Annuum Accessions Research Articles

Exploring the Metabolome and Antimicrobial Properties of Capsicum annuum L. (Baklouti and Paprika) Dried Powders from Tunisia.

In this study, for the first time, the volatile fraction from two domesticated Capsicum annuum accessions ("Paprika" and "Baklouti") collected in Tunisia was investigated by two complementary analytical techniques, such as Solid-Phase Microextraction-Gas Chromatography/Mass Spectrometry (SPME-GC/MS) and Proton Transfer Reaction-Time-of-Flight-Mass Spectrometry (PTR-ToF-MS). The obtained results highlighted the presence of a high number of Volatile Organic Compounds (VOCs), including monoterpene and sesquiterpene compounds with α-curcumene, I-zingiberene, β-bisabolene and β-sesquiphellandrene as the major components. In addition, GC/MS was used to investigate the non-volatile chemical composition of the dried powders and their extracts, which were found to be rich in sulfur compounds, fatty acids and sugars. Eleven bacterial strains were chosen to assess the antimicrobial effectiveness of the extracts. The results showed that the extracts exhibited strain-dependent behavior, and the type strains displayed a greater susceptibility to the treatments, if compared to the wild strains, and, in particular, showed the best antimicrobial activity against Gram-positive bacteria, such as Listeria monocytogenes and Staphylococcus aureus.

Multi-environment association study highlights candidate genes for robust agronomic quantitative trait loci in a novel worldwide Capsicum core collection.

Investigating crop diversity through genome-wide association studies (GWAS) on core collections helps in deciphering the genetic determinants of complex quantitative traits. Using the G2P-SOL project world collection of 10038 wild and cultivated Capsicum accessions from 10 major genebanks, we assembled a core collection of 423 accessions representing the known genetic diversity. Since complex traits are often highly dependent upon environmental variables and genotype-by-environment (G × E) interactions, multi-environment GWAS with a 10195-marker genotypic matrix were conducted on a highly diverse subset of 350 Capsicum annuum accessions, extensively phenotyped in up to six independent trials from five climatically differing countries. Environment-specific and multi-environment quantitative trait loci (QTLs) were detected for 23 diverse agronomic traits. We identified 97 candidate genes potentially implicated in 53 of the most robust and high-confidence QTLs for fruit flavor, color, size, and shape traits, and for plant productivity, vigor, and earliness traits. Investigating the genetic architecture of agronomic traits in this way will assist the development of genetic markers and pave the way for marker-assisted selection. The G2P-SOL pepper core collection will be available upon request as a unique and universal resource for further exploitation in future gene discovery and marker-assisted breeding efforts by the pepper community.

Estimation of the genetic parameters of hybridized peppers (Capsicum annuum L.) F2 progeny begomovirus resistance

Pepper is an essential vegetable commodity in Indonesia. Pepper yellow leaf curl disease caused by the infection Begomoviruses caused tremendous damage to pepper production in the country. The breeding process through crosses is necessary to produce Begomovirus resistance material to overcome the constraint. In this present study, we estimated the genetic parameters of hybridized F2 pepper under natural infected conditions. Two C. annuum accessions, BaPep-5 has resistance material for pepy-1 Begomovirus (locally called Perintis) and BaPep-4 as a susceptible parent (called Kencana) were crossed to produce F2 progenies. F2 generation from the cross as much as 500 plants were transplanted along with 200 plants of each parent as control to the field. The estimation results indicated that the high heritability value was found in the fruit weight per plant (51.31%), the number of fruits per plant (65.58%), the thickness of fruit flesh (92.24%), fruit stalk length (52.43%), and fruit diameter (96.83%), suggesting that these characters have a level of broad genetic diversity. Moreover, a 100% genotypic coefficient of variance (GCV) is observed in the fruit weight per plant, the number of fruits per plant, the thickness of fruit flesh, and fruit diameter meaning that these characters have a high level of genetic diversity broad. In addition, a 100% very broad phenotypic coefficient of variance (PCV) criteria is observed in fruit weight per plant, the number of fruits per plant, the thickness of fruit flesh, and fruit diameter, suggesting that these characteristics have a variety of appearances. Conclusively, fruit weight per plant, number of fruits per plant, the thickness of fruit flesh, and fruit diameter are the characters with high heritability values followed by very broad GCV and PCV values which potentially be inherited and can be used as a reference for selecting further Begomovirus resistance traits.

