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

冻害会造成严重的农作物损失，特别是在不可预测的晚霜或早霜之后。因此，植物性状的鉴定将导致更好的耐霜性，对农业非常重要。当细胞外结冰时，由于细胞外的水被吸出细胞，以及在冻融循环中细胞膜破裂，冷冻通过干燥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耐寒性，这是一种由秋季典型的低温引发的转录和新陈代谢调节计划。转录学研究表明，细胞壁重塑可能在冷驯化中发挥重要作用，尽管到目前为止还没有人关注这一点。这个项目试图了解细胞壁的变化如何提高植物耐受冰冻温度的能力。首席主管的实验室最近发现了一种基因(对冷冻敏感-8；SFr8)，它通过促进植物细胞壁的修改来提高耐寒性。通过对SFr8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提高抗冻性。在确定了在冷冻过程中有潜在益处的基因时，这些基因将在拟南芥中过表达，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的方法，检查细胞壁的物理和生化性质，以及它与冰核和细胞周围冰传播的关系。该项目还将研究细胞壁的性质如何影响细胞脱水，这是冰冻破坏的后果之一。在这个项目中，学生将获得广泛的分子、生理、生化和成像技术方面的经验。在细胞壁特征发生改变的突变拟南芥植物中，将使用定量电解质渗漏分析来测试其抗冻性，而在对冷冻敏感和耐寒的植物中，将使用原子力显微镜来测量细胞壁弹性。将使用红外线视频热像仪跟踪植物组织内的冰核形成和传播。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)，并将测量气孔导度，以构建细胞壁如何影响保卫细胞关闭和脱水耐受性的图景(Anne Borland教授，纽卡斯尔)。通过使用qRT-PCR和使用碳水化合物微阵列(William Willats教授，纽卡斯尔)来表征冷上调的细胞壁基因，将建立野生类型植物在低温驯化期间发生的细胞壁成分变化的概况。这种获得全面细胞壁多糖图谱的高通量方法使用一组单抗来探测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生涯中的广泛未来机会提供一个极好的平台。

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.