Capsicum Cultivars Research Articles

Tissue specific colonization of Phytophthora capsici in Capsicum spp.: molecular insights over plant-pathogen interaction

Root and crown rot (RCR) caused by Phytophthora capsici is present in all crop production areas of pepper and chili worldwide. This pathogen was recently reported at the Pacific coast of Ecuador (province of Manabi), as an etiological agent of wilt and root and crown rot in commercial fields of bell pepper (Capsicum annuum). This study aimed to evaluate the resistance of ten Capsicum spp. genotypes artificially infected with P. capsici and to compare the tissue-specific colonization of P. capsici under greenhouse conditions. Disease intensity, mycelial growth incidence and pathogen DNA content in root and hypocotyl tissues of P. capsici infected Capsicum germplasm was evaluated at 17 days after infection (dai). Results indicated that genotypes Nathalie, ECU-12831, ECU-9129, Codigo 5, and ECU-1296 were found to be resistant, and ECU-11995, ECU-2254 B, California Wonder, Quetzal and Marcato showed susceptibility to the disease. The amount of pathogen DNA in roots was the only variable that did not correlate with the resistance or susceptibility of the genotypes. In fact, in resistant genotypes the pattern of pathogen DNA content was higher in roots than hypocotyls (but also in the susceptible ECU-11995), while in the susceptible genotypes (e.g. ECU-2254 B, C. Wonder, Quetzal and Marcato) showed the opposite pattern. The present work provides new insights of host-pathogen interaction, which might be used in breeding programs aiming to develop Capsicum cultivars with resistance to RCR.

Fate of free and bound phytol and tocopherols during fruit ripening of two Capsicum cultivars

Phytol and tocopherols and their fatty acid esters (PFAE and TFAE) are isoprenoid lipid components which can be found for instance in vegetables. Their behavior during maturation of fruits and vegetables could reveal valuable information on their biosynthetic formation and biological function. As pods of the genus Capsicum contain considerable amounts of both PFAE and TFAE, two cultivars (i.e. Capsicum annuum var. Forajido and Capsicum chinense var. Habanero) were grown in a greenhouse project. The date of flowering and fruit formation of each blossom was noted and fruits were harvested in four specific periods which corresponded with different stages of ripening, i.e. unripe, semi-ripe, ripe and overripe. Quantification by means of gas chromatography mass spectrometry and creation of development profiles strongly supported the suggestion that PFAE and TFAE were formed as storage molecules during fruit ripening and parallel degradation of chlorophyll. Additionally, compound-specific carbon isotope ratios (δ13C values (‰)) of originally in PFAE and chlorophyll bound phytol ultimately proved that PFAE, besides tocopherols, serve as sink for the cytotoxic phytol moiety released from chlorophyll degradation during fruit ripening. Furthermore, color measurements were successfully implemented to simplify the usually cumbersome separation of chili fruits into different ripening degrees.

Chili Pepper Landrace Survival and Family Farmers in Central Chile

Chili pepper is produced by family farmers in central Chile incorporating modern technologies and maintaining traditional practices. Although chili pepper is deeply rooted in the local culture, the agricultural system supporting its production and the germplasm involved are poorly studied. This work focused on two main landraces lacking information about what features (agronomic, morphological and chemical) distinguish them and how distinct they are. It is also of high importance to deepen our understanding of the agricultural system and the aspects that may affect its sustainability. An integrated approach was applied for the evaluation of social characteristics of farmers, the growing system, morphological traits, and selected chemical components. Between landraces, flower and fruit morphology was clearly distinct. Total phenolic content, antioxidant capacity and total carotenoid content showed higher values in fruits of cacho de cabra than in chileno negro. Both landraces had a higher total phenolic content than other Capsicum cultivars in the world. Farmers ascribe distinct attributes for the landraces regarding agronomic performance, fruit quality and processing applications. Characteristics that may affect the sustainability of the agricultural system are small farm size, relatives working as employees, and low farmers’ educational attainment. The study landraces are distinct and represent unique genetic material produced in an agricultural system facing important challenges where farmers have adapted to socio-economic pressures, externalizing plant production, reducing harvest costs, and developing innovations in product and marketing.

