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Aquaporins (APQs) belong to the major intrinsic protein superfamily and play a key role in the transport of water and other solutes across cell membranes. Coffea canephora is an evergreen shrub used for making instant coffees. Genome analysis of C. canephora identified 33 putative aquaporin genes assigned to five subfamilies including seven plasma membrane intrinsic proteins (PIP), 9 tonoplast intrinsic proteins (TIP), 11 NOD26-like intrinsic proteins (NIP), 3 small basic intrinsic proteins (SIP), and 3 X intrinsic proteins (XIP). Generally, the AQPs gene structure was conserved within each subfamily, with exon numbers ranging from one to five. The prediction of the aromatic/arginine selectivity filter (ar/R) and Froger's positions indicated a noticeable difference in substrate specificity between subfamilies. Synteny analysis revealed high conservation of aquaporin genes in coffee. In silico expression analysis of the CcAQPs genes indicated that they were differentially expressed in various tissues. Members of CcPIPs and CcTIPs subfamilies were validated by real-time quantitative analysis in leaves of two genotypes of C. canephora with contrasting responses to water deficit (clone 14: drought-tolerant and clone 109A: drought-susceptible). Under severe water deficit, the relative expression of isoforms of both genes decreased in clone 14 compared with that under the irrigated condition, while clone 109A showed comparatively higher mRNA levels, with the exception of CcPIP1;2 in the stress condition. This study was the first to characterize and validate aquaporin genes in C. canephora in response to water deficit, and the findings may provide insights for biotechnological approaches to increase tolerance to drought. [ABSTRACT FROM AUTHOR]

This study evaluated the transcriptional profile of genes related to nitrogen (N) assimilation in coffee plants susceptible and resistant to rust fungi under N sufficiency and N suppression. For this purpose, we inoculated young coffee leaves with Hemileia vastatrix uredospores and collected them at 0, 12, 24 and 48 hours post-inoculation (HPI) to evaluate the relative expressions of genes encoding cytosolic glutamine synthetase (CaGS1), plastid glutamine synthetase (CaGS2), nitrate reductase (CaNR), and asparagine synthetase (CaAS). The genes exhibited distinct patterns of transcriptional modulation for the different genotypes and N nutritional regimes. The resistant genotype (I59) presented high levels of transcription in response to pathogen inoculation for CaNR and CaGS1 genes, evaluated under N sufficiency in the initial moments of infection (12 HPI). The gene CaGS1 also showed a peak at 48 HPI. The susceptible genotype (CV99) showed increased transcript rates of CaNR at 12 and 24 HPI in response to rust inoculation. The transcriptional patterns observed for CV99, under N suppression, were high levels for CaAS and CaGS2 at all post-inoculation times in response to coffee leaf rust disease. In addition, CaGS1 was up-regulated at 48 HPI for CV99. Cultivar I59 showed high transcript levels at 12 HPI for CaAS and peaks at 24 and 48 HPI for CaGS2 in inoculated samples. Consequently, total chlorophyl concentration was influenced by N suppression and by rust infection. Regarding enzyme activities in vitro for glutamine synthetase and CaNR, there was an increase in infected coffee leaves (I59) and under N sufficiency. Moreover, CV99 was modulated in both N nutritional regimes for GS activity in response to rust. Our results indicate that N transport genes trigger a differential modulation between genotypes through the action of rust disease. [ABSTRACT FROM AUTHOR]

Copyright of Colloquium Agrariae is the property of Asociacao Prudentina de Educacao e Cultura (APEC) and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Coffea arabica L. is an important crop in several developing countries. Despite its economic importance, minimal transcriptome data are available for fruit tissues, especially during fruit development where several compounds related to coffee quality are produced. To understand the molecular aspects related to coffee fruit and grain development, we report a large-scale transcriptome analysis of leaf, flower and perisperm fruit tissue development. Illumina sequencing yielded 41,881,572 high-quality filtered reads. De novo assembly generated 65,364 unigenes with an average length of 1,264 bp. A total of 24,548 unigenes were annotated as protein coding genes, including 12,560 full-length sequences. In the annotation process, we identified nine candidate genes related to the biosynthesis of raffinose family oligossacarides (RFOs). These sugars confer osmoprotection and are accumulated during initial fruit development. Four genes from this pathway had their transcriptional pattern validated by quantitative reverse transcription polymerase chain reaction (qRT-PCR). Furthermore, we identified ~24,000 putative target sites for microRNAs (miRNAs) and 134 putative transcriptionally active transposable elements (TE) sequences in our dataset. This C. arabica transcriptomic atlas provides an important step for identifying candidate genes related to several coffee metabolic pathways, especially those related to fruit chemical composition and therefore beverage quality. Our results are the starting point for enhancing our knowledge about the coffee genes that are transcribed during the flowering and initial fruit development stages. [ABSTRACT FROM AUTHOR]

Coffea arabicais the most important agricultural commodity in the world, and salinity is a major threat to its sustainable irrigation. Coffee leaf polysaccharides from plants subjected to salt stress were extracted and the leaves visualized through optical and electron microscopy. Alterations were detected in the monosaccharide composition of the pectin and hemicelluloses, with increases in uronic acid in all fractions. Changes in the polysaccharides were confirmed by HPSEC and FTIR. Moreover, the monolignol content was increased in the final residue, which suggests increased lignin content. The cytoplasm was altered, and the chloroplasts appeared irregular in shape. The arrangement of the stroma lamellae was disordered, and no starch granules were present. It was concluded that leaves ofC. arabicaunder salt stress showed alterations in cell wall polysaccharides, increased monolignol content and structural damage to the cells of the mesophyll. [ABSTRACT FROM AUTHOR]

Abstract: Coffee plants were subjected to heat stress (37°C) and compared with control plants (24°C). Cell wall polysaccharides were extracted using water (W), EDTA (E) and 4M NaOH (H30 and H70). In addition, monolignols were analyzed, and the leaves were observed by microscopy. Plants under heat stress accumulated higher contents of arabinose and galactose in fraction W. Xylose contents were observed to decrease in H30 fractions after the heat stress, whereas galactose and uronic acid increased. H70 fractions from plants exposed to heat stress showed increased xylose contents, whereas the contents of arabinose and glucose decreased. Differences in the molar-mass profiles of polysaccharides were also observed. The primary monolignol contents increased after the heat stress. Structural alterations in palisade cells and ultrastructural damage in chloroplasts were also observed. Our results demonstrate that the chemical profile of coffee cell-wall polymers and structural cell anatomy change under heat stress. [Copyright &y& Elsevier]

Abiotic stresses are among the most important factors that affect food production. One important step to face these environmental challenges is the transcriptional modulation. Quantitative real-time PCR is a rapid, sensitive, and reliable method for the detection of mRNAs and it has become a powerful tool to mitigate plant stress tolerance; however, suitable reference genes are required for data normalization. Reference genes for coffee plants during nitrogen starvation, salinity and heat stress have not yet been reported. We evaluated the expression stability of ten candidate reference genes using geNorm PLUS, NormFinder, and BestKeeper softwares, in plants submitted to nitrogen starvation, salt and heat stress. EF1, EF1α, GAPDH, MDH, and UBQ10 were ranked as the most stable genes in all stresses and software analyses, while RPL39 and RPII were classified as the less reliable references. For reference gene validation, the transcriptional pattern of a Coffea non-symbiotic hemoglobin ( CaHb1) was analyzed using the two new recommended and the most unstable gene references for normalization. The most unstable gene may lead to incorrect interpretation of CaHb1 transcriptional analysis. Here, we recommend two new reference genes in Coffea for use in data normalization in abiotic stresses: MDH and EF1. [ABSTRACT FROM AUTHOR]

Copyright of Genome is the property of Canadian Science Publishing and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Abstract: Galactinol synthase (EC 2.4.1.123; GolS) catalyzes the first step in the synthesis of raffinose family oligosaccharides (RFOs). Their accumulation in response to abiotic stresses implies a role for RFOs in stress adaptation. In this study, the expression patterns of three isoforms of galactinol synthase (CaGolS1-2-3) from Coffea arabica were evaluated in response to water deficit, salinity and heat stress. All CaGolS isoforms were highly expressed in leaves while little to no expression were detected in flower buds, flowers, plagiotropic shoots, roots, endosperm and pericarp of mature fruits. Transcriptional analysis indicated that the genes were differentially regulated under water deficit, high salt and heat stress. CaGolS1 isoform is constitutively expressed in plants under normal growth conditions and was the most responsive during all stress treatments. CaGolS2 is unique among the three isoforms in that it was detected only under severe water deficit and salt stresses. CaGolS3 was primarily expressed under moderate and severe drought. This isoform was induced only at the third day of heat and under high salt stress. The increase in GolS transcription was not reflected into the amount of galactinol in coffee leaves, as specific glycosyltransferases most likely used galactinol to transfer galactose units to higher homologous oligosaccharides, as suggested by the increase of raffinose and stachyose during the stresses. [Copyright &y& Elsevier]