Capsicum annuum with causal allele of hybrid weakness is prevalent in Asia.

Reproductive isolation, including hybrid weakness, plays an important role in the formation of species. Hybrid weakness in Capsicum, the cessation of plant growth, is caused by two complementary dominant genes, A from C. chinense or C. frutescens and B from C. annuum. In the present study, we surveyed whether 94 C. annuum accessions had B or b alleles by crossing with C. chinense having the A allele. Of the 94 C. annuum accessions, five had the B allele, three of which were native to Latin America and two were native to Asia. When combined with previous studies, the percentage of B carriers was 41% in Japan, 13% in Asia excluding Japan, 6% in Latin America, and 0% in Europe and Africa. In addition, 48 accessions of C. annuum from various countries were subjected to SSR analysis. Clades with high percentages of B-carriers were formed in the phylogenetic trees. In the principal coordinate analysis, most B-carriers were localized in a single group, although the group also included b-carriers. Based on these results, we presumed that the B allele was acquired in some C. annuum lines in Latin America, and B-carriers were introduced to the world during the Age of Discovery, as along with the b-carriers.

Identification and Mapping of bs8, a Novel Locus Conferring Resistance to Bacterial Spot Caused by Xanthomonas gardneri.

Although cultivars possessing recessive resistance alleles provide effective control of bacterial spot of pepper (Capsicum annuum), the deployed resistance gene, bs5, is ineffective against Xanthomonas gardneri, one of the pathogenic species. Resistance against X. gardneri was identified in C. annuum accession PI 163192, and this study sought to characterize this novel resistance and to map the resistance gene(s) to the pepper genome. We crossed PI 163192 with the susceptible cultivar Early Calwonder (ECW) to develop resistant near-isogenic lines (NILs) of ECW, designated ECW80R. The novel resistance in ECW80R was determined to be quantitative, recessively inherited, and non-hypersensitive-response causing, and inhibits lesion expansion and chlorosis. Presence of the resistance in NILs decreased the in planta bacterial population by ninefold compared with ECW. Bulked segregant analysis of resistant and susceptible individuals from an F2 population using whole genome single nucleotide polymorphisms identified a major resistance locus within an approximate 6-Mbp interval on the subtelomeric region of chromosome 11. We developed markers spanning this region and used these to genotype backcross F2 populations, which further delimited the resistance locus within a 2.3-Mbp interval. The novel resistance locus has been designated bs8. ECW80R and the linked markers developed in this study should prove useful for breeders seeking to advance this resistance into commercially relevant germplasm and for pyramiding bs8 with other resistance alleles such as bs5 and bs6. The allele bs8 will help prolong the durability of bacterial spot resistance in pepper and improve resistance to multiple species of Xanthomonas.

Identification of Genetic Factors Controlling the Formation of Multiple Flowers Per Node in Pepper (Capsicum spp.).

Flower production provides the foundation for crop yield and increased profits. Capsicum annuum is a pepper species with a sympodial shoot structure with solitary flowers. By contrast, C. chinense produces multiple flowers per node. C. annuum accounts for 80% of pepper production worldwide. The identification of C. chinense genes that control multiple flowers and their transfer into C. annuum may open the way to increasing fruit yield. In this study, we dissected the genetic factors were dissected controlling the multiple-flower-per-node trait in Capsicum. 85 recombinant inbred lines (RILs) between the contrasting C. annuum ‘TF68’ and C. chinense ‘Habanero’ accessions were phenotyped and genotyped. Quantitative Trait Loci (QTL) analysis identified four novel QTLs on chromosomes 1, 2, 7, and 11 that accounted for 65% of the total phenotypic variation. Genome-wide association study was also performed on a panel of 276 genotyped and phenotyped C. annuum accessions, which revealed 28 regions significantly associated with the multiple-flower trait, of which three overlapped the identified QTLs. Five candidate genes involved in the development of the shoot and flower meristems were identified and these genes could cause multiple flowers per node in pepper. These results contribute to our understanding of multiple flower formation in Capsicum and will be useful to develop high-yielding cultivars.

