Lilium dauricum is a rare and endangered species belonging to the family Liliaceae. The species contains several bioactive compounds used as functional foods and medicinal agents in Northeast Asia. This study aimed (1) to establish an in vitro bulblet culture using an air-lift bioreactor and callus culture for the conservation of L. dauricum and obtaining its bioactive compounds; (2) investigate the plant phenolic compounds from both cultures system. The highest bulblet production with 12.5-fold increase in growth rate was obtained using MS medium supplemented with 0.5 g L-1 BA and 3% sucrose. Addition of 7% sucrose facilitated bulblet enlargement, with approximate 2.5- and 7-fold increases in diameter and fresh weight, respectively. The highest rate of callus (100%) was obtained using a combination of 1.0 mg L-1 picloram and 0.5 mg L-1 Kinetin. The callus proliferation occurred on MS medium supplemented with 1.0 mg L-1 picloram, 0.25 mg L-1 kinetin, and 0.25 g L-1 casein hydrolysate. There was a significant difference in the total phenolic compound content of callus, which was 1.5-fold higher than that in the bulblets. These findings indicate a suitable system for optimizing both bulblet and callus culture of L. dauricum, therefore, providing useful bio-materials for industrial purposes and contributing to the conservation of this species.

The objective of the study was to identify 52 Asian pear accessions, two primary pear species, and one reference pear Asian pear with 12 microsatellite markers to maintain pear germplasm collection. The number of alleles of 12 microsatellites detected ranged from eight at CH03d12 to 18 at CH01f07. Gene diversity ranged from 0.7053 at CH01d08 to 0.9224 at CH01f07. The lowest value of PIC was 0.6600 at CH01d08 and the highest was 0.9171 at CH01f07. A group consisting of ‘Ooharabeni,’ ‘Bartlett,’ and P. calleryana was out-grouped and served as a reference to determine the relationship among Asian pear accessions. Except for the out-group, 50 Asian pears were segregated into two groups. Group I was divided in two small groups. Each small group was characterized by P. bretschneideri and P. ussuriensis, respectively. Group II was characterized as P. pyrifolia, and the group was divided in four small groups. The eigenvalue, difference, proportion, and cumulative of six principal components based on PCA to 12 microsatellite. The eigenvalue of the first principal components was 5.5850. The proportion of the first principal component was 0.9308. The cumulative value of the first two principal components was 0.9801. Consequently, nearly all of the results were elucidated by the two principal components. The results from analysis of the standard set of microsatellites in this study may be used as basic materials for the management of Asian pear germplasm collections, and the data might be useful in the development of a core collection.

In this study, we sought to identify primary pears species and Korean native pears, without the use of morphological characteristics. In addition, this study was to establish pear DNA fingerprinting data for Korean native pears using 12 microsatellite markers, and to accurately classify a database for management of the Korean pear collection. Forty two pear accessions (7 primary pears, 5 Asian pears, 29 Korean pears, and 2 reference pears) were analyzed with twelve primers covering whole pear genome. In the present study, all pear accessions were successfully classified along with their pedigrees, and the distribution of primary pears was parallel to those of the previous taxonomic results. Korean pears were divided into 3 groups. Group I was characterized by Pyrus calleryana, and included Korean pea pears. Group II was characterized by P. pyrifolia, and was classified into 2 small groups. The first small group comprised of ‘Najucheongbae’, ‘Sunchanggulimdolbae’, ‘Andongmookbae’, ‘Andongdangsilri’, and ‘Najucheongbae’ and was presumed to be cultivars of P. pyrifolia. The second small group consisted of ‘Cheongdangrori’ and ‘Pyeongchangsuhyangri’. These two accessions were assumed to be a hybrid of P. pyrifolia and the other cultivar. Group III was characterized by P. ussuriensis. ‘Goesanhwangbae’, ‘Andongcheongsilri’, ‘Gongjucheongsilri’, and ‘Yecheoncheongbae’ were assumed to be cultivars of P. ussuriensis. Contrary to ‘Ulreungdocheongbae A’, ‘Ulreungdocheongbae B’ was classified as belonging to the P. ussuriensis group. It is possible that this is a consequence of, P. ussuriensis genes being transferred into ‘Ulreungdocheongbae B’. The result of this research reaffirmed the efficiency of a standard set of microsatellite markers and provides data, which will be useful for developing a core collection of pears.

