Transcriptomic analysis of bell pepper (Capsicum annuum L.) revealing key mechanisms in response to low temperature stress.

BACKGROUND: Bell pepper (Capsicum annuum L.) is one of the most economically and nutritionally important vegetables worldwide. However, its production can be affected by various abiotic stresses, such as low temperature. This causes various biochemical, morphological and molecular changes affecting membrane lipid composition, photosynthetic pigments, accumulation of free sugars and proline, secondary metabolism, as well as a change in gene expression. However, the mechanism of molecular response to this type of stress has not yet been elucidated. METHODS AND RESULTS: To further investigate the response mechanism to this abiotic stress, we performed an RNA-Seq transcriptomic analysis to obtain the transcriptomic profile of Capsicum annuum exposed to low temperature stress, where libraries were constructed from reads of control and low temperature stress samples, varying on average per treatment from 22,952,190.5-27,305,327 paired reads ranging in size from 30 to 150 bp. The number of differentially expressed genes (DEGs) for each treatment was 388, 417 and 664 at T-17 h, T-22 h and T-41 h, respectively, identifying 58 up-regulated genes and 169 down-regulated genes shared among the three exposure times. Likewise, 23 DEGs encoding TFs were identified at T-17 h, 30 DEGs at T-22 h and 47 DEGs at T-42 h, respectively. GO analysis revealed that DEGs were involved in catalytic activity, response to temperature stimulus, oxidoreductase activity, stress response, phosphate ion transport and response to abscisic acid. KEGG pathway analysis identified that DEGs were related to flavonoid biosynthesis, alkaloid biosynthesis and plant circadian rhythm pathways in the case of up-regulated genes, while in the case of down-regulated genes, they pertained to MAPK signaling and plant hormone signal transduction pathways, present at all the three time points of low temperature exposure. Validation of the transcriptomic method was performed by evaluation of five DEGs by quantitative polymerase chain reaction (q-PCR). CONCLUSIONS: The data obtained in the present study provide new insights into the transcriptome profiles of Capsicum annuum stem in response to low temperature stress. The data generated may be useful for the identification of key candidate genes and molecular mechanisms involved in response to this type of stress.

First Draft Genome Sequence Resource of a Strain of Pseudocercospora fijiensis Isolated in North America.

Black Sigatoka disease, caused by the fungus Pseudocercospora fijiensis, is one of the most devastating diseases of banana around the world. Fungicide applications are the primary tool used to manage black Sigatoka, but fungicide resistance in P. fijiensis, as in other fungal pathogens, is one of the major limitations in the efficient management and prevention of this disease. In the current study, we present the draft genome of P. fijiensis strain IIL-20, the first genomic sequence published from a strain of this fungus isolated in North America. Bioinformatic analysis showed putative genes involved in fungus virulence and fungicide resistance. These findings may lead us to a better understanding of the molecular pathogenesis of this fungal pathogen and also to the discovery of the mechanisms conferring fungicide resistance.

Complete genome sequence of Phobos: a novel bacteriophage with unusual genomic features that infects Pseudomonas syringae.

The GenBank database contains over 2580 complete genome sequences from bacteriophages. However, limited reports are available concerning phages can that lyse members of Pseudomonas syringae, although this is a widespread bacterial species that can infect almost 200 plant species. In the present study, we isolated and characterized a new Siphoviridae phage, named "Pseudomonas phage vB_PsyS_Phobos" (for brevity, referred to here as Phobos). To our knowledge, this is one of the first genome sequences reported for a phage with lytic activity against P. syringae pv. syringae. The genome of Phobos is dsDNA of 56,734 bp with a GC content of 63.3%, containing 65 ORFs. Genome analysis revealed that Phobos is a novel lytic phage with unique genomic features and low similarity to other phages, suggesting that Phobos represents a new phage genus. Genome sequencing did not reveal sequences with significant similarity to known virulence factors, antibiotic resistance genes, potential immunoreactive allergens, or lysogeny-related proteins, suggesting suggests that phage Phobos is strictly lytic. Therefore, Phobos may be suitable for formulation as a biocontrol agent against P. syringae pv. syringae.