Genetic variance and heritability estimation of hybridized pepper plants (Capsicum annuum L.) F2 progeny for begomovirus resistance in growth stage

Pepper is widely cultivated as a condiment and cash crop in Indonesia. However, Pepper yellow leaf curl disease (PepYLCD) caused by begomovirus is currently seriously affect the domestic pepper production. Breeding for begomovirus resistance material by crossing is currently necessary to overcome the constraint. The present study is aimed to determine the resistance of pepper (C. annuum) plants F2 progenies to begomovirus infection in the growth stage. Two local C. annuum accessions, BaPep-5 as a resistance donor for pepy-1 begomovirus resistance gene (locally called Perintis) and BaPep-4 as a susceptible parent (locally called Kencana) were crossed to generate F2 progenies. The research was conducted in Agricultural Extension Training Centre (BLPP) Saree and Horticulture Laboratory of Syiah Kuala University from February to July 2020. 500 F2 progenies were transplanted to the field along with 15 plants of each parent as control. The result suggested that plant height and crown width had the highest broad sense heritability value, whereas the dichotomous height, stem diameter, secondary branch, and tertiary branch had the lowest broad sense heritability value. Coefficient of genetic variance and coefficient of phenotypic variance from overall characteristics were relatively low which suggest the narrow sense to slightly narrow sense heritability.

Genetic diversity and population structure analysis – a prerequisite for constructing a mini core collection of Balkan Capsicum annuum germplasm

Pepper (Capsicum annuum L.) is one of the most important vegetable crops worldwide. The Balkans, including Bulgaria, are considered as the secondary centre of pepper diversity especially for C. annuum, where local forms with diverse phenotypes and qualities have formed due to the specific agro-climatic conditions and breeding traditions. Evaluation of the genetic diversity and structure of a pepper collection is an important tool for further development of new varieties and the maintenance of sustainable agriculture. In this study, a set of 179 C. annuum accessions collected from different locations in the Balkan Peninsula was genotyped with 21 simple sequence repeat (SSR; microsatellite) markers. In total, 146 alleles were amplified among which the majority were with low frequencies (<5%). The mean He, Ho and PIC for the 21 SSR loci in the whole set were 0.531, 0.249 and 0.483, respectively. Model-based structure analysis divided the collection into 3 main clusters (K = 3) that grouped accessions with distinct fruit traits like shape, size, pungency. Further genetic structure analysis at increasing Ks suggested the presence of sub-clustering within the three main clusters. A Balkan C. annuum mini core collection was constructed based on the allelic diversity and the inferred genetic structure. As far as the mini core collection captured substantial part of the allele richness, genetic and phenotypic diversity of the analysed 176 non-redundant accessions, while maintaining good representativeness, we believe it will be of high interest to pepper breeders and germplasm conservation specialists. Supplemental data for this article is available online at https://doi.org/10.1080/13102818.2021.1946428 .

Uncovering Candidate Genes Controlling Major Fruit-Related Traits in Pepper via Genotype-by-Sequencing Based QTL Mapping and Genome-Wide Association Study.

All modern pepper accessions are products of the domestication of wild Capsicum species. However, due to the limited availability of genome-wide association study (GWAS) data and selection signatures for various traits, domestication-related genes have not been identified in pepper. Here, to address this problem, we obtained data for major fruit-related domestication traits (fruit length, width, weight, pericarp thickness, and fruit position) using a highly diverse panel of 351 pepper accessions representing the worldwide Capsicum germplasm. Using a genotype-by-sequencing (GBS) method, we developed 187,966 genome-wide high-quality SNP markers across 230 C. annuum accessions. Linkage disequilibrium (LD) analysis revealed that the average length of the LD blocks was 149 kb. Using GWAS, we identified 111 genes that were linked to 64 significant LD blocks. We cross-validated the GWAS results using 17 fruit-related QTLs and identified 16 causal genes thought to be associated with fruit morphology-related domestication traits, with molecular functions such as cell division and expansion. The significant LD blocks and candidate genes identified in this study provide unique molecular footprints for deciphering the domestication history of Capsicum. Further functional validation of these candidate genes should accelerate the cloning of genes for major fruit-related traits in pepper.

