Investigating the role of the plant cell wall in crop freezing tolerance.

冻害造成严重的作物损失，特别是在不可预测的晚霜或早霜之后。因此，鉴定将导致更好的抗冻性的植物性状对农业具有重要意义。冷冻通过细胞外形成冰时水分从细胞中抽出而引起的干燥以及通过冻融循环期间细胞膜的破裂而对植物组织造成损害。许多温带植物通过冷驯化来提高其抗冻性，这是一种由秋季典型的低正温度触发的转录和代谢调节程序。转录组学研究表明，细胞壁重塑可能在冷驯化中起着重要作用，但迄今为止对此关注甚少。该项目旨在了解细胞壁的变化如何提高植物耐受冷冻温度的能力。首席主管的实验室最近发现了一个基因（对冷冻敏感的8; SFR 8），它通过促进植物细胞壁的修饰而有助于耐冷冻性。通过对sfr 8突变体和其他细胞壁突变体的分析，本项目旨在了解细胞壁的组成、结构和物理性质的动态变化如何增强抗冻性。在冷冻过程中的潜在利益的基因被确定，这些将在拟南芥中过表达和它们的耐受性和细胞壁特性的影响进行了分析。该项目将涉及多学科方法，研究细胞壁的物理和生化性质及其与细胞周围冰成核和冰传播的关系。该项目还将研究细胞壁的性质如何影响细胞脱水，这是冰冻损害的后果之一。在项目期间，学生将获得广泛的分子，生理，生物化学和成像技术的经验。将使用定量电解质渗漏测定法在具有改变的细胞壁特征的突变拟南芥植物中测试抗冻性，同时将使用原子力显微镜在抗冻敏感和耐受植物中测量细胞壁弹性。冰的成核和植物组织内的传播将使用红外视频热成像跟踪。学生还将评估细胞壁突变体和转基因植物的水分利用效率（WUE），并测量气孔导度，以了解细胞壁如何影响保卫细胞关闭和耐干燥性（纽卡斯尔的Anne Borland教授）。将通过使用qRT-PCR和使用碳水化合物微阵列表征冷上调的细胞壁基因来建立在冷驯化期间野生型植物中发生的细胞壁组成变化的概况（William Willats教授，纽卡斯尔）。这种获得全面细胞壁多糖谱的高通量方法使用单克隆抗体组来探测CW提取物。这种多学科的培训将为科学研究或以科学为基础的职业的广泛的未来机会提供一个很好的平台。

Freezing damage causes severe crop losses, particularly after unpredictably late or early frosts. The identification of plant traits that will lead to better frost tolerance is, therefore, of great importance to agriculture. Freezing causes damage to plant tissues through desiccation as water is drawn out of the cell when ice forms extracellularly and through rupture of cellular membranes during freeze-thaw cycles. Many temperate plants increase their freezing tolerance through cold acclimation, a program of transcriptional and metabolic adjustments triggered by low positive temperatures typical of those that occur during autumn. Transcriptomic studies indicate that cell wall remodelling may play a major role in cold acclimation, though little attention has been focused on this so far. This project seeks to understand how changes in the cell wall may improve the ability of plants to tolerate freezing temperatures. The lead supervisor's laboratory has recently identified a gene (SENSITIVE-TO-FREEZING-8; SFR8) that contributes to freezing tolerance by facilitating modifications to the plant cell wall. Through analysis of the sfr8 mutant and other cell wall mutants, this project aims to understand how dynamic changes in the composition, structure and physical properties of the cell wall may enhance freezing tolerance. Where genes of potential benefit during freezing are identified, these will be overexpressed in Arabidopsis and their effect on tolerance and cell wall properties analysed. The project will involve a multidisciplinary approach that examines the physical and biochemical nature of the cell wall and its relationship with ice nucleation and ice propagation around the cell. The project will also examine how the nature of the cell wall impacts upon cellular dehydration, one of the consequences of freezing damage. During the project the student will gain experience in a wide range of molecular, physiological, biochemical and imaging techniques. Freezing tolerance will be tested in mutant Arabidopsis plants with altered cell wall characteristics using quantitative electrolyte leakage assays, whilst cell wall elasticity will be measured in freezing-sensitive and tolerant plants using Atomic Force Microscopy. Ice nucleation and propagation within plant tissues will be tracked using infra-red video thermography. The student will also assess water use efficiency (WUE) in cell wall mutants and transgenic plants and stomatal conductance will be measured to build a picture of how the cell wall can influence guard cell closure and desiccation tolerance (Prof Anne Borland, Newcastle). A profile of cell wall compositional changes occurring in wild type plants during cold acclimation will be built up by characterising cold-upregulated cell wall genes using qRT-PCR and by using carbohydrate microarrays (Prof William Willats, Newcastle). This high-throughput method of obtaining comprehensive cell wall polysaccharide profiles uses panels of monoclonal antibodies to probe CW extracts. This multi-disciplinary training will provide an excellent platform for a wide range of future opportunities in scientific research or science-based careers.