New Genetic Loci Associated with Preharvest Sprouting and Its Evaluation Based on the Model Equation in Rice.

Preharvest sprouting (PHS) in rice panicles is an important quantitative trait that causes both yield losses and the deterioration of grain quality under unpredictable moisture conditions at the ripening stage. However, the molecular mechanism underlying PHS has not yet been elucidated. Here, we explored the genetic loci associated with PHS in rice and formulated a model regression equation for rapid screening for use in breeding programs. After re-sequencing 21 representative accessions for PHS and performing enrichment analysis, we found that approximately 20,000 SNPs revealed distinct allelic distributions between PHS resistant and susceptible accessions. Of these, 39 candidate SNP loci were selected, including previously reported QTLs. We analyzed the genotypes of 144 rice accessions to determine the association between PHS and the 39 candidate SNP loci, 10 of which were identified as significantly affecting PHS based on allele type. Based on the allele types of the SNP loci, we constructed a regression equation for evaluating PHS, accounting for an R2 value of 0.401 in japonica rice. We validated this equation using additional accessions, which exhibited a significant R2 value of 0.430 between the predicted values and actual measurements. The newly detected SNP loci and the model equation could facilitate marker-assisted selection to predict PHS in rice germplasm and breeding lines.

Evaluation of Resistance to Ralstonia solanacearum in Tomato Genetic Resources at Seedling Stage.

Bacterial wilt of tomatoes caused by Ralstonia solanacearum is a devastating disease that limits the production of tomato in Korea. The best way to control this disease is using genetically resistant tomato plant. The resistance degree to R. solanacearum was evaluated for 285 tomato accessions conserved in the National Agrobiodiversity Center of Rural Development Administration. These accessions of tomato were originated from 23 countries. Disease severity of tomato accessions was investigated from 7 days to 14 days at an interval of 7 days after inoculation of R. solanacearum under greenhouse conditions. A total of 279 accessions of tomato germplasm were susceptible to R. solanacearum, resulting in wilt and death in 70 to 90% of these plants. Two tomato accessions were moderately resistant to R. solanacearum. Only four accessions showed high resistance against R. solanacearum. No distinct symptom of bacterial wilt appeared on the resistant tomato germplasms for up to 14 days after inoculation of R. solanacearum. Microscopy of resistant tomato stems infected with R. solanacearum revealed limited bacterial spread with thickening of pit membrane and gum production. Therefore, these four resistant tomato germplasms could be used in tomato breeding program against bacterial wilt.

Transcriptome Analysis of Two Vicia sativa Subspecies: Mining Molecular Markers to Enhance Genomic Resources for Vetch Improvement.

The vetch (Vicia sativa) is one of the most important annual forage legumes globally due to its multiple uses and high nutritional content. Despite these agronomical benefits, many drawbacks, including cyano-alanine toxin, has reduced the agronomic value of vetch varieties. Here, we used 454 technology to sequence the two V. sativa subspecies (ssp. sativa and ssp. nigra) to enrich functional information and genetic marker resources for the vetch research community. A total of 86,532 and 47,103 reads produced 35,202 and 18,808 unigenes with average lengths of 735 and 601 bp for V. sativa sativa and V. sativa nigra, respectively. Gene Ontology annotations and the cluster of orthologous gene classes were used to annotate the function of the Vicia transcriptomes. The Vicia transcriptome sequences were then mined for simple sequence repeat (SSR) and single nucleotide polymorphism (SNP) markers. About 13% and 3% of the Vicia unigenes contained the putative SSR and SNP sequences, respectively. Among those SSRs, 100 were chosen for the validation and the polymorphism test using the Vicia germplasm set. Thus, our approach takes advantage of the utility of transcriptomic data to expedite a vetch breeding program.

The complete chloroplast genome of Capsicum annuum var. glabriusculum using Illumina sequencing.

Chloroplast (cp) genome sequences provide a valuable source for DNA barcoding. Molecular phylogenetic studies have concentrated on DNA sequencing of conserved gene loci. However, this approach is time consuming and more difficult to implement when gene organization differs among species. Here we report the complete re-sequencing of the cp genome of Capsicum pepper (Capsicum annuum var. glabriusculum) using the Illumina platform. The total length of the cp genome is 156,817 bp with a 37.7% overall GC content. A pair of inverted repeats (IRs) of 50,284 bp were separated by a small single copy (SSC; 18,948 bp) and a large single copy (LSC; 87,446 bp). The number of cp genes in C. annuum var. glabriusculum is the same as that in other Capsicum species. Variations in the lengths of LSC; SSC and IR regions were the main contributors to the size variation in the cp genome of this species. A total of 125 simple sequence repeat (SSR) and 48 insertions or deletions variants were found by sequence alignment of Capsicum cp genome. These findings provide a foundation for further investigation of cp genome evolution in Capsicum and other higher plants.