Genetic diversity analysis in the Turkish pepper germplasm using iPBS retrotransposon- based markers

Capsicum is one of the most important and diverse plant taxa, widely used as a spice and vegetable worldwide, including Turkey. Germplasm characterization is an essential step for crop breeding. In the present study, we characterized the genetic diversity and population structure of a collection of 94 pepper accessions using inter-primer binding site (iPBS) retrotransposon-based markers. A total of 20 iPBS primers were used that generated 172 bands (mean = 8.6 bands/primer), of which ~92% were polymorphic in the entire germplasm collection, whereas 83%, 69%, and 80% of the bands were polymorphic within the C. annuum, C. chinense, and C. frutescens subsets, respectively. All of the taxa analyzed were clearly differentiated by the iPBS markers. The polymorphism information content of the markers ranged between 0.15 and 0.99, with an average of 0.66. Cluster analyses by different methods (UPGMA, STRUCTURE, and principal coordinate analysis) revealed a clear separation of all of the C. annuum accessions from the other pepper species, with a few subclusters observed among the latter, including groups with accessions of both C. frutescens and C. chinense. At the interspecies level, the 3 clustering methods clearly discriminated C. annuum from C. frutescens and C. chinense. No clear association was found between the iPBS-based clustering and geographical origin or fruit characteristics of the accessions. This is the first report characterizing the genetic diversity and population structure in the Turkish pepper germplasm using iPBS markers. It is expected that these data will serve as a foundation for the development of new and improved pepper varieties.

Phenomics of elite heirlooms of peppers (Capsicum annuum L.) from the Spanish centre of diversity: Conventional and high-throughput digital tools towards varietal typification

Spain is a relevant secondary centre of diversity for Capsicum annuum peppers, especially for the bell types known as Pimiento Morrón or Pimiento de Morro. Thus, a myriad of highly regarded landraces adapted to a wide range of conditions can be found throughout the country, as a result of centuries of farmers breeding. Despite that, these materials lack of proper characterization, of paramount importance for farmers, breeders and germplasm management. In this regard, in addition to internationally accepted conventional descriptors, high-throughput digital phenotyping tools like Tomato Analyzer, a software originally developed to process scanned images of cut tomato fruits and to record a range of morphological parameters, may provide an important help towards exhaustive germplasm characterization. With this aim, 32 conventional and 35 Tomato Analyzer digital traits were used herein to characterize a large collection of C. annuum accessions from all Spanish regions, including Protected Designations of Origin and Protected Geographical Indications, with emphasis on Morrón peppers, in order to assess the diversity within Spanish elite germplasm and to test the efficiency of those methods to differentiate varietal types and closely related materials. A considerable amount of variation was found using both conventional and digital traits, even within Morrón pepper groups, reflecting the diversity of Spanish peppers in terms of plant and fruit morphology, essential for future breeding programs. Both conventional descriptors and digital parameters were able to distinguish varietal groups. However, on the whole, digital phenotyping was able to discriminate in a more accurate way. Most digital parameters were able to discriminate varietal groups into higher numbers of categories (≥4) than conventional traits (usually 2–4). In addition, the number of significant pairwise differences among varietal groups was considerably higher for digital parameters than for conventional descriptors, enabling a powerful separation, particularly relevant for closely related groups such as Morrón peppers. Likewise, as revealed by Principal Components Analysis, digital phenotyping allowed a more powerful intra-varietal separation compared to conventional descriptors. Finally, a subset of 4 conventional descriptors and 13 Tomato Analyzer traits were identified as the most discriminant to distinguish among closely related C. annuum accessions, explaining 81.81 % of total variance found by Principal Components Analysis. Fruit traits explained the highest percentage of variance for our collection.

Genetic structure and identification of molecular markers associated with agrobiological traits in Capsicum annuum accessions

Genetic structure and identification of molecular markers associated with agrobiological traits in Capsicum annuum accessions

Mitotypes Based on Structural Variation of Mitochondrial Genomes Imply Relationships With Morphological Phenotypes and Cytoplasmic Male Sterility in Peppers.

