Structural and histochemical attributes of secretory ducts and cavities in leaves of four species of Calophyllaceae J. Agardh in Amazonian savannas.

This study represents an important contribution to the structural, histochemical and biological understanding of ducts and cavities in leaves of four species of Calophyllaceae that occur in Amazonian savannas. Samples of adult leaves were processed using light, scanning and transmission electron microscopy, as per usual methods for plant anatomy. In paradermal sections, the lumina of ducts are elongated while those of cavities are short. Ducts occur exclusively in the central rib and are abundant in Kielmeyera rubriflora Cambess and Kielmeyera coriacea Mart. and Zucc and larger than in Calophyllum brasiliense Cambess and Caraipa densifolia Mart. In mesophyll, the type of secretory structure and distribution pattern of the ducts and cavities are distinct. In most species, the secreted metabolites are similar and consist of phenolic compounds, lipids, essential oils with oleoresins, mucilage, neutral polysaccharides, proteins and alkaloids, except in K. coriacea, which does not contain oleoresin. The secretion is probably synthesized by mitochondria, rough endoplasmic reticulum, ribosomes and dictyosomes and is externalized toward the lumen by granulocrine and eccrine processes. In addition to being of diagnostic value for species identification, the attributes of the lumen shape, type of secretory structure, distribution pattern, identified metabolites and secretion mechanism are important for understanding the biological roles of ducts and cavities. The identified metabolites reveal a capacity for adaptation, resistance and protection from the action of herbivores and pathogens, and in water retention.

Purification, biochemical characterization, and antimicrobial activity of a new lipid transfer protein from Coffea canephora seeds.

Coffee, an agronomical crop of great economic importance, is also among the most commonly traded commodities in worldwide markets. Antimicrobial peptides, which play a role in plant defense, have been identified and isolated particularly from seeds. We isolated and immunolocalized Cc-LTP2, a new lipid transfer protein (LTP) from Coffea canephora seeds. We report its antimicrobial activity against various phytopathogenic fungi of economic importance, and against the bacterium Xanthomonas euvesicatoria. Peptides from C. canephora seeds were initially extracted using acid buffer and subjected to ion-exchange and reverse-phase chromatographies. A purified peptide of approximately 9 kDa, which we named Cc-LTP2, was then subjected to amino acid sequencing. The analyses showed that it was similar to LTPs isolated from various plants. The tissue and subcellular localization of C. canephora LTPs indicated that they were located in cell walls and intracellular palisade parenchyma, mainly in large vacuoles. The results of immunohistochemistry and histochemistry superposed from C. canephora seed tissues showed that LTPs and lipid bodies are present in organelles, supporting the hypothesis that LTPs from seeds are involved in lipid mobilization during germination. Cc-LTP2 did inhibit the development of the phytopathogenic fungi Colletotrichum lindemuthianum, Colletotrichum gloeosporioides, Fusarium solani, Fusarium lateritium, and Colletotrichum sp, but did inhibit X. euvesicatoria. Cc-LTP2 also increased membrane permeability and induced endogenous production of reactive oxygen species in all the fungi tested.