Aluminium Uptake and Translocation in Al Hyperaccumulator Rumex obtusifolius Is Affected by Low-Molecular-Weight Organic Acids Content and Soil pH

Abstract

Background and AimsHigh Al resistance of Rumex obtusifolius together with its ability to accumulate Al has never been studied in weakly acidic conditions (pH > 5.8) and is not sufficiently described in real soil conditions. The potential elucidation of the role of organic acids in plant can explain the Al tolerance mechanism.MethodsWe established a pot experiment with R. obtusifolius planted in slightly acidic and alkaline soils. For the manipulation of Al availability, both soils were untreated and treated by lime and superphosphate. We determined mobile Al concentrations in soils and concentrations of Al and organic acids in organs.ResultsAl availability correlated positively to the extraction of organic acids (citric acid < oxalic acid) in soils. Monovalent Al cations were the most abundant mobile Al forms with positive charge in soils. Liming and superphosphate application were ambiguous measures for changing Al mobility in soils. Elevated transport of total Al from belowground organs into leaves was recorded in both lime-treated soils and in superphosphate-treated alkaline soil as a result of sufficient amount of Ca available from soil solution as well as from superphosphate that can probably modify distribution of total Al in R. obtusifolius as a representative of “oxalate plants.” The highest concentrations of Al and organic acids were recorded in the leaves, followed by the stem and belowground organ infusions.ConclusionsIn alkaline soil, R. obtusifolius is an Al-hyperaccumulator with the highest concentrations of oxalate in leaves, of malate in stems, and of citrate in belowground organs. These organic acids form strong complexes with Al that can play a key role in internal Al tolerance but the used methods did not allow us to distinguish the proportion of total Al-organic complexes to the free organic acids.

Bacterial Isolate Inhabiting Spitsbergen Soil Modifies the Physiological Response of Phaseolus coccineus in Control Conditions and under Exogenous Application of Methyl Jasmonate and Copper Excess

“…We detected generally higher LMWOA concentrations in the leaves than the roots, with the exception of tartrate [55]. Thus, the tendency was analogical in the case of malate, citrate, and succinate, which stays in line with earlier statements [21,39].…”

Effect of difference between day and night temperature on tomato (Lycopersicon esculentum Mill.) root activity and low molecular weight organic acid secretion

“…Previous studies showed that rice roots mainly secreted tartaric acid, while wheat roots mainly secreted oxalic acid, propionic acid and acetic acid (Cieśliński et al 1998). Roots of the aluminum (Al) hyperaccumulator bitter dock (Rumex obtusifolius L.) mainly secreted citric acid, which forms a stable complex with aluminum, thereby reducing the activity of aluminum ion (Vondráčková et al 2015).…”

Distribution Of Micro (Fe, Zn, Cu, and Mn) and Risk (Al, As, Cr, Ni, Pb, and Cd) Elements in the Organs of R. Alpinus L.

“…Hence, the plant can absorb and transport metals and store them in their senescent (above-ground biomass), the declining part (Baker 1981, Lorestani et al 2011). In connection with the results of Vondráčková et al (2015), where R. obtusifolius is a hyperaccumulator of Al, we expected a similar strategy with R. alpinus. However, the results showed that R. alpinus is an excluder of Al and can exudate chelating ligands, form a pH barrier at the rhizosphere, cell wall immobilization, and selective permeability of the plasma membrane.…”