Nuclear localised more sulphur accumulation1 epigenetically regulates sulphur homeostasis in Arabidopsis thaliana

Sulphur (S) is an essential element for all living organisms. The uptake, assimilation and metabolism of S in plants are well studied. However, the regulation of S homeostasis remains largely unknown. Here, we report on the identification and characterisation of the more sulphur accumulation1 (msa1-1) mutant. The MSA1 protein is localized to the nucleus and is required for both S adenosylmethionine (SAM) production and DNA methylation. Loss of function of the nuclear localised MSA1 leads to a reduction in SAM in roots and a strong S-deficiency response even at ample S supply, causing an over- accumulation of sulphate, sulphite, cysteine and glutathione. Supplementation with SAM suppresses this high S phenotype. Furthermore, mutation of MSA1 affects genome-wide DNA methylation, including the methylation of S-deficiency responsive genes. Elevated S accumulation in msa1-1 requires the increased expression of the sulphate transporter genes SULTR1;1 and SULTR1;2 which are also differentially methylated in msa1-1. Our results suggest a novel function for MSA1 in the nucleus in regulating SAM biosynthesis and maintaining S homeostasis epigenetically via DNA methylation

Methanogenic activity and biomass in Holocene permafrost deposits of the Lena Delta, Siberian Arctic and its implication for the global methane budget

Permafrost environments within the Siberian Arctic are natural sources of the climate relevant trace gas methane. In order to improve our understanding of the present and future carbon dynamics in high latitudes, we studied the methane concentration, the quantity and quality of organic matter, and the activity and biomass of the methanogenic community in permafrost deposits. For these investigations a permafrost core of Holocene age was drilled in the Lena Delta (72°22′N, 126°28′E). The organic carbon of the permafrost sediments varied between 0.6% and 4.9% and was characterized by an increasing humification index with permafrost depth. A high CH4 concentration was found in the upper 4 m of the deposits, which correlates well with the methanogenic activity and archaeal biomass (expressed as PLEL concentration). Even the incubation of core material at −3 and −6°C with and without substrates showed a significant CH4 production (range: 0.04–0.78 nmol CH4 h−1 g−1). The results indicated that the methane in Holocene permafrost deposits of the Lena Delta originated from modern methanogenesis by cold-adapted methanogenic archaea. Microbial generated methane in permafrost sediments is so far an underestimated factor for the future climate development

The Interplay between Sulfur and Iron Nutrition in Tomato

12siFree full-text sul sito dell'editore e su PubMed CentralreservedPlant response mechanisms to deficiency of a single nutrient, such as sulfur (S) or iron (Fe), have been described at agronomic, physiological, biochemical, metabolomics, and transcriptomic levels. However, agroecosystems are often characterized by different scenarios, in which combined nutrient deficiencies are likely to occur. Soils are becoming depleted for S, whereas Fe, although highly abundant in the soil, is poorly available for uptake because of its insolubility in the soil matrix. To this end, earlier reports showed that a limited S availability reduces Fe uptake and that Fe deficiency results in the modulation of sulfate uptake and assimilation. However, the mechanistic basis of this interaction remains largely unknown. Metabolite profiling of tomato (Solanum lycopersicum) shoots and roots from plants exposed to Fe, S, and combined Fe and S deficiency was performed to improve the understanding of the S-Fe interaction through the identification of the main players in the considered pathways. Distinct changes were revealed under the different nutritional conditions. Furthermore, we investigated the development of the Fe deficiency response through the analysis of expression of ferric chelate reductase, iron-regulated transporter, and putative transcription factor genes and plant sulfate uptake and mobilization capacity by analyzing the expression of genes encoding sulfate transporters (STs) of groups 1, 2, and 4 (SlST1.1, SlST1.2, SlST2.1, SlST2.2, and SlST4.1). We identified a high degree of common and even synergistic response patterns as well as nutrient-specific responses. The results are discussed in the context of current models of nutrient deficiency responses in crop plants. © 2015 American Society of Plant Biologists. All rights reserved.mixedZuchi S; Watanabe M; Hubberten HM; Bromke M; Osorio S; Fernie AR; Celletti S; Paolacci AR; Catarcione G; Ciaffi M; Hoefgen R; Astolfi SZuchi, S; Watanabe, M; Hubberten, Hm; Bromke, M; Osorio, S; Fernie, Ar; Celletti, S; Paolacci, Ar; Catarcione, G; Ciaffi, M; Hoefgen, R; Astolfi,