Gene expression patterns in response to hydrostatic pressure were determined by whole genome microarray hybridization. Functional classi¢cation of the 274 genes a¡ected by pressure treatment of 200 MPa for 30 min revealed a stress response expression pro¢le. The majority of the s 2-fold upregulated genes were involved in stress defense and carbohydrate metabolism while most of the repressed ones were in cell cycle progression and protein synthesis categories. Furthermore, uncharacterized genes were among the 10 highest expressed sequences and represented 45% of the total upregulated genes. The results of this study revealed a hydrostatic pressure-speci¢c stress response pattern and suggested interesting information about the mechanisms involved in adaptation of cells to a high-pressure environment. ß

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Banana, papaya and pineapple are the most consumed tropical fruits in the world, being Brazil one of the main producers. Fungi Colletotrichum musae, Colletotrichum gloeosporioides and Fusarium subglutinans f.sp. ananas cause severe post harvest diseases and losses in fruits quality. The aim of this work was to evaluate the effectiveness of five monoterpenes to inhibit the mycelial growth and conidia germination of these three phytopathogens. The monoterpenes citral, citronellal, L-carvone, isopullegol and α-pinene were diluted in ethanol to final concentrations from 0.2 to 1%. All monoterpenes were found to inhibit the growth of the three studies fungi in a dose-dependent manner. Citral was the most effective of the oils tested and showed potent fungicidal activity at concentrations above 0.5%. Also, in vivo evaluation with these tropical fruits demonstrated the efficiency of citral to inhibit fungal growth. These results indicate the potential use of citral as a natural pesticide control of post-harvest fruit diseases.

Papaya (Carica papaya L.) hosts the only described laticifer-infecting virus (Papaya meleira virus, PMeV), which is the causal agent of papaya sticky disease. To understand the systemic effects of PMeV in papaya, we conducted a comprehensive proteomic analysis of leaf samples from healthy and diseased plants grown under field conditions. First, a reference 2-DE map was established for proteins from healthy samples. A total of 486 reproducible spots were identified, and MALDI-TOF-MS/MS data identified 275 proteins accounting for 159 distinct proteins from 231 spots that were annotated. Second, the differential expression of proteins from healthy and diseased leaves was determined through parallel experiments, using 2-DE and DIGE followed by MALDI-TOF-MS/MS and LC-IonTrap-MS/MS, respectively. Conventional 2-DE analysis revealed 75 differentially expressed proteins. Of those, 48 proteins were identified, with 26 being upregulated (U) and 22 downregulated (D). In general, metabolism-related proteins were downregulated, and stress-responsive proteins were upregulated. This expression pattern was corroborated by the results of the DIGE analysis, which identified 79 differentially expressed proteins, with 23 identified (17 U and 6 D). Calreticulin and the proteasome subunits 20S and RPT5a were shown to be upregulated during infection by both 2-DE and DIGE analyses. These data may help shed light on plant responses against stresses and viral infections.

heterotrimeric G protein-coupled cell surface receptor (encoded by STE3 or STE2). Many of the other components of this transduction pathway are known. The induction of mating pheromone-specific genes occurs through the action of the STE12 gene product as a consequence of its binding to a pheromone-specific transcription-activating sequence known as the pheromone response element (11,14). Several of these pheromone-specific genes are known to be involved in the mating process. In contrast, the mechanism by which the same pathway results in G1-specific cell cycle arrest is not understood. Although STE12 function has been implicated in this arrest, the nature of its involvement is not known (10).Cell cycle progression in budding yeasts is known to require the activity of the CDC28 gene product (20,34,35), a serine/threonine protein kinase of the Cdk (cyclin-dependent kinase) family, which includes the Cdc2 protein kinase (reviewed by Pines and Hunter [32]). The function of the CDC28 gene product is essential for passage through the G1/S and G2/M transitions. Its role at each of these transitions is performed in conjunction with those of distinct families of cyclin proteins, the G2/M function requiring B-type cyclins encoded by the CLB genes (16,40) and the role during G1 phase requiring the G1 cyclins encoded by the CLN genes. The CLN gene family consists of three genes, CLN1, CLN2, and CLN3, which perform an overlapping function that is essential for progression through G1 phase (5,18,27,36

Spontaneous latex exudation is the main symptom of papaya sticky (meleira) disease caused by the Papaya meleira virus (PMeV), a double-stranded RNA (dsRNA) virus. This paper describes different effects of PMeV on papaya latex. Latex samples were subjected to different histochemical tests to evaluate their chemical composition. Additionally, the integrity of the latex particles was assessed by transmission and scanning electron microscopy analysis. Biochemical and micro- and macro-element measurements were performed. PMeV dsRNA extraction was performed to evaluate the interaction of the virus with the latex particles. Sticky diseased latex was positive for alkaloid biosynthesis and showed an accumulation of calcium oxalate crystals. PMeV also increased H(2)O(2) synthesis within sticky diseased laticifers. The protein, sugar and water levels were altered, probably due to chemical changes. The morphology of the latex particles was further altered; PMeV particles seemed to be bound to the latex particles. The alkaloid and H(2)O(2) biosynthesis in the papaya laticifers indicate a papaya defense response against PMeV. However, such efforts failed, as the virus affected the plant latex. The effects described here suggest some advantages of the infection process, including facilitating the movement of the virus within the papaya plant.

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