Halophyte ion regulation traits support saline adaptation of Lepidium latifolium, L. draba, and L. alyssoides

Abstract

Identification of saline resistance traits of invasive plants has received little study and could reveal how some plant species utilize salt to encroach upon salinized landscapes. We conducted a 3-mo greenhouse study to identify saline resistance mechanisms of three North American invasive Brassicaceae species, Lepidium latifolium, L. draba, and L. alyssoides, in response to increasing salinity. Seedlings of central and southern New Mexico, USA populations were exposed to NaCl irrigation solutions at 0, − 0.1, and − 0.2 MPa (0, 24, and 48 mM, respectively). Saline resistance of these populations was attributable to salt tolerance behavior commonly observed as signature traits of halophytes, including a combined Na and Cl accumulation in leaves of up to 13% of dry weight with no injury, dominance of leaves as the salt accumulation site, leaf tissue water Na and Cl at ≈ 300–400 mM, leaf K:Na molar ratio of less than 1, and the development of leaf succulence. In saline environments, high salt loads in shoots may increase soil salinity through annual litter fall and potentially alter vegetation community structure. A broader implication of this study is in the need to detect salt resistant traits of additional plant species to broaden the narrow understanding of how salinity affects vegetation communities.