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，鉴定具有较强抗冻性的植物性状对农业具有重要意义。当冰在细胞外形成时，水分从细胞中被抽出，在冻融循环中，通过细胞膜破裂，冷冻会对植物组织造成损害。许多温带植物通过冷驯化来提高它们的抗冻能力，这是一种转录和代谢调节程序，由秋季典型的低正温度触发。转录组学研究表明细胞壁重塑可能在冷适应中起主要作用，尽管迄今为止很少有人关注这一点。该项目旨在了解细胞壁的变化如何提高植物耐受冰冻温度的能力。首席导师的实验室最近发现了一个基因（SENSITIVE-TO-FREEZING-8; SFR8），它通过促进植物细胞壁的修饰来促进抗冻性。本项目旨在通过对sfr8突变体和其他细胞壁突变体的分析，了解细胞壁组成、结构和物理性质的动态变化是如何增强抗冻性的。如果在冷冻过程中发现了潜在的有益基因，这些基因将在拟南芥中过度表达，并分析它们对耐受性和细胞壁特性的影响。该项目将涉及一种多学科方法，检查细胞壁的物理和生化性质及其与细胞周围冰核和冰繁殖的关系。该项目还将研究细胞壁的性质如何影响细胞脱水，这是冷冻损伤的后果之一。在项目期间，学生将获得广泛的分子、生理、生化和成像技术方面的经验。将使用定量电解质泄漏法测试细胞壁特性改变的突变拟南芥植物的抗冻性，同时使用原子力显微镜测量对冷冻敏感和抗冻的植物的细胞壁弹性。植物组织内的冰核和繁殖将使用红外视频热成像技术进行跟踪。该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，以建立细胞壁如何影响保护细胞关闭和干燥耐受性的图片（Anne Borland教授，纽卡斯尔）。通过使用qRT-PCR和碳水化合物微阵列表征冷上调细胞壁基因，将建立野生型植物在冷驯化过程中细胞壁组成变化的特征（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面板来探测CW提取物。这种多学科的培训将为未来广泛的科学研究或以科学为基础的职业提供一个良好的平台。

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.