Genetic assessment of safflower (Carthamus tinctorius L.) collection with microsatellite markers acquired via pyrosequencing method.

A genetic evaluation of safflower germplasm collections derived from different geographical regions and countries will provide useful information for sustainable conservation and the utilization of genetic diversity. However, the molecular marker information is limited for evaluation of genetic diversity of safflower germplasm. In this study, we acquired 509 putative genomic SSR markers for sufficient genome coverage using next-generation sequencing methods and characterized thirty polymorphic SSRs in safflower collection composed of 100 diverse accessions. The average allele number and expected heterozygosity were 2.8 and 0.386, respectively. Analysis of population structure and phylogeny based on thirty SSR profiles revealed genetic admixture between geographical regions contrary to genetic clustering. However, the accessions from Korea were genetically conserved in distinctive groups in contrast to other safflower gene pool. In conclusion, these new genomic SSRs will facilitate valuable studies to clarify genetic relationships as well as conduct population structure analyses, genetic map construction and association analysis for safflower.

Development of 65 novel polymorphic cDNA-SSR markers in common vetch (Vicia sativa subsp. sativa) using next generation sequencing.

Vetch (Vicia sativa L.) is one of the most important annual forage legumes in the World due to its multiple uses (i.e., hay, grain, silage and green manure) and high nutritional value. However, detrimental cyanoalanine toxins in its plant parts including seeds and its vulnerability to hard winter conditions are currently reducing the agronomic values of vetch varieties. Moreover, the existence in the public domain of very few genomic resources, especially molecular markers, has further hampered breeding efforts. Polymorphic simple sequence repeat markers from transcript sequences (cDNA; simple sequence repeat [SSR]) were developed for Vicia sativa subsp. sativa. We found 3,811 SSR loci from 31,504 individual sequence reads, and 300 primer pairs were designed and synthesized. In total, 65 primer pairs were found to be consistently scorable when 32 accessions were tested. The numbers of alleles ranged from 2 to 19, frequency of major alleles per locus were 0.27-0.87, the genotype number was 2-19, the overall polymorphism information content (PIC) values were 0.20-0.86, and the observed and expected heterozygosity values were 0.00-0.41 and 0.264-0.852, respectively. These markers provide a useful tool for assessing genetic diversity, population structure, and positional cloning, facilitating vetch breeding programs.

Development and molecular characterization of 55 novel polymorphic cDNA-SSR markers in faba bean (Vicia faba L.) using 454 pyrosequencing.

Faba bean (Vicia faba L.) is a major food source and fodder legume, popularly known for its high content of seed-protein. Its role is critical in crop rotation, and for fixing nitrogen effectively. Polymorphic simple sequence repeat markers from transcript sequences (cDNA; simple sequence repeat [SSR]) were developed for faba bean (Vicia faba). We found that 1,729 SSR loci from 81,333 individual sequence reads and 240 primer pairs were designed and synthesized. In total, 55 primer pairs were found to be polymorphic and scorable consistently when screened in 32 accessions. The number of alleles ranged from 2 to 15, frequency of major alleles per locus varied from 0.17 to 0.91, the genotypes number ranged from 2 to 17, observed and expected heterozycosity values ranged from 0.00 to 0.44 and 0.17 to 0.89 and overall PIC values ranged from 0.16 to 0.88 respectively. These markers will be a useful tool for assessing the genetic diversity, understanding the population structure, and breeding patterns of faba bean.

Iris Nertschinskia ethanol extract differentially induces cytotoxicity in human breast cancer cells depending on AKT1/2 activity.

Recently, we reported that an ethanol extract of Iris nertschinskia induces p53-dependent apoptosis in the MCF7 human breast cancer cell line. However, the detailed mechanisms were not fully explored. Here, we demonstrate another aspect of the activity of I. nertschinskia in breast cancer cells. We compared the response to an ethanol extract of I. nertschinskia in two different human breast cancer cell lines, Hs578Tand MDA-MB231, respectively with relatively low and high AKT1/2 activity by trypan blue exclusion assay and FACS analysis. Knockdown of endogenous AKT1 or AKT2 in breast cancer cells by RNA interference determined the sensitivity to I. nertschinskia ethanol extract compared to control cells. The I. nertschinskia ethanol extract induced cell death in a manner that depended on the level of phosphorylated AKT1/2 protein and was associated with a significant increase in the sub-G1 cell population, indicative of apoptosis. Our results indicate that an ethanol extract of I. nertschinskia differentially induces cell death in breast cancer cells depending on their level of phosphorylated AKT1/2.

p34 (SEI-1) inhibits ROS-induced cell death through suppression of ASK1.

