Plant salt tolerance relies on a coordinated functioning of different tissues and organs. Salinity tissue tolerance is one of the key traits that confer plant adaptation to saline environment. This trait implies maintenance low cytosolic Na⁺/K⁺ ratio in metabolically active cellular compartments. In this study, we used Nitraria sibirica Pall., a perennial woody halophyte species, to understand the mechanistic basis of its salinity tissue tolerance. The results showed that the growth of seedlings was stimulated by 100-200 mM NaCl treatment. The ions distribution analysis showed that the leaves act as an Na⁺ sink, while the plant roots possess superior K⁺ retention. The excessive Na⁺ absorbed from the soil was mainly transported to the shoot and was eventually sequestrated into mesophyll vacuoles in the leaves. As a result, N. sibirica could keep the optimal balance of K⁺/Na⁺ at a tissue- and cell-specific level under saline condition. To enable this, N. sibirica increased both vacuolar H+-ATPase and H+-PPase enzymes activities and up-regulated the expressions of NsVHA, NsVP1 and NsNHX1 genes. Vacuolar Na⁺ sequestration in the leaf mesophyll, mediated by NsVHA, NsVP1 and NsNHX1, reduced the Na⁺ concentration in cytosol and inhibited further K⁺ loss. Meanwhile, N. sibirica enhanced the Two Pore K⁺ expression at the transcriptional level to promote K⁺ efflux from vacuole into cytoplasm, assisting in maintaining cytosolic K⁺ homeostasis. It is concluded that the tissue tolerance traits such as vacuolar Na⁺ sequestration and intracellular K⁺ homeostasis are critical to confer adaptation of N. sibirica to soil salinity.

Item Type:	Refereed Article
Keywords:	salinity, sodium sequestration, potassium homeostasis, K+/Na+ homeostasis, salt stress, tissue-specific ions distribution
Research Division:	Biological Sciences
Research Group:	Plant biology
Research Field:	Plant physiology
Objective Division:	Plant Production and Plant Primary Products
Objective Group:	Forestry
Objective Field:	Hardwood plantations
UTAS Author:	Shabala, S (Professor Sergey Shabala)
ID Code:	147851
Year Published:	2020
Web of Science® Times Cited:	12
Deposited By:	Agriculture and Food Systems
Deposited On:	2021-11-18
Last Modified:	2022-04-22
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