Specificity and Plasticity of the Functional Ionome of Brassica napus and Triticum aestivum Subjected to Macronutrient Deprivation

Abstract

The composition of the functional ionome was studied in Brassica napus and Triticum aestivum with respect to the response of 20 elements under macronutrient deprivation. Analysis of relative root contents showed that some nutrients, such as Fe, Ni, Cu, Na, V, and Co, were largely sequestered in roots. After 10 days of deprivation of each one of these 6 macronutrients, plant growth was similar to control plants, and this was probably the result of remobilization from roots (Mg and Ca) or old leaves (N, P, K, S). Some tissue concentrations and net nutrient uptakes into roots were either decreased or increased, revealing multiple interactions (93 in wheat, 66 in oilseed rape) that were common to both species (48) or were species specific. While some interactions have been previously described (increased uptake of Na under K deficiency; or increased uptake of Mo and Se under S deficiency), a number of new interactions were found and some key mechanisms underlying their action have been proposed from analysis of Arabidopsis mutants. For example, nitrate uptake seemed to be functionally linked to Na(influx, while the uptake of vanadium was probably mediated by sulfate transporters whose expression was stimulated during S deprivation.

Comparative Omics Analysis of Brassica napus Roots Subjected to Six Individual Macronutrient Deprivations Reveals Deficiency-Specific Genes and Metabolomic Profiles

“…For example, P and S deprivations led to an upregulation of gene sets that encoded their own root transporters, as previously described in different plant species [ 11 , 54 , 55 ], but also a modulation of the expression of genes encoding other ion transporters ( Figure 3 ). This wide-ranging modulation of the gene expression of numerous elemental transporters can be linked to recent studies performed in Brassica napus and Triticum aestivum where nutrient uptake and the element composition of plant tissues were broadly modified in response to a single macronutrient deprivation [ 9 , 11 ]. These generic responses observed in roots of plants subjected to six single macronutrient deprivations could be a consequence of the crucial roles of macronutrients in primary metabolism reported by many authors [ 3 , 12 , 13 ].…”

“…Seeds were germinated on perlite over demineralized water for five days in the dark and then under natural light until the first leaf appearance. At this stage, 10 seedlings were transferred into 10 L plastic containers (400 × 300 × 115 mm), each holding ten seedlings that were exposed to natural light supplemented by high-pressure sodium lamps (HPS 400 Watt, Hortilux Schreder, Monster, Netherlands), which, in combination, attained 350 μmol m −2 s −1 of photosynthetically active radiation for 16 h. As previously described by [ 9 , 10 ], the complete nutrient solution contained: 1 mM KNO 3 , 1.25 mM Ca(NO 3 ) 2 , 0.2 mM KH 2 PO 4 , 0.4 mM MgSO 4 , 0.5 µM NaFe-EDTA, 50 µM NaFe-EDDHA, 10 μM H 3 BO 3 , 3 μM MnSO 4 , 3 μM ZnSO 4 , 0.7 μM CuSO 4 , 0.008 μM (NH 4 ) 6 Mo 7 O 24 , 0.1 μM CoCl 2 , 0.15 μM NiCl 2 , 0.9 mM Si(OH) 4 , 0.5 mM CaCl 2 , 0.1 mM KCl, 0.01 µM Na 2 SeO 4 , 0.1 mM K 2 SO 4 , and 0.2 mM Na 2 SiO 3 buffered to pH 6.8 with 0.36 mM CaCO 3 . The NO 3 − concentration was monitored with nitrate test strips (Macherey-Nagel, Düren, Germany) in order to maintain optimal nutrition conditions.…”

“…In higher plants, severe macronutrient deficiencies are usually associated with phenotypic symptoms [ 3 ] such as leaf chlorosis [ 4 ], root ramification [ 5 ], and, ultimately, reduction in plant growth [ 6 ]. In addition, a single macronutrient deficiency commonly leads to profound alterations in the elemental content of plant tissues, reflecting a modulation of the uptake of several nutrients with a corresponding modification of plant ionomic composition [ 7 , 8 , 9 , 10 ]. While the root uptake of other nutrients is reduced by individual deficiencies in most cases, there are also many instances of increased mineral uptake that result from the numerous crosstalks between nutrients.…”

“…While the root uptake of other nutrients is reduced by individual deficiencies in most cases, there are also many instances of increased mineral uptake that result from the numerous crosstalks between nutrients. For example, S deficiency [ 9 , 10 , 11 ] is associated with an increase in plant contents of molybdenum (Mo), selenium (Se), and vanadium (V) because root sulfate transporters, which are up-regulated under S deficiency, are also able to mediate transport of these structurally similar anions. Contrastingly, one macronutrient deficiency can massively decrease the uptake of another.…”

“…Contrastingly, one macronutrient deficiency can massively decrease the uptake of another. This can be illustrated by N deficiency, which massively decreases sodium (Na) uptake [ 9 ].…”