Apoptosis signal-regulating kinase 1 (ASK1) is a key factor for controlling several cellular events including the cell cycle, senescence and apoptosis, in response to reactive oxygen species (ROS). However, the mechanisms that regulate ASK1 protein levels remain largely unexplored. In this study, we demonstrate that p34 (SEI-1) , a positive cell cycle regulator with an oncogenic potential, inhibits ROS-induced cell death by suppressing ASK1. We first found that p34 (SEI-1) -expressing cells have enhanced resistance to hydrogen peroxide (H 2O 2). Moreover, ectopic expression of p34 (SEI-1) clearly inhibited H 2O 2-induced phosphorylation of ASK1 in the colon cancer cell lines- HCT116 and SW620-in association with a decrease in ASK1 protein levels. Interestingly, p34 (SEI-1) induced ubiquitination of ASK1, however, no direct interaction was found between p34 (SEI-1) and ASK1. These results suggest that p34 (SEI-1) inhibits ROS-induced cell death through by indirectly inducing ubiquitination of ASK1.

An ethanol extract of Iris nertschinskia induces p53-dependent apoptosis in the MCF7 human breast cancer cell line.

Iris nertschinskia, an ornamental plant, is utilized in traditional East Asian medicine for the treatment of skin diseases. However, the biological activity underlying its therapeutic effects remains to be established. In this study, we investigated the anti-tumor effect of the plant extract on MCF7 human breast cancer cells. An ethanol extract of Iris nertschinskia triggered cell death in a dose-dependent manner. Moreover, treatment with the extract promoted p53 phosphorylation in MCF7 cells. Increased phosphorylation of p53, in turn, led to induction of Bax protein, a key regulator of p53-dependent apoptotic cell death, as well as of caspase-7 cleavage in MCF7 cells. Consistently, cells treated with p53-specific siRNA or the caspase inhibitor, Z-VAD, resisted apoptotic cell death induced by the Iris nertschinskia extract. Our results suggest that p53 sensitizes tumor cells to the ethanol extract of Iris nertschinskia by Bax protein induction and caspase-dependent apoptosis.

Development of a core set from a large rice collection using a modified heuristic algorithm to retain maximum diversity.

A new heuristic approach was undertaken for the establishment of a core set for the diversity research of rice. As a result, 107 entries were selected from the 10 368 characterized accessions. The core set derived using this new approach provided a good representation of the characterized accessions present in the entire collection. No significant differences for the mean, range, standard deviation and coefficient of variation of each trait were observed between the core and existing collections. We also compared the diversity of core sets established using this Heuristic Core Collection (HCC) approach with those of core sets established using the conventional clustering methods. This modified heuristic algorithm can also be used to select genotype data with allelic richness and reduced redundancy, and to facilitate management and use of large collections of plant genetic resources in a more efficient way.

Development and characterization of new microsatellite markers for the oyster mushroom (Pleurotus ostreatus).

We developed and characterized 36 polymorphic microsatellite markers for the oyster mushroom (Pleurotus ostreatus). In total, 169 alleles were identified with an average of 4.7 alleles per locus. Values for observed (HO) and expected (HE) heterozygosities ranged from 0.027 to 0.946 and from 0.027 to 0.810, respectively. Nineteen loci deviated from Hardy-Weinberg equilibrium. Significant (P<0.05) excess heterozygosity was observed at nine loci. Linkage disequilibrium (LD) was significant (P<0.05) between pairs of locus alleles. Cluster analysis revealed that five species of genus Pleurotus made a distinct group, and the individual cultivars were grouped into major five groups from G-1 to G-5. The diverse cultivars of P. ostreatus were discriminated and the other four species revealed a different section in the UPGMA tree. These microsatellite markers proved to be very useful tools for genetic studies, including assessment of the diversity and population structure of P. ostreatus.

Development of SSR markers for studies of diversity in the genus Fagopyrum.

The numbers of SSR markers and their utilization have not been determined and investigated as extensively in Fagopyrum species as compared to other crop species. The current report presents 136 new SSR markers in Fagopyrum esculentum ssp. esculentum and their application to related species in the genus Fagopyrum. Of the 136 SSRs, 10 polymorphic SSR markers were utilized in a genetic diversity analysis of a common buckwheat population consisting of 41 accessions of diverse origin. The study showed observed (H(O)) and expected (H(E)) heterozygosities ranging from 0.071 to 0.924 (mean = 0.53) and from 0.073 to 0.902 (mean = 0.412), respectively. Forty-one of the 136 SSRs amplified sequences in other Fagopyrum species, including the cymosum and urophyllum groups. The phylogenetic relationships revealed using the SSRs was consistent with results obtained using other marker systems, with one exception. The sequence and diversity information obtained using these new SSRs and their cross-transferability to related Fagopyrum species will increase our understanding of genetic structures and species relationships within the Fagopyrum genus.