The response of the mangrove Avicennia marina to heterogeneous salinity measured using a split-root approach

Hydrogen isotope ratios ((2) H/(1) H, δ(2) H) of leaf waxes covary with those in precipitation and are therefore a useful paleohydrologic proxy. Mangroves are an exception to this relationship because their δ(2) H values are also influenced by salinity. The mechanisms underlying this response were investigated by measuring leaf lipid δ(2) H and leaf and xylem water δ(2) H and δ(18) O values from three mangrove species over 9.5 months in a subtropical Australian estuary. Net (2) H/(1) H fractionation between surface water and leaf lipids decreased by 0.5-1.0‰ ppt(-1) for n-alkanes and 0.4-0.8‰ ppt(-1) for isoprenoids. Xylem water was (2) H depleted relative to surface water, reflecting (2) H discrimination of 4-10‰ during water uptake at all salinities and opportunistic uptake of freshwater at high salinity. However, leaf water (2) H enrichment relative to estuary water was insensitive to salinity and identical for all species. Therefore, variations in leaf and xylem water δ(2) H values cannot explain the salinity-dependent (2) H depletion in leaf lipids, nor the 30‰ range in leaf lipid δ(2) H values among species. Biochemical changes in direct response to salt stress, such as increased compatible solute production or preferential use of stored carbohydrates, and/or the timing of lipid production and subsequent turnover rates, are more likely causes.

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“…; Reef et al . ; Santini et al . ), and foliar uptake of rain or dew (reviewed in Reef & Lovelock ).…”

Section: Discussionmentioning

confidence: 98%

Hydrogen isotope response to changing salinity and rainfall in Australian mangroves

Ladd

Sachs

2015

Plant Cell & Environment

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“…However, mangroves that cope with persistently highly saline soil must continue to spend water for carbon gain. Water uptake (Ball ; Bazihizina et al ; Reef et al ), transport (Sperry et al ; Melcher et al ; Ewers et al ; Lopez‐Portillo et al ; Lovelock et al ) and use (Ball & Farquhar , b; Clough & Sim ; Nguyen et al ) are typically lower in high than low salinities. These characteristics would lead to a higher requirement for leaf water storage for transient water use at high salinity.…”

Section: Introductionmentioning

confidence: 99%

Leaf water storage increases with salinity and aridity in the mangrove Avicennia marina: integration of leaf structure, osmotic adjustment and access to multiple water sources

Nguyen

Meir

Sack

et al. 2017

Plant Cell & Environment

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Leaf structure and water relations were studied in a temperate population of Avicennia marina subsp. australasica along a natural salinity gradient [28 to 49 parts per thousand (ppt)] and compared with two subspecies grown naturally in similar soil salinities to those of subsp. australasica but under different climates: subsp. eucalyptifolia (salinity 30 ppt, wet tropics) and subsp. marina (salinity 46 ppt, arid tropics). Leaf thickness, leaf dry mass per area and water content increased with salinity and aridity. Turgor loss point declined with increase in soil salinity, driven mainly by differences in osmotic potential at full turgor. Nevertheless, a high modulus of elasticity (ε) contributed to maintenance of high cell hydration at turgor loss point. Despite similarity among leaves in leaf water storage capacitance, total leaf water storage increased with increasing salinity and aridity. The time that stored water alone could sustain an evaporation rate of 1 mmol m s ranged from 77 to 126 min from subspecies eucalyptifolia to ssp. marina, respectively. Achieving full leaf hydration or turgor would require water from sources other than the roots, emphasizing the importance of multiple water sources to growth and survival of Avicennia marina across gradients in salinity and aridity.

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“…Plant roots restrict the water uptake from high-salinity area/zone; however, roots increase the water uptake from low-saline area/zone consequently, uptake of water remains unchanged by entire root and even the same mechanism with NO 3 uptake with slight effect (Bazihizina et al, 2009;Flores, Angeles Botella, Martínez & Cerdá, 2002). The mangrove (Avicennia marina L.) seedlings grown in split-root experiment showed preferential freshwater uptake that also increased stomatal conductance (Reef, Markham, Santini & Lovelock, 2015).…”

Section: Hrns and Salinity Stress Approach And Plant Responsesmentioning

confidence: 97%

Exploring half root-stress approach: current knowledge and future prospects

Iqbal

Hussain

Raza

et al. 2019

Plant Production Science

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A half-root stress is a half portion of the root system exposed to treatment while the remaining half portion kept under normal conditions. A half-root stress including half-root drought stress, half-root nutrient stress, and half-root salinity stress has become a general approach to improve plant performance and adaptability. Plants produce some chemical signals in stressed part of root, and other parts sense these signals to improve the acclimation and adaptive responses to environmental stresses. Plants adapt the compensatory functions and discriminate the systemic and local regulatory mechanisms, but the understanding of these mechanisms is controversial. Chemical signals (Abscisic acid, sap pH, cytokinins, content of malate, amino acid, and ureide) have been involved in root to shoot signaling under half-root stress. Furthermore, naturally appeared half-root stress in intercropping systems could be an additional attribute of half-root stress approach. Therefore, much more study is required to elaborate its acceptability in intercropping. In this review, we summarized the current knowledge and identified some key future researches areas regarding half-root stress approach. ARTICLE HISTORY

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The response of the mangrove Avicennia marina to heterogeneous salinity measured using a split-root approach

Cited by 40 publications

References 42 publications

Hydrogen isotope response to changing salinity and rainfall in Australian mangroves

Hydrogen isotope response to changing salinity and rainfall in Australian mangroves

Leaf water storage increases with salinity and aridity in the mangrove Avicennia marina: integration of leaf structure, osmotic adjustment and access to multiple water sources

Exploring half root-stress approach: current knowledge and future prospects

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