Plant mitochondrial genomes characteristically contain extensive structural variation that can be used to define and classify cytoplasm types. We developed markers based on structural variation in the mitochondrial genomes of fertile and cytoplasmic male sterility (CMS) pepper lines and applied them to a panel of Capsicum accessions. We designed a total of 20 sequence characterized amplified region (SCAR) markers based on DNA rearrangement junctions or cytoplasm-specific segments that did not show high similarity to any nuclear mitochondrial DNA segments. We used those markers to classify the mitotypes of 96 C. annuum accessions into 15 groups. Precise genotyping of other Capsicum species (C. frutescens, C. chinense, and C. baccatum) was hampered because of various stoichiometric levels of marker amplicons. We developed a multiplex PCR system based on four of the markers that efficiently classified the C. annuum accessions into five mitotype groups. Close relationships between specific mitotypes and morphological phenotypes implied that diversification or domestication of C. annuum germplasm might have been accompanied by structural rearrangements of mitochondrial DNA or the selection of germplasms with specific mitotypes. Meanwhile, CMS lines shared the same amplification profile of markers with another mitotype. Further analysis using mitochondrial DNA (mtDNA) markers based on single-nucleotide polymorphisms (SNPs) or insertions and deletions (InDels) and CMS-specific open reading frames (orfs) provided new information about the origin of the CMS-specific mitotype and evaluation of candidates for CMS-associated genes, respectively.

Resistance to three thrips species in Capsicum spp. depends on site conditions and geographic regions

AbstractCapsicum species are commercially grown for pepper production. This crop suffers severely from thrips damage and the identification of natural sources of thrips resistance is essential for the development of resistant cultivars. It is unclear whether resistance to Frankliniella occidentalis as assessed in a specific environment holds under different conditions. Additionally, other thrips species may respond differently to the plant genotypes. Screening for robust and general resistance to thrips encompasses testing different Capsicum accessions under various conditions and with different thrips species. We screened 11 Capsicum accessions (C. annuum and C. chinense) for resistance to F. occidentalis at three different locations in the Netherlands. Next, the same 11 accessions were screened for resistance to Thrips palmi and Scirtothrips dorsalis at two locations in Asia. This resulted in a unique analysis of thrips resistance in Capsicum at five different locations around the world. Finally, all accessions were also screened for resistance to F. occidentalis in the Netherlands using a leaf disc choice assay, allowing direct comparison of whole plant and leaf disc assays. Resistance to F. occidentalis was only partially consistent among the three sites in the Netherlands. The most susceptible accessions were consistently susceptible, but which accession was the most resistant differed among sites. In Asia, one C. chinense accession was particularly resistant to S. dorsalis and T. palmi, but this was not the most resistant accession to F. occidentalis. Overall, resistance to F. occidentalis correlated with S. dorsalis but not with T. palmi resistance in the C. annuum accessions. Damage inflicted on leaf discs reflected damage on the whole plant level. Our study showed that identifying broad spectrum resistance to thrips in Capsicum may prove to be challenging. Breeding programmes should focus on developing cultivars suitable for growing in defined geographic regions with specific thrips species and abiotic conditions.

Genetic diversity and population structure of Ethiopian Capsicum germplasms.

We established a collection of 142 Capsicum genotypes from different geographical areas of Ethiopia with the aim of capturing genetic diversity. Morphological traits and high-resolution melting analysis distinguished one Capsicum baccatum, nine Capsicum frutescens and 132 Capsicum annuum accessions in the collection. Measurement of plant growth parameters revealed variation between germplasms in parameters including plant height, stem thickness, internode length, number of side branches, fruit width, and fruit length. Broad-sense heritability was maximum for fruit weight, followed by length and width of leaves. We used genotyping by sequencing (GBS) to identify single-nucleotide polymorphisms (SNPs) in the panel of 142 Capsicum germplasms and found 2,831,791 genome-wide SNP markers. Among these, we selected 53,284 high-quality SNPs and used them to estimate the level of genetic diversity, population structure, and phylogenetic relationships. From model-based ancestry analysis, the phylogenetic tree and principal-coordinate analysis (PCoA), we identified two distinct genetic populations: one comprising 132 C. annuum accessions and the other comprising the nine C. frutescens accessions. GWAS analysis detected 509 SNP markers that were significantly associated with fruit-, stem- and leaf-related traits. This is the first comprehensive report of the analysis of genetic variation in Ethiopian Capsicum species involving a large number of accessions. The results will help breeders utilize the germplasm collection to improve existing commercial cultivars.

