Persimmon anthracnose is a major disease affecting fruit quality and yield in persimmon-growing regions, yet information on the species diversity of causal pathogens in Korea remains limited. This study aimed to identify Colletotrichum species associated with anthracnose symptoms on persimmon fruits and to evaluate their pathogenicity. Sixteen fungal isolates were obtained from symptomatic fruits collected pear research center in Naju, Korea, and their morphological characteristics—colony features, conidial morphology, and appressoria— were examined. Multilocus sequence analysis using internal transcribed spacer, actin, β-tubulin, glyceraldehyde-3-phosphate dehydrogenase, chitin synthase I, calmodulin, the intergenic spacer region between Apn2 and Mat1-2-1 (ApMat) was performed to determine species identity and phylogenetic relationships. Phylogenetic analysis revealed that most isolates (87.5%) belonged to Colletotrichum horii. One isolate each of C. siamense and C. fructicola were also identified; notably, C. fructicola represents the first report of this species on persimmon in Korea. Pathogenicity tests showed that all three species induced typical sunken lesions on wounded fruits, and the inoculated pathogens were successfully re-isolated, fulfilling Koch’s postulates. These findings demonstrate that persimmon anthracnose in Korea is caused by multiple Colletotrichum species with clear genetic differentiation. The detection of C. fructicola suggests that the species spectrum of anthracnose pathogens may be broader than previously recognized. This study provides essential baseline information for disease diagnosis, epidemiological monitoring, and the development of resistant cultivars in future breeding programs.

Haewon Jung, Yoon-Keyong Kim, Kyungho Won, Keumsun Kim, Il Sheob Shin, Jinho Choi, Sam-seog Kang, Hojin Seo, Young Sik Cho, and Ah Rang Kang. Korean J. Breed. Sci. 2024;56:160-8. https://doi.org/10.9787/KJBS.2024.56.2.161

Pear scab is a major disease of pear worldwide and is caused by two distinct species that are aligned with different commercial Pyrus species: Venturia pirina with European pear (P. communis) and V. nashicola with Asian pear species P. pyrifolia, P. ussuriensis and P. X bretschneideri. As these host-pathogen systems are mutually exclusive, interspecific pear breeding provides an avenue for breeding new scab-resistant cultivars. Here we describe the genetic mapping of resistance to V. nashicola in a pear progeny between interspecific pear selection P019R045T042 and ‘Shinko’ (P. pyrifolia) consisting of 274 seedlings, which was phenotyped twice with V. nashicola inoculum prepared from scab-infected leaves collected from trees of susceptible ‘Niitaka’ (P. pyrifolia). A set of 613 polymorphic DNA markers were selected from the apple and pear Illumina Infinium® II 9K single nucleotide polymorphism array and genotyping-by-sequencing for the creation of the parental genetic maps with JoinMap v4.1. Using the Interval Mapping module in MapQTL v6.0 software, two significant quantitative trait loci were detected in P019R045T042: one on linkage group (LG) 7 and another on LG10, which we name Rvn5 and Rvn6, respectively. Both Rvn5 and Rvn6 displayed weak additive effects for pear scab (V. nashicola) resistance when both loci worked together in this family. They will contribute to more strong resistance based on gene pyramiding through marker-assisted selections for the introduction of non-host resistance into both Asian and European pears through interspecific hybridization.

Two pear cultivars with different degrees of resistance to Venturia nashicola were evaluated on the basis of a disease severity rating for pear scab resistance under controlled environmental condition. Two inoculation techniques were tested: the procedure for inoculation by dropping conidia suspension of V. nashicola; the procedure by deposition of agar plug on the abaxial surface of pear leaves. All tested cultivars resulted in blight symptoms on the inoculated leaves and became spread to uninoculated region or other leaves. Although both methods provide satisfactory infection of V. nashicola on pear leaves, the mycelial plug method of inoculation was more reliable than the spray inoculation method for the evaluation of pear scab disease resistance. The incubation period of V. nashicola in the resistant pear cultivar, Greensis was longer than that in the susceptible cultivar, Hwasan.

