Pepper F1 Hybrids Research Articles

Morphological characterization of floral traits to predict ideal stage for haploid production in bell pepper

Double haploid (DH) breeding not only helps in shortening the breeding cycle, also in fastening the release of homozygous inbred lines with superior and desirable traits. In vitro microspore culture is the fastest approach for the production of haploid plantlets. The key parameter for success of the haploid production in any crop species is the stage of microspore or pollens at the time of culture as it decides the fate of cultured anthers/pollens. Therefore an easy, precise, fast, and reliable criterion to identify flower buds carrying microspores or pollen at particular stages are essential. In the present investigation, we developed easiest and accurate criterion to correlate visible, measurable traits of bud and anther development with individual stages of microsporogenesis in two sweet pepper F1 hybrids (Orobelle and Bomby). Anthers containing microspores at late uninucleate to early binucleate stage are optimal for induction of androgenesis in wide range of crop species. Anther containing uninucleate pollens were observed in flower buds with an average size of 5.39 mm in Orobelle and 4.8mm in Bomby, average anther length of 2.75 mm in Orobelle and 2.71mm in Bomby and corolla was slightly longer than that of the calyx in both the hybrids. Anthers were without any purple pigmentation in Orobelle and slight/no pigmentation at the top of the anther sac end in Bomby.

Development of the HybProb molecular marker for the L4 allele for marker-assisted selection of sweet pepper Capsicum spp. on the real-time PCR platform

Relevance. One of the conditions for creating a modern high-tech hybrid of sweet pepper is the presence of resistance to the Pepper mild mottle virus (PMMoV). This virus belongs to the genus Tobamovirus. This virus can spread through seeds, causing enormous damage to the sweet pepper crop. The main method of controlling of virus is the cultivation of F1 hybrids of pepper with genetic resistance. To date, the L4 gene is able to confer resistance to all known strains of this virus. However, there is still no reliable marker system that could be integrated into the MAS. Methods. Based on data from the NCBI, we generated a molecular diagnostic system based on hybridization probes. Validation was performed on seven pepper accessions from the world's germplasm banks. After validation, the new marker was successfully tested on 2540 plants of F2 and F3 generation. Results. Using the experimental marker system Fret4, we tested 7 reference samples of pepper germplasm with full correspondence of the melt peaks to the declared alleles of the L gene (L0/L1/L3/L4). Then, using a marker system, MAS was carried out on 10 populations of an number of 10 thousand plants to identify the L4 allele. As a result, we were able to create a highly accurate and cost-effective marker system for the most important pepper resistance gene. This marker system based on hybridization probes is easily integrated into the MAS, allowing fast and reliable determination of the L4 allele state in sweet pepper breeding to Tobamovirus.

Selection of Habanero Pepper F1 Hybrids (Capsicum chinense Jacq.) at the Yucatan Peninsula, Mexico with a High Potential for Different Markets

This study evaluated 29 F1 lines and the 11 genotypes of habanero peppers used in the crossbreeding program developed by the Scientific Research Center of Yucatan, México. A randomized complete block design with four repetitions was used. Eight plants of each of the genotypes were studied per block. A total of 22 qualitative and 18 quantitative descriptors established in the manuals of the International Plant Genetic Resources Institute (IPGRI) and the National Service for Seed Inspection and Certification (SNICS) was used. The multiple correspondence analysis of the qualitative traits explained 38.2% of the total variability. The trait that contributed the most to the qualitative variability identified was the presence of anthocyanins in the node. Principal component analysis showed that the first two axes explained 85.1% of the total variability and that capsaicin content and fruit pericarp thickness were the major contributors to the variation recorded. Based on these results, four F1 hybrids of habanero pepper were selected because of their promising traits for the different markets, i.e., high productive potential and/or high pungency. These traits are described in the section on Results.

Morphological markers to correlate bud and anther development with microsporogenesis and microgametogenesis in pepper (Capsicum annuum L.)

The identification of microspores or pollen grains at particular developmental stages during microsporogenesis or microgamentogenesis is an important step for different basic and applied purposes. Among them, the most relevant example from a biotechnological perspective is the production of androgenic doubled haploids. For this and other techniques, precise, fast, easy and reliable criteria to identify flower buds carrying microspores or pollen at particular stages are essential. In anthocyanin-producing pepper types, the particularities of flower development allow for the identification of several morphological markers potentially useful as criteria for such an identification. In this work, our aim was to determine the easiest and more accurate criterion to correlate visible, measurable traits of bud and anther development with each of the individual stages of microsporogenesis and microgametogenesis. For this, we used three Spanish sweet pepper F1 hybrids (‘Herminio’, ‘Gacela’ and ‘Águila’). We analyzed and discussed the accuracy and practical usefulness of using anther length, bud length, anther purple pigmentation and the ratio between calyx length and bud length (calyx/bud ratio) as predictors of individual microspore/pollen developmental stages. According to our results, we propose a combination of calyx/bud ratio and anther pigmentation as an easy, fast and accurate criterion potentially applicable to anthocyanin-producing pepper cultivars to determine their particular markers.

