title: Salt tolerance in soybean WF-7 is partially regulated by ABA and ROS signaling and involves withholding toxic Cl- ions from aerial tissues.
abstract: Salt tolerance in plants is a complex trait involving multiple mechanisms. Understanding these mechanisms and their regulation will assist in developing novel strategies to engineer salt-tolerant crops. In the current study, we investigated salt-tolerant mechanisms in soybean (Glycine max) cultivar WF-7 in comparison to salt-sensitive Union. In vivo and in vitro salt assays demonstrated the salt tolerance of WF-7 at the seedling stage and during germination. After a 10-day 200 mM NaCl treatment, chlorophyll content in Union was reduced by 50 % compared to a 17 % reduction in WF-7. WF-7 was also less affected by abscisic acid (ABA) and NaCl during germination than Union. Upon ABA and NaCl treatment, the ABA-responsive genes SCOF1, ASN1, bZIP44, and AAPK1 are differentially expressed in WF-7 and Union seedlings. These results suggest that salt tolerance in WF-7 is in part regulated through an ABA-dependent pathway. In addition, following a 4-day 200 mM NaCl treatment, WF-7 produced more H₂O₂ than Union indicating the involvement of reactive oxygen species (ROS) in regulating salt tolerance in WF-7. Yet another mechanism WF-7 employs is withholding toxic chloride (Cl⁻) ions from aerial tissues. Following 200 mM NaCl treatment, Cl⁻ accumulation was mostly localized to the roots of WF-7. In contrast, most of the Cl⁻ in Union was transported into the stems and leaves. Taken together, our results demonstrated a role of ABA and ROS in regulating salt tolerance in WF-7, and the critical role of Cl⁻ in NaCl-induced mortality in soybean. Key message Withholding toxic Cl⁻ ions from leaves and, to a lesser extent, stems, confers salt tolerance to soybean WF-7. In addition, ABA and ROS may be involved in salt-stress signal transduction.
authors.affiliation: Agricultural Research Station, Virginia State University, Petersburg, VA 23806, USA. sren@vsu.edu
authors.forename: Shuxin
authors.initials: S
authors.lastname: Ren
authors.forename: Sarah
authors.initials: S
authors.lastname: Weeda
authors.forename: Haiwen
authors.initials: H
authors.lastname: Li
authors.forename: Brodie
authors.initials: B
authors.lastname: Whitehead
authors.forename: Yangdong
authors.initials: Y
authors.lastname: Guo
authors.forename: Asmare
authors.initials: A
authors.lastname: Atalay
authors.forename: John
authors.initials: J
authors.lastname: Parry
mesh_terms: D000040:Abscisic Acid / Q000378:metabolism* / Q000494:pharmacology; D001681:Biological Assay; D002712:Chlorides / Q000633:toxicity*; D002734:Chlorophyll / Q000378:metabolism; D020869:Gene Expression Profiling; D018506:Gene Expression Regulation, Plant / Q000187:drug effects; D018525:Germination / Q000187:drug effects; D006861:Hydrogen Peroxide / Q000378:metabolism; D007477:Ions; D009928:Organ Specificity / Q000187:drug effects / Q000235:genetics; D017382:Reactive Oxygen Species / Q000378:metabolism*; D055049:Salt Tolerance / Q000187:drug effects* / Q000235:genetics; D012639:Seeds / Q000187:drug effects / Q000254:growth & development; D015398:Signal Transduction / Q000187:drug effects; D012965:Sodium Chloride / Q000494:pharmacology; D013025:Glycine max / Q000187:drug effects / Q000235:genetics / Q000378:metabolism* / Q000502:physiology*
chemical_list: D002712:Chlorides; D007477:Ions; D017382:Reactive Oxygen Species; D002734:Chlorophyll; D012965:Sodium Chloride; D000040:Abscisic Acid; D006861:Hydrogen Peroxide