Baccatum Accessions Research Articles

Phenotypic, molecular and pathogenic characterization of Colletotrichum scovillei infecting Capsicum species in Rio de Janeiro, Brazil.

Anthracnose is a disease caused by Colletotrichum spp., one of the world’s most damaging sweet and chili pepper pathogens, especially in tropical and subtropical regions. In the state of Rio de Janeiro, anthracnose is one of the main obstacles for pepper crops. However, to date no research has focused on the identification and characterization of the pathogen, which is fundamental to understand the scope of the disease in the state. Thus, the correct identification of the fungal species and pathogenicity studies can provide important support for disease management and control, apart from identifying possible resistance sources for exploitation in peppers breeding programs. In this study, 11 Colletotrichum isolates were collected from peppers with typical symptoms in the Rio de Janeiro state. These isolates were characterized based on morpho-cultural characteristics and sequencing data from five regions (ITS, ACT, CAL, β-TUB and GAPDH), and the genetic variability was estimated by AFLP markers. Simultaneously, microscopy images of the colonization by the fungal species on unripe Capsicum annuum fruits were taken. Pathogenicity was tested and resistance sources were sought by means of infection of ripe and unripe fruits of 50 Capsicum baccatum accessions. The resulting data showed that all isolates belong to Colletotrichum scovillei specie. About the pathogenicity of Capsicum baccatum, differentiated, stage-specific responses, with higher resistance of ripe fruits were recorded. In addition, four possible sources of Colletotrichum scovillei resistance were detected among the tested accessions. The combination of these data can contribute to future studies on the interaction of Colletotrichum scovillei-Capsicum spp., a research line that is still unexploited in the main areas of this anthracnose fungus.

Genetic variability in peppers accessions based on morphological, biochemical and molecular traits

The evaluation of genetic diversity among the accessions of a germplasm collection results in information about promising materials suitable for breeding programs. Thus, the goal of this work was to characterize Capsicum baccatum accessions from different Brazilian regions, based on morphological, biochemical and molecular traits, aiming to support chili pepper breeding programs. The fruits were morphologically characterized based on fruit length, diameter, fresh mass and pericarp thickness, and biochemically analyzed for their content in ascorbic and phenolic acids, flavonoid and antioxidant activity by 2,2-diphenyl-1-picrylhydrazyl radical (DPPH•) and ferric reducing antioxidant power (FRAP) assays. All phenotypic traits showed significant differences among the chili pepper accessions, indicating a wide variability. The fruits were also characterized using amplified fragment length polymorphism (AFLP) molecular markers. The combination of six AFLP primers resulted in 1117 bands, 1033 of which were polymorphic. Divergence between accessions was estimated by the Ward’s hierarchical agglomerative clustering method, resulting in three and two clusters for fruit phenotypic traits and molecular data, respectively. In Bayesian analysis, molecular data also clustered the accessions in two groups. There was no association between the phenotypic descriptors and AFLP markers, indicating that both characterizations are important to better understand the genetic variability. Furthermore, it was not possible to group the accessions solely based on their origin for neither phenotypic descriptors and AFLP markers. The accessions G1, G5, G6, and G20 showed interesting characteristics and can be used in breeding programs, aiming the development of Capsicum spp. cultivars with desirable morphological and biochemical traits.

Bioanalytical method validation for the quantification of the chlorogenic acid in Capsicum baccatum through High Performance Liquid Chromatography (HPLC-DAD)

The fruit pulp extracts of the species Capsicum baccatum are associated with a number of phenolic compounds. The aim of this study was to validate a bioanalytical method for the quantification of the chlorogenic acid present in the UENF 1613 de C. baccatum accession. The quantification was carried out through HPLC. The results obtained for the extract of C. baccatum indicated selectivity for chlorogenic acid. The values obtained for relative standard deviation, as well as for precision, in terms of repeatability and intermediate precision, did not exceed the maximum of 15% set in the criteria for the acceptance of bioanalytical methods. In terms of recovery, the accuracy rate for the phenolic compound of interest was from 77 to 93%. The validated method through external standardization was applied for the quantification of chlorogenic acid of the UENF accession.