Characterization of newly developed pepper cultivars (Capsicum chinense) 'Dieta0011-0301', 'Dieta0011-0602', 'Dieta0041-0401', and 'Dieta0041-0601' containing high capsinoid concentrations and a strong fruity aroma.

p-AMT: putative aminotransferase; C. annuum: Capsicum annuum; C. chinense: Capsicum chinense; dCAPS: derived Cleaved Amplified Polymorphic Sequences.

Improved Resistance to Root-knot Nematode Species in an Advanced Inbred Line of Specialty Pepper (Capsicum annuum)

Bell and chili peppers are important vegetable and spice commodities worldwide. Significant yield reductions have been attributed to damage caused by root-knot nematodes (RKNs; Meloidogyne spp.). This study addresses the need for developing pepper varieties that have high resistance to RKN, which is now of increasing importance due to restrictions on the use of fumigant nematicides. Our goal is to provide a nonchemical alternative to sustain commercial pepper production in Florida, which is a major producer of peppers in the United States. We evaluated ‘UFRJ107(6)A3’, an advanced inbred line developed from a cross between Capsicum annuum L. ‘Jalapeno’ and ‘Round of Hungary’, for resistance against the nematode in comparison with the parental and three other Capsicum cultivars, namely, C. annuum ‘Charleston Belle’, ‘California Wonder’, and C. chinense Jacq. ‘Datil’ in two separate growth chamber experiments. Based on egg mass indices and reproduction factors, ‘UFRJ107(6)A3’ was significantly more resistant to M. incognita compared with the other five cultivars. When tested with five RKN species, ‘UFRJ107(6)A3’ showed comparably high levels of resistance to M. arenaria and M. floridensis as ‘California Wonder’ based on the nematode reproduction factor. In ‘UFRJ107(6)A3’, however, there were no detectable M. arenaria egg masses, and M. incognita reproduction was minimal compared with that of ‘California Wonder’; both cultivars supported the reproduction of M. enterolobii and M. javanica, although the reproduction factors of M. enterolobii were ≈10-fold higher than M. javanica. To characterize the mechanism of high resistance to M. incognita in ‘UFRJ107(6)A3’, we examined the extent to which infective second-stage juveniles (J2s) were able to penetrate its roots in comparison with the susceptible ‘California Wonder’ and ‘Datil’ in two independent experiments; we conducted RKN root penetration assays with a single plant in a pot and two plants in a single-pot choice test using ‘Datil’ and ‘California Wonder’, respectively, as susceptible standards. In both assays, M. incognita J2s were absent in the roots of ‘UFRJ107(6)A3’ 7 days after inoculation but were present in the susceptible cultivars, indicating that resistance has an effect at the root invasion stage. In growth chamber experiments, at constant temperatures of 28 and 30 °C, ‘UFRJ107(6)A3’ exhibited M. incognita resistance superior to its parents and to the standard resistant bell pepper ‘Charleston Belle’, thus offering the potential to enhance specialty pepper production and for use as a nematode-resistant rootstock for commercial bell peppers.

Value of Seed Protein Profile in the Taxonomy of cultivars of Capsicum in Nigeria

Over a decade, the taxonomy of the genus Capsicum in Nigeria has remained largely unrevised, unclassified and unidentified. As such, there is a dearth of information on the proper identification of Capsicum spp and relatives found in the country. The aim of this study was to re-examine the taxonomic status of the Capsicum in Nigeria in order to establish genetic diversity between them for proper identification and classification. Sodium dodecyl polyacrylamide gel electrophoresis of total seed protein was performed on five varieties of Nigerian Capsicum spp., following standard procedures. Six protein bands were observed across the five cultivars of Capsicum, of which 12-14 Kda was the only polymorphic band. Only C. fructescens var. ijosi and C. fructescens var. sombo were unique for manifesting 20-24 and 15-16 Kda bands respectively. Dendrogram of analysis obtained resolved the taxa into two distinct groups. In the first group were cultivars of C. fructescens var. ijosi and sombo while in the second group were C. chinense, which was distinctly separated from C. fructescens var. bawa and C. annum. Artificial dichotomous key was constructed for the identification of members of the genus Capsicum available in Nigeria based on the protein profiles of their seeds.
 Keywords: Capsicum, seed protein, electrophoresis, identification, diversity.

