Lyderson Facio Viccini

Biotechnological potential of antimicrobial peptides from flowers

Flowers represent a relatively unexplored source of antimicrobial peptides of biotechnological potential. This review focuses on flower-derived defense peptide classes with inhibitory activity towards plant pathogens. Small cationic peptides display diverse activities, including inhibition of digestive enzymes and bacterial and/or fungal inhibition. Considerable research is ongoing in this area, with natural crop plant defense potentially improved through the application of transgenic technologies. In this report, comparisons were made of peptide tertiary structures isolated from diverse flower species. A summary is provided of molecular interactions between flower peptides and pathogens, which include the role of membrane proteins and lipids. Research on these peptides is contributing to our understanding of pathogen resistance mechanisms, which will, given the perspectives for plant genetic modification, contribute long term to plant genetic improvement for increased resistance to diverse pathogens.

Chromosome numbers in the genus Lippia (Verbenaceae)

The genus Lippia (Verbenaceae) comprises about 200 taxa mainly distributed in Brazil, Mexico, Central America, Africa, Argentina and Paraguay. Some problems involving the number and delimitation of species have been reported. In order to contribute to the solving of these problems, the chromosome numbers of 14 Lippia species are documented. The following species were collected at Espinhaço Range, Southeast Brazil: Section Zapania (L. corymbosa, L. diamantinensis, L. hermannioides, L. lacunosa, L. rotundifolia, L. rubella), section Rhodolippia (L. florida, L. lupulina, L. pseudothea, L. rosella), section Goniostlachyum (L. glandulosa, L. pohliana, L. sidoides) and section Dioicolippia (L.filifolia). Immature inflorescences were collected and the ideal size for chromosome observation was determined. The majority of species have a haploid chromosome number from 10 to 14. Few species have a higher chromosome number, which suggests the occurrence of polyploidy. The relationships between chromosome numbers and the taxonomic sections are also discussed.

Genetic diversity among nine species of Lippia (Verbenaceae) based on RAPD Markers

Abstract.Nine species of Lippia (Verbenaceae) were studied by RAPD markers in order to evaluate the degree of genetic diversity. The following species were collected at the Cadeia do Espinhaço Mountains, Southeast Brazil: L. corymbosa, L. diamantinensis, L. filifolia, L. florida, L. hermannioides, L. lupulina, L. rotundifolia, L. rosella and L. sidoides. The analysis was performed using 18 primers that generated 490 fragments and only one primer was found to be monomorphic in all individuals. The average interspecific genetic distances were similar for all species and higher than the intraspecific genetic distances. Species with narrow occurrence did not show low intraspecific diversity. The molecular data were used to generate an UPGMA dendrogram that showed two major groups with a clear distribution among the species. RAPD analysis was efficient to address the genetic diversity of Lippia species and contributed to understand the adaptation to the environment, conservation and taxonomic implications.

Cytogenotoxicity of Cymbopogon citratus (DC) Stapf (lemon grass) aqueous extracts in vegetal test systems

The lemon grass, Cymbopogon citratus (DC) Stapf, is an important species of Poaceae family commonly used in the folk medicine in many countries. The aim of this study was to investigate the cytotoxic and genotoxic effects of aqueous extracts from C. citratus leaves on Lactuca sativa (lettuce) root tip meristem cells by cytogenetic studies that have never been done before for lemon grass extracts. For this, lettuce seeds were treated for 72h with different concentrations of lemon grass aqueous extracts (5; 10; 20 and 30 mg/mL). The percentage of germination, root development and cellular behavior were analyzed, and the results showed that the highest concentration of aqueous extracts reduced the mitotic index, the seed germination and the root development of lettuce. The extracts have also induced chromosome aberrations and cellular death in the roots cells of L. sativa.

Cytotoxicity of aluminum on meristematic cells of Zea mays and Allium cepa

Abstract Aluminum (Al) is the most abundant metal, the third most common element in the earth crust and the main factor on limiting plant growth in most strongly acid soils. Harmful effects in plants have been attributed to aluminum. The objective of this study is to compare the effect of aluminum exposure on Allium cepa and Zea mays. The root growth of A. cepa and Z. mays has been evaluated before and after the aluminum exposure. A strong inhibition on root growth in higher concentrations of Al has been observed both for A. cepa and Z. mays. For cytogenetic analysis, slides have been prepared by the air drying technique with enzymatic maceration. Results showed reduction of mitotic index and an increase of different abnormalities as the aluminum concentration increased. We observed, bridges, breaks, sticky metaphases, nuclear dissolution, cell death and in some cells chromosome duplication. Chromosome bridges constitute an important variable analyzed in maize. A pronounced toxic effect is observed in concentrations above 10–5M. These effects are more evident in A. cepa. Cell death deserves special attention in analyzing cytotoxicity of the aluminum.

Cytotoxic and genotoxic effects of two medicinal species of Verbenaceae

Abstract Lantana camara L. and Lippia alba (Mill.) N. E. Br. are two important species of Verbenaceae family and are commonly used in folk medicine in many countries of Central and Southern America. The aim of this study was to investigate, for the first time, the cytotoxic and genotoxic effects of aqueous extracts from leaves of both species on Lactuca sativa (lettuce) root tip meristem cells using a cytogenetic approach. Seeds of lettuce were separately treated during 72h with different concentrations of L. camara and L. alba aqueous extracts (5, 10, 20 and 30g/L). The percentage of germination, root development and cellular behavior were analyzed and the results showed that the highest concentration of aqueous extracts reduced the mitotic index, the seeds germination and the root development of lettuce. The extracts also induced chromosome aberrations and cellular death in roots cells of L. sativa. The cytogenotoxicity of L. camara and L. alba extracts was comparatively described.