Korea is a origin of three basic species, P. ussuriensis, P. pyrifolia and P. fauriei. Genetic relationship among Korean pear cultivars compared with their parents were also identified that they are closely related P. pyrifolia, P. ussuriensis and/or hybrid between two species. SSRs or Microsatellites are co-dominant and typically neutral inheritance showing high degree of polymorphism, large number of alleles per locus, abundance in genomes, and suitability for automation. SSR markers were developed in apple and pear where they were used for construction of genetic linkage maps, evaluation of the genetic diversity, cultivar identification, genotype identification, and in the determination of genetic relatedness. Many apple (Malus × domestica Borkh.) SSRs would be useful for genetic mapping in European and Asian pears in previous experiments and cross-species amplification was observed between apple and pear. The objectives of this study were to develop polymorphic SSR markers in ‘Whangkeumbae’ and ‘Minibae’, which were chosen as the representative cultivars of P. pyrifolia and P. ussuriensis in each among Korean pears, from ‘Golden Delicious’ genomic sequences generated by next generation sequencing technology and to evaluate the utility of the SSR markers based on ‘Golden Delicious’ sequences. Of 51 SSR markers, 18 were polymorphic in ‘Whangkeumbae’ and ‘Minibae’. The cross-species transportability of primers designed in ‘Golden Delicious’ sequences makes SSR markers more useful, given the current high level of investment in mapping the genomes of related Rosaceae.

Currently, the type of short insertions and deletions (InDels) polymorphisms are increasingly focused in genomic research. InDels have been known as a source of genetic markers that are widely spread across the genome. Genetic relationship among Korean pear cultivars compared with their parents was also identified that they are closely related P. pyrifolia, P. ussuriensis and/or hybrids between two species. Lack of genetic resources including molecular markers has made it difficult to study pears severely. Recently developed next generation sequencing (NGS) platforms offer opportunities for high-throughput and inexpensive genome sequencing and rapid marker development. The main goal of this study was to develop polymorphic InDel markers in ‘Whangkeumbae’ and ‘Minibae’, which were chosen as the representative cultivars of P. pyrifolia and P. ussuriensis × pyrifolia in each among Korean pears using genomic sequences generated by NGS technology. In this study, more than 18.6 Gbp and 15.8 Gbp sequences were obtained from NGS of ‘Whangkeumbae’ and ‘Minibae’, respectively. ‘Whangkeumbae’ contained 197,210 InDels and 197,272 InDels in ‘Minibae’. In InDels validations between ‘Whangkeumbae’ and ‘Minibae’, the number of polymorphic InDels were 149,338 and non-polymorphic InDels were 122,572. For InDel primer set designing, 11,308 of primers were designed from polymorphic InDels and 10,919 of InDel primers were recommended. The study shows that the utility of NGS technology to design amount of efficient InDels and the developed InDel primers will be used for genetic mapping, breeding by marker assisted selection (MAS) and QTL mapping of Korea native pear as well as further genetic studies.

Single nucleotide polymorphisms (SNPs) are the most frequent type among variations found in genomic regions and are valuable markers for genetic mapping, genetic diversity studies and association mapping in plants. There are three basic species known as Korean native which are Pyrus ussuriensis, P. pyrifolia, and P. fauriei. Genetic relationship among Korean pear cultivars compared with their parents was identified that they are closely related P. pyrifolia, P. ussuriensis and/or hybrids between two species. Lack of genetic resources, including molecular markers to study pears are very severe. Recently developed next generation sequencing (NGS) platforms offer opportunities for high-throughput and inexpensive genome sequencing and rapid marker development. The objective of this study was to develop polymorphic SNP markers in ‘Whangkeumbae’ and ‘Minibae’, which were chosen as the representative cultivars of P. pyrifolia and P. ussuriensis × pyrifolia in each among Korean pears, using genomic sequences generated by NGS technology. In this study, more than 18.6 Gbp and 15.8 Gbp sequences were obtained from NGS of ‘Whangkeumbae’ and ‘Minibae’, respectively. ‘Whangkeumbae’ and ‘Minibae’ contained 2,712,288 and 2,747,224 SNPs, respectively. In SNPs validations between ‘Whangkeumbae’ and ‘Minibae’, the number of polymorphic SNPs were 2,516,438 and non-polymorphic SNPs were 1,179,391. For HRM primer design, 2,125,479 HRM candidate primers were obtained from polymorphic SNPs and 343,731 SNP primers were developed. This study shows that the utility of NGS technology to discover efficiently a large number of SNPs and SNP primers can provide valuable information in the genome study of Pyrus spp.