Improved QuEChERS for Analysis of Polybrominated Diphenyl Ethers and Novel Brominated Flame Retardants in Capsicum Cultivars Using Gas Chromatography

One of the main challenges for analytical laboratories and food safety authorities is the control of food contaminants hazardous to human health. For the first time, a simple, fast, and cost-effective sample preparation method is proposed as an extraction technique to determine 12 brominated flame retardants (BFRs) (seven polybrominated diphenyl ether (PBDE) congeners and five novel BFRs) in Capsicum cultivars. Different QuEChERS and dispersive solid-phase extract (d-SPE) sorbent compositions were evaluated in terms of recovery and matrix effects. The best results were obtained with citrate-buffered version QuEChERS and a cleanup step, with 150 mg of MgSO4, 50 mg of primary secondary amine (PSA), 50 mg of C18, and 5 mg of carbon. The limit of detection (LOD) was between 1.4 and 9.3 μg/kg and R2 > 0.99. Recoveries and matrix effects were between 66 and 104% and 0.58 and 2.18, respectively. The relative standard deviations from repeatability and reproducibility studies and estimation of measurement uncertainty were lower than 20%. Gas chromatography coupled with a mass spectrometer was used to confirm the presence of BFRs in the samples. Novel BFRs were detected lower than the LOD.

Androgenic studies in the production of haploids and doubled haploids in Capsicum spp.

Capsicum spp. is a horticultural crop of agronomic interest and is considered the fourth most important vegetable in the world. It is an important nutritional and medicinal source, and its production generates employment in the tropics. In this species, the genetic variability is wide and with great potential, which has been exploited to generate outstanding varieties. Breeding programs seek different alternatives to accelerate the production of improved varieties with desirable agronomic characteristics. These objectives can be achieved with the production of haploid and double haploid plants via androgenesis or gynogenesis, being androgenesis the approach most used for paprika cultures. The purpose of this review is to present the results of different researches in obtaining haploids and doubled haploids in cultivars of Capsicum spp. and its impact on the genetic improvement of this crop.

Microsatellites for detecting inconsistencies in Capsicum cultivars registration in Brazilian database: more than meets the eye

ABSTRACT In Brazil, cultivars are registered by National Register of Cultivars (RNC), which besides enabling commercialization of cultivar propagative material, also guarantees the producers genetic purity and identity of propagules. However, it is possible that the information about registration and commercialization of some cultivars is inaccurate. This study aims to analyze the use of microsatellite markers to detect inconsistencies in data of Capsicum spp. cultivars obtained from the official database (CultivarWeb). Seven cultivars were evaluated, three of them were through genetic identity analysis (Amarela Comprida, De Cayenne and Cayenne Long Slin) and the others were used as standard for the species C. annuum, C. frutescens and C. chinense. Thirty-three microsatellite loci were polymorphic and presented 76 alleles (an average of 2.3 alleles/locus). Fixation Index (F) showed high homozygosis and estimators of genetic diversity (Ho and I) presented low genetic diversity among cultivars. The molecular analysis, represented in a dendrogram and in Principal Coordinate Analysis Chart (PCOA), showed that the investigated cultivars belong to C. annuum, contrary to what is registered in CultivarWeb, which indicates that such cultivars belong to the species C. frutescens. Thus, the authors recommend that the data in the CultivarWeb should be checked and enhanced.

