Capsinoids, low-pungent compounds, have the same biological effects as capsaicinoids such as anticancer and anti-obesity. A precursor of capsinoids, vanillyl alcohol, is known to be produced by mutations in the putative-aminotransferase (pAMT) gene. In the previous study, ‘SNU11-001’ (Capsicum chinense) containing high levels of capsinoids was identified in germplasm collections of Capsicum. This collection has a unique mutation in the pAMT gene that can cause dysfunction of this gene. In order to develop pepper varieties containing high capsinoids contents, marker-assisted foreground and background selections were performed during backcross breeding. Compared to the conventional backcrossing, marker-assisted backcrossing (MABC) is extremely useful for recovery of a recurrent parent’s genetic background. For foreground selection, plants carrying the pAMT/pamt genotype were selected from a BC1F1 and BC2F1 populations using SCAR markers derived from the unique pAMT mutation of ‘SNU11-001’. To obtain background selection markers, a total of 412 single nucleotide polymorphism (SNP) markers was screened on ‘Shinghong’ parental lines and ‘SNU11-001’ to obtain polymorphic SNP markers. Of the 412 SNP markers, 144 and 204 polymorphic SNP markers evenly distributed in pepper genome were finally selected. BC1F1 and BC2F1 plants carrying the pAMT/pamt genotype were subjected to background selection using the selected marker sets. Multiple genotype analysis was done using a high-throughput genotyping system (EP1TM, Fluidigm®, USA). As a result, one BC1F1 plant 84% similar to the recurrent parent and several BC2F1 plants more than 96% recovery rate of the recurrent parent were selected. Genetic backgrounds of the selected BC2F1 plants were evaluated by the genotype-by-sequencing (GBS) method in order to confirm the background selection results using the SNP marker set. GBS results showed that recovery rate and positions of introgressed segments were well matched between two methods demonstrating MABC can be successfully done with a couple hundred SNP markers.

Capsinoids, low-pungent compounds, have the same biological effects as capsaicinoids such as anticancer and anti-obesity. A precursor of capsinoids, vanillyl alcohol, is known to be produced by mutations in the p-aminotransferase (p-AMT) gene. In the previous study, SNU11-001 (C. chinense) containing high levels of capsinoids was found in germplasm collections of Seoul National University. We found that this collection has a unique mutation in the p-AMT gene. In order to develop a cultivar containing high capsinoids contents, marker-assisted foreground and background selection were performed in this study. Backcrossing is an effective breeding method for introducing useful traits to an elite cultivar. Compared to conventional backcrossing, marker-assisted backcrossing (MABC) is extremely useful for recovery of a recurrent parent’s genetic background. To obtain background selection markers, a total of 412 single nucleotide polymorphism (SNP) markers was screened to obtain polymorphic SNP markers between ‘Takanotsume (C. annuum)’ and ‘SNU11-001’. Of the 412 SNP markers, 96 polymorphic SNP markers evenly distributed in pepper genome were finally selected. Plants carrying the pAmt/pamt genotype were selected from a BC1F1 population using SCAR markers derived from the unique p-AMT mutation of SNU11-001. BC1F1 plants carrying the pAmt/pamt genotype were subjected to background selection. Multiple genotype analysis was done using Fluidigm platform (BioMark). Once we obtain plants carrying most similar genetic background to recurrent parent, capsinoids contents will be measured and another round of MABC be done to obtain plants containing high levels of capsinoids.

Next-generation sequencing (NGS) technology and fast improvement in plant genetics have elevated to massive development of molecular genetic markers through fast analysis of huge molecular biological data. Furthermore, in domestic commercial breeding of horticultural crops, the application of marker assisted breeding (MAB) has been introduced recently. For effective improvement of cultivar breeding, in this research, transcriptome analysis and single nucleotide polymorphism (SNP) comparison with high density pepper map in UC-DAVIS were performed using four lines of Capsicum annuum and C. chinense. For rapid analysis of MAB of tolerant pepper lines, 412 Fluidigm probes were newly designed in this study. These designed probes and SSR and COSII markers were applied for background selection through the MAB program. In addition, powdery mildew (PM), tomato spot wilt virus (TSWV) resistance related markers were subjected to foreground selection of BC1, BC2, and BC3 progenies. The MAB system using Fluidigm probes, and trait-related and common markers was introduced into domestic pepper breeding, which will rapidly approach to a new elite line and a commercial tolerant cultivar.

Capsinoids, low-pungent compounds, have the same biological effects as capsaicinoids such as anticancer and anti-obesity. A precursor of capsinoids, vanillyl alcohol, is known to be produced by mutations in the p-aminotransferase (p-AMT) gene. In the previous study, SNU11-001 (C. chinense) containing high levels of capsinoids was found in germplasm collections of Seoul National University. We found that this collection has a unique mutation in the p-AMT gene. In order to develop a cultivar containing high capsinoids contents, marker-assisted foreground and background selection were performed in this study. Backcrossing is an effective breeding method for introducing useful traits to an elite cultivar. Compared to conventional backcrossing, marker-assisted backcrossing (MABC) is extremely useful for recovery of a recurrent parent’s genetic background. To obtain background selection markers, a total of 412 single nucleotide polymorphism (SNP) markers was screened to obtain polymorphic SNP markers between ‘Takanotsume (C. annuum)’ and ‘SNU11-001’. Of the 412 SNP markers, 96 polymorphic SNP markers evenly distributed in pepper genome were finally selected. Plants carrying the pAmt/pamt genotype were selected from a BC1F1 population using SCAR markers derived from the unique p-AMT mutation of SNU11-001. BC1F1 plants carrying the pAmt/pamt genotype were subjected to background selection. Multiple genotype analysis was done using Fluidigm platform (BioMark). Once we obtain plants carrying most similar genetic background to recurrent parent, capsinoids contents will be measured and another round of MABC be done to obtain plants containing high levels of capsinoids