Floração, germinação e estaquia em espécies de Lippia L. (Verbenaceae)

Plantas de dez especies de Lippia foram coletadas na Cadeia do Espinhaco, MG, Brasil e cultivadas em canteiros em Juiz de Fora, MG. A epoca de florescimento das especies de Lippia foi observada nos ambientes de origem e em canteiro. A germinacao foi testada com sementes coletadas em ambiente natural. Os materiais estabelecidos ex situ foram avaliados quanto ao enraizamento de estacas. As analises das plantas em ambiente natural e das cultivadas em canteiro evidenciaram que a maioria das especies estudadas apresenta floracao no periodo seco (inverno), enquanto um menor numero, no chuvoso (verao). Uma unica especie floresceu nessas duas estacoes. Em cultivo controlado, o periodo de floracao das especies com floracao caracteristica no verao foi aumentado. Algumas especies germinaram melhor quando recem coletadas enquanto outras quando armazenadas, evidenciando a ocorrencia de perda de viabilidade e de dormencia. O GA3 estimulou a germinacao em algumas especies, enquanto inibiu ou nao apresentou efeitos sobre outras. Sementes de algumas especies germinaram melhor no escuro, enquanto de outras sob luz branca, existindo ainda especies que germinaram tanto na luz quanto no escuro. O enraizamento das estacas das especies nao domesticadas de Lippia foi muito baixo, independente da estacao do ano e da concentracao da auxina. O enraizamento em estacas de L. alba (Mill.) N.E. Br. variou em resposta a epoca de coleta das estacas e quanto ao tipo e a concentracao das auxinas utilizadas. Os resultados do presente trabalho constituem os primeiros relatos envolvendo a reproducao de especies de Lippia endemicas da Cadeia do Espinhaco. Eles indicam a possibilidade de utilizacao das sementes na propagacao das plantas desse genero e tambem evidenciam que a reproducao das plantas das especies nao domesticadas de Lippia atraves de tecnicas convencionais de propagacao assexuada apresenta eficiencia bastante reduzida.

Karyotype analysis, DNA content and molecular screening in Lippia alba (Verbenaceae)

Cytogenetic analyses, of pollen viability, nuclear DNA content and RAPD markers were employed to study three chemotypes of Lippia alba (Mill.) (Verbenaceae) in order to understand the genetic variation among them. Different ploidy levels and mixoploid individuals were observed. This work comprises the first report of different chromosome numbers (cytotypes) in L. alba. The chromosome numbers of La2-carvone and La3-linalool chemotypes suggested that they are polyploids. Flow cytometric analysis showed an increase of nuclear DNA content that was not directly proportional to ploidy level variation. A cluster analysis based on RAPD markers revealed that La3-linalool shares genetic markers with La1-citral and La2-carvone. The analysis showed that the majority of genetic variation of La3-linalool could be a consequence of ixoploidy. ur data indicates that sexual reproduction aong those three chemotypes is unlikely and suggests the beginning of reproductive isolation. The results demonstrated that chromosome analysis, nuclear DNA content estimation and RAPD markers constitute excellent tools for detecting genetic variation among L. alba chemotypes.

Cytogenetic characterization of Lippia alba and Lantana camara (Verbenaceae) from Brazil

The aim of this work was to determine the cytogenetic characteristics of Brazilian Lippia alba (Mill) N. E. Brown and Lantana camara Plum. that could be useful for future characterization of these genera. Our analyses revealed that Li. alba has 2n=30 chromosomes consisting of ten metacentric and five submetacentric pairs, while La. camara has 44 metacentric chromosomes. The large blocks of heterochromatin seen in both species suggest an apomorphic condition. Six 45S rDNA sites were detected in both species by fluorescence in situ hybridization (FISH). Two and four 5S rDNA sites were observed in Li. alba and La. camara, respectively. Meiotic analysis revealed a normal chromosomal behaviour. The number of chromosomes and the presence of 45S rDNA and 5S rDNA sites do not exclude a possible polyploid origin. The cytogenetic differences between La. camara and Li. alba may be useful markers for differentiating these species.

Analysis of the chemical composition of the essential oils extracted from Lippia lacunosa Mart. & Schauer and Lippia rotundifolia Cham. (Verbenaceae) by gas chromatography and gas chromatography-mass spectrometry

Lippia lacunosa and L. rotundifolia (Verbenaceae) are two Brazilian species of complex taxonomic delimitation. The composition of the essential oils from leaves and flowers of these plants was investigated by gas chromatography (GC) and gas chromatography coupled with mass spectrometry (GC-MS) analysis. The major components of the essential oils of flowers and leaves of L. lacunosa were: myrcene (14.7% and 11.9%), myrcenone (45.2% and 64.2%), Z-ocimenone (5.7% and 5.2%), and E-ocimenone (14.7% and 4.1%), respectively; whereas in L. rotundifolia (flowers and leaves) were a-pinene (8.7% and 1.8%), myrcene (5.1% and 3.6%), limonene (26.0% and 7.9 %), cis-pinocamphone (4.5% and 3.1%) and myrtenal (22.3% and 16.7%), respectively. The essential oils from L. lacunosa exhibited a strong and pleasant mango aroma, which was related to the presence of myrcene and myrcenone. The marked differences in the chemical composition of their essential oils may represent a powerful tool for the botanical classification.