Genetic divergence between pepper accessions based on quantitative fruit traits

The development of new Capsicum cultivars aiming to meet market requirements will depend, above all, on the genetic diversity of the study population. To quantify this genetic divergence, several multivariate techniques assessing quantitative traits have been employed. This study aimed to: i. estimate the genetic diversity among Capsicum chinense accessions from the Active Germplasm Bank of Plants of the Federal University of Vicosa (BGH-UFV); ii. indicate promising accessions for prospective studies of specific market niches; iii. evaluate the disposal of redundant traits. The experiment was conducted in a completely randomized design with four repli­cates, in which 11 C. chinense accessions were evaluated, based on 11 quantitative fruit traits. The data were subjected to cluster analysis by the UPGMA and Tocher methods, based on the quadratic Euclidean distance, to assess diversity. Afterwards, we used principal component analysis, Jolliffe’s method and procrustes analysis for the disposal of traits. The highest genetic dissimilarity was obtained between accessions 2 and 10. The pheno­typic correlation coefficients obtained were 0.75 (UPGMA) and 0.91 (Tocher), the latter being significant by the Mantel test (p < 0.05). Six clusters were formed by using the Tocher method, four of which were composed by a single accession. Regarding the disposal of variables, traits TFDW, TFFW, PUN, %DM, FW, PT, and FL were shown to be disposable, and do not affect diversity prediction in terms of graphic dispersion. Accessions 9, 10, and 11 are indicated for in natura consumption, while accessions 2 and 3 are indicated for industrial purposes. These accessions showed the best results among the evaluated traits for the mentioned niches.

Nitrogen differentially modulates photosynthesis, carbon allocation and yield related traits in two contrasting Capsicum chinense cultivars

Yield-related traits of Capsicum chinense are highly dependent on coordination between vegetative and reproductive growth, since the formation of reproductive tissues occurs iteratively in new sympodial bifurcations. In this study, we used two C. chinense cultivars (Biquinho and Habanero), contrasting for fruit size and fruit set, to investigate the responses of nitrogen (N) deficiency and excess on growth, photosynthesis, carbon (C) and N metabolisms as well as yield-related traits. Both cultivars increased biomass allocation to leaves in conditions of higher N supply and exhibited a parabolic behavior for fruit biomass allocation. Plants growing under N-deficiency produced a lower number of flowers and heavier fruits. Contrarily, plants under high N condition tended to decrease their CO2 assimilation rate, harvest index and fruit weight. Biquinho, the cultivar with lower fruit size and higher fruit set, was initially less affected by excess of N due to its continuous formation of new reproductive sinks in relation to Habanero (which has lower fruit set and higher fruit size). The results suggest that N amount influences sucrose supply to different organs and can differentially affect yield-related traits between Capsicum cultivars with contrasting source-sink relations.

Current perspectives on pollen cryopreservation in horticultural species

Cryopreserved pollen collections provide long-term security for wildflora, ornamentals, fruit and vegetable crops, medicinal herbs and endangered species. Technology has been developed for long-term cryopreservation of pollen in the form of nuclear genetic diversity (NGD) of mango, amla, pomegranate, jackfruit, guava, passion fruit, jamun, different species and cultivars of citrus, papaya (different species), grape, tomato, eggplant (Solanum gene pool), onion, capsicum, rose, gladiolus, gerbera, carnation and RET species of medicinal plants. Pollen collecting is usually done on a bright sunny day between 10-11 am. Pollen collections are subjected to viability indexing by germination in vitro by the hanging drop or cellophane techniques. Pollen samples are packed either in gelatin capsules or butter paper packets, sealed air tight in polyethylene aluminium laminated pouches and lowered into a canister of a cryoflask. The fertility of stored pollen is tested under field conditions through controlled pollination. The pollen cryobank is managed by periodic replenishment of the cryogen. With the recent advances in allied bio-scientific areas in which cryopreserved pollen could be used in general crosses, shuttle breeding maintenance of B line in male sterile based hybrid seed production. Security of male parent is also ensured in the cryobank. Pollen cryopreservation protocols developed for different horticultural species will be discussed in details.