서 언 배나무속(Pyrus)의 낙엽성 교목인 배는 유럽, 아시아와 북아 프리카의 산간지역 등에 분포하고 있다(Hancock 2008).우리나라 를 비롯한 일본과 중국에서 주로 재배되는 동양배(P

Mitochondrial genome sequences have been used in diverse fields of biology. In this study, we sequenced the complete mitochondrial genomes (mitogenome) of two pear pests: Cacopsylla jukyungi, the most damaging insect pest to commercial pears in South Korea, and Cacopsylla burckhardti (Hemiptera: Psyllidae). The two mitogenomes were compared to confamilial species to accumulate genetic information and understand evolutionary characteristics of the family Psyllidae. The 15,438 bp-and 14,799 bp-long complete mitogenomes of C. jukyungi and C. burckhardti, respectively, had many features typical of insect mitogenomes; however, at 1283 bp, the C. jukyungi mitogenome had an unusually long A+T-rich region, which was composed of two identical 540-bp repeat sequences. Among the intergenic spacer regions, the one located at the ND1 and trnS2 junction was relatively well conserved in length (mostly within 23–36 bp). This region had a high sequence identity in all Psyllidae, possessing a 5-bp consensus sequence (CGGTA), which is speculated to have a functional role. Though the A+T-rich region in available Psyllidae mitogenomes varied substantially in length (662–1430 bp) and sequence divergence, all species had a conserved sequence stretch at the 3′-end of srRNA, which is also speculated to have a functional role. Genetic divergence among genes indicated the lowest variability in srRNA, lrRNA, and COI, whereas ATP8 and ND6 showed the highest variability at both family and genus (Cacopsylla) levels. Our data provide evidence that the family Psyllidae, including current C. jukyungi and C. burckhardti, have evolutionary unique features that were previously undetected, along with the unique A+T-rich region structure in C. jukyungi.

Genetic linkage map of pear ((Pyrus pyrifolia × P. communis) × P. pyrifolia) was constructed to validate the effectiveness of the two-enzyme approach in GBS library preparation. In addition, allele inheritance was analyzed to investigate the usefulness of the pear pseudo-BC1 in genetic analysis. A total of 905 GBS-SNPs and 69 SSRs were anchored in 17 linkage groups with total genetic distance of 1760.1 cM and average marker distance of 1.88 cM. The genetic linkage map represents 80.5% of pear genome. GBS two-enzyme approach improved marker density and genome coverage compared to the single-enzyme approach. In addition, the inheritance analysis of SSR alleles demonstrated that pseudo-BC could allow genetic dissection of donor parent specific trait segregating in the F2. The high-resolution genetic linkage map of pear pseudo-BC1 will be used for candidate gene identification. Moreover, genetic analysis of donor parent specific traits segregating in the pseudo-BC1 hybrids will promote marker development for molecular breeding in pear.

Venturia nashicola is a fungal pathogen causing scab disease in Asian pears. It is particularly important in the Northeast Asia region where Asian pears are intensively grown. Venturia nashicola causes disease in Asian pear but not in European pear. Due to the highly restricted host range of Venturia nashicola, it is hypothesized that the small secreted proteins deployed by the pathogen are responsible for the host determination. Here we report the whole genome based phylogenetic analysis and predicted secretomes for V. nashicola isolates. We believe that our data will provide a valuable information for further validation and functional characterization of host determinants in V. nashicola.

White root rot (WRR) disease caused by Rosellinia necatrix, a fungal pathogen, results in severe damage to various fruit trees, decreasing their marketability. Regular monitoring is a major process because the pathogen can remain in the soil around the host for a long time. Loop-mediated isothermal amplification (LAMP) is a highly sensitive and efficient amplification technology of nucleic acids (DNA or RNA) that can be performed at constant temperatures. Thus, it has been spotlighted as a useful tool for detecting several infectious agents. In the present study, LAMP-based Turn-on Fluorescent Paper (ToFP) devices were designed and applied to detect R. necatrix. LAMP conditions were optimized and found to be optimal at a reaction temperature (62 °C) and a reaction time (30 minutes). These reaction conditions were confirmed by applying them to infectious soil samples collected from the field. The limitation of detection was identified as 10 fg of genomic DNA under optimized LAMP conditions. These LAMP-based ToFP devices were generated with easily available stationery materials and the utility of these devices to analyze the LAMP results were confirmed through several experiments on a total of 14 field samples. The results showed that the developed LAMP-based detection system was very sensitive and had the advantages of rapid detection and high availability in the field.

