Physio-biochemical and transcriptomic analysis reveals underlying mechanism of Cys-induced amelioration of Cd...

Cysteine (Cys) has the potential to mitigate heavy metal stress. However, the molecular mechanisms of the ameliorative role of Cys in Cd stress are still unknown. This study aimed to reveal beneficial roles of Cys (250 µM) in mitigating Cd stress (75 µM) in maize seedlings. The results demonstrated that Cys alleviated the inhibitory effects of Cd stress on seedling growth by reducing Cd accumulation in the shoot by 19.5%, enhancing chlorophyll content by 39.4%, and decreasing MDA levels by 35.9% compared to Cd treatment alone. By using transcriptome analysis, 2422 (953 up-regulated and 1469 down-regulated) and 2577 (1540 up-regulated and 1037 down-regulated) differentially expressed genes (DEGs) were determined in Cd and Cys+Cd treatments compared to control, respectively. In addition, 543 DEGs (520 up-regulated and 23 down-regulated) were determined in Cys+Cd treatment compared to Cd. Comparing the groups (CK_vs_Cd, CK_vs_Cys+Cd, and Cd_vs_Cys+Cd) by Venn diagram, 115 common DEGs were detected. GO and KEGG analyses showed that Cys+Cd treatment improved Cd tolerance by regulating the expression of genes in different pathways, like photosynthesis, membrane transport, antioxidant enzyme system, and secondary metabolite biosynthesis. The expression levels of membrane transporters (ABC, PIP1-2, HMA, ZIP, etc.), photosynthesis (Lhcb, psa, psb, petM, PSBO, etc.), antioxidant enzyme system (CAT, GST, PER, etc.), secondary metabolite biosynthesis (PAL, 4CLL, etc.), and transcription factors (C2C2-CO-like, C2C2-GATA, C2H2, GRAS, NAC) genes were up-regulated by Cys+Cd compared to Cd. The up-regulation of these genes in different metabolic pathways by Cys+Cd treatment may suggest that Cys ameliorates Cd stress-induced metabolic inhibition. These results revealed physio-biochemical and molecular mechanisms of Cys-induced maize tolerance to Cd stress.

The online version contains supplementary material available at 10.1007/s12298-025-01648-5.