Understanding how the natural environment influences DMSP production by plants

二甲基磺丙酸酯（DMSP）是生物和环境中丰富而重要的化合物，在营养循环、逆境耐受性中起关键作用，是气候活性气体二甲基硫醚（DMS）的主要前体。一些植物产生DMSP，例如米草属植物，它可能是盐沼环境中DMSP的主要生产者-盐沼环境是DMSP/DMS生产的全球热点。事实上，DMSP的生产被认为使植物能够忍受与海岸生长有关的条件。目前，已知很少有植物能制造DMSP， DMSP的确切作用尚不清楚，这是迄今为止没有植物DMSP合成基因被描述的结果。在我们鉴定和批准植物DMSP合成基因的基础上，学生将研究植物如何以及为什么产生DMSP。我们的工作将对更好地评估自然环境中植物对全球DMS和DMSP生产的贡献具有重要意义。评估植物在自然环境中产生DMSP/DMS的情况目前尚不清楚植物何时何地产生DMSP/DMS。因此，学生将评估从诺福克盐沼取样的英国米草属植物的DMSP水平，使用已建立的气相色谱和LCMS技术测量不同组织（根，叶，茎，花序）的DMSP水平。学生还将比较不同的地点，以评估高沼泽环境和低沼泽环境中植物的产量和DMSP/DMS通量。为了验证我们的假设，即植物产生DMSP以耐受环境胁迫，学生将在受控的实验室条件下在存在/不存在不同胁迫的情况下种植模型物种，并评估植物的生长情况（如鲜重/干重，根长），并使用GC测量DMSP水平。学生将首先关注盐和渗透压力，因为我们认为这是影响美国DMSP生产的最重要的压力。氮和硫的影响也将被探讨，因为它们对调节微生物DMSP的产生很重要，因此可能对植物也很重要。确定控制DMSP产生的环境因素我们已经确定了s.anglica中DMSP合成的候选基因，学生将使用qRT-PCR在目标1中收集的样品中测量这些基因的表达。还将在目标2的样品中测量基因表达，以确定非生物应激如何调节DMSP的产生。此外，酶的功能将通过体外测定DMSP合成率的方法进行研究。确定DMSP在植物中的生产范围学生将使用现有的基因组/转录组数据集进行生物信息学分析，以评估DMSP合成基因的分布。根据这些预测，将从其自然环境中取样不同的植物，并评估DMSP的产量。这项工作将包括其他盐沼植物、模式物种和作物，并将确定植物DMSP生产的规模和多样性。学生将参与项目的各个方面，包括实验设计、数据收集、分析和管理。这个项目将为他们提供独立的绝佳机会，并在环境过程的前沿研究的各个方面接受广泛的培训。

Dimethylsulfoniopropionate (DMSP) is an abundant and important compound in biology and the environment, where it has key roles in nutrient cycling, stress tolerance and as the major precursor to the climate-active gas dimethyl sulfide (DMS). Some plants produce DMSP, e.g. Spartina, which is likely the major DMSP producer in saltmarsh environments - global hotspots for DMSP/DMS production. Indeed, DMSP production is thought to allow plants to tolerate conditions associated with growing at the coast. Currently, few plants are known to make DMSP and the precise role of DMSP is unknown - a consequence of no plant DMSP synthesis genes having hitherto been described. Building on our identification and ratification of plant DMSP synthesis genes, the student will study how and why plants produce DMSP. Our work will have important consequences for better evaluating plant contributions to global DMS and DMSP production in the natural environment.Objectives:1. Evaluate plant production of DMSP/DMS in the natural environmentIt is currently unclear when and where plants produce DMSP/DMS. The student will therefore assess DMSP levels in Spartina anglica sampled from Norfolk saltmarshes, measuring DMSP in different tissues (roots, leaves, stems, inflorescence) over an annual season using established GC and LCMS techniques. The student will also compare different sites to assess production and DMSP/DMS flux in plants from high- and low-marsh environments.2. Assess DMSP production in plants grown under controlled environmentsTo test our hypothesis that plants produce DMSP to tolerate environmental stress, the student will grow model species under controlled lab conditions in the presence/absence of different stresses and assess plant growth (e.g. fresh/dry weight, root length) and measure DMSP levels using GC. The student will initially focus on salt and osmotic stress, as we believe these are the most important stresses governing DMSP production in S. anglica. The effects of nitrogen and sulfur will also be explored, as these are important for regulating microbial DMSP production and thus likely important in plants too.3. Determine environmental factors that govern DMSP productionWe have identified candidate DMSP synthesis genes in S. anglica and the student will measure expression of these in the samples collected in Objective 1 using qRT-PCR. Gene expression will also be measured in samples from Objective 2 to determine how abiotic stress regulates DMSP production. Enzyme function will additionally be studied using established in vitro assays to measure DMSP synthesis rates.4. Establish how widespread DMSP production is in plantsThe student will perform bioinformatics analyses using existing genomic/transcriptomic datasets to assess distribution of DMSP synthesis genes. Based on these predictions, diverse plants will be sampled from their natural environments and assessed for DMSP production. This work will include other saltmarsh plants, model species and crops, and will determine the scale and diversity of plant DMSP production. The student will be involved in all aspects of the project including experimental design, data collection, analysis and management. This project will give them excellent opportunities for independence and to receive a broad training in diverse aspects of cutting-edge research on environmental processes.