Venturia nashicola, the cause of scab disease of Asian pears, is a host-specific, biotrophic fungus. It is restricted to Asia and is regarded as a quarantine threat outside this region. European pear displays nonhost resistance (NHR) to V. nashicola and Asian pears are nonhosts of V. pyrina (the cause of European pear scab disease). The host specificity of these two fungi is likely governed by differences in their effector arsenals, with a subset hypothesized to activate NHR. The Pyrus-Venturia pathosystem provides an opportunity to dissect the underlying genetics of nonhost interactions in this potentially more durable form of resistance. The V. nashicola genome will enable comparisons to other Venturia spp. genomes to identify effectors that potentially activate NHR in the pear scab pathosystem.

This study was conducted to determine the optimal physiological ripening time and suggest a reasonable harvest time indicator by analyzing the relationship between change in physicochemical characteristics and the sugar composition change patterns during development of 'Hanareum' fruit from 54 days after full bloom (DAFB) to 130 DAFB. The weight of fruits from 96 to 115 DAFB rapidly increased and then became gentle showing a typical sigmoidal curve. Flesh hardness decreased steadily after 96 DAFB; there was no significant difference in flesh hardness for 115, 125 and 130 DAFB fruits. The starch content began to reduce around the core for 119 DAFB. Moreover, sucrose and fructose contents started to increase with fruit development; however, the sucrose content continuously increased, whereas the fructose content started to decrease for 110 DAFB. Fruits of 125 and 130 DAFB did not show coloration according to the iodine test. Based on these results, it was estimated that the optimal physiological ripening time of 'Hanareum' was between 119 and 125 DAFB. The results of correlation analysis between fruit development change and sugar composition change patterns of fruits of 'Hanareum' showed that there was a strong linear relationship. Correlation coefficient between the sucrose/fructose (S/F) ratio and flesh hardness is -0.57, between S/F ratio and iodine test results is 0.80. Namely, S/F ratio is possible to use for harvest time determination indicator and the point of S/F ratio of 0.9–1.1 was considered to be ideal for the determination of the optimal physiological ripening time at which starch completely degrades.

Genotyping-by-sequencing (GBS) was used to investigate the genetic diversity and population structure of kiwifruits (Actinidia spp.). Using single nucleotide polymorphisms detected by GBS, phylogenetic tree and population structure were constructed for 89 kiwifruit accessions including Korean native A. arguta. The kiwifruit accessions were clearly divided into two groups in the phylogenetic tree. These groups were characterized by the presence or absence of hairs on pericarp. In the population structure analysis, the peak of delta K was detected at K=5, suggesting that the 89 kiwifruit accessions were divided into five clusters. Each cluster represented A. chinensis, A. deliciosa, A. eriantha with wild accessions, female A. arguta, and male A. arguta. The result of the population structure supported the genetic background of each accession. We also performed genetic diversity analysis of A. arguta accessions. Consequently, A. arguta accessions were characterized by sex and 13 A. arguta accessions, occupying 33.3% of the total collection, were selected as a core set for use as germplasm to develop disease and cold stress resistant cultivars in future kiwifruit breeding programs. These results suggest that GBS approach is suitable for genetic diversity analysis of kiwifruits. Moreover, our results could be applied in kiwifruit breeding program to develop disease and cold stress resistant cultivars using Korean native A. arguta. Particularly, the developed Korean native A. arguta core set will be used as breeding materials for crop improvement strategies.

