Elevated pH-mediated mitigation of aluminum-toxicity in sweet orange (Citrus sinensis) roots involved the regulation of energy-rich compounds and phytohormones

• Published in: Environmental pollution (1987) 2022-10, Vol.311, p.119982-119982, Article 119982
• Main Authors: Wu, Bi-Sha, Lai, Yin-Hua, Peng, Ming-Yi, Ren, Qian-Qian, Lai, Ning-Wei, Wu, Jincheng, Huang, Zeng-Rong, Yang, Lin-Tong, Chen, Li-Song
• Format: Article
• Language: English
• Subjects: Cytokinin; Indole-3-acetic acid; Jasmonic acid; pH-aluminum interactions; Salicylic acid; Targeted metabolome
• ISSN: 0269-7491; 1873-6424
• DOI: 10.1016/j.envpol.2022.119982

For the first time, we used targeted metabolome to investigate the effects of pH-aluminum (Al) interactions on energy-rich compounds and their metabolites (ECMs) and phytohormones in sweet orange (Citrus sinensis) roots. The concentration of total ECMs (TECMs) was reduced by Al-toxicity in 4.0-treated roots, but unaffected significantly in pH 3.0-treated roots. However, the concentrations of most ECMs and TECMs were not lower in pH 4.0 + 1.0 mM Al-treated roots (P4AR) than in pH 3.0 + 1.0 mM Al-treated roots (P3AR). Increased pH improved the adaptability of ECMs to Al-toxicity in roots. For example, increased pH improved the utilization efficiency of ECMs and the conversion of organic phosphorus (P) from P-containing ECMs into available phosphate in Al-treated roots. We identified upregulated cytokinins (CKs), downregulated jasmonic acid (JA), methyl jasmonate (MEJA) and jasmonates (JAs), and unaltered indole-3-acetic acid (IAA) and salicylic acid (SA) in P3AR vs pH 3.0 + 0 mM Al-treated roots (P3R); upregulated JA, JAs and IAA, downregulated total CKs, and unaltered MEJA and SA in P4AR vs pH 4.0 + 0 mM Al-treated roots (P4R); and upregulated CKs, downregulated JA, MEJA, JAs and SA, and unaltered IAA in P3AR vs P4AR. Generally viewed, raised pH-mediated increments of JA, MEJA, total JAs, SA and IAA concentrations and reduction of CKs concentration in Al-treated roots might help to maintain nutrient homeostasis, increase Al-toxicity-induced exudation of organic acid anions and the compartmentation of Al in vacuole, and reduce oxidative stress and Al uptake, thereby conferring root Al-tolerance. In short, elevated pH-mediated mitigation of root Al-stress involved the regulation of ECMs and phytohormones. [Display omitted] •High pH reduced P-containing energy-rich compounds (ECs) in Al-toxic Citrus roots.•High pH increased the utilization efficiency of ECs at Al-toxic roots.•High pH increased IAA, SA and JA levels and decreased CKs levels in Al-toxic roots.•ECs and phytohormones involved in high pH-mediated alleviation of root Al-toxicity.