Root exudation of oxalic acid in Lotus corniculatus in response to aluminum toxicity

Abstract

The objective of this research was to identify the existence of root exudation of organic acid in Lotus corniculatus germplasms subjected to toxic aluminum (Al) levels and investigate the effect of this mechanism on the Al content in the root tissue and in morphological parameters of plant development. Two experiments were performed in nutrient solution to evaluate the Al accumulation and exudation of organic acids, using cultivars INIA Draco and São Gabriel and genotypes UFRGS and UF-T2. The plants were cultivated in Al-free solution, which was applied on the 45th day in half of the pots of each genotype. Root exudation was highly correlated with the reduced accumulation of Al in the root tissue (r 2 = 0.75 at 72 h). Genotype UF-T2, selected for Al tolerance, extruded 80% more oxalic acid in the presence of Al compared with the other germplasms, indicating that this mechanism is involved with Al tolerance in L. corniculatus. This experiment showed strong evidence that L. corniculatus exhibits Type I tolerance, in which anionic channels are rapidly activated by Al exposure. Exudation of oxalic acid is likely a crucial mechanism that allows the maintenance of L. corniculatus growth when exposed to toxic Al conditions, and this characteristic should be used to identify tolerant genotypes in the future.

CsBPC2 is a key regulator of root growth and development

“…Excessive zinc induces rice to secrete oxalic acid, fumaric acid, and acetic acid (Fan et al, 2016). Excessive aluminum induces the secretion of oxalic acid from Lotus corniculatus , malic acid from Arabidopsis and isohydroxamic acid from maize (Santos et al, 2022; Wang et al, 2018; Zhao et al, 2019). Excessive copper induces the secretion of catechin from Imperata condensata and cinnamic acid from Helianthus annuus (Meier et al, 2012).…”

“…Excessive aluminum induces the secretion of oxalic acid from Lotus corniculatus, malic acid from Arabidopsis and isohydroxamic acid from maize (Santos et al, 2022;Wang et al, 2018;Zhao et al, 2019).…”