AUTHOR=Hryvusevich Palina , Navaselsky Ilya , Talkachova Yuliya , Straltsova Darya , Keisham Monika , Viatoshkin Aliaksei , Samokhina Veranika , Smolich Igor , Sokolik Anatoliy , Huang Xin , Yu Min , Bhatla Satish Chander , Demidchik Vadim TITLE=Sodium Influx and Potassium Efflux Currents in Sunflower Root Cells Under High Salinity JOURNAL=Frontiers in Plant Science VOLUME=11 YEAR=2021 URL=https://www.frontiersin.org/journals/plant-science/articles/10.3389/fpls.2020.613936 DOI=10.3389/fpls.2020.613936 ISSN=1664-462X ABSTRACT=

Helianthus annuus L. is an important oilseed crop, which exhibits moderate salt tolerance and can be cultivated in areas affected by salinity. Using patch-clamp electrophysiology, we have characterized Na⁺ influx and K⁺ efflux conductances in protoplasts of salt-tolerant H. annuus L. hybrid KBSH-53 under high salinity. This work demonstrates that the plasma membrane of sunflower root cells has a classic set of ionic conductances dominated by K⁺ outwardly rectifying channels (KORs) and non-selective cation channels (NSCCs). KORs in sunflower show extreme Na⁺ sensitivity at high extracellular [Ca²⁺] that can potentially have a positive adaptive effect under salt stress (decreasing K⁺ loss). Na⁺ influx currents in sunflower roots demonstrate voltage-independent activation, lack time-dependent component, and are sensitive to Gd³⁺. Sunflower Na⁺-permeable NSCCs mediate a much weaker Na⁺ influx currents on the background of physiological levels of Ca²⁺ as compared to other species. This suggests that sunflower NSCCs have greater Ca²⁺ sensitivity. The responses of Na⁺ influx to Ca²⁺ correlates well with protection of sunflower growth by external Ca²⁺ in seedlings treated with NaCl. It can be, thus, hypothesized that NaCl tolerance in sunflower seedling roots is programmed at the ion channel level via their sensitivity to Ca²⁺ and Na⁺.