Wild relatives of cultivated tomato (Solanum lycopersicum) are resistant to a wide range of abiotic and biotic stress conditions. In an effort to understand the molecular mechanisms of salt stress resistance in the wild and cultivated Solanum species, a basic leucine zipper (bZIP) transcription factor was identified in S. chilense, S. peruvianum and S. lycopersicum and named ScAREB1, SpAREB1 and SlAREB1, respectively. Deduced amino acid sequences of the three proteins are 97% identical among them and present high homology with the ABF/AREB subfamily of transcription factors described in different plant species, including Arabidopsis (ABF2, 54% identical) and tobacco (PHI-2, 50% identical). Expression of these orthologous genes is upregulated similarly in the three species by salt stress. The expression of SlAREB1 was further investigated in S. lycopersicum and found to be induced by drought, cold and abscisic acid. To investigate the possible role of this transcription factor in response to abiotic stress, a simple transient expression assay was used for rapid analysis of genes regulated by SlAREB1 in tomato and tobacco by means of Agrobacterium-mediated transformation. Tobacco leaves expressing SlAREB1 showed upregulation of stress-responsive genes such as RD29B, the LEA genes ERD10B and TAS14, the transcription factor PHI-2 and a trehalose-6-phosphate phosphatase gene. These results suggest that this class of bZIP plays a role in abiotic stress response in the Solanum genus.

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We have previously shown that high density lipoprotein is the most abundant protein in the carp plasma and displays bactericidal activity in vitro. Therefore the aim of this study was to analyze the contribution of its principal apolipoproteins, apoA-I and apoA-II, in defense. Both apolipoproteins were isolated by a two step procedure involving affinity and gel filtration chromatography and were shown to display bactericidal and/or bacteriostatic activity in the micromolar range against Gram-positive and Gram-negative bacteria, including some fish pathogens. In addition, a cationic peptide derived from the C-terminal region of carp apoA-I was synthesized and shown to posses antimicrobial activity (EC 50 ¼ 3-6 lM) against Planococcus citreus. This peptide was also able to potentiate the inhibitory effect of lysozyme in a radial diffusion assay at subinhibitory concentrations of both effectors. Finally, limited proteolysis of HDL-associated apoA-I with chymotrypsin in vitro was shown to generate a major truncated fragment, which indicates that apoA-I peptides liberated in vivo through a regulated proteolysis could also be involved in innate immunity.

Casaretto, JA (reprint author), Univ Talca, Inst Biol Vegetal & Biotecnol, Talca, Chile.Growing evidence suggests that the phytohormone abscisic acid (ABA) plays a role in fruit development. ABA signaling components of developmental programs and responses to stress conditions include the group of basic leucine zipper transcriptional activators known as ABA-response element binding factors (AREBs/ABFs). AREB transcription factors mediate ABA-regulated gene expression involved in desiccation tolerance and are expressed mainly in seeds and in vegetative tissues under stress; however, they are also expressed in some fruits such as tomato. In order to get an insight into the role of ABA signaling in fruit development, the expression of two AREB-like factors were investigated during different developmental stages. In addition, tomato transgenic lines that overexpress and downregulate one AREB-like transcription factor, SlAREB1, were used to determine its effect on the levels of some metabolites determining fruit quality. Higher levels of citric acid, malic acid, glutamic acid, glucose and fructose were observed in SlAREB1-overexpressing lines compared with those in antisense suppression lines in red mature fruit pericarp. The higher hexose concentration correlated with increased expression of genes encoding a vacuolar invertase (EC 3.2.1.26) and a sucrose synthase (EC 2.4.1.13). No significant changes were found in ethylene content which agrees with the normal ripening phenotype observed in transgenic fruits. These results suggest that an AREB-mediated ABA signal affects the metabolism of these compounds during the fruit developmental program

Artículo de publicación ISIRoot hypoxia in fruit trees affects growth, vegetative development, and reproductive development, which is reflected in low productivity, poor fruit quality, and premature decay of trees. Using Illumina Hiseq2000, we performed transcriptome analysis of roots from two different rootstocks, ‘Mariana 2624’ and ‘Mazzard F12/1,’ which are tolerant and sensitive to hypoxia, respectively. Transcriptomes from control and hypoxia-stressed plants (6, 24, and 72 h) were compared, using Prunus persica (L.) as reference genome. Hypoxic conditions altered the transcription in both genotypes. There were a high number of common differentially expressed genes (DEG) between the two genotypes for each sampling time, but also exclusive DEG for each genotype, with a few DEG that presented opposite modes of regulations during the hypoxia treatment. An important group of DEGs exclusively upregulated in the tolerant genotype are associated to enzymes of posttranslational protein modifications, such as leucinerich repeat (LRR), kinases and ubiquitin-protein ligases, regulation of transcription, and process of oxide reduction. Singular enrichment analysis of gene ontology (GO), detected at least 115 GOs involved in the response to root hypoxia in the sensitive and/or tolerant genotypes. At least 25 GOs were identified as part of the baseline differences between the genotypes, most GO were disturbed in the sensitive genotype. The contribution from the baseline gene expression to the differential response between the Prunus genotypes is evidence that the resistant genotype is already Bprepared^ for a hypoxia event. An example are GO BP:0042221 of response to chemical stimulus; BP:0006979 of response to oxidative stress; MF:0016209 of antioxidant activity; MF:0016684 of oxidoreductase activity, acting on peroxide as acceptor; and MF:0004601 of peroxidase activity, which were disturbed only in the sensitive genotype, but not in the tolerant.FONDECYT (No. 1121117) and CEAF_R08I100