Strontium as a tracer for calcium: uptake, transport and partitioning within tomato plants

Abstract

PurposeCalcium (Ca 2+ ) is a major structural plant nutrient whose low mobility in the phloem causes deleterious nutritional disorders in non-transpiring organs. Since strontium (Sr 2+ ) and Ca 2+ share many chemical properties, Sr 2+ is frequently used as a tracer to study Ca 2+ cycles in ecosystems. However, the level of agreement between Sr 2+ and Ca 2+ distribution pattern in plants is debatable, and several studies have reported toxic effects of Sr 2+ . Therefore, we investigated Sr 2+ and Ca 2+ uptake rates and distribution pattern to determine how reliably Sr 2+ can be used as a tracer of Ca 2+ in tomato plants (Solanum lycopersicum L.). MethodsWe conducted six independent experiments of various duration: from a few hours to several weeks, in hydroponic and perlite substrate. We treated plants with either Ca 2+ or Sr 2+ at equivalent concentrations and monitored their accumulation in shoot and fruits. ResultsUnder short-term exposure (hours), Ca 2+ and Sr 2+ uptake and distribution within the plant were comparable, while the long-term exposure (days and weeks) to 4 mM Sr 2+ reduced transpiration and biomass accumulation. The toxic effect of Sr 2+ was more prominent when growth conditions were favourable. Nonetheless, Sr 2+ accumulated similarly to Ca 2+ in shoot and fruit. Surprisingly, Sr 2+ deposition in tomato fruit cell walls prevented blossom end rot (BER) to the same degree as Ca 2+ . ConclusionSr 2+ can credibly be used as a tracer of Ca 2+ uptake and allocation in the short-term, making Sr 2+ a powerful tool to study the factors governing Ca 2+ allocation to plant organs, primarily fruit Ca 2+ delivery.

High calcium and strontium uptake by the green microalgaTetraselmis chuiis related to micropearl formation and cell growth

“…However, the specific function of these proteins is still not clear. Regarding Sr, it has been shown that many plants incorporate this element following Ca uptake pathways since they are not able to discriminate between these two elements (Drouet & Herbauts, 2008 ; Jovanović et al, 2021 ; Watanabe et al, 2007 ). However, we do not know yet if the import pathways of Sr to the nucleation sites are the same as those of Ca, or if other transport systems presenting high affinities for Sr are involved.…”

Species- and Metal-Specific Responses of the Ionome of Three Duckweed Species under Chromate and Nickel Treatments

“…punctata and Le. minor can explain the higher Sr content in the biomass of this species as well [ 49 ].…”

Calcium nutrition nanoagent rescues tomatoes from mosaic virus disease by accelerating calcium transport and activating antiviral immunity

“…Vacuole deposition of calcium imposes the low mobility in phloem, which causes deleterious nutritional disorders ( Gilliham et al., 2011 ; Kumar et al., 2015 ; Jovanović et al., 2021 ). The first step for the plant uptake of calcium is facilitated by cation exchange in soil, then calcium is transported apoplastically to endodermis, and finally calcium reaches the xylem sap and is translocated via the transpiration stream to aerial plant parts ( Bauer et al., 2011 ; Ghosh et al., 2022 ).…”

“…Deficiency symptoms are usually observed in developing tissues such as young leaves and fruits, due to the low remobilization of calcium from old to young tissues. Symplastic pathway is mainly used for short-distance calcium delivery, and the long-distance translocation is dependent on apoplastic pathway via xylem ( Jovanović et al., 2021 ). Transpiring organs tend to accumulate high calcium levels, and calcium is usually deposited inside the vacuoles or sequestrated into leaf-trichomes to impose calcium phloem immobility, which leads to low calcium levels in young leaves and fruits ( White, 2001 ; Gilliham et al., 2011 ; Kumar et al., 2015 ).…”