Some virulence effectors secreted from pathogens target host proteins and induce biochemical modifications that are monitored by nucleotide-binding and leucine-rich repeat (NLR) immune receptors. Arabidopsis RIN4 protein (AtRIN4: RPM1-interacting protein 4) homologs are present in diverse plant species and targeted by several bacterial type III effector proteins including the cysteine protease AvrRpt2. RIN4 is 'guarded' by several independently evolved NLRs from various plant species, including Arabidopsis RPS2. Recently, it was shown that the MR5 NLR from a wild apple relative can recognize the AvrRpt2 effector from Erwinia amylovora, but the details of this recognition remained unclear. The present contribution reports the mechanism of AvrRpt2 recognition by independently evolved NLRs, MR5 from apple and RPS2, both of which require proteolytically processed RIN4 for activation. It shows that the C-terminal cleaved product of apple RIN4 (MdRIN4) but not AtRIN4 is necessary and sufficient for MR5 activation. Additionally, two polymorphic residues in AtRIN4 and MdRIN4 are identified that are crucial in the regulation of and physical association with NLRs. It is proposed that polymorphisms in RIN4 from distantly related plant species allow it to remain an effector target while maintaining compatibility with multiple NLRs.

Venturia nashicola is a fungal pathogen that causes Asian pear scab disease. This pathogen is of particular importance in Northeast Asian countries, where Asian pears are grown industrially. Scab disease in Asian pear is currently controlled by fungicide spraying and this situation calls for developing scab resistant cultivars. High-quality genome data are therefore required for in-depth comparative genome analysis of different isolates of V. nashicola and V. pyrina, a closely related species, which only infects European pear plants. Here, we report the high-contiguity whole genome assembly of two V. nashicola isolates, which is expected to enable genome comparisons for identification of the genes involved in host range determination of V. nashicola.

Obesity is one of the major public concerns due to its various side-effects such as metabolic and chronic ailments. In this study, two lactic acid bacteria (LAB) strains, Leuconostoc mesenteroides and Lactobacillus sakei, isolated from Kimchi were investigated for their anti-obesity activity in obese mice model. To induce obesity in model mice (C57BL/6), high fat diet (HFD) with 60 kcal% fat was fed for 10 weeks. LAB supplementation reduced blood urea nitrogen, glucose, and triglyceride levels in serum from obesity induced mice. The study also observed significant decrease of fibrosis, triglyceride, and total cholesterol level in fatty liver tissue by LAB supplementation. The results suggest that supplementation of L. mesenteroides and L. sakei could be used as alternative nutritional interventions to decrease symptoms caused by obesity with no safety or intolerance related problem.

Interspecific hybridization is a popular breeding method employed to introduce effective factors into crops. To evaluate the potential of this method to enrich the quality of pear fruits, we carried out crosses between P. pyrifolia and other species using the pollens of 'OPR114' and 'OPR260' of P. betulaefolia, 'Dangshansuli' , 'Xuehuali ' , and 'Yali' of P. bretschneideri, 'OPR125 ' , 'OPR195 ' , and 'OPR249' of P. calleryana, 'Bartlett', `Bose', 'Canal pear', and 'Max Red Bartlett' of P. communis, and 'Chuhwangbae' of P. pyrifolia to pollinate flowers of P. pyrifolia 'Niitaka'. Fruit set in 'Niitaka' pear after artificial pollination was investigated under both field and controlled conditions, which encompassed temperature control and use of water-cuttings of winter twigs. To assess compatibility of hybridizations, pollen tube elongation was analyzed in squashed styles under controlled temperature, and the self-incompatibility (SI) gene pattern was validated by PCR. Under field conditions, crosses of 'Niitaka' with 'OPR114' of P. betulaefolia and `Bose' and 'Canal pear' of P. communis resulted in incompatibility, as the fruit set was low. However, when 'Niitaka' was pollinated by 'Xuehuali', some of the pollen tubes reached the ovary but they then arrested and appeared swollen in the middle part of the style. PCR confirmed the incompatibility of these crosses, as the gene product from pollens was a different size from that of the 'Niitaka'. However, interspecific hybridization under controlled conditions resulted in fruit production. We show that interspecific hybridization with P. pyrifolia and other species was feasible under controlled conditions. Suggesting that self-incompatibility of crosses was dependent on environmental factors rather than genetic predisposition.