English

In this study, the capsaicin content of chile pepper extracts from 29 unexplored varieties of Capsicum (twenty five varieties of Capsicum chinense and five of Capsicum annuum) was quantified and correlated with the antimicrobial potential against bacterial and fungal pathogens. The capsaicin content and bactericidal activity against numerous human pathogens (Salmonella, Escherichia coli O157:H7, Listeria monocytogenes, Staphylococcus aureus, Candida albicans) was compared to identify the most effective chile pepper varieties in the treatment of bacterial and fungal pathogens. The capsaicin content of the tested varieties varied from 29 to 42,633 ppm (139 - 682,135 SHU). On average, the fruits of C. chinense cultivars contained much higher concentrations of capsaicin than C. annuum cultivars. The undiluted chile peppers extracts with capsaicin concentrations greater than 25,000 SHU demonstrated bactericidal and antifungal effects. Overall, it was determined that L. monocytogenes and S. aureus were more susceptible to the antimicrobial effects of capsaicin than Salmonella and E. coli O157:H7, while C. albicans was markedly more susceptible than all bacterial species examined. The extract of the sixth most pungent cultivar, C. chinense Bhut Jolokia Red, showed the greatest antimicrobial potency of all screened peppers. The antimicrobial activity of pepper extracts was not directly correlated with increasing capsaicin concentrations, indicating that various Capsicum cultivars may possess distinct capsaicin derivatives. This is the first study which showed the relationship between capsaicin contents in different Capsicum varieties and their antimicrobial potential, and opens avenues in the study of capsaicin derivatives and their role in health and medicines. Key words: Capsicum, pathogen, capsaicin, peppers, antimicrobial, bactericidal.

Effect of pruning systems on growth and yield traits of greenhouse grown bell pepper (Capsicum annuum L. var. grossum)

The present investigation was carried out during 2016-2017 with the objective of observing the effect of the tested systems of pruning on vegetative, fruiting, yield and quality traits of capsicum varieties. The experiment was laid out in a factorial randomized block design with four replications and nine treatments with Indra, Bachata and Inspiration cultivars of capsicum pruned with three intensities i.e. two shoots, four shoots and un-pruned (control). The results showed that the two stem pruning treatment significantly affected the plant growth and flowering characteristics in terms of plant height (194.75cm), number of days to first flower (20.25 days) in cv. Indra. Same cultivar when left un-pruned recorded more number of fruits per plant (23.64 fruits), but fruit yield per plant (4.14kg) was observed in four stem pruning treatment in Indra cultivar of capsicum than other cultivars tried.

Suitable cultivars of broccoli, red cabbage, capsicum and french bean for alluvial tracts of West Bengal

An experiment was conducted to find out the best suitable varieties of Broccoli, Red Cabbage, Capsicum and French Bean for the district South 24 Parganas in the Instructional Farm of Sasya Shyamala Krishi Vigyan Kendra, Ramakrishna Mission Vivekananda University, Arapanch and different blocks of the district during rabi season from 2014 to 2016. The experiment was carried out in randomized block design (RBD) with different varieties taken as different treatments replicated seven times. Genotypes taken under observation were Fiesta, Princess, Sultan, Centauro, Priya and Packmen for Brocolli whereas the varieties considered for Red Cabbage were Ruby Mart, Red Queen, Primero and Red Cabbage. Four varieties of Capsicum viz. Chinese Giant, Green Gold, California Wonder and Sindhoori were tested. The study was also carried out with four varieties of French bean (Contender, Pusa Himlata, Pusa Parvati and Falguni). Among all the varieties of Broccoli, California Wonder was found superior which gave highest yield in combination with best head formation. In case of Red cabbage, variety Red Queen showed the overall best performances. California Wonder of Capsicum and Falguni variety of French bean were found to be the best suitable varieties as compared to others. So, these varieties were found to be best for sustainable livelihood promotion with high productivity under wide range of environmental condition for this zone.

