The aim of this study was to determine if hydrogen peroxide (H2O2) generated by glucose oxidase (GO) induces apoptosis or necrosis of BJAB cells and which radical is the direct mediator of cell death. We found that GO produced H2O2 continuously in low concentrations, similar to in vivo conditions, and decreased proliferation and cell viability in a dose-dependent manner. The GO-mediated cytotoxicity resulted from apoptosis, and was confirmed by monitoring the cells after H33342/Annexin V/propidium iodide staining. Decreases of mitochondrial membrane potential and intracellular glutathione level were found to be critical events in the H2O2-mediated apoptosis. Additional experiments revealed that H2O2 exerted its apoptotic action through the formation of hydroxyl radicals via the Fenton rather than the Haber-Weiss reaction. Moreover, intracellular redox-active iron, but not copper, participated in the H2O2-mediated apoptosis.

A pepper genetic map was constructed from F2 mapping population of 93 individuals from a cross between Capsicum annuum 'F68' and C. chinense 'Habanero'. Survey was made for the map distribution and polymorphism level of these marker groups; reverse random amplification microsatellite polymorphism (rRAMP), WRKY and amplified fragment length polymorphisms (AFLP). A total of 912 molecular markers [356 rRAMP, 190 WRKY, 305 AFLP, and 61 simple sequence repeats (SSR)] were developed in this study. The rRAMP and WRKY markers were more evenly scattered in the pepper genome than the AFLP and SSR markers, and filled the gaps not populated by the other markers. The interspecific pepper map contained 28 linkage groups with 625 linked markers and covered 3377.2 cM with an average interval of 5.9 cM. On the basis of the map, the fruit length quantitative trait loci (QTL) was analyzed and these QTL regions were detected near rRAMP and WRKY markers on the chromosome 3, 5, 11, and LG3. These marker system, map information, and detected QTLs could be one of basic information for pepper research.Additional key words: Capsicum, genetic marker, map-assisted breeding, SSR Hort. Environ. Biotechnol. 52(6):602-613. 2011.

Two genes, CsLRR-RPK2 (CsGy5G015660) and CsaMLO8 (Csa5G623470), have been considered as powdery mildew (PM) resistance genes in cucumbers. In this study, we evaluated the involvement of the alleles of these two genes in PM resistance in 100 commercial Korean cucumber inbred lines. To achieve this, we developed cleaved amplified polymorphic sequences (CAPS) and InDel markers from CsLRR-RPK2 and CsaMLO8. Genotyping analysis indicated that the CsLRR-RPK2-CAPS marker showed a stronger correlation with the PM-resistant phenotype, with an 84% consistency compared to the CsaMLO8-InDel marker. The use of the CsaMLO8-InDel marker showed a 70% consistency between phenotype and genotype results. It was proposed that the CsLRR-RPK2-CAPS marker successfully eliminated PM-susceptible inbred lines, since both genotype and phenotype results were 100% identical. Furthermore, the present study revealed that the introduction of one of these alleles is probably enough to confer PM resistance in cucumbers. However, seven PM-resistant inbred lines harbored either CsaMLO8 or CsLRR-RPK2 alleles, indicating that there is another PM-resistant resource(s) besides CsaMLO8- and CsLRR-RPK2–originated resistance in the commercial Korean inbred lines. Our results provide reliable evidence confirming two PM-resistant candidate genes for the detection of PM resistance resources in cucumber inbred lines.

No abstract