time increased, while panicle length, number of spikelets, and 1,000-grain weight increased. Furthermore, late cultivation time also reduced pasting properties, peak viscosity, trough viscosity, and final viscosity. Hardness and adhesiveness among the texture properties increased with cultivation time, but stickiness decreased. The variation in 1,000-grain weight is mostly dominated by genotype, whereas heading date and yield are heavily influenced by environmental factors. All pasting property characteristics varied with environment changes, and genotype variation was dominant for all texture properties. Boramchal yielded the most in early and ordinary cultivation and Sinseonchal, together with Boramchal, yielded the most in late cultivation. Cultivars with excellent grain quality were Sinseonchal in early cultivation and Baegseolchal and Baekogchal in ordinary and late cultivation. A comparative analysis of characteristics based on cultivation time can assist in the selection of glutinous rice suitable for the Honam Plain and in the breeding of cultivars with improved yield and excellent grain quality. [ABSTRACT FROM AUTHOR]

Rice is an important food crop that feeds most of the world's population. However, due to the increased frequency of pest outbreaks, it is necessary to cultivate complex pest-resistant rice cultivars. A mutant population was derived by culturing tissue of ‘Hwayeong’ at the Plant Molecular Breeding laboratory of Kyungpook National University in the Republic of Korea. The cultivar ‘Drimi4ho’, a line that was resistant to complex disease, was finally selected by backcrossing with ‘Junam’. The heading date of ‘Drimi4ho’ is August 11 (107 days after sowing). Drimi4ho’ has culm length of 69 cm, panicle length of 21 cm, 16 panicles per hill, 115 spikelets per panicle, a ratio of ripened grain of 92.7%, and a 1,000-grain weight of 24.3 g. No lodging occurred when ‘Drimi4ho’ was grown in the field by standard fertilization. It is also resistant to leaf/neck blast disease, bacterial blight (K1, K2, K3), rice dwarf virus, rice black-streaked dwarf virus, rice stripe virus, BPH, and SBPH. ‘Drimi4ho’ is a round and short-type grain, and is very clear and transparent without chalkiness. In addition, it has excellent physicochemical properties that make up food, so its taste is good. When ‘Drimi4ho’ was planted under ordinary conditions in the southern mountainous area of Korea, the yield was 5.53 MT/ha. [ABSTRACT FROM AUTHOR]

Rice is a staple food in most countries, and thus, diversifying its value is necessary. Recently, the focus on good health has increased, and rice cultivars with improved properties should be bred based on consumer demands. At the Plant Molecular Breeding Laboratory of Kyungpook National University, “Hwayeong” was tissue-cultured to derive mutant populations. In the mutant lines, “P35” with high protein content and excellent agricultural traits, was backcrossed with “Ilmi” three times, and the final selected line was called “Drimi5ho.” The heading date of “Drimi5ho” was August 11 (107 d after sowing), which was 5 d later than that of “Ilmi” (August 5, 101 d after sowing). The culm length of “Drimi5ho” was 71 cm, the panicle length was 18 cm, the number of panicles per hill was 13, the number of spikelets per panicle was 113, the ratio of ripened grain was 90.5%, and the 1,000-grain weight was 22.6 g. When "Drimi5ho" was planted ordinary plantation, the yield in the southern mountainous area was 526 kg/10a. Lodging was not observed when “Drimi5ho” was grown in the field with standard fertilization (N-P2O5-K2O = 9-4.5-5.7 kg/10a). This rice cultivar was resistant to leaf/neck blast, bacterial blight (K1, K2, and K3), rice stripe virus, rice black-streaked dwarf virus, and rice dwarf virus. The milled grain of “Drimi5ho” was clear and transparent without any chalkiness; moreover, the grain shape was round and short. Although it is a specialty rice with increased protein content, the taste of the rice and the grain quality were excellent (Registration No. 6829). [ABSTRACT FROM AUTHOR]