The ability to manipulate ROS metabolism in pepper may affect aphid virulence

Myzus persicae has severe economic impact on pepper (Capsicum) cultivation. Previously, we identified two populations of M. persicae, NL and SW, that were avirulent and virulent, respectively on C. baccatum accession PB2013071. The transcriptomics approach used in the current study, which is the first study to explore the pepper−aphid interaction at the whole genome gene expression level, revealed genes whose expression is differentially regulated in pepper accession PB2013071 upon infestation with these M. persicae populations. The NL population induced ROS production genes, while the SW population induced ROS scavenging genes and repressed ROS production genes. We also found that the SW population can induce the removal of ROS which accumulated in response to preinfestion with the NL population, and that preinfestation with the SW population significantly improved the performance of the NL population. This paper supports the hypothesis that M. persicae can overcome the resistance in accession PB2013071 probably because of its ability to manipulate plant defense response especially the ROS metabolism and such ability may benefit avirulent conspecific aphids.

Reduced phloem uptake of Myzus persicae on an aphid resistant pepper accession

BackgroundThe green peach aphid (GPA), Myzus persicae, is economically one of the most threatening pests in pepper cultivation, which not only causes direct damage but also transmits many viruses. Breeding aphid resistant pepper varieties is a promising and environmentally friendly method to control aphid populations in the field and in the greenhouse. Until now, no strong sources of resistance against the GPA have been identified. Therefore the main aims of this study were to identify pepper materials with a good level of resistance to GPA and to elucidate possible resistance mechanisms.ResultsWe screened 74 pepper accessions from different geographical areas for resistance to M. persicae. After four rounds of evaluation we identified one Capsicum baccatum accession (PB2013071) as highly resistant to M. persicae, while the accessions PB2013062 and PB2012022 showed intermediate resistance. The resistance of PB2013071 resulted in a severely reduced uptake of phloem compared to the susceptible accession, as determined by Electrical Penetration Graph (EPG) studies. Feeding of M. persicae induced the expression of callose synthase genes and resulted in callose deposition in the sieve elements in resistant, but not in susceptible plants.ConclusionsThree aphid resistant pepper accessions were identified, which will be important for breeding aphid resistant pepper varieties in the future. The most resistant accession PB2013071 showed phloem-based resistance against aphid infestation.

Genetic variability in Brazilian Capsicum baccatum germplasm collection assessed by morphological fruit traits and AFLP markers.

Capsicum baccatum is one of the main pepper species grown and consumed in South America. In Brazil, it is commonly cultivated by family farmers, using mostly the genotypes bishop's hat genotypes (locally cambuci) and red chili pepper (dedo-de-moça). This study had the objective of characterizing 116 C. baccatum accessions from different regions of Brazil, based on morphological fruit descriptors and AFLP (Amplified Fragment Length Polymorphisms) markers. Broad phenotypic variability among the C. baccatum accessions was detected when using morphological fruit descriptors. The Ward modified location model (Ward-MLM) discriminated five groups, based mainly on fruit shape. Six combinations of AFLP primers detected polymorphism in 97.93% of the 2466 identified bands, indicating the high genetic variability in the accessions. The UPGMA coincided with the Bayesian clustering analysis and three large groups were formed, separating the wild variety C. baccatum var. praetermissum from the other accessions. There was no relation between genetic distance and geographical origin of the accessions, probably due to the intense exchange of fruits and seeds between farmers. Morphological descriptors used together with AFLP markers proved efficient in detecting the levels of genetic variability among the accessions maintained in the germplasm collections. These results can be used as an additional source of helpful information to be exploited in C. baccatum breeding programs.

Variability among Capsicum baccatum accessions from Goiás, Brazil, assessed by morphological traits and molecular markers.

Capsicum peppers are native to the Americas, with Brazil being a significant diversity center. Capsicum baccatum accessions at Instituto Federal (IF) Goiano represent a portion of the species genetic resources from central Brazil. We aimed to characterize a C. baccatum working collection comprising 27 accessions and 3 commercial cultivars using morphological traits and molecular markers to describe its genetic and morphological variability and verify the occurrence of duplicates. This set included 1 C. baccatum var. praetermissum and 29 C. baccatum var. pendulum with potential for use in breeding programs. Twenty-two morphological descriptors, 57 inter-simple sequence repeat, and 34 random amplified polymorphic DNA markers were used. Genetic distance was calculated through the Jaccard similarity index and genetic variability through cluster analysis using the unweighted pair group method with arithmetic mean, resulting in dendrograms for both morphological analysis and molecular analysis. Genetic variability was found among C. baccatum var. pendulum accessions, and the distinction between the two C. baccatum varieties was evident in both the morphological and molecular analyses. The 29 C. baccatum var. pendulum genotypes clustered in four groups according to fruit type in the morphological analysis. They formed seven groups in the molecular analysis, without a clear correspondence with morphology. No duplicates were found. The results describe the genetic and morphological variability, provide a detailed characterization of genotypes, and discard the possibility of duplicates within the IF Goiano C. baccatum L. collection. This study will foment the use of this germplasm collection in C. baccatum breeding programs.

