Plant regeneration from protoplast of Brazilian citrus cultivars

A procedure is described to regenerate plants from protoplasts of Brazilian citrus cultivars, after isolation, fusion and culture. Protoplasts were isolated from embryogenic cell suspension cultures and from leaf mesophyll of seedlings germinated in vitro. The enzyme solution for protoplast isolation was composed of mannitol (0.7 M), CaCl2 (24.5 mM), NaH2PO4 (0.92 mM), MES (6.15 mM), cellulase (Onozuka RS - Yakult, 1%), macerase (Onozuka R10 - Yakult, 1%) and pectolyase Y-23 (Seishin, 0.2%). Protoplast culture in liquid medium after chemical fusion lead to the formation of callus colonies further adapted to solid medium. Somatic embryo formation occurred spontaneously after two subcultures, on modified MT medium supplemented with 500 mg/L of malt extract. Well defined embryos were germinated in modified MT medium with addition of GA3 (2.0 muM) and malt extract (500 mg/L). Plant regeneration was also achieved by adventitious shoots obtained through direct organogenesis of not well defined embryos in modified MT medium with addition of malt extract (500 mg/L), BAP (1.32 muM), NAA (1.07 muM) and coconut water (10 mL/L). Plantlets were transferred to root medium. Rooted plants were transferred to a greenhouse for further adaptation and development.

Genetic variability of Brazilian phytoplasma and spiroplasma isolated from maize plants

The objective of this work was to characterize the genetic variability of phytoplasma and Spiroplasma kunkelii isolated from maize plants showing symptoms of stunt collected from different Brazilian geographic regions. A DNA fragment of 500 base pairs (bp) was amplified from the spiralin gene in S. kunkelii and one fragment of 1,200 bp was generated from 16S rDNA gene in phytoplasma. The partial sequences of the spiralin gene showed similarity of 98% among the isolates of S. kunkelii analyzed. These sequences were compared with the sequence of the spiralin gene from other Spiroplasma species deposited in the GenBank, resulting in a similarity varying from 76.9% to 88.1%. The 16S rDNA sequence from the phytoplasma were completely similar within the Brazilian isolates and showed up to 98% of the similarity with sequences already found from other phytoplasmas. A very narrow genetic variability was detected by these gene fragments within phytoplasma and Spiroplasma analyzed. However, other genomic regions with higher polymorphic levels shall be identified in order to better evaluate the genetic diversity within these microorganisms population.

Genetic diversity and population structure of Brazilian native bovine breeds

Conservation and improvement strategies should be based on the association between genetic and phenotypic characteristics. The objective of this work was to characterize five native Brazilian cattle breeds (Caracu, Crioulo Lageano, Curraleiro, National Polled and Pantaneiro) and two commercial breeds (Holstein and Nellore) using RAPD technique to estimate genetic distances and variability between and within breeds. Genetic relationships were investigated using 22 primers which generated 122 polymorphic bands. Analysis of molecular variance indicated that most of the genetic variation lay among individuals within populations. The genetic variabilities between pairs of breeds were statistically significant. The smallest genetic divergence was between Crioulo Lageano and Curraleiro.The National Polled, although historically considered to be of Bos taurus aquitanicus origin,similar to theCaracu, was grouped together with the other breeds of Bos taurus ibericus origin. Generally, the individual breeds formed distinct clusters except the National Polled. The RAPD technique was capable to distinguish genetically between the breeds studied; the Caracu, Crioulo Lageano, Curraleiro and Pantaneiro may be considered distinct genetic entities thereby proving the uniqueness of the populations; the National Polled has not been able to re-establish itself after its decline in the 1950s, thereby losing its genetic identity.

Genetic diversity of Brazilian triticales evaluated with genomic wheat microsatellites

The objective of this work was to determine the genetic variability available for triticale (X Triticosecale Wittmack) crop improvement in Brazil. Forty-two wheat genomic microsatellites were used to estimate the molecular diversity of 54 genotypes, which constitute the base of one of the major triticale breeding programs in the country. Average heterozygosity was 0.06 and average and effective number of alleles per locus were 2.13 and 1.61, respectively, with average allelic frequency of 0.34. The set of genomic wheat microsatellites used clustered the genotypes into seven groups, even when the germplasm was originated primarily from only two triticale breeding programs, a fact reflected on the average polymorphic information content value estimated for the germplasm (0.36). The 71.42% transferability achieved for the tested microsatellites indicates the possibility of exploiting these transferable markers in further triticale genetic and breeding studies, even those mapped on the D genome of wheat, when analyzing hexaploid triticales.