An improved micropropagation protocol for the recalcitrant plant Capsicum – a study with ten cultivars of Capsicum spp. (C. annuum, C. chinense, and C. frutescens) collected from diverse geographical regions of India and Mexico

ABSTRACTCapsicum spp. is a commercially important crop of the Solanaceae family, well-known for its multipurpose use as a vegetable, spice, medicinal and ornamental plants. The genus Capsicum is a recalcitrant species in terms of in vitro morphogenesis and plant regeneration. An efficient method was developed for multiple shoot regeneration in 10 cultivars of Capsicum collected from diverse geographical regions of India and Mexico. Seeds germinated in vitro on a half-strength Murashige and Skoog (MS) medium supplemented with 3.0 % sucrose. Nodes of the in vitro germinated seedlings were used as explant for micropropagation. The combination of the 6-benzylaminopurine, indole-3-acetic acid, and spermidine was found to be the best for multiple shoot induction. However, the optimum responcse varied accompanied by different cultivers with maximum 8.9 ± 0.52 (Capsi-10) to 15.3 ± 0.69 (Capsi-5) multiple shoot per explant. Depending on the cultivar, multiplied shoots were successfully rooted with maximum 18.4 ± 0.20 (highest for Capsi-9) to 36.8 ± 0.29 (highest for Capsi-5) roots per shoot on half-strength MS medium supplemented with 2.0 mg l−1 indole-3-butyric acid, 1.0 mg l−1 α-naphthalene acetic acid, and 1.5 mM spermidine. Finally, the micropropagated plantlets were acclimatized with 40.0–86.7 % survival rate, depending on different cultivars.

Effect of postharvest handling procedures on cut Capsicum stems

‘Rio Light Orange’ and ‘Cappa Round Red’ ornamental peppers (Capsicum annuum L.) are attractive cultivars used as cut stems, but postharvest handling protocols need to be optimized. ‘Rio Light Orange’ stems harvested when most of the fruits were pale orange had the longest vase life, while harvest stage had no effect on vase life of ‘Cappa Round Red’. Stems of both cultivars showed less incidence of wilted foliage during postharvest when stored in water. Cold storage was tolerated for up to 1 week for ‘Rio Light Orange’ and for up to 2 weeks for ‘Cappa Round Red’ for stems kept in water. These cultivars do not appear to be sensitive to ethylene and anti-ethylene agents had a minimal effect on postharvest characteristics of cut stems. Of nine Capsicum cultivars tested, the use of a holding solution had a positive effect on the vase life of ‘Black Pearl’, ‘Rooster’ and ‘Stromboli’ ornamental peppers and increased the number of days foliage remained acceptable for eight of the cultivars. However, use of a commercial hydrator either reduced (one cultivars) or had no effect (eight cultivars) on vase life. Vase life and quality of ‘Rio Light Orange’ and ‘Cappa Round Red’ ornamental peppers stems can be extended by following appropriate postharvest handling procedures and the use of a holding solution can have a beneficial effect on vase life and foliage quality of many additional cultivars of peppers tested in this study.

Characterization of some Indian Himalayan Capsicums through floral morphology and EMA-based chromosome analysis

The North Eastern Himalayan (NEH) regions of India are considered as one of the major repositories of the "Capsicum annuum complex" which comprises of three cultivated species namely C. annuum, C. frutescens, and C. chinense. The interspecific delimitation within this large complex is ill-defined due to poorly developed crossing barriers and lack of discontinuous morphological characters. The present study elucidates the relationship among nine different cultivars of three Capsicum species on the basis of floral morphology and karyological parameters for the first time. Different floral characteristics such as margins and constrictions of calyx, type of pedicel, flower size, and color were found to have paramount importance in the species delimitation within the studied members of "C. annuum complex." The present karyomorphometric study explicitly revealed differences between the observed chromosomal data such as karyotype formulae, ordering of satellite bearing chromosome pairs and total diploid chromatin length which aid in resolving interspecific relationship among the studied cultivars of Capsicum. The present analyses unambiguously distinguished all cultivars of C. annuum from the members of C. frutescens and C. chinense and also proposed that among the five cultivars of C. annuum, Ghee lanka was comparatively distant from the other four cultivars on the basis of their karyomorphological characteristics. For the first time karyotype of hottest Indian chili is included in this paper. Comprehensive knowledge on floral morphology and karyotypes of some Himalayan Capsicums not only help to conserve genetic diversity but also help capsicum breeders for their basic and applied research.