Genome-Wide Divergence and Linkage Disequilibrium Analyses for Capsicum baccatum Revealed by Genome-Anchored Single Nucleotide Polymorphisms.

Principal component analysis (PCA) with 36,621 polymorphic genome-anchored single nucleotide polymorphisms (SNPs) identified collectively for Capsicum annuum and Capsicum baccatum was used to characterize population structure and species domestication of these two important incompatible cultivated pepper species. Estimated mean nucleotide diversity (π) and Tajima's D across various chromosomes revealed biased distribution toward negative values on all chromosomes (except for chromosome 4) in cultivated C. baccatum, indicating a population bottleneck during domestication of C. baccatum. In contrast, C. annuum chromosomes showed positive π and Tajima's D on all chromosomes except chromosome 8, which may be because of domestication at multiple sites contributing to wider genetic diversity. For C. baccatum, 13,129 SNPs were available, with minor allele frequency (MAF) ≥0.05; PCA of the SNPs revealed 283 C. baccatum accessions grouped into 3 distinct clusters, for strong population structure. The fixation index (FST) between domesticated C. annuum and C. baccatum was 0.78, which indicates genome-wide divergence. We conducted extensive linkage disequilibrium (LD) analysis of C. baccatum var. pendulum cultivars on all adjacent SNP pairs within a chromosome to identify regions of high and low LD interspersed with a genome-wide average LD block size of 99.1 kb. We characterized 1742 haplotypes containing 4420 SNPs (range 9–2 SNPs per haplotype). Genome-wide association study (GWAS) of peduncle length, a trait that differentiates wild and domesticated C. baccatum types, revealed 36 significantly associated genome-wide SNPs. Population structure, identity by state (IBS) and LD patterns across the genome will be of potential use for future GWAS of economically important traits in C. baccatum peppers.

Etiological and epidemiological concerns about Pepper root and lower stem rot caused by Fusarium oxysporum f. sp. radicis-capsici f. sp. nova

Inoculum sources of Fusarium oxysporum f. sp. radicis-capsici and host susceptibility were studied in commercial pepper cultivars and related Capsicum spp. The pathogen could not be identified in irrigation water or in the microbiologically enriched potting medium, or associated with the seeds used in the nursery where the disease was initially reported in Spain. Although the disease was asymptomatic on older pepper plants, pathogenic strains could still be isolated from the soil of those greenhouses where the disease had been previously observed. Host susceptibility in commercial pepper cultivars and related Capsicum spp. was studied. All pepper cultivars tested (n = 19), including three rootstocks, developed symptoms when inoculated with Fusarium oxysporum f. sp. radicis-capsici. Three C. baccatum accessions and one C. annuum accession exhibited resistance, whereas two C. chinense accessions showed only partial resistance. The disease symptoms could not be distinguished from those caused by one F. oxysporum f. sp. capsici isolate, and molecular analysis also showed identical tef sequences for both formae speciales.

<b>Karyotypic characterization of <i>Capsicum</i> sp. accessions

This study aimed to determine the chromosome number and the karyotype of Capsicum annuum, Capsicum chinense, Capsicum frutencens and Capsicum baccatum accessions in the active Capsicum sp. genebank at the Federal University of Piaui (BGC-UFPI). These species have great economic importance throughout the world, and their cytogenetic characterization can inform taxonomy and lead to improvement in the genus. Karyotypes were obtained from the rootlet meristems of the studied accessions using the squash method and Giemsa staining. The chromosome number 2n=2x=24 was verified for each of the four species. Chromosomal polymorphisms were observed for the C. frutencens accession BGC 37, which presented 12 pairs of metacentric chromosomes instead of 11 pairs of metacentric chromosomes and 1 submetacentric chromosome pair present in other accessions. In the accessions BGC 01 and BGC 37, secondary constrictions were observed in the 1 and 12 as well as in the 6 and 11 homologs, respectively. The karyotypes of the studied species were asymmetrical among themselves. The results obtained in this study confirm the high genetic diversity previously described in the literature for this genus.

