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.

‘Inchangkyool’ varieties, which are believed to have been cultivated in Jeju for a long time, have leaves and flowers with a lemon-like fragrance. They have been suggested to be given the same scientific name as Citrus ichangensis, which is known to originate from China’s Southwest and Midwest regions. However, the genetic characterization of ‘Inchangkyool’ has not been reported, and literature is not readily available. Hence, in this study, 30 citrus chloroplast (cp)DNA (trnL-trnF) regions and nuclear ribosomal DNA internal transcribed spacer (ITS) regions were tested to identify the genetic relationship between ‘Inchangkyool’ and C. ichangensis and the origin of ‘Inchangkyool’ cultivars. Our results indicated that the total nucleotide sequence length of the trnL-trnF intergenic spacer (IGS) region and the G + C content was 373 bp and 36.73%, respectively, in the cpDNA of C. ichangensis and ‘Inchangkyool’, whereas the ITS1 regions were 247 and 248 bp and the ITS2 regions were 228 and 226 bp, respectively. Furthermore, the sequence lengths of the total ITS (ITS1 + 5.8S rDNA + ITS2) regions were 638 and 637 bp, respectively, whereas the G+C content was 70.16%, 71.26%, 69.03%, 70.61%, 64.6%, and 65.49%, respectively - showing differences in the nuclear ribosomal DNA region. However, the nucleotide sequence length of the 5.8S rDNA region was 163 bp and the G + C content was 54.6%, which were the same for both varieties. In addition, sequence divergence and phylogenetic analysis of the trnL-trnF and ITS regions in chloroplast DNA showed that the sequence divergence of the trnL-trnF region on the chloroplast was 0–0.008. This result indicates that ‘Inchangkyool’ is most closely related to Jeju eight native citrus cultivars including ‘Dongjeongkyool’. It is also closely related to C. ichangensis cultivars and six common citrus cultivars. In other words, the ‘Inchangkyool’ cultivar was inherited from the same maternal line as the Chinese C. ichangensis. The divergence values of the nuclear ribosomal DNA region between ‘Inchangkyool’ and ‘Dongjeongkyool’ and C. ichangensis were 0.008 and 0.026, respectively. These results indicated that ‘Inchangkyool’ was most closely related to ‘Dongjeongkyool’, and was farther from the C. ichangensis cultivar. In addition, phylogenetic relationships found ‘Inchangkyool’ to belong to the same group as the ‘Dongjeongkyool’ cultivar of jeju native citrus cultivars and a different group from C. ichangensis. From the above results, it is suggested that ‘Inchangkyool’ cultivar has been classified from the same maternal cultivar as the C. ichangensis in China, but has been obtained through long-term crossing with the same species as ‘Dongjeongkyool’. Moreover, based on the above results, it is believed that a distinct cultivar name for ‘Inchangkyool’ can be presented.

Recent climate changes have resulted in high temperatures, a greater frequency of flooding, and outbreaks of various plant diseases and insect pests, the latter of which has been characterized by a change in pest type from crop chewing to sap-sucking insects. To date, however, there has been limited study of plant resistance to sap-sucking insects. This study was carried out to evaluate the resistance and genetic patterns of the foxglove aphid Aulacorthum solani, a sap-sucking pest of soybean. We investigated the growth and reproduction of the foxglove aphid on five different varieties of soybean showing either susceptibility or resistance to this aphid in a non-choice test. Genetic analysis was conducted using the two F₂ populations derived from Daepung (susceptible to foxglove aphid)×IT104704 (resistant to foxglove aphid) and Daepung×IT188399 (resistant to foxglove aphid) crosses, which were evaluated for their responses to foxglove aphids. Differences in the responses of resistant and susceptible varieties were confirmed by monitoring aphid growth and reproduction. Although the two resistant germplasms (IT104704 and IT188399) have a strong antibiosis effect, they showed a slight difference with respect to aphid viability. Genetic analysis of foxglove aphid resistance showed that resistance was governed by a single dominant gene in IT104704 (3:1, p=0.11). We accordingly identified two resistant resources showing antibiosis to foxglove aphid, which is reported here for the first time, and also detected differences in genetic behavior. These results could be useful not only with respect to securing materials showing resistance to the foxglove aphid but also in the breeding of new foxglove aphid-resistant soybean cultivars.

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.