Kurmanbayeva Assylay, Brychkova Galina, Bekturova Aizat, Khozin Inna, Standing Dominic, Yarmolinsky Dmitry, Sagi Moshe
French Associates Institute for Agriculture and Biotechnology of Drylands, Blaustein Institutes for Desert Research, Ben-Gurion University, Sede Boqer Campus, P.O.B. 653, Beer Sheva, 84105, Israel.
Plant and AgriBiosciences Research Centre (PABC), School of Natural Sciences, National University of Ireland Galway, University Road, Galway, Ireland.
Methods Mol Biol. 2017;1631:253-271. doi: 10.1007/978-1-4939-7136-7_15.
In response to oxidative stress the biosynthesis of the ROS scavenger, glutathione is induced. This requires the induction of the sulfate reduction pathway for an adequate supply of cysteine, the precursor for glutathione. Cysteine also acts as the sulfur donor for the sulfuration of the molybdenum cofactor, crucial for the last step of ABA biosynthesis. Sulfate and sulfite are, respectively, the precursor and intermediate for cysteine biosynthesis and there is evidence for stress-induced sulfate uptake and further downstream, enhanced sulfite generation by 5'-phosphosulfate (APS) reductase (APR, EC 1.8.99.2) activity. Sulfite reductase (SiR, E.C.1.8.7.1) protects the chloroplast against toxic levels of sulfite by reducing it to sulfide. In case of sulfite accumulation as a result of air pollution or stress-induced premature senescence, such as in extended darkness, sulfite can be oxidized to sulfate by sulfite oxidase. Additionally sulfite can be catalyzed to thiosulfate by sulfurtransferases or to UDP-sulfoquinovose by SQD1, being the first step toward sulfolipid biosynthesis.Determination of total sulfur in plants can be accomplished using many techniques such as ICP-AES, high-frequency induction furnace, high performance ion chromatography, sulfur combustion analysis, and colorimetric titration. Here we describe a total sulfur detection method in plants by elemental analyzer (EA). The used EA method is simple, sensitive, and accurate, and can be applied for the determination of total S content in plants.Sulfate anions in the soil are the main source of sulfur, required for normal growth and development, of plants. Plants take up sulfate ions from the soil, which are then reduced and incorporated into organic matter. Plant sulfate content can be determined by ion chromatography with carbonate eluents.Sulfite is an intermediate in the reductive assimilation of sulfate to the essential amino acids cysteine and methionine, and is cytotoxic above a certain threshold if not rapidly metabolized and can wreak havoc at the cellular and whole plant levels. Plant sulfite content affects carbon and nitrogen homeostasis Therefore, methods capable of determining sulfite levels in plants are of major importance. Here we present two robust laboratory protocols which can be used for sulfite detection in plants.Thiosulfate is an essential sulfur intermediate less toxic than sulfite which is accumulating in plants in response to sulfite accumulation. The complexity of thiosulfate detection is linked to its chemical properties. Here we present a rapid, sensitive, and accurate colorimetric method based on the enzymatic conversion of thiosulfate to thiocyanate.The plant sulfolipid sulfoquinovosyldiacylglycerol (SQDG) accounts for a large fraction of organic sulfur in the biosphere. Aside from sulfur amino acids, SQDG represents a considerable sink for sulfate in plants and is the only sulfur-containing anionic glycerolipid that is found in the photosynthetic membranes of plastids. We present the separation of sulfolipids from other fatty acids in two simple ways: by one- and two-dimensional thin-layer chromatography.
作为对氧化应激的响应,活性氧清除剂谷胱甘肽的生物合成被诱导。这需要诱导硫酸盐还原途径,以充分供应半胱氨酸,即谷胱甘肽的前体。半胱氨酸还作为钼辅因子硫化的硫供体,这对脱落酸生物合成的最后一步至关重要。硫酸盐和亚硫酸盐分别是半胱氨酸生物合成的前体和中间体,有证据表明应激会诱导硫酸盐吸收,并且在更下游,5'-磷酸硫酸酯(APS)还原酶(APR,EC 1.8.99.2)活性会增强亚硫酸盐生成。亚硫酸盐还原酶(SiR,E.C.1.8.7.1)通过将亚硫酸盐还原为硫化物来保护叶绿体免受有毒水平亚硫酸盐的侵害。在由于空气污染或应激诱导的早衰(如长时间黑暗)导致亚硫酸盐积累的情况下,亚硫酸盐可被亚硫酸盐氧化酶氧化为硫酸盐。此外,亚硫酸盐可被硫转移酶催化为硫代硫酸盐,或被SQD1催化为UDP-磺基奎诺糖,这是硫脂生物合成的第一步。植物中总硫的测定可以使用多种技术来完成,如电感耦合等离子体原子发射光谱法(ICP-AES)、高频感应炉、高效离子色谱法、硫燃烧分析法和比色滴定法。在这里,我们描述了一种通过元素分析仪(EA)测定植物中总硫的方法。所使用的EA方法简单、灵敏且准确,可用于测定植物中的总硫含量。土壤中的硫酸根阴离子是植物正常生长发育所需硫的主要来源。植物从土壤中吸收硫酸根离子,然后将其还原并整合到有机物中。植物硫酸盐含量可以通过使用碳酸盐洗脱液的离子色谱法来测定。亚硫酸盐是硫酸盐还原同化生成必需氨基酸半胱氨酸和甲硫氨酸过程中的中间体,如果不迅速代谢,在一定阈值以上具有细胞毒性,并且会在细胞和整个植物水平上造成严重破坏。植物亚硫酸盐含量影响碳和氮的稳态。因此,能够测定植物中亚硫酸盐水平的方法至关重要。在这里,我们提出了两种可靠的实验室方案,可用于植物中亚硫酸盐的检测。硫代硫酸盐是一种必需的硫中间体,毒性比亚硫酸盐小,它会在植物中因亚硫酸盐积累而积累。硫代硫酸盐检测的复杂性与其化学性质有关。在这里,我们提出了一种基于硫代硫酸盐酶促转化为硫氰酸盐的快速、灵敏且准确的比色法。植物硫脂磺基奎诺糖基二酰基甘油(SQDG)在生物圈中占有机硫的很大一部分。除了含硫氨基酸外,SQDG是植物中硫酸盐的一个重要储存库,并且是质体光合膜中发现的唯一含硫阴离子甘油脂。我们介绍了两种简单的方法从其他脂肪酸中分离硫脂:一维和二维薄层色谱法。