Search

Germplasm banks are essential as sources of genetic variability for plant breeding programs. To characterize a Brazilian Capsicum frutescens collection, 21 malagueta and 5 Tabasco hot pepper accessions were evaluated under field and greenhouse conditions regarding morphological and molecular traits, as well as resistance to viruses. Morphological characterization was performed using 53 IPGRI (International Plant Genetic Resources Institute) descriptors, 15 vegetative, 13 inflorescence, 22 fruit, and 3 seed. Molecular characterization was carried out with 60 polymorphic markers from 29 RAPD primers. The incidence of major viruses infecting Capsicum spp, Tomato spotted wilt virus (TSWV), Groundnut ringspot virus (GRSV), Potato virus Y (PVY), Pepper yellow mosaic virus (PepYMV), Pepper mild mottle virus (PMMoV), and Cucumber mosaic virus (CMV) was evaluated by ELISA. Based on the average genetic distance among genotypes, six groups were defined for the 53 IPGRI descriptors. When considering only 11 quantitative traits (five vegetative and six fruit), six groups were also determined, and the traits plant canopy width (56.05%) and days to fruiting (25.07%) most explained the genetic diversity among genotypes. Molecular analysis defined five groups of accessions with partial correspondence to the morphological characterization data. The incidence of viruses in field-grown plants varied among genotypes and according to virus species, from 5.6% (GRSV; CNPH 3286) to 100% (PMMoV; CNPH2871), and indicated some accessions as potential sources of virus resistance. These results demonstrate the genetic variability within the group of 26 hot pepper accessions, as well as virus-resistant genotypes that can be used in breeding programs.

Characterization studies provide essential information for the conservation and use of germplasm in plant breeding programs. In this study, 103 Capsicum frutescens L. accessions from the Active Germplasm Bank of Embrapa Hortaliças, representative of all five Brazilian geographic regions, were characterized based on morphological characteristics and microsatellite (or simple sequence repeat - SSR) molecular markers. Morphological characterization was carried out using 57 descriptors, and molecular characterization was based on 239 alleles from 24 microsatellite loci. From the estimates of genetic distances among accessions, based on molecular characterization, a cluster analysis was carried out, and a dendrogram was established. Correlations between morphological and molecular variables were also estimated. Twelve morphological descriptors were monomorphic for the set of C. frutescens accessions, and those with the highest degree of polymorphism were stem length (14.0 to 62.0 cm), stem diameter (1.0 to 4.2 cm), days to flowering (90 to 129), days to fruiting (100 to 140), fruit weight (0.1 to 1.4 g), fruit length (0.6 to 4.6 cm), and fruit wall thickness (0.25 to 1.5 mm). The polymorphism information content for the SSR loci varied from 0.36 (EPMS 417) to 0.75 (CA49), with an overall mean of 0.57. The correlation value between morphological and molecular characterization data was 0.6604, which was statistically significant. Fourteen accessions were described as belonging to the morphological type tabasco, 85 were described as malagueta, and four were malaguetinha, a morphological type confirmed in this study. The typical morphological pattern of malagueta was described. Six similarity groups were established for C. frutescens based on the dendrogram and are discussed individually. The genetic variability analyzed in the study highlights the importance of characterizing genetic resources available for the development of new C. frutescens cultivars with the potential for various niche markets.

In order to support further genetic, diversity, and phylogeny studies of Capsicum species, the transferability of a Capsicum annuum L. simple sequence repeat (SSR) microsatellite set was analyzed for C. frutescens L. ("malagueta" and "tabasco" peppers) and C. chinense Jacq. (smell peppers, among other types). A total of 185 SSR primers were evaluated in 12 accessions from 115 C. frutescens L. and 480 C. chinense Jacq, representing different types within each species. Transferability to C. frutescens L. and C. chinense Jacq. occurred for 116 primers (62.7%). Nineteen (16.37%) were polymorphic in C. frutescens L. and 36 (31.03%) in C. chinense Jacq., 17 of which were coincident and could be used to analyze samples obtained for the 2 species. Among these primers, CA49 showed a different amplitude range of alleles between the 2 species (130-132 base pairs for C. frutescens L. and 120-128 base pairs for C. chinense Jacq.), and could differentiate the species. A total of 55 alleles were identified among the 19 polymorphic SSR loci among accessions of C. frutescens L., with the number of alleles per locus ranging from 2 to 5, a mean of 2.89, and the polymorphic information content ranging from 0.30 to 0.65. The number of alleles identified in C. chinense Jacq. was 119, ranging from 2 to 5 alleles per locus, an average of 3.30, and polymorphic information content from 0.19 to 0.68. The C. annuum L. SSR primers were most often transfer-able and polymorphic for C. frutescens L. and C. chinense Jacq., and we present a set of SSR for each species.