Tsw, a single dominant resistant gene against Tomato spotted wilt virus (TSWV), has been mapped on chromosome 10 in Capsicum chinense species. Previously reported molecular markers linked to the Tsw gene are not transferable for all pepper breeding materials. To develop additional markers and do genome-based fine mapping of the Tsw gene, approaches of mapping comparison, pooled transcriptome analysis, and genome walking were applied. Eleven additional SNP molecular markers tightly linked to the Tsw gene were developed using tomato and pepper whole genome sequencing databases. Among them, four SNP markers, SNP7715-1, SNP68-1, SNP17918-1, and SNP1072-1, showed no recombination in two segregating populations of F2 ‘Telmo’ (210 individuals) and ‘SP’ (843 individuals). Three scaffold sequences from the C. annuum BAC database and two BAC clones from the BAC library of C. annuum ‘CM334’ covering the Tsw gene were identified by transcriptome analysis and genome walking. A pepper scaffold sequence covering three pepper scaffold sequences was identified from a final version of the C. annuum BAC database. The Tsw gene was delimited within 149 kb by alignment analysis of two BAC clone sequences and the pepper scaffold sequence. A total of 22 predicted genes were resided in the target region between SNP7715-1 and SNP1072-1 co-segregating markers. Among them, five predicted genes showing annotations of CC/TIR-NBS-LRR resistance proteins, mRNA-6, mRNA-7, mRNA-11, mRNA-12, and mRNA-13, were identified. The transcriptome analysis and gene expression study showed that the mRNA-13 was expressed in ‘PI152225’ but was absent in ‘Special’, demonstrating the mRNA-13 could be a strong candidate gene for the Tsw gene. This result will be favorable for cloning the Tsw gene and developing cultivars which carry the TSWV-resistance gene.

eIF4E family is well known for recessive resistance gene of potyvirus in many crops. And Turnip mosaic virus (TuMV) is one of the major viruses in Brassicaceae crops which belong to the genus Potyvirus. To elucidate the key amino acids in the interaction between TuMV VPg and Brassica eIF(iso)4E, amino acids of eIF(iso)4E were mutated. Seven amino acids in cap binding pocket were chose for the candidate amino acid that may play a role in the interaction of TuMV VPg. We demonstrated that a single amino acid mutation in cap binding pocket of Brassica eIF(iso)4E can abolish the interaction with TuMV VPg. eIF(iso)4E which has a mutation at each W49, W95 and K150 positions impaired in its interaction with VPg prominently according to the yeast two hybrid analysis. Complementation of an eIF4E knockout yeast strain by mutated eIF(iso)4E proteins showed that all eIF(iso)4E mutants were able to complement eIF4E of yeast. To find out if these mutations affect the susceptibility of Chinese cabbage, transformant analysis was performed. eIF(iso)4E W95L, W95L/K150E and susceptible wild type were over-expressed in susceptible Chinese cabbage. According to the TuMV screening result of T1 and T2 transformants, over-expression of the eIF(iso)4E mutants showed resistance to four TuMV strains (CHN2, 3, 4 and 5). Our results support that the mutations in eIF(iso)4E may control the broad spectrum TuMV resistance.

Tsw, a single dominant resistant gene against Tomato spotted wilt virus (TSWV), has been mapped on chromosome 10 in Capsicum. Previously found molecular markers linked to the Tsw gene are not transferable for all pepper breeding materials. To develop segregating populations for the Tsw, commercial F1 cultivar C. annuum ‘Telmo’ was self-pollinated. An F2 population was obtained from the self-pollination of F1 plants deriving from a cross between C. annuum ‘Special’ and C. chinense ‘PI152225’. Twelve additional molecular markers linked to the Tsw gene were developed using tomato and pepper genome sequence database. A tomato scaffold sequence of 7841 kb in size covering the corresponding region of the Tsw locus was identified based on the sequence of Tsw-linked marker. Analyzing the tomato scaffold sequence, two sequences of pepper scaffold and contig at down and up site of the Tsw locus, respectively, were located. Three SNP markers linked to the Tsw locus (HRM1, HRM2, and HRM3) were developed using the pepper scaffold sequence of 419 kb in size. All three markers showed 2 recombinants (1.0 cM) out of 198 individuals of F2 ‘Telmo’ population. When analyzing these SNP markers in an F2 population deriving from C. annuum ‘Special’ and C. chinense ‘PI152225’, we detected 5 recombinants (0.76 cM) out of 659 individuals. HRM4, a SNP marker linked to the Tsw gene, was developed with a 99 kb pepper contig sequence. It showed 7 recombinants (3.5 cM) out of 198 individuals of F2 ‘Telmo’ population. We found 5 recombinants (0.76 cM) out of 659 individuals when HRM4 was analyzed in F2 population derived from C. annuum ‘Special’ and C. chinense ‘PI152225’. To narrow down the molecular markers linked to the Tsw locus, four SNP markers, HRM5, HRM6, HRM7, and HRM8, were developed with the pepper scaffold sequence. All of them showed 5 recombinants (0.76 cM) out of 659 individuals of F2 ‘SP’ population. Four other SNP markers, HRM9, HRM10, HRM11, and HRM12, were developed using the pepper contig sequence. HRM9 showed 5 recombinants (0.76 cM), HRM10 showed 4 recombinants (0.61 cM), and HRM11 and HRM12 showed 3 recombinants (0.46 cM) out of 659 individuals of F2 ‘SP’ population. The SNP markers developed in this study will be useful for fine mapping of the Tsw gene and for developing cultivars which carry TSWV-resistance gene.