Horticultural and chemical quality characterization of accessions selected from four species of Capsicum

Pepper accessions with promising adaptations to the Korean growing environment were selected from Capsiucm annuum, C. frutescens, C. baccatum, and C. chinense. ‘Cherry Sweet,’ ‘Papri Sweet,’ and ‘Papri Mild’ accessions of C. annuum were selected for their fresh fruit quality. The fruit of ‘Cherry Sweet’ and ‘Papri Mild’ matured into a bright red color, with a high American Spice Trade Association (ASTA) color value, while the fruit of ‘Papri Sweet’ was characterized by a good taste and chewing texture. KC01299, KC01333, KC01338, and KC01345 accessions of C. frutescens had relatively low ASTA color values, but were highly pungent with a capsaicinoid content similar to or higher than Tabasco (375.5 mg·100 g−1) and 3 to 5 times that of ‘Cheongyang’ (103.3 mg·100 g−1), which is a popular Korean hot pepper cultivar. The three selected C. baccatum accessions (KC01739, KC00625, and KC00628) were tolerant to powdery mildew and viruses, with KC01691 and KC00625 having high sugar content. A good diversity in fruit shape and chemical quality components was found among the selected C. chinense accessions. The fruit of KC01693 (with a temporary RDA genebank number 800080) were light emerald green when immature and ivory to ripe apricot color when mature, with a high sweet taste and the characteristic aroma of C. chinense. The mature fruits contained similar levels of capsaicinoids as ‘Cheonyang,’ and had the highest sugar content of all tested accessions in this study. The red and orange lines bearing Korean chile pepper type fruits with tolerance to powdery mildew and viruses were selected from PI224445 (KC00163). The red fruit selection had the highest ASTA color value among all tested accessions, with the appropriate pungency for making Korean Kimchee. Bhut Jolokia had the highest ranking for capsaicinoid content, but its fruit set was poor. A red Habanero, KC01787, was selected for productivity, high capsaicinoid content, and tolerance to viruses in the field.

Genetic diversity analysis of Capsicum spp germplasm bank accessions based on α/β-esterase polymorphism

Genetic diversity and structure were analyzed in 10 accessions belonging to Banco Ativo de Germoplasma de Capsicum located at Federal University of Piauí in northwestern Brazil that receives pepper samples grown in community gardens in various regions and Brazilian states. Selections were made from seeds of C. chinense (4 accessions), C. annuum (5 accessions), and C. baccatum (1 accession). Samples consisting of leaves were collected from 4-10 plants of each accession (a total of 85 plants). Native polyacrylamide gel electrophoresis was used to identify α- and β-esterase polymorphisms. Polymorphism was clearly detected in 5 loci. Sixteen alleles were found at 5 α/β-esterase loci of the three Capsicum species. In the C. chinense samples, the highest HO and HE values were 0.3625 and 0.4395, respectively, whereas in C. annuum samples, HO and HE values were 0.2980 and 0.3310, respectively; the estimated HO and HE values in C. chinense samples were higher than those detected in C. annuum samples. A deficit of homozygous individuals was found in C. chinense (FIS = -0.6978) and C. annuum (FIS = 0.7750). Genetic differentiation between C. chinense and C. annuum at these loci was high (FST = 0.1867) indicating that C. chinense and C. annuum are genetically structured species for α/β- esterase isozymes. The esterase analysis showed high genetic diversity among the C. chinense and C. annuum samples and very high genetic differentiation (FST = 0.6321) among the C. chinense and C. annuum samples and the C. baccatum accession.

고추 흰가루병 저항성 평가방법 개발

고추 흰가루병은 시설재배의 증가로 경제적인 피해가 증가하는 병해이다. 본 연구에서는 고추 유전자원의 흰가루병 저항성 평가를 위한 새로운 저항성 평가 방법을 개발하였다. S index라고 명명한 평가방법의 공식은 다음과 같다; (최상위 발병 엽수/정단부 엽수) - (최하위 발병 엽수/정단부 엽수). 흰가루병에 의해 발병된 고추 식물체에서 이병엽율과 S index는 81%(P = 0.01)의 정의 상관으로 고도의 유의성을 보였다. 그리고 34종의 유전자원에서 저항성을 평가한 결과, S index는 흰가루병 저항성 계통을 구분할 수 있는 것으로 확인되었다. 이들 중 Capsicum frutescens 인 3CA131과 C. baccatum인 3CA0162, 3CA174, 3CA176은 흰가루병에 강한 저항성으로 평가되었다. 이 결과는 고추 흰가루병 저항성품종 육성에서 Sindex의 유용성을 증명한 결과이다. Pepper powdery mildew causes increasingly economical damage due to increased cultivation of pepper in greenhouses. To assess resistance of pepper resources against pepper powdery mildew, we developed a novel evaluation formula for pepper resistance against powdery mildew. The evaluation formula named S index is as follows; (number of the highest disease leaf/top leaf number)-(number of the lowest disease leaf/top leaf number). Positive correlation (81%, P = 0.01) between S index and authentic disease leaf rate was observed from the pepper plants infected by powdery mildew. Various pepper species from our genetic resources were evaluated to identify pepper varieties conferring resistance against powdery mild using S-index. Capsicum frutescens accessions 3CA131 and C. baccatum accessions 3CA0162, 3CA174, 3CA176 showed high resistance to powdery mildew, but none of C. annuum was resistant. Results suggest that S-index proposed in this study is useful to assess resistance evaluation of powdery mildew in chili pepper breeding.