A MYB transcription factor is a candidate to control pungency in Capsicum annuum.

Identification of a novel pungency-controlling gene Pun3, which acts as a master regulator of capsaicinoid biosynthetic genes in Capsicum annuum. Capsaicinoid is a unique compound that gives hot peppers (Capsicum spp.) their spicy taste. The Pun1 and Pun2 loci are known to control pungency in Capsicum species. Whereas Pun1 encodes an acyltransferase, the identity of Pun2 is currently unknown. Here, we used recombinant inbred lines and F2 plants derived from a cross between the non-pungent C. annuum accession 'YCM334' and the pungent C. annuum cultivar 'Tean' to identify a novel non-pungency locus. Inheritance studies showed that non-pungency in C. annuum 'YCM334' is controlled by a single recessive gene, which we named Pun3. Using a high-density SNP map derived from genotyping-by-sequencing, Pun3 was mapped to chromosome 7. By comparing physical information about the Pun3 region in the C. annuum 'Zunla-1' and C. chinense 'PI159236' reference genomes, we identified candidate genes in this target region. One cDNA sequence from 'PI159236' was homologous to an unannotated gene in 'Zunla-1.' This sequence was also homologous to CaMYB31, which is expressed only in 'Tean' and harbors one stop codon in the non-pungent accession 'YCM334.' RNA-Seq analysis showed that major structural genes in the capsaicinoid biosynthetic pathway were significantly downregulated in 'YCM334' compared to pungent pepper. Therefore, CaMYB31 is a candidate gene for Pun3, which may act as a master regulator of capsaicinoid biosynthetic genes in pepper.

Identification of Resistance to Powdery Mildew in Chile Pepper

Powdery mildew [Leveillula taurica (Lév.) Arn] is a fungus causing epidemics on chile peppers (Capsicum sp.) worldwide. It was first observed in New Mexico in the late 1990s and has been a reoccurring issue. During the 2017 growing season, environmental conditions were highly favorable for powdery mildew development and severe infection was observed. This provided a unique opportunity to identify novel sources of resistance in Capsicum to powdery mildew. In the present study, the incidence and severity of powdery mildew was evaluated for 152 chile pepper accessions comprising different cultivars and species. Major differences in disease severity and incidence were observed among the accessions. Of the 152 accessions, 53 were resistant, i.e., received a disease index (DI) score of ≤1. When examining across Capsicum species, 16 Capsicum annuum accessions, all 8 Capsicum baccatum, all 21 Capsicum chinense, 5 of 6 Capsicum frutescens, the Capsicum chacoense accession, and the Capsicum rhomboideum accession were resistant. These results provide several accessions with resistance that can be used in breeding programs. Especially important are the C. annuum resistant accessions, as this resistance can be more quickly incorporated into commercially important C. annuum cultivars as compared with interspecific hybridizations.

Capsicum-Colletotrichum interaction: Identification of resistance sources and quantification of secondary metabolites in unripe and ripe fruits in response to anthracnose infection

