The ability of halophytes to thrive under saline conditions implies efficient ROS detoxification and signalling. In this work, the causal relationship between key membrane transport processes involved in maintaining plant ionic homeostasis and oxidative stress tolerance was investigated in a succulent perennial halophyte Sarcocornia quinqueflora. The flux responses to oxidative stresses induced by either hydroxyl radicals (OH^•) or hydrogen peroxide (H₂O₂) were governed largely by (1) the type of ROS applied; (2) the tissue-specific origin and function (parenchymatic or chlorenchymatic); and (3) the tissue location in respect to the suberized endodermal barrier. The latter implied significant differences in responses between outer (water storage-WS; palisade tissue-Pa) and inner (internal photosynthetic layer-IP; stele parenchyma-SP) stem tissues. The ability of the cell to retain K⁺ under OH^• stress varied between different tissues and was ranked in the following descending order: WS>Pa>IP>SP. OH^• always led to Ca²⁺ influx in all stem tissues, while treatment with H₂O₂ induced tissue-specific Ca²⁺ "signatures". The inner/outer K⁺ ratio was the highest (~2.6) under the optimum NaCl dosage (200 mM) in comparison to non-saline (~0.4) and severe (800 mM; ~0.7) conditions, implying that a higher K⁺ concentration in the inner tissues is important for optimum growth. The overall results demonstrate a clear link between plant anatomical structure and ability of its tissues to maintain ionic homeostasis, via modulating their ROS sensitivity.

Item Type:	Refereed Article
Keywords:	halophytes, salinity, calcium, ion flux, oxidative stress, perennial halophytes, potassium, reactive oxygen species, salinity stress, succulence, tissue-specificity
Research Division:	Biological Sciences
Research Group:	Plant biology
Research Field:	Plant physiology
Objective Division:	Plant Production and Plant Primary Products
Objective Group:	Other plant production and plant primary products
Objective Field:	Other plant production and plant primary products not elsewhere classified
UTAS Author:	Ahmed, HAI (Dr Hassan Ahmed)
UTAS Author:	Shabala, L (Associate Professor Lana Shabala)
UTAS Author:	Shabala, S (Professor Sergey Shabala)
ID Code:	147611
Year Published:	2021
Web of Science® Times Cited:	3
Deposited By:	TIA - Research Institute
Deposited On:	2021-11-09
Last Modified:	2022-04-14
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