Implications for plant breeding
Most of our knowledge of the genetic and physiological underpinnings of salt tolerance comes from crop species and plant model species that are generally not salt tolerant, with limited studies of highly salt-tolerant plant species. Additionally, studies on the genetic basis of salt tolerance in halophytes have been limited to a small number of species, few of which are grasses (Fan, 2020; Mishra & Tanna, 2017). This is problematic because soil salinity affects agricultural fields worldwide, and breeding for increased tolerance in cereal crops, which are all grasses, has been slow. Understanding the mechanisms and genes involved in salt tolerance in halophytic grass species may allow us to transfer that knowledge to develop more salt tolerant cereals. Our finding that salt tolerance in the wild may be associated with whole-genome dosage effects indicates that a single gene approach may be insufficient and that changes to copy number or expression of multiple interacting genes and pathways may be the key to improving crop salt tolerance.
Breeding programs for seashore paspalum turfgrass have been hampered by the lack of genetic diversity in publicly available germplasm, as confirmed in this study. The apparent presence of natural crosses between fine and coarse-textured ecotypes points to the possibility of introgression of useful traits from coarse-textured populations. This could provide a valuable source of genetic diversity in turf breeding programs for the genetically depauperate, but more economically relevant, fine-textured ecotypes. Future work to identify these traits and genetic markers associated with them in the coarse-textured ecotypes will be required.