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.