Rice is one of the most important food crops in the world, but brown planthopper (BPH, Nilaparvata lugens stal) causes a significant loss of rice yield. Due to climate change, different races of rice-damaging species are evolving at an accelerated pace, thus, creating a need to breed multi-resistant rice cultivars for a stable food supply. In 2001, “Samgang” and “Nagdong” were crossed at the Plant Molecular Breeding Laboratory of the Department of Applied Biosciences, Graduate School, Kyungpook National University, Daegu Korea. “Drimi3ho” is a resistant and high-quality rice cultivar that was bred by backcrossing a line having excellent agronomic traits with “Ilmi.” The heading date of “Drimi3ho” was August 12 (104 d after sowing), and it was a medium-maturing cultivar that matured 3 d earlier than “Ilmi” (August 15, 107 d after sowing). Its culm length was 81 cm, panicle length was 18 cm, panicle number per hill was 16, spikelet number per panicle was 113, ripened grain ratio was 93.2%, and 1,000-grain weight was 24.3 g. “Drimi3ho” was highly resistant to blast disease and bacterial blight (K1, K2, and K3), rice stripe virus, rice dwarf virus, rice black-streaked dwarf virus, and BPH. When “Drimi3ho” was milled, the milled grain was clear and transparent; moreover, the grains were semi-round and short-type. Moreover, “Drimi3ho” had lower protein and amylose content and tasted better than “Ilmi.” When “Drimi3ho” was grown on an ordinary plantation in the southern mountainous area, the yield was 563 kg/10a (Registration No. 5621). [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

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 [ABSTRACT FROM AUTHOR]

Temperate japonica is used as the parent for crossing in the breeding of new rice cultivars in Korea, and the grain shape of the developed lines or cultivars is a semi-round and medium-short grain length. To overcome the current low quantity of japonica cultivar germplasm and deterioration in quality caused by climate change, it is necessary to diversify the grain characteristics of japonica. Most of the United States (US) cultivars are classified as medium, long, extra-long, and half spindle- and spindle-shaped grains. The qSW5 allelotype, a major gene involved in grain width, is found in all US cultivars. In addition, the US cultivar ‘Saber’ has both qgl3 and GS3_B alleles, which have low allele frequencies among Korean rice cultivars, and ‘A020’ had gw8, an allele with a reduced grain width. The pasting properties and texture of medium-grain length and half-spindle-shaped cultivars were relatively similar to those of the Korean rice cultivar, but different from those of long-grain and long spindle-shaped cultivars. Therefore, grain shape is associated with pasting properties and texture traits. Among the rice cultivars in the US, tropical japonica belongs to the same japonica as the Korean rice cultivar; however, its grain shape is similar to that of indica. As grain shape is also related to grain quality, US cultivars can be used as a useful genetic resource for diversifying the grain characteristics of Korean japonica cultivars and breeding new cultivars. [ABSTRACT FROM AUTHOR]

The rice cultivar ‘Chamdongjin’ exhibits a distinctively large grain size and excellent eating quality but is weak with regard to pre-harvest sprouting (PHS), requiring genetic improvement. In contrast, the premium-quality rice cultivar ‘Younghojinmi’ exhibits strong PHS tolerance. This study conducted quantitative trait loci (QTL) analysis on PHS and low-temperature germinability (LTG) using recombinant inbred lines derived from a cross between ‘Chamdongjin’ and ‘Younghojinmi’ to elucidate the genetic factors. Thus, an elite line with improved PHS tolerance was selected. QTL analysis revealed that qPHS3 and qLTG3 were associated with PHS and LTG, respectively, and the candidate gene was identified as qLTG3-1. The loss-of-function allele qltg3-1 in ‘Younghojinmi’ enhanced PHS tolerance compared to the functional allele qLTG3-1 in ‘Chamdongjin,’ but it also showed a trade-off relationship by decreasing LTG. CY_RILs carrying qltg3-1 exhibited lower PHS and LTG rates of 17.9% and 41.6%, respectively, compared to 44.1% and 55.7%, respectively, for CY_RILs with qLTG3-1. The elite line, CY_RIL79, carrying qltg3-1, was selected from CY_RIL. This line was recognized for its PHS tolerance while maintaining the key agricultural traits of ‘Chamdongjin,’ thus designated ‘Jeonju697.’ ‘Jeonju697’ is expected to be utilized as a practical alternative for addressing the issue of enhancing PHS tolerance in ‘Chamdongjin’; however, considering its weak LTG, it is desirable to improve this trait through further breeding efforts. [ABSTRACT FROM AUTHOR]