Anthracnose, caused by Colletotrichum species complex, is one of the main fungal diseases in pepper (Capsicum spp.) crops, resulting in extensive fruit losses during pre- and post-harvesting. Plants have structural and biochemical defense mechanisms produced before and/or after the pathogen attack. Biochemical defense involve the production of compounds that accumulate at the site of infection and are toxic to the pathogen. However, the accumulation and biosynthesis of these compounds during Capsicum-Colletotrichum interaction, especially during fruit development stages remain poorly understood. In order to identify potential resistant genotypes and to improve our knowledge about the metabolites produced by pepper fruits against fungus infection, we inoculated unripe and ripe fruits of 59 accessions of Capsicum spp. with C. gloeosporioides and analyzed the disease severity during 8 days after inoculation. In this study, we observed a wide variability of fungus resistance response in unripe and ripe fruits of Capsicum spp. accessions, and ripe fruits presented greater resistance to anthracnose than unripe. Six accessions (GBUEL06, GBUEL28, GBUEL73, GBUEL87, GBUEL104 and GBUEL106) were considered as resistant for both fruits development stages and have potential to be used in future breeding programs. In addition, we selected two C. annuum accessions GBUEL103 (susceptible) and GBUEL104 (resistant), to describe the histological aspects of C. gloeosporioides infection in pepper fruits, followed by the quantification of secondary metabolites produced during this plant-pathogen interaction, using light microscopy and ultra-high performance liquid chromatography (UHPLC), respectively. The quantification of secondary metabolites produced in pepper fruits during fungus infection showed different values according genotype characteristic (susceptible or resistant), fruit development stages (unripe and ripe) and time (1st and 8th day post-inoculation). Interestingly, high concentrations of caffeic and chlorogenic acid were quantified in unripe and ripe fruits characterized as resistant genotype, showing that these biochemical compounds are putatively involved in fruit defense mechanism in response to anthracnose disease.

Overcoming post-zygotic hybridization barriers in Capsicum annuum var. annuum

Hybridization is essential for gene introgression in plant breeding. However, embryo abortion may prevent the production of hybrid seeds because of post-zygotic genetic barriers. A breeding program for ornamental Capsicum did not achieve seed germination using crosses of two accessions, although both accessions were from C. annuum var. annuum, resulting in an intraspecific cross. Here we report the use of an in vitro embryo rescue technique to overcome post-zygotic barriers in crosses of two C. annuum var. annuum accessions (UENF 1632 and UENF 1623). Microsatellite markers were used to confirm the plant species and ensure that both accessions were representatives of C. annuum var. annuum. Anatomical and morphological studies were conducted on parental and hybrid seeds to determine the causes of incompatibility. In the in vitro rescue, five concentrations of sucrose (0, 5, 10, 15, and 20 g L−1) and three combinations of phytoregulators (0.057 μmol L−1 of indoleacetic acid (IAA) + 0.046 μmol L−1 of zeatin, 0.057 μmol L−1 of IAA + 0.029 μmol L−1 of gibberellic acid and without phytoregulators) were tested. Anatomical analysis and in vitro culture results indicated that the intraspecific incompatibility between C. annuum UENF 1632 and UENF 1623 was caused by endosperm malformation. Using in vitro embryo rescue was an efficient strategy to produce hybrid seedlings. The use of sucrose and phytoregulators was not necessary for embryo germination in vitro. Nonetheless, seedling growth in vitro required the use of sucrose in the medium culture. Embryo rescue was efficient for overcoming post-zygotic barriers in this intraspecific cross of C. annuum, allowing the production of fertile hybrids and the use of the offspring in breeding programs.

Exploring the genetic variations and population structure of Turkish pepper (Capsicum annuum L.) genotypes based on peroxidase gene markers.

Capsicum is thought as one of the most diverse and significant genera due to its varied uses in different parts of the world. In this study, we worked with a total of 71 pepper genotypes from different locations of Turkey to investigate the level of their diversity using the peroxidase gene polymorphism (POGP) markers to reveal their population structure. For this purpose, 14 peroxidase primer pairs were used. They produced 139 bands (mean = 9.9 bands/primer), of which ~ 85.6% were polymorphic in the all germplasm collection. Polymorphism information content (PIC) ranged between 0.48 and 0.97 with an average of 0.75. Range and mean values for gene diversity (h) were 0.09-0.22 and 0.17, respectively. Shannon's information index (I) per POGP marker ranged from 0.18 to 0.35 with a mean of 0.29. Using three clustering methods (unweighted pair-group method with arithmetic means, principal coordinate analysis, and STRUCTURE) revealed a clear separation of all the C. annuum accessions from C. frutescens and C. chinense accessions in our study. Clusters did not establish an association between the accessions and their geographical origin. This is the first study exploring the population structure through the genetic diversity of Turkish peppers from different regions of the country based on the peroxidase gene markers.