US EPA

4293005 

Journal Article 

Physiological and molecular mechanisms mediating xylem Na+loading in barley in the context of salinity stress tolerance 

Zhu, M; Zhou, M; Shabala, L; Shabala, S 

2017 

1 

Plant, Cell and Environment
ISSN: 0140-7791
EISSN: 1365-3040 

40 

7 

1009-1020 

English 

26881809 

10.1111/pce.12727 

WOS:000402737300003 

Time-dependent kinetics of xylem Na+loading was investigated using a large number of barley genotypes contrasting in their salinity tolerance. Salt-sensitive varieties were less efficient in controlling xylem Na+loading and showed a gradual increase in the xylem Na+content over the time. To understand underlying ionic and molecular mechanisms, net fluxes of Ca2+, K+and Na+were measured from the xylem parenchyma tissue in response to H2O2and ABA; both of them associated with salinity stress signalling. Our results indicate that NADPH oxidase-mediated apoplastic H2O2production acts upstream of the xylem Na+loading and is causally related to ROS-inducible Ca2+uptake systems in the root stelar tissue. It was also found that ABA regulates (directly or indirectly) the process of Na+retrieval from the xylem and the significant reduction of Na+and K+fluxes induced by bumetanide are indicative of a major role of chloride cation co-transporter (CCC) on xylem ion loading. Transcript levels of HvHKT1;5_like and HvSOS1_like genes in the root stele were observed to decrease after salt stress, while there was an increase in HvSKOR_like gene, indicating that these ion transporters are involved in primary Na+/K+movement into/out of xylem.