Overexpression of BdMATE Gene Improves Aluminum Tolerance in Setaria viridis.

Acidic soils are distributed worldwide, predominantly in tropical and subtropical areas, reaching around 50% of the arable soil. This type of soil strongly reduces crop production, mainly because of the presence of aluminum, which has its solubility increased at low pH levels. A well-known physiological mechanism used by plants to cope with Al stress involves activation of membrane transporters responsible for organic acid anions secretion from the root apex to the rhizosphere, which chelate Al, preventing its absorption by roots. In sorghum, a membrane transporter gene belonging to multidrug and toxic compound extrusion (MATE) family was identified and characterized as an aluminum-activated citrate transporter gene responsible for Al tolerance in this crop. Setaria viridis is an emerging model for C4 species and it is an important model to validate some genes for further C4 crops transformation, such as sugarcane, maize, and wheat. In the present work, Setaria viridis was used as a model plant to overexpress a newly identified MATE gene from Brachypodium distachyon (BdMATE), closely related to SbMATE, for aluminum tolerance assays. Transgenic S. viridis plants overexpressing a BdMATE presented an improved Al tolerance phenotype, characterized by sustained root growth and exclusion of aluminum from the root apex in transgenic plants, as confirmed by hematoxylin assay. In addition, transgenic plants showed higher root citrate exudation into the rhizosphere, suggesting that Al tolerance improvement in these plants could be related to the chelation of the metal by the organic acid anion. These results suggest that BdMATE gene can be used to transform C4 crops of economic importance with improved aluminum tolerance.

The coffee genome provides insight into the convergent evolution of caffeine biosynthesis.

Coffee is a valuable beverage crop due to its characteristic flavor, aroma, and the stimulating effects of caffeine. We generated a high-quality draft genome of the species Coffea canephora, which displays a conserved chromosomal gene order among asterid angiosperms. Although it shows no sign of the whole-genome triplication identified in Solanaceae species such as tomato, the genome includes several species-specific gene family expansions, among them N-methyltransferases (NMTs) involved in caffeine production, defense-related genes, and alkaloid and flavonoid enzymes involved in secondary compound synthesis. Comparative analyses of caffeine NMTs demonstrate that these genes expanded through sequential tandem duplications independently of genes from cacao and tea, suggesting that caffeine in eudicots is of polyphyletic origin.

Lipid transfer proteins in coffee: isolation of Coffea orthologs, Coffea arabica homeologs, expression during coffee fruit development and promoter analysis in transgenic tobacco plants.

The aim of the present study was to perform a genomic analysis of non-specific lipid-transfer proteins (nsLTPs) in coffee. Several nsLTPs-encoding cDNA and gene sequences were cloned from Coffea arabica and Coffea canephora species. In this work, their analyses revealed that coffee nsLTPs belong to Type II LTP characterized under their mature forms by a molecular weight of around 7.3 kDa, a basic isoelectric points of 8.5 and the presence of typical CXC pattern, with X being an hydrophobic residue facing towards the hydrophobic cavity. Even if several single nucleotide polymorphisms were identified in these nsLTP-coding sequences, 3D predictions showed that they do not have a significant impact on protein functions. Northern blot and RT-qPCR experiments revealed specific expression of Type II nsLTPs-encoding genes in coffee fruits, mainly during the early development of endosperm of both C. arabica and C. canephora. As part of our search for tissue-specific promoters in coffee, an nsLTP promoter region of around 1.2 kb was isolated. It contained several DNA repeats including boxes identified as essential for grain specific expression in other plants. The whole fragment, and a series of 5' deletions, were fused to the reporter gene ß-glucuronidase (uidA) and analyzed in transgenic Nicotiana tabacum plants. Histochemical and fluorimetric GUS assays showed that the shorter (345 bp) and medium (827 bp) fragments of nsLTP promoter function as grain-specific promoters in transgenic tobacco plants.

An EST-based analysis identifies new genes and reveals distinctive gene expression features of Coffea arabica and Coffea canephora.

BACKGROUND: Coffee is one of the world's most important crops; it is consumed worldwide and plays a significant role in the economy of producing countries. Coffea arabica and C. canephora are responsible for 70 and 30% of commercial production, respectively. C. arabica is an allotetraploid from a recent hybridization of the diploid species, C. canephora and C. eugenioides. C. arabica has lower genetic diversity and results in a higher quality beverage than C. canephora. Research initiatives have been launched to produce genomic and transcriptomic data about Coffea spp. as a strategy to improve breeding efficiency. RESULTS: Assembling the expressed sequence tags (ESTs) of C. arabica and C. canephora produced by the Brazilian Coffee Genome Project and the Nestlé-Cornell Consortium revealed 32,007 clusters of C. arabica and 16,665 clusters of C. canephora. We detected different GC3 profiles between these species that are related to their genome structure and mating system. BLAST analysis revealed similarities between coffee and grape (Vitis vinifera) genes. Using KA/KS analysis, we identified coffee genes under purifying and positive selection. Protein domain and gene ontology analyses suggested differences between Coffea spp. data, mainly in relation to complex sugar synthases and nucleotide binding proteins. OrthoMCL was used to identify specific and prevalent coffee protein families when compared to five other plant species. Among the interesting families annotated are new cystatins, glycine-rich proteins and RALF-like peptides. Hierarchical clustering was used to independently group C. arabica and C. canephora expression clusters according to expression data extracted from EST libraries, resulting in the identification of differentially expressed genes. Based on these results, we emphasize gene annotation and discuss plant defenses, abiotic stress and cup quality-related functional categories. CONCLUSION: We present the first comprehensive genome-wide transcript profile study of C. arabica and C. canephora, which can be freely assessed by the scientific community at http://www.lge.ibi.unicamp.br/coffea. Our data reveal the presence of species-specific/prevalent genes in coffee that may help to explain particular characteristics of these two crops. The identification of differentially expressed transcripts offers a starting point for the correlation between gene expression profiles and Coffea spp. developmental traits, providing valuable insights for coffee breeding and biotechnology, especially concerning sugar metabolism and stress tolerance.

Post-secretory events alter the peptide content of the skin secretion of Hypsiboas raniceps.

A novel family of antimicrobial peptides, named raniseptins, has been characterized from the skin secretion of the anuran Hypsiboas raniceps. Nine cDNA molecules have been successfully cloned, sequenced, and their respective polypeptides were characterized by mass spectrometry and Edman degradation. The encoded precursors share structural similarities with the dermaseptin prepropeptides from the Phyllomedusinae subfamily and the mature 28-29 residue long peptides undergo further proteolytic cleavage in the crude secretion yielding consistent fragments of 14-15 residues. The biological assays performed demonstrated that the Rsp-1 peptide has antimicrobial activity against different bacterial strains without significant lytic effect against human erythrocytes, whereas the peptide fragments generated by endoproteolysis show limited antibiotic potency. MALDI imaging mass spectrometry in situ studies have demonstrated that the mature raniseptin peptides are in fact secreted as intact molecules within a defined glandular domain of the dorsal skin, challenging the physiological role of the observed raniseptin fragments, identified only as part of the crude secretion. In this sense, stored and secreted antimicrobial peptides may confer distinct protective roles to the frog.