High-frequency in vitro flowering, hand-pollination and fruit setting in ten different cultivars of Capsicum spp. (C. annuum, C. chinense, and C. frutescens): an initial step towards in vitro hybrid production

We developed an efficient method for inducing high-frequency in vitro flowering and fruiting in 10 cultivars (Cap-1 to -10) of three different species of Capsicum (C. annuum, C. chinense, and C. frutescens) collected from diverse geographical regions of India and Mexico. Shoot tips of in vitro germinated seedlings were cultured on MS media supplemented with different concentrations of 6-benzylaminopurine (BAP) alone or in combination with silver nitrate or silver thiosulphate. Low BAP concentration was a good inducer of flower buds in vitro. Synergism between silver ions and cytokinin improved flower induction. Flowering frequency improved significantly when silver nitrate or silver thiosulphate was supplemented with optimum BAP. Maximum responses, 7.5 ± 0.20 (in Cap-1) to 15.8 ± 0.27 (in Cap-5) flowers, were induced in the medium containing 0.75 mg l−1 BAP and 30 μM silver thiosulphate within 60 days of culture. Both in vitro hand-pollination and high sucrose concentration (5.0–6.0 %) in the medium improved fruit setting. In general, fruits were very small (mini-fruit) and seedless; however, three cultivars (Cap-3, -5, and -6) produced normal fruits with seeds. On an average, 144 days were required from seed implantation to fruit ripening. The frequency of meiotic abnormalities was higher in flowers produced in vitro than in those produced in vivo, and pollen viability was relatively lower in the in vitro flowers than in the in vivo flowers. The present protocol offers a repeatable system for studying the physiological mechanism of flowering and fruiting as well as providing the basis for further investigation for rapid in vitro cross-breeding programmes in Capsicum spp. for commercial hybrid production.

Transcriptome Analysis of Capsicum Chlorosis Virus-Induced Hypersensitive Resistance Response in Bell Capsicum.

BackgroundCapsicum chlorosis virus (CaCV) is an emerging pathogen of capsicum, tomato and peanut crops in Australia and South-East Asia. Commercial capsicum cultivars with CaCV resistance are not yet available, but CaCV resistance identified in Capsicum chinense is being introgressed into commercial Bell capsicum. However, our knowledge of the molecular mechanisms leading to the resistance response to CaCV infection is limited. Therefore, transcriptome and expression profiling data provide an important resource to better understand CaCV resistance mechanisms.Methodology/Principal FindingsWe assembled capsicum transcriptomes and analysed gene expression using Illumina HiSeq platform combined with a tag-based digital gene expression system. Total RNA extracted from CaCV/mock inoculated CaCV resistant (R) and susceptible (S) capsicum at the time point when R line showed a strong hypersensitive response to CaCV infection was used in transcriptome assembly. Gene expression profiles of R and S capsicum in CaCV- and buffer-inoculated conditions were compared. None of the genes were differentially expressed (DE) between R and S cultivars when mock-inoculated, while 2484 genes were DE when inoculated with CaCV. Functional classification revealed that the most highly up-regulated DE genes in R capsicum included pathogenesis-related genes, cell death-associated genes, genes associated with hormone-mediated signalling pathways and genes encoding enzymes involved in synthesis of defense-related secondary metabolites. We selected 15 genes to confirm DE expression levels by real-time quantitative PCR.Conclusion/SignificanceDE transcript profiling data provided comprehensive gene expression information to gain an understanding of the underlying CaCV resistance mechanisms. Further, we identified candidate CaCV resistance genes in the CaCV-resistant C. annuum x C. chinense breeding line. This knowledge will be useful in future for fine mapping of the CaCV resistance locus and potential genetic engineering of resistance into CaCV-susceptible crops.