Doubled haploid technology has been used by various private companies. However, information regarding chromosome duplication methodologies, particularly those concerning techniques used to identify duplication in cells, is limited. Thus, we analyzed and characterized artificially doubled haploids using microsatellites molecular markers, pollen viability, and flow cytometry techniques. Evaluated material was obtained using two different chromosome duplication protocols in maize seeds considered haploids, resulting from the cross between the haploid inducer line KEMS and 4 hybrids (GNS 3225, GNS 3032, GNS 3264, and DKB 393). Fourteen days after duplication, plant samples were collected and assessed by flow cytometry. Further, the plants were transplanted to a field, and samples were collected for DNA analyses using microsatellite markers. The tassels were collected during anthesis for pollen viability analyses. Haploid, diploid, and mixoploid individuals were detected using flow cytometry, demonstrating that this technique was efficient for identifying doubled haploids. The microsatellites markers were also efficient for confirming the ploidies preselected by flow cytometry and for identifying homozygous individuals. Pollen viability showed a significant difference between the evaluated ploidies when the Alexander and propionic-carmin stains were used. The viability rates between the plodies analyzed show potential for fertilization.

The aim of this study was to characterize maize lines tolerant to cold temperatures during the germination process. Seeds from lines with different levels of tolerance to low temperatures were used; 3 lines were classified as tolerant and 3 as susceptible to low germination temperatures. A field was set up to multiply seeds from selected lines. After the seeds were harvested and classified, we conducted physiological tests and analyzed fatty acid content of palmitic, stearic, oleic, linoleic, linolenic, and eicosenoic acids. In proteomic analysis, the expression of heat-resistant proteins, including catalase, peroxidase, esterase, superoxide dismutase, and α-amylase, were evaluated. Transcript analysis was used to measure the expression of the genes AOX1, AOX2, ZmMPK-17, and ZmAN-13. The material showing the highest susceptibility to low germination temperatures contained high saturated fatty acid content. Expression of α-amylase in seeds soaked for 72 h at a temperature of 10°C was lower than expression of α-amylase when soaked at 25°C for the same amount of time. We observed variation in the expression of heat-resistant proteins in seeds of the lines evaluated. The genes AOX and Zm-AN13 were promising for use in identifying maize materials that are tolerant to low germination temperatures.

The genus Passiflora L. is the most representative of Passifloraceae, with over 500 known species, among which 150-200 originated from Brazil. In addition to the great commercial importance of this genus for the fruit market, many of the species have exotic flowers with a huge diversity of colors and can thereby be exploited as ornamental plants. This study was aimed at investigating the transferability of microsatellite primers in wild Passiflora species (P. cacao, P. cincinnata, P. glandulosa, P. gibertii, and P. mucronata) and characterizing 29 P. alata accessions using microsatellite primers that were previously developed in a library enriched with microsatellites from P. edulis f. flavicarpa for P. alata. The interspecies cross-amplification rate varied, and P. cacao exhibited the highest rate of amplification, suggesting a greater degree of proximity to P. edulis. The study of intraspecific accessions in P. alata found genetic similarity, with values ranging from 0.47 to 1.00 and an average similarity of 0.74. Hence, this study revealed the intraspecific genetic variability of P. alata in the Universidade Estadual de Santa Cruz's Active Germplasm Bank and will lead to the adoption of mating strategies between accessions; thus making their use more suitable for breeding purposes.

