RESEARCH-PGR: Transdisciplinary Comparative Analyses of Halophytic and Glycophytic Grasses to Reveal Novel Mechanisms of Salt Tolerance

土壤盐碱化是世界范围内一个日益严重的问题，极大地限制了作物产量。大多数农作物对盐敏感(糖类植物)，提高耐盐性的育种取得的成功有限。然而，一小部分开花植物可以在盐分条件下完成它们的生活史，被认为是盐生植物。一些盐生植物与对盐敏感的作物关系密切，研究糖类作物与其盐生近缘植物在遗传、形态、生理和生化方面的差异可能会发现新的机制，可用于提高作物的耐盐性。此外，据推测，与盐生植物相关的糖分物种可能已经具备了耐盐性所需的大部分基本机制。该项目将侧重于盐生草坪草海滨雀麦和结缕草，它们的叶片适应能力使植物能够隔离和/或排泄盐，以及它们对盐敏感的近亲高粱和指谷，这两种谷类作物。了解盐生植物盐适应背后的遗传学，最终将在提高耐盐性的育种中得到应用。此外，该项目将被用作培训研究生和本科生的工具，并向6-12年级的学生介绍基于探究的学习，并向他们灌输对植物科学的热情。该项目建立在初步研究结果的基础上，这些研究确定了叶表面的结构适应性以及存在新的硫化多糖作为盐生草本植物海滨雀麦的标志。该项目结合元素图谱、MALDI-MS成像和生化、生理和遗传分析，旨在研究(1)硫酸盐是否对盐生植物在高盐条件下的生长是必需的；(2)离子(如Na、K)和含硫化合物是否在盐生植物和糖类植物中差异积累；(3)硫酸多糖的组成和生物合成途径；(4)叶片适应在盐生植物耐盐性中的作用；以及(5)参与这些结构和生化适应的基因。分类组内盐生植物和糖类近缘植物之间的比较分析代表了一种识别导致耐盐性的特征的新方法。这一奖项反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。

Soil salinity is an increasing problem worldwide, and greatly limits crop production. Most crop plants are salt sensitive (glycophytes), and breeding for improved salt tolerance has met with limited success. A small percentage of flowering plants, however, can complete their life cycle under saline conditions, and are considered halophytes. Some halophytes are closely related to salt-sensitive crop plants and an investigation of the genetic, morphological, physiological and biochemical differences between glycophytic crops and their halophytic relatives may identify novel mechanisms that can be used to increase the salt tolerance of crops. Furthermore, it has been hypothesized that glycophytic species related to halophytes may already have most of the basic machinery needed for salt tolerance. This project will focus on the halophytic turfgrasses seashore paspalum and zoysiagrass, which have leaf adaptations that allow plants to sequester and/or excrete salt, and their salt-sensitive relatives sorghum and finger millet, two cereal crops. Understanding the genetics behind salt-adaptations in halophytes will ultimately find applications in breeding for enhanced salt tolerance. Furthermore, the project will be used as a vehicle to train graduate and undergraduate students, and to introduce 6-12 graders to inquiry-based learning and instill in them a passion for plant science. The project builds on the results of preliminary studies that identified structural adaptations on the leaf surface as well as the presence of novel sulfated glycans as hallmarks of the halophytic grass seashore paspalum (Paspalum vaginatum). Combining element mapping, MALDI-mass spectrometry imaging, and biochemical, physiological and genetic analyses in halophytic and glycophytic grasses belonging to two taxonomic groups, the Panicoideae and Chloridoidea, the project aims to investigate (1) whether sulfate is essential to halophytic growth under high salt; (2) whether ions (e.g. Na+, K+) and sulfur-containing compounds accumulate differentially in halophytes and glycophytes; (3) the composition and biosynthetic route of sulfated glycan; (4) the role of leaf adaptations in salt tolerance of halophytes; and (5) the genes involved in these structural and biochemical adaptations. The comparative analyses between halophytes and glycophytic relatives within taxonomic groups represent a novel approach to identify traits that contribute to salt tolerance.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.