Genetic diversity and population structure of Capsicum baccatum genetic resources

Capsicum baccatum is one of five domesticated pepper species which, despite its morphological and ecological variability, has been underexploited for germplasm improvement. Utilizing a broad spectrum of domesticated and wild C. baccatum germplasm, we utilize AFLP markers to describe the species’ molecular diversity and population structure in the South American gene pool. Analysis of molecular variance (AMOVA) revealed greater genetic diversity in the wild form of C. baccatum (C. baccatum var. baccatum) than in the domesticated form of the species (C. baccatum var. pendulum). Both Bayesian and distance based clustering analysis, as well as principal coordinates analysis (PCA), concordantly demonstrated admixture/shared ancestry between wild and cultivated C. baccatum botanical varieties. Two principal genetic groups were identified in the domesticated C. baccatum accessions largely based on their geographic distribution in South America. One group was predominated by accessions from the western territories of the species’ distribution (Peru, Colombia, Ecuador, Bolivia, Chile and northwestern Argentina) and the second by accessions from the eastern regions, Paraguay and eastern Argentina). The two genetic groups overlapped in the geographic location of present-day Bolivia. The grouping pattern suggested that C. baccatum was domesticated in multiple sites and that its evolution took two lineages followed by lineage differentiation. The wild accessions most closely related to the cultigens were found in the highlands of Peru and Bolivia, which support the early hypothesis that this region is one of the domestication sites of this species. A Bayesian assignment analysis demonstrated that Brazilian wild forms of C. baccatum were genetically distant to all other accessions and made little to no contribution to the domesticated genepool. Moreover, results of clustering analysis suggested that C. baccatum likely originated from present day Paraguay. Analysis of inter-specific relationships across selected Capsicum species supported independent lineages for the two crossability groups within Capsicum, the baccatum species-complex (including C. baccatum) and the annuum species-complex (including C. annuum, C. chinense and C. frutescens). However, the results did not support taxonomic distinction of C. baccatum var. umbilicatum from C. baccatum var. pendulum. The present study provides new insights into the domestication of C. baccatum. The results will be useful for identifying accessions for crop improvement and guiding the development of in situ and ex situ conservation programs.

Marcadores RAPD e caracteres morfoagronômicos na determinação da diversidade genética entre acessos de pimentas e pimentões

A diversidade genética existente em coleções e bancos de germoplasma pode ser estimada por meio de diversos métodos, sendo que a escolha destes depende da disponibilidade dos recursos e da precisão desejada pelo pesquisador. Neste trabalho, marcadores RAPD e caracteres morfoagronômicos foram usados para estimar a divergência genética entre 52 acessos de Capsicum spp. Um total de 57 variáveis binárias geradas pela caracterização morfoagronômica e 84 bandas polimórficas obtidas a partir da análise por RAPD foram analisadas separadamente e em conjunto, permitindo a construção de três dendrogramas. Observou-se a formação de dois grupos principais, tanto na análise morfoagronômica e molecular separadamente, quanto na análise conjunta dos dados. O agrupamento dos acessos pela análise conjunta seguiu o mesmo padrão verificado para a análise molecular, que se constituiu em um grupo formado por acessos de C. baccatum e outro grupo formado pelos acessos de C. chinense, C. frutescens e C. annuum. Esse agrupamento segue a proposta vigente para a classificação de Capsicum spp. em complexos gênicos. A associação dos métodos permitiu uma melhor distinção entre os acessos, o agrupamento desses em nível de espécie e a conclusão de que não há duplicatas na coleção, demonstrando a importância do uso de diferentes técnicas na caracterização de um banco de germoplasma.