Pear (Pyrus spp.) is one of the most important temperate fruit species in the world. The identification of Pyrus spp. based on analysis and comparison of their phenotypes has been causing a number of synonyms and homonyms among Pyrus spp. For accurate identification, genotype analysis with molecular marker such as microsatellite is necessarily to use. However, It is difficult to share and compare of microsatellite profiles obtained among different laboratories because no effort has made to standardize equipment or protocols. A strategy for data comparison by dint of reference to the alleles detected in well-known cultivars will be helpful for co-work with laboratories and developing international databases. Thus the study was performed to compare results between laboratories of microsatellite DNA profiling for reproducibility and standardize allele scoring by defining reference alleles efficiently. In this study, ninety pear species including forty-four comparison Asian pears, six of comparison suspicious Asian pears and reference pears, seven basic pear species, and twenty-seven Korean native pear cultivars to development of a standard set of SSR reference alleles. Twelve primers covering most of pear genome were chosen, which are CH02b10, CH03g07, CH04e03, CH03d12, EMPc117, CH01f07a, EMPc11, CH01d09, GD147, CH01d08, CH05c06, and GD96 located in pear chromosome of 2, 3, 5, 6, 7, 10, 11, 12, 13, 15, 16, and 17 respectively. Genotyping was conducted with Fragment Analyzer. After genotyping, a set of defined standard alleles based on reference pear cultivars can facilitate data comparison among laboratories and will permit the improvement of a common international database.

Recent climate changes due to global warming are gradually introducing adverse circumstances for winter survival of temperate fruit trees. Particularly, late winter or early spring thaws followed by hard freezes can cause severe injury to deacclimated flower buds. Thus, the selection of later or slower deacclimating cultivars is needed to avoid frost injury in late winter or early spring. This study was performed to investigate relationship between cold hardiness and bud development under an experimental deacclimation condition for 10 Prunus persica cultivars (Aikawanakajima, Daewol, Izumi Hakuto, Janghowon Hwangdo, Kiraranokiwami, Mihong, Misshong, Soomee, Suhong, and Sun Gold). The rate of deacclimation was not correlated with hardiness before the deacclimation treatment. On the other hand, a strong positive correlation was found between cold hardiness and stage of bud opening.

Changes in cold hardiness were confirmed with relative electrolyte leakage (REL) method in the shoots of two peach cultivars (Prunus persica Janghowon Hwangdo and Odoroki) during cold acclimation and deacclimation. Changes in proline (Pro) content and related gene expressions were also analyzed. Particularly, transcript accumulations of P5CS and P5CR were examined using quantitative real-time RT-PCR. REL in the shoots of two peach cultivars was significantly different during the entire experimental period. Cold hardiness of two cultivars increased gradually to December 2012, and then decreased to April 2013, whereas Pro contents of ‘Janghowon Hwangdo’ and ‘Odoroki’ were reduced from the beginning of the experiment to February 2012 and then increased in the spring. Interestingly, P5CS gene encoding an enzyme, which catalyzes conversion from glutamic acid (Glu) into glutamic-γ-semialdehyde (GSA) in the first step of Pro pathway, showed the contrasting patterns with Pro contents of two cultivars. On the other hand, P5CR gene encoding an enzyme, which catalyzes conversion from Δ1-pyrroline-5-carboxylate(P5C)intoPro in the final step of Pro pathway, showed the similar patterns to Pro contents in two cultivars. Our results demonstrate that Pro responds negatively to low temperatures in the shoot of different peach cultivars, including the supplemental 10 peach cultivars, and expression of both P5CS and P5CR genes could show contrasting patterns from each other. Our results suggest that identification of both P5CS and P5CR genes are required necessarily for accurate analysis of Pro biosynthesis because Pro accumulation is affected more by expression of P5CR gene.