Molecular genetic analysis of off-type plants identified from normal F1 hybrid cultivars of sweet pepper (Capsicum annuum L.)

SummaryOff-type plants occasionally appear when growing F1 hybrid cultivars of sweet pepper (Capsicum annuum L.). In this study, possible genetic factors responsible for the appearance of off-types were evaluated using two off-type sweet peppers selected out of 120 F1 hybrids. The general morphology of off-type plants showed a stunted stature, narrow leaf shape, and small round-shaped fruits. We hypothesised that these off-type plants might have arisen by inadvertent self-pollination of maternal parental lines, since most sweet pepper F1 hybrids are known to be produced by hand-emasculation. Indeed, none of the sweet pepper cultivars analysed in this study contained male-sterile cytoplasm, confirming that cytoplasmic male-sterility was not used during F1 hybrid seed production. If the off-type plants were derived from self-pollination of maternal lines, the genetic make-up of the off-type plants should be different from that of normal F1 hybrids. However, the RAPD and SSR marker amplification profiles of off-type and normal F1 hybrids showed no polymorphism, whereas one RAPD and five polymorphic SSR markers were identified among five other F1 sweet pepper cultivars, indicating that the genetic make-up of the off-type and normal F1 hybrids were almost identical. Furthermore, two SSR markers that showed heterozygosity in both off-type and normal F1 hybrids, segregated in the self-pollinated progenies of both off-type and normal F1 hybrids, indicating that the off-type plants were not maternal inbred lines. Taken together, these results suggest that the off-type F1 sweet pepper plants could have arisen due to other environmental factors or by infection with an unknown pathogen.

The importance of earliness for creating new ms F1 pepper hybrids

Breeding new line pepper genotypes is an important goal for the Institute for Vegetable Crops, Smederevska Palanka. Years of selection resulted in great number of varieties, however, the selection of F1 pepper hybrids started recently. Pepper F1 hybrids have proved to be better than cultivars in the terms of earliness, yield, plant uniformity, pathogen resistance etc. Considering significant heterosis values for earliness, this paper deals with the genetic analysis of F1 and F2 pepper hybrids, obtained by crossing four lines, including ms line HM-6.

Haplotype analysis of CMS-associated DNA markers in sweet peppers

Cytoplasmic male sterility (CMS)/restorer-of-fertility (Rf) is an economical and efficient system to produce F1 hybrid seeds. Although the CMS/Rf system has been used to produce hybrid seeds of hot peppers, this system has never been used for sweet pepper seed production, presumably due to the inability to select stable restorer lines during the breeding process. To test the feasibility of the CMS/Rf system in sweet pepper breeding, we investigated the distribution of haplotypes of previously developed, CMS-associated markers (orf456, ψ atp6-2, CRF-SCAR, OPP13-CAPS, PR-CAPS, and PR-SNP) in 27 commercial sweet pepper F1 hybrids and 12 breeding lines. When CMS-associated cytoplasmic markers orf456 and ψ atp6-2 were applied, male sterile cytoplasm was not detected in commercial sweet pepper cultivars. When nuclear haplotype markers linked to Rf were applied, all sweet pepper cultivars showed haplotype 3, haplotype 1, and the rf genotype for OPP13-CAPS, PR-CAPS, and CRF-SCAR, respectively. In contrast, we were able to detect male sterile cytoplasm in some breeding lines, and we were also able to detect polymorphisms for PR-CAPS between stable and unstable maintainer lines. The 17T7-SNP also showed polymorphisms between unstable and stable maintainer (or restorer) lines. In conclusion, we expect that it will be possible to develop stable A, B, and C sweet pepper lines using CMS-associated markers and that this will eventually lead to successful implementation of the CMS/Rf system to produce F1 hybrid sweet pepper seeds.

Parent grouping of 31 elite inbred lines in hot pepper (<I>Capsicum annuum </I>L.)

Genetic differences were examined among thirty-one elite inbred lines in Capsicum annuum L. Two types of analytic technologies, i.e. SRAP markers and genotypes of traits, were used, and their relative effectiveness was compared. 27 of 30 primer combinations could amplify 310 polymorphic bands among inbred lines, indicating SRAP marker was efficient to detect polymorphism among pepper inbred lines. A dendrogram of 31 inbred lines based on SRAP markers and Yule coefficients could basically separate lines of C. annuum var. grossum and C. annuum var. longum, and reveal the pedigrees of inbred lines. A dendrogram of 31 inbred lines based on genotypes of traits and standardized Euclidean coefficients could separate lines of C. annuum var. grossum and C. annuum var. longum. The SRAP marker genetic distances were correlated with distances based on the genotypes of traits. These results and their application in the development of hot pepper F1 hy-brids were also discussed.

Comparative performance of F1 hybrids and open-pollinated ‘Bell’ pepper varieties (Capsicum annuum L.) under suboptimal temperature regimes

Two ‘Bell’ pepper F1 hybrids demonstrated a significant advantage over open-pollinated varieties under growing conditions of suboptimal temperatures. Both hybrids gave significantly higher marketable yields than most of the varieties compared with them.