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.