In Arabidopsis thaliana Cd differentially impacts on hormone genetic pathways in the methylation defective ddc mutant compared to wild type

Abstract

DNA methylation plays an important role in modulating plant growth plasticity in response to stress, but mechanisms involved in such control need further investigation. We used drm1 drm2 cmt3 mutant of Arabidopsis thaliana, defective in DNA methylation, to explore metabolic pathways downstream epigenetic modulation under cadmium (Cd) stress. To this aim, a transcriptomic analysis was performed on ddc and WT plants exposed to a long-lasting (21 d) Cd treatment (25/50 µM), focusing on hormone genetic pathways. Growth parameters and hormones amount were also estimated. Transcriptomic data and hormone quantification showed that, under prolonged Cd treatment, level and signalling of growth-sustaining hormones (auxins, CKs, GAs) were enhanced and/or maintained, while a decrease was detected for stress-related hormones (JA, ABA, SA), likely as a strategy to avoid the side effects of their long-lasting activation. Such picture was more effective in ddc than WT, already at 25 µM Cd, in line with its better growth performance. A tight relationship between methylation status and the modulation of hormone genetic pathways under Cd stress was assessed. We propose that the higher genome plasticity conferred to ddc by DNA hypomethylated status underlies its prompt response to modulate hormones genetic pathways and activity and assure a flexible growth.

Physiological and transcriptomic analyses reveal the cadmium tolerance mechanism of Miscanthus lutarioriparia

“…In addition, endogenous ABA is vital to Cd transport from roots to shoots under Cd stress [ 65 ]. It has been suggested that the levels and signaling pathways of growth maintenance hormones (IAAs, CKs, GAs, and ABAs) are enhanced and/or maintained under Cd treatment, which may be a strategy for plants to avoid long-term Cd toxicity [ 42 ]. In addition, we found that some genes, such as the TCH4 gene (NCGR_LOCUS59709, NCGR_LOCUS59710, and NCGR_LOCUS62590), exhibited opposite changes in the leaves and roots.The expression level first increased and then decreased in the leaves but continued to increase in the roots under Cd stress.…”

Transcriptome Analysis Reveals the Stress Tolerance Mechanisms of Cadmