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Gene transcripts responsive to drought stress identified in Citrus macrophylla bark tissue transcriptome have a modified response in plants infected by Citrus tristeza virus

Publication . da Silva, Melina; Pinto, Patricia IS; Guerra, Rui Manuel Farinha das Neves; Duarte, Amilcar; Power, Deborah; Marques, N T.

Citrus macrophylla Wester (CM) has valuable agronomic characteristics such as the ability to grow in saline soils, although with low tolerance to prolonged drought stress (DS). To understand the mechanisms that characterize CM response to water scarcity, this study compared transcriptome profile changes in CM stem tissue when exposed to DS and identified a total of 2745 differentially expressed transcripts (DETs, fold change > 2), of which 631 were up-regulated and 2114 were down-regulated. DETs up-regulated by DS were enriched in pathways such as the redox and osmotic system or soluble carbohydrates and in transcripts for low molecular weight proteins such as late embryogenesis abundant protein (LEA). Down-regulated transcripts were mainly assigned to photosynthesis, transport, phenylpropanoids, calcium dependent kinases, brassinosteroids and other hormones including salicylic acid and abscisic acid. To assess the interplay between DS and Citrus tristeza virus (CTV) infection, twelve genes were profiled by quantitative Real-Time PCR (qPCR) analysis in control and CTV-infected CM plants, with or without DS. The twelve analyzed transcripts were significantly correlated (r = 0.82, p < 0.001) with the RNA-Seq results and gave insight into the responses of CM to drought and/or to infection with CTV. Transcriptome results unveiled highly responsive genes to DS in stem tissue, which may be candidates for genetic selection of high drought tolerant plants of CM.

2023-01Journal article

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Nitrogen uptake kinetics of an enteric methane inhibitor, the red seaweed Asparagopsis armata

Publication . Torres, Raquel; Mata, Leonardo; Santos, Rui; Alexandre, Ana

The use of red seaweeds of the genus Asparagopsis as a feed ingredient drastically decreases the enteric methane production by ruminant livestock, thereby reducing the environmental impact of this industry. To address the world demand for Asparagopsis mass production, it is essential to understand the species nutrition. In this study, we evaluated for the first time the uptake kinetics of inorganic and organic nitrogen forms of the tetrasporophyte of Asparagopsis armata, to identify the different uptake phases (surge and internally controlled) and to reveal the species preferential nitrogen sources. The time course of nitrogen uptake rates was followed, and the preferential nitrogen sources were assessed in choice-uptake experiments through the incorporation of (15) N-labelled ammonium, nitrate and amino acids. As expected, the short-term, surge uptake rates were much higher than the stabilized internally controlled uptake rates. Ammonium was the preferred form during the internally controlled phase but surprisingly, the surge uptake rates of amino acids were much higher than those of inorganic forms. The importance of amino acids for A. armata nutrition was further supported by its internally controlled uptake rates that where higher than those of nitrate. Ammonium is, thus, the main nitrogen form for the species nutrition, but pulses of organic nitrogen may be considered in the mass production of Asparagopsis for the enteric methane inhibition of the livestock industry.

2021Journal article

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Competition for nitrogen between the seaweed Caulerpa prolifera and the seagrass Cymodocea nodosa

Publication . Alexandre, Ana; Santos, Rui

The rhizophytic seaweed Caulerpa prolifera has been expanding rapidly in the Ria Formosa lagoon, southern Portugal, taking over deeper unvegetated areas and mixing with the native seagrass Cymodocea nodosa in shallower areas. In the Ria Formosa lagoon, belowground ammonium uptake from the sediment represents the main source of nitrogen for the 2 macrophytes, except during the ammonium pulses from the sediment to the water column that are incorporated through aboveground plant parts. We examined the competition for inorganic and organic nitrogen between C. prolifera and C. nodosa through a series of N-15-ammonium and N-15-amino acid surge uptake experiments combining single-species and mixed incubations at a range of nutrient concentrations. Our results showed that C. prolifera is generally faster than C. nodosa in the acquisition of ammonium and amino acids by both above- and belowground parts, and that the uptake rates of ammonium and amino acids of one species were not affected by the presence of the other species. The exception was the amino acid uptake through the rhizoids of C. prolifera, which was slightly enhanced in the presence of C. nodosa. In this situation, the aboveground ammonium uptake becomes the main contributor to the nitrogen budget of C. nodosa but not to that of C. prolifera. When ammonium pulses are considered, C. nodosa is more competitive for nitrogen than C. prolifera. In this case, the leaf uptake of ammonium is the largest contributor to the total nitrogen (ammonium plus amino acids) budget of the seagrass. Our results showed that the different nutritional strategies of the 2 macrophytes allow their coexistence in the Ria Formosa lagoon.

2020-08Journal article

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Proteome dataset of sea bass (Dicentrarchus labrax) skin-scales exposed to fluoxetine and estradiol

Publication . L, Anjos; PI Pinto, PPinto; Santos, Soraia; Estêvão, M. Dulce; Santa, Cátia; Manadas, Bruno; Canario, A.V.M.; Power, Deborah

Contamination of aquatic ecosystems with anthropogenic pollutants, including pharmaceutical drugs, is a major concern worldwide. Aquatic organisms such as fish are particularly at risk of exposure to pollutants. The surface of fish is the first point of contact with pollutants, but few studies have considered the impact of pollutants on the skin-scale barrier. The present proteome data are the basis of the findings discussed in the associated research article "Proteomics of sea bass skin-scales exposed to the emerging pollutant fluoxetine compared to estradiol" [1]. Juvenile sea bass were exposed by intraperitoneal injections to: a) the antidepressant fluoxetine (FLX), a widely prescribed psychotropic drug and an emerging pollutant; b) the natural estrogen 17 beta-estradiol (E2) and c) the vehicle, coconut oil (control). The scale proteome of fish exposed to these compounds for 5 days was analysed using quantitative label-free proteomics technology SWATH-MS (sequential windowed data-independent a cquisition of the total high-resolution-mass spectra). The proteome data generated was submitted to the ProteomeXchange Consortium via the PRIDE partner repository with the dataset identifier PXD020983. LC-MS data from pooled protein extracts from the scales of all experimental groups was acquired using information-dependent acquisition (IDA) and 1,254 proteins were identified by searching against the sea bass genome database. 715 proteins were quantified by SWATH acquisition, and 213 proteins had modified levels (p < 0.05) between the E2- or FLX-exposed fish compared to the control. The main biological processes and KEGG pathways affected by E2 or FLX treatments were identified using Cytoscape/ClueGO enrichment analyses. (c) 2022 The Authors. Published by Elsevier Inc. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/)

2022-04Journal article

Open Access