Soybean rust (SBR), caused by the fungus Phakopsora pachyrhizi, has been reported in common bean (Phaseolus vulgaris L.) cultivars and elite lines that were infected under controlled and natural field conditions in South Africa, the United States, Argentina, and Brazil. Although SBR is currently not a top priority problem for the common bean crop, many bean breeders are concerned about this disease because of the high severity and virulence diversity of P. pachyrhizi and its broad host range. In this study, a set of 44 P. vulgaris genotypes were tested for resistance to P. pachyrhizi; these genotypes included resistance sources to several fungal common bean diseases, carioca-, black- and red-seeded Brazilian cultivars, and elite lines that were developed by the main common bean breeding programs in Brazil. Twenty-four SBR resistance sources were identified. They presented the reddish-brown (RB) lesion type, characterizing resistance reactions. In addition to the RB lesion type, the PI181996 line presented the lowest disease severity mean score, considering its associated standard error value. For this reason, it was crossed with susceptible lines to study the inheritance of resistance. The results support the hypothesis that resistance to SBR in PI181996 is monogenic and dominant. We propose that this SBR resistance gene, the first to be identified and characterized in common bean, might be designated as Pkp-1.

17-α-methyltestosterone (MT) is a synthetic hormone used in fish hatcheries to induce male monosex. Snails hold promise as possible test models to assess chemicals acting on the endocrine system. Biomphalaria glabrata is an aquatic gastropod mollusk (Pulmonata, Planorbidae) that can be easily maintained in aquaria, predisposing the species for use in ecotoxicological testing. This study evaluated the reproductive effects of MT on B. glabrata by examining histological changes and its reproductive performance. Ten snails per group were exposed for 4 weeks to different concentrations of MT (0.01, 0.1, and 1.0 mg/L). The total number of laid eggs, egg mass per group, size of type V oocytes, and production of spermatozoids were determined. Reproduction of B. glabrata was affected by MT. At the lowest concentration (0.01 mg/L), MT caused a statistically significant increase in the number of egg mass per snail compared with controls unexposed to MT. Histopathology analyses showed an increase in the sperm production at the higher MT concentrations of 0.1 and 1.0 mg/L. Chromatographic analyses of water samples showed that MT concentrations rapidly declined within a 96-h period. These results highlight the importance of giving more support to regulatory authorities, since MT is not registered for use on fish hatcheries in many countries around the world. Wastewater from fish farms discharged into aquatic ecosystems should be monitored for MT residues, since its presence could compromise the reproduction of other native snail species.

Several interspecific Passiflora hybrids are produced in the northern hemisphere for the ornamental plant market. In Brazil, production of passion flower hybrids is limited to the introgression of genes into the main cultivated species, yellow passion fruit, to be used as rootstocks. Confirmation of hybridization in the initial developmental stage is important for breeding perennial and sub-perennial plants, such as passion flowers, reducing time and costs in plant stock maintenance. In order to obtain F₁ hybrids with ornamental potential, four species of Passiflora (P. alata, P. gardneri, P. gibertii, and P. watsoniana) from the Active Germplasm Bank at UESC were hybridized. Flower buds, in pre-anthesis, of the genitors were previously protected, and the female buds were emasculated. To confirm hybridization, the genomic DNA of the genitor species and the supposed hybrids was extracted and RAPD primers were used to obtain molecular markers and select passion flower interspecific hybrids. Eight primers were used to confirm hybrids derived from P. gardneri with P. alata, P. watsoniana with P. alata, P. watsoniana with P. gardneri, and P. gardneri with P. gibertii; 75, 50, 45, and 46% of the informative bands, respectively, confirmed the hybrid nature of these plants. The RAPD technique was effective in the early identification of hybrids; this will be useful for development of hybrid Passiflora progeny.

Evaluation of transgenic crops under field conditions is a fundamental step for the production of genetically engineered varieties. In order to determine if there is pollen dispersal from transgenic to nontransgenic soybean plants, a field release experiment was conducted in the Cerrado region of Brazil. Nontransgenic plants were cultivated in plots surrounding Roundup Ready transgenic plants carrying the cp4 epsps gene, which confers herbicide tolerance against glyphosate herbicide, and pollen dispersal was evaluated by checking for the dominant gene. The percentage of cross-pollination was calculated as a fraction of herbicide-tolerant and -nontolerant plants. The greatest amount of transgenic pollen dispersion was observed in the first row, located at one meter from the central (transgenic) plot, with a 0.52% average frequency. The frequency of pollen dispersion decreased to 0.12% in row 2, reaching 0% when the plants were up to 10 m distance from the central plot. Under these conditions pollen flow was higher for a short distance. This fact suggests that the management necessary to avoid cross-pollination from transgenic to nontransgenic plants in the seed production fields should be similar to the procedures currently utilized to produce commercial seeds.