Carotenoid cleavage dioxygenases (CCDs) are a class of enzymes involved in the biosynthesis of a broad diversity of secondary metabolites known as apocarotenoids. In plants, CCDs are part of a genetic family with members which cleave specific double bonds of carotenoid molecules. CCDs are involved in the production of diverse and important metabolites such as vitamin A and abscisic acid (ABA). Bixa orellana L. is the main source of the natural pigment annatto or bixin, an apocarotenoid accumulated in large quantities in its seeds. Bixin biosynthesis has been studied and the involvement of a CCD has been confirmed in vitro. However, the CCD genes involved in the biosynthesis of the wide variety of apocarotenoids found in this plant have not been well documented. In this study, a new CCD1 gene member (BoCCD1) was identified and its expression was charaterized in different plant tissues of B. orellana plantlets and adult plants. The BoCCD1 sequence showed high homology with plant CCD1s involved mainly in the cleavage of carotenoids in several sites to generate multiple apocarotenoid products. Here, the expression profiles of the BoCCD1 gene were analysed and discussed in relation to total carotenoids and other important apocarotenoids such as bixin.

Annatto (Bixa orellana) is the sole source of the commercially important pigment bixin. The broad diversity of annatto phenotypes and the wide variation in pigment contents have restricted its use. Therefore, genetic improvement focusing on this variation is important in order to achieve optimal exploitation of annatto. To characterize and understand some of the genetic basis governing carotenoid production, two annatto cultivars with either pink or white flowers were selected on the basis of their contrasting pigment levels. Several complementary DNA (cDNA)-probes corresponding to genes involved in carotenoid biosynthesis (dxs, psy, pds, β-lcy, and ε-lcy) were cloned and analyzed by reverse transcriptase-polymerase chain reaction (RT-PCR) in different tissues of these two annatto cultivars during flower and fruit development. In general, expression of most selected genes could be associated with pigment overaccumulation in these cultivars. The pink cultivar exhibited higher carotenoid contents and higher pigment-related gene expression, and the two variants analyzed showed notable differences in gene expression in the highest pigment producing tissues.

A reliable protocol is described for isolation of large full-length cDNA from Bixa orellana mature tissues containing large quantities of pigments, phenols, and polysaccharides. This protocol involves the optimization of a commercial RNA extraction protocol in combination with a long distance reverse transcript PCR protocol. The principal advantages of this protocol are its high RNA yield and quality. The resulting RNA is suitable for RNA expression evaluation and production of large, full-length cDNA. This is the first time RNA has been isolated from all mature tissues in the tropical perennial plant B. orellana and has been proved viable for downstream applications, especially important for molecular biology studies on this economically important pigment-producing plant.

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A protocol is described for rapid DNA isolation from marine biofilm microorganisms embedded in large amounts of exopolysaccharides. The method is a modification of the hot phenol protocol used for plants tissues, where nonexpensive and easily available enzymes were used. The method is based on the incubation of biofilm biomass samples in an extraction buffer mixed with phenol preheated at 65 degrees C. The procedure can be completed in 2 h and up to 20 samples can be processed simultaneously with ease and DNA of excellent quality, as shown by successfully amplification of polymerase chain reaction (PCR) products. DNA was recovered from a range of intertidal marine biofilms with varying amounts of exopolysaccharides.

Phytophthora blight of peppers, caused by oomycete Phytophthora capsici, currently causes economic losses in crops such as peppers, tomatoes, eggplant and cucurbits. In this work, we evaluated the effect of chitosan with low degree of polymerization (LDP) on growth and gene expression of P. capsici cultures. LDP chitosan inhibited 88% of P. capsici mycelial growth at concentrations up to 0,4 mg/l, whereas at concentrations higher than 1,6 mg/l it completely inhibit growth. Gel mobility shift assays demonstrated that chitosan interacts with DNA and RNA of the fungus at concentrations ranging from 2 to 4mg/l for DNA and 0,5 to 3mg/l for RNA. The differential display analysis of RT-PCR-amplification products of P. capsici messenger RNA revealed changes in gene expression profiles after the chitosan treatment. Bioinformatic analysis of sequences from selected differentially-expressed bands showed the gene regulation of elements involved in chitin synthesis and carbohydrate-binding proteins.

Anthracnose produced by Colletotrichum gloeosporioides is a post-harvest mango disease causing big economic losses worldwide. Plant pathogens have increased their resistance to chemical fungicides. The use of natural formulations for disease control represents a healthier alternative. Therefore, testing new natural antimicrobial agents is necessary.Several natural agents for phytopathogen control have been described. Their effectiveness depends on various factors such as their composition, concentration and the environment. We evaluated the antifungal activity of organic crude extracts of Citrus x paradisi (grapefruit), Citrus reticulata (tangerine) and Citrus aurantium (sour orange) and a treatment with chitosan in mango fruits cv. Tommy Atkins against C. gloeosporioides.The extracts obtained with hexane from dried sour orange peels had a considerable fungicidal effect on the radial growth of the fungus. Also, the parameters evaluated in mango fruits demonstrate that the chitosan treatment delays the development of symptoms of anthracnose.

La alelopatía es un fenómeno biológico en el que las substancias químicas liberadas por una especie vegetal influyen directamente sobre el crecimiento y desarrollo de otra; por tanto, las especies alelopáticas pueden ser fuente natural de herbicidas. Se ha demostrado que Metopium brownei y Viguiera dentata tienen un efecto inhibidor sobre plantas y microorganismos. El presente trabajo tuvo como objetivo determinar el efecto supresor de diferentes dosis de extractos crudos de M. brownei y V. dentata sobre la germinación in vitro de una arvense tropical (Senna uniflora) y Raphanus sativus, una especie altamente sensible a aleloquímicos. Se demostró que los extractos acuosos de frutos de M. brownei aplicados a dosis tan bajas como de 0.5% suprimieron la germinación de la arvense S. uniflora al 100%. Los extractos etanólicos de ambas especies demostraron un efecto inhibitorio de la germinación de semillas de S. uniflora en concentraciones de 8% o superiores. Por otra parte, los extractos acuosos de flores de V. dentata fueron los más efectivos en inhibir la germinación de semillas de R. sativus al aplicarse en dosis superiores al 15%. De acuerdo con los resultados obtenidos en el presente trabajo se concluye que V. dentata tiene un fuerte efecto alelopático sobre S. uniflora cuando se emplea en extractos etanólicos y acuosos, por lo que puede emplearse como bioherbicida para el control de la arvense en cultivos tropicales.