Lipid Peroxide-Derived Short-Chain Aldehydes are Involved in Aluminum Toxicity of Wheat (Triticum aestivum) Roots

Abstract

Lipid peroxidation is a common event during aluminum (Al) toxicity in plants, and it generates an array of aldehyde fragments. The present study investigated and compared the profile and physiological functions of lipid peroxide-derived aldehydes under Al stress in two wheat genotypes that differed in Al resistance. Under Al stress, the sensitive genotype Yangmai-5 suffered more severe plasma membrane damage and accumulated higher levels of aldehydes in roots than the Al-tolerant genotype Jian-864. The complementary use of high-resolution mass spectrometry and standard compounds allowed the identification and quantification of 13 kinds of short-chain aldehydes sourced from lipids in wheat roots. Among these aldehydes, acetaldehyde, isovaldehyde, valeraldehyde, (E)-2-hexenal (HE), heptaldehyde, and nonyl aldehyde were the predominant species. Moreover, it was found that HE in the sensitive genotype was over 2.63 times higher than that in the tolerant genotype after Al treatment. Elimination of aldehydes using carnosine rescued root growth inhibition by 19.59 and 11.63% in Jian-864 and Yangmai-5, respectively, and alleviated Al-induced membrane damage and protein oxidation. Exogenous aldehyde application further inhibited root elongation and exacerbated oxidative injury. The tolerant genotype Jian-864 showed elevated aldehyde detoxifying enzyme activity and transcript levels. These results suggest that lipid peroxide-derived short-chain aldehydes are involved in Al toxicity, and a higher aldehyde-detoxifying capacity may be responsible for Al tolerance.

Lipid-Derived Aldehydes: New Key Mediators of Plant Growth and Stress Responses

“…For example, Mano et al reported that Arabidopsis fad7fad8 mutants, which were unable to convert dienic fatty acids to trienoic fatty acids due to the deficiency of fatty acid desaturases localized in the plastid, contained low levels of aldehydes, such as malondialdehyde (MDA), acrolein, ( E )-2-pentenal and n-hexanal [ 10 ]. To date, more than 200 kinds of aldehyde have been identified in living organisms [ 29 , 34 ], but only a dozen aldehydes have been investigated in plants [ 6 , 10 , 26 , 35 ].…”

“…The contents of acetaldehyde, isovaleraldehyde, valeraldehyde, HE, heptanal and nonanal were all more than 10 nmol g −1 FW and significantly higher than other aldehyde species after 24 h of Al stress. Acrolein and HE were 1.94 and 2.63 times higher in the Al-sensitive wheat genotype than in the Al-tolerant wheat genotype, respectively [ 35 ].…”

“…Metal toxicity is one of the significant abiotic stresses and has hazardous effects on plants [ 88 , 100 , 101 , 102 ]. A common consequence of metal stress is ROS accumulation, which accounts for the formation of toxic aldehydes [ 26 , 35 , 64 ]. Under Al stress, more than a dozen aldehydes were characterized in tobacco and wheat roots [ 26 , 35 , 63 ].…”

“…A common consequence of metal stress is ROS accumulation, which accounts for the formation of toxic aldehydes [ 26 , 35 , 64 ]. Under Al stress, more than a dozen aldehydes were characterized in tobacco and wheat roots [ 26 , 35 , 63 ]. Aldehydes are proposed as the major factor suppressing root growth induced by Al stress.…”