Optimization of particle bombardment parameters for the genetic transformation of Brazilian maize inbred lines

The objective of this work was to develop a genetic transformation system for tropical maize genotypes via particle bombardment of immature zygotic embryos. Particle bombardment was carried out using a genetic construct with bar and uidA genes under control of CaMV35S promoter. The best conditions to transform maize tropical inbred lines L3 and L1345 were obtained when immature embryos were cultivated, prior to the bombardment, in higher osmolarity during 4 hours and bombarded at an acceleration helium gas pressure of 1,100 psi, two shots per plate, and a microcarrier flying distance of 6.6 cm. Transformation frequencies obtained using these conditions ranged from 0.9 to 2.31%. Integration of foreign genes into the genome of maize plants was confirmed by Southern blot analysis as well as bar and uidA gene expressions. The maize genetic transformation protocol developed in this work will possibly improve the efficiency to produce new transgenic tropical maize lines expressing desirable agronomic characteristics.

Genetic diversity of Brazilian Pantaneiro horse and relationships among horse breeds

The objective of this work was to evaluate the genetic diversity of Brazilian Pantaneiro horse by microsatellite markers, investigate the effect of genetic bottlenecks and estimate genetic differentiation among four horse breeds. Genetic variation was estimated through allele frequencies and mean breed heterozygosity. Nei's genetic distances among the breeds Pantaneiro, Thoroughbred, Arabian, Spanish Pure Breed (Andalusian), and Uruguay Creole were calculated, and it was used to construct an UPGMA dendrogram. Clustering at different K values was calculated to infer population structure and assign individuals to populations. Nei's distances showed a minimum distance between Pantaneiro horse and Spanish Pure Breed (0.228), and similar distances from Spanish Pure Breed to Thoroughbred and to Arabian (0.355 and 0.332). It was observed a great level of diversity, clear distance from Pantaneiro horse to other breeds, and genetic uniformity within breed. It was verified a certain level of substructure of Pantaneiro horse showing no influences from the other studied breeds.

Genetic variability of Brazilian rice landraces determined by SSR markers

The objective of this study was to evaluate the genetic variability of rice (Oryza sativa) landraces collected in Brazilian small farms. Twelve simple sequence repeat (SSR) markers characterized 417 landraces collected in 1986, 1987 and 2003, in the state of Goiás, Brazil. The number of landraces with long and thin grain type increased in the evaluated period, probably due to market demand. Based on the molecular data, the genetic variability increased during this period and, as per to the factorial correspondence analysis, most of the accessions were grouped according to the year of collection. The incorporation of modern rice cultivars in landrace cultivation areas and the selection carried out by small farmers are the most probable factors responsible for increasing landrace genetic variability, during the evaluated period. Genotype exchange between farmers, selection practice and local environmental adaptation are able to generate novel adapted allele combinations, which can be used by breeding programs, to reinitiate the process.

Screening of Brazilian soybean genotypes with high potential for somatic embryogenesis and plant regeneration

The aim of this work was to identify Brazilian soybean (Glycine max) genotypes with potential to respond to in vitro culture stimuli for primary somatic embryo induction, secondary embryo proliferation and plant regeneration. Differences among eight tested cultivars were observed at each stage. Two cultivars, IAS-5 and BRSMG 68 Vencedora, were selected for the evaluation of the capacity for embryo differentiation and plant regeneration. These cultivars had high embryo induction frequencies, repetitive embryogenic proliferation, and low precocious embryo germination in the initial experiment. The effect of abscisic acid (ABA) and charcoal addition on plant regeneration was investigated. The addition of ABA to proliferation medium and of ABA and activated charcoal to maturation medium increased embryo differentiation rates, which resulted in a higher number of regenerated plants. The BRSMG 68 Vencedora cultivar was found to have a high potential for embryo induction, embryo proliferation and plant regeneration. The potential of this cultivar for somatic embryogenesis was similar to that observed for cultivar IAS-5, which is currently used for soybean transformation in Brazil. BRSMG 68 Vencedora may be a good alternative genotype for soybean genetic engineering via somatic embryogenesis protocols.

