Rice is a staple crop in South Korea and globally. The era of global boiling, characterized by rising temperatures and abnormal climatic conditions, significantly impacts crop production worldwide. This study examines the effects of high temperatures and rainfall on early maturing rice varieties, focusing on enhancing heat tolerance during the ripening stage and preharvest sprouting resistance. Utilizing ‘Milyang247,’ a progeny line from ‘Nampyeong,’ we developed the intermediate line ‘MY362VP.’ During 2020–2022, regional adaptability tests were conducted at five locations across Korea. Results showed that ‘MY362VP’ had a viviparous germination rate of 1.9% compared to 19.0% in the control variety ‘Jopyeong.’ Furthermore, ‘MY362VP’ maintained a head rice rate of 90.6% under high temperature conditions, outperforming ‘Jopyeong,’ which has a rate of 62.1%. ‘MY362VP’ produced an average yield of 529 kg/10a, comparable to the control’s 518 kg/10a. This study offers valuable insights for breeding climate-resilient early-maturing rice varieties, positioning ‘MY362VP’ as a promising candidate for future cultivation.

A total of 285 Korean rice cultivars were used for amylose content and genetic analyses using KASP markers related to the amylose content. We used three polymorphic KASP markers targeting the Waxy (Wx) gene and compared the genotyping efficiency with previously reported molecular markers. The rice cultivars were raised in Miryang, Korea, for one period. Genetic analysis of the rice cultivars revealed that the three KASP markers on the Wx gene were functional for genomic selection of SNPs related to amylose content variation. Therefore, the three KASP markers targeting different Wx alleles can be used for genomic selection. In addition, KASP markers were more efficient than previously reported molecular markers that target the same alleles. These findings can be beneficial for the breeding and genomic selection of high-quality rice in Korea.

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.

Rice doubled haploid (DH) lines derived from crosses of the indica cultivar 93-11 and japonica line Milyang352 were used in genetic mapping and QTL analysis studies of days to heading (DTH), an important trait that controls rice yield and biomass. QTL mapping was conducted using the inclusive composite interval mapping method. We used 234 single-nucleotide polymorphic markers in the whole-genome region, including 100 KASP markers and 134 Fluidigm markers, to construct a genetic map. DH populations were raised in Milyang, Korea, over three different periods. Two major DTH QTLs, qDTH3-1 and qDTH7, were detected under natural conditions in Milyang, and explained 14.88%~24.56% and 24.20%~37.39% of the phenotypic variation, respectively, in 93-11×Milyang352 DH populations. During three different rice cultivation periods, qDTH3-1 and qDTH7 were repeatedly detected with significant logarithm of the odds scores and phenotypic variability explained. The findings of this study will make a valuable contribution to breeding high-yielding and early-maturing rice in Korea.

AbstractThe high-molecular-weight glutenin subunit (HMW-GS) composition of wheat is the main factor controlling gluten strength related to bread baking quality. Reported molecular markers for HMW-GS were validated and selected for improved breeding efficiency in South Korean wheat breeding programs. Sodium dodecyl sulfate polyacrylamide gel electrophoresis, lab-on-a-chip electrophoresis, sequence-tagged site (STS) markers, and Kompetitive Allele-Specific PCR were performed to re-evaluate the known HMW-GS of 14 wheat cultivars. Glu-A1b and Glu-A1c alleles were separated by the STS marker, UMN19, and KASP marker, namely Glu-Ax1/2*_SNP, at Glu-1 loci. At the Glu-B1 locus, Glu1-By8 and Glu1-By9 could be distinguished from Glu-B1b and Glu-B1c alleles by two STS markers, namely ZSBy8 and ZSBy9a, respectively. Glu1-Bx17 and Glu1-7^OE could respectively be separated from non-Glu-B1i and non-Glu-B1al alleles by cauBx642 and BX7^OE_866_SNP. The Glu-D1d allele, used to determine bread baking quality, could easily be distinguished from other alleles by Glu-D1d_SNP at Glu-D1 loci. Validated molecular markers in this study could therefore be used to select wheat lines for good bread baking quality in South Korean wheat breeding programs.

A speed-breeding system using photoperiod characteristics has recently been developed to reduce the entire growth period in wheat. In this study, the entire growth period of four Korean varieties was examined to investigate whether this speed-breeding system would be beneficial for our wheat breeding program. When four varieties were cultivated under a 22-hour light/2-hour dark cycle in a glasshouse, the number of days to heading of Jokyoung and Baekkang was 44 and 43, respectively, and the number for Keumgang and Joongmo2008 was more than 75. Around twelve seeds per plant were obtained from Jokyoung and Baekkang, and the seeds of these varieties completely germinated when harvested at 20 days after heading. These results suggest that this speed-breeding system can be a reliable method of reducing the growth period in Korean wheat breeding.