Chamdongjin’ is a near-isogenic line with enhanced disease resistance compared to ‘Sindongjin,’ a mega-cultivar in Korea. ‘Younghojinmi’ is the rice cultivar with the highest taste quality among the premium cultivars. This study conducted quantitative trait loci (QTL) analysis on yield-related traits using the recombinant inbred lines derived from a cross between ‘Chamdongjin’ and ‘Younghojinmi’ to elucidate genetic interaction. We utilized KASP markers and a target-capture sequencing SNP genotyping platform to address the insufficient genetic diversity of the population using Korean japonica cultivars. A QTL associated with heading date (HD), qHd8, was detected, and the candidate gene Hd18 was identified. The hd18 allele delayed HD by 3 days and reduced the brown/rough rice ratio (BRR) by 0.3%. QTLs associated with culm length (CL), panicle length (PL), and yield (g/plant), namely qCL1, qPL1_2023, and qYield1_2023, respectively, were detected, and the candidate gene SD1 was identified. The sd1 allele shortened CL and PL by 11 and 0.8 cm, respectively, and reduced the yield by 2.3 g. It also reduced the number of spikelets per panicle (NS) by 10 and decreased the ratio of ripened grains (RRG) by 2.6 %. QTLs associated with 1,000-grain weight (TGW), NS, and BRR, namely qTGW3, qNS3, and qBRR3_ 2023, respectively, were detected, and the candidate gene GS3 was identified. The gs3 allele increased TGW and BRR by 3.8 g and 0.4%, respectively, and reduced NS by 12. It also reduced RRG content by 1.9% and increased the yield by 1.7 g. The QTL associated with the number of panicles per hill (PN), qTN3, and the candidate gene, OsTB1, were identified. The OsTB1TGTG allele reduced PN by 1.3 and affected the increase in NS and RRG by 10 and 1.4%, respectively. The allele combinations of SD1, GS3, and OsTB1 were analyzed to assess their effects on yield-related traits. NS and RRG were influenced by trait variations, depending on the combination background of other alleles during allele substitution. ‘Jeonju 697,’ an elite breeding line exhibiting improved lodging resistance with shortened CL, was selected by substituting SD1 with sd1 while maintaining the Hd18-gs3-OsTB1TGTG allele combination of ‘Chamdongjin.’ This is expected to be a practical alternative for addressing the lodging problem in ‘Chamdongjin.’ [ABSTRACT FROM AUTHOR]

The rice cultivar ‘Namchan’ was developed to achieve high yields under low-nitrogen fertilizer conditions and enhance cultivation stability. ‘Namchan’ was derived from a cross between ‘Nikomaru’, a Japanese rice cultivar known for its excellent ripening ability in high-temperature conditions, and ‘Saenuri’, a Korean mega rice cultivar renowned for its high cultivation stability. To shorten the breeding period, anther culture was applied to F1 plants. ‘Namchan’ was selected through the pedigree method, yield trials, and local adaptability tests, with high selection pressure for ripening ability and cultivation stability. The heading date of ‘Namchan’ was August 16, four days later than that of ‘Nampyeong’. ‘Namchan’ exhibited strong tolerance to lodging and preharvest sprouting, indicating high cultivation stability. Despite having more grains and panicles compared to that in ‘Nampyeong’, ‘Namchan’ exhibited excellent ripening ability, presumed to be inherited from ‘Nikomaru’. ‘Namchan’ showed intermediate resistance to rice blast and resistance to bacterial blight and rice stripe virus. ‘Namchan’ had excellent grain appearance, improved milling performance, and superior taste compared to ‘Nampyeong’. ‘Namchan’ exhibited a yield of 6.34 MT/ha under normal nitrogen fertilizer conditions, and its index at 115%, when compared to that of ‘Nampyeong’, is the highest among Korean japonica rice varieties. It exhibited a high yield of 5.45 MT/ha even under low-nitrogen fertilizer conditions. ‘Namchan’ is promising as an outstanding cultivar that can contribute to carbon neutrality through the reduction of nitrogen fertilizers and greenhouse gases (Registration No. 8134). [ABSTRACT FROM AUTHOR]

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’. [ABSTRACT FROM AUTHOR]

“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). [ABSTRACT FROM AUTHOR]