Studies on the acid activation of Brazilian smectitic clays

Fuller's earth and acid activated smectitic clays are largely used as bleaching earth for the industrial processing of vegetable, animal and mineral oils and waxes. The paper comments about the nomenclature used for these materials, the nature of the acid activation of smectitic clays (bentonites), activation laboratory procedures and presents a review of the acid activation of bentonites from 20 deposits from several regions of Brazil. The activated clays were tested and show good decolorizing power for soybean, castor, cottonseed, corn and sunflower oils.

Bauer-7-en-3beta-yl acetate: a major constituent of unusual samples of Brazilian propolis

The pentacyclic triterpenoid bauer-7-en-3beta-yl acetate was obtained from the chloroform extract of an unusual sample of propolis from southeast Brazil with the yield of 7%. The compound was identified by comparison of IR, MS and NMR analysis with published data.

The pre-history of cryoscopy: what was done before raoult?

Cryoscopy is considered one of the foundations of the modern theory of solutions and of physical chemistry. This paper shows in order the first regularities pointed out by several scientists on the subject, in the first chapter of its birth as a scientific discipline. The study is focused on the identification of the different steps that helped, first qualitatively and then quantitatively, to adjust the different classes of possible solutions, including those that formed hydrates, to a basic formulation that the French scientist François-Marie Raoult would later generalize in the law that bears his name.

The history of the rectilinear diameter law

The formulation of the so-called law of rectilinear diameter for the determination of the critical volume of substances in the concluding decades of the nineteenth century became in a very useful and acceptably exact alternative tool for researchers in the field of critical phenomena. Its corresponding original expression, and even those of its early few modifications, were so mathematically simple that their use did not limit to exclusively contribute to remove the by then experimental obstacle for the estimating of this critical parameter, but also extended along several decades in the increasing applications of the principle of corresponding states.

Chemical profiling of six samples of Brazilian propolis

Six samples of Brazilian propolis from Minas Gerais and Paraná states were analyzed to identify the constituents (GC/MS and HPLC/MS) and to determine their contents (HPLC and external standardization). All samples contained characteristic constituents of green propolis, but the samples from Minas Gerais had higher contents of prenylated phenylpropanoids and caffeoylquinic acids. Kaempferide and two other flavonoids were among the major constituents of the samples from Minas Gerais. Luteolin 5-O-methyl ether was detected only in samples from Paraná. Baccharis dracunculifolia was a source of resins for all samples analyzed, but the samples from Paraná had more complex plant origin.

Phenolic composition and antioxidant properties of Brazilian honeys

The antioxidant activities and polyphenolic levels of "assa peixe," "cambara," and "morrão de candeia" Brazilian honeys were investigated. Phenolic extracts of 11 honeys were evaluated spectrophotometrically to determine their total phenolic and flavonoid contents, and their antioxidant activities were measured using DPPH, ABTS, and FRAP assays. High-performance liquid chromatography coupled with diode array detection was applied to determine the phenolic composition of the honey extracts. The presence of fourteen phenolic compounds was established (eleven phenolic acids and three flavonoids), as well as HMF and abscisic acid. Principal component analysis was applied to classify the honey samples according to their floral origins.

Molecular characterization of Brazilian Dicyma pulvinata isolates

Forty-nine Brazilian Dicyma pulvinata isolates were examined by morphological traits and RFLP, RAPD and AFLP analyses. This fungus is a mycoparasite of Microcyclus ulei, the causal agent of the most devastating rubber (Hevea brasiliensis) disease, known as "South American Leaf Blight" (SALB). These isolates were compared with an Indian isolate from Cercosporidium sp., and a French isolate from Cladosporium fulvum. They were also compared with Dicyma ampullifera from Papua New Guinea. The morphological parameters analyzed confirmed the identification of the Brazilian isolates. The graphic representations of the distance matrices of each molecular marker showed similar results. Dicyma pulvinata isolates from M. ulei were closely related, whereas the reference isolates examined were dispersed. Among the D. pulvinata isolates obtained from M. ulei, a significant pairwise distance was obtained, for all the molecular markers, between the isolates from the areas favorable to the occurrence of SALB (North and Northeast of Brazil) and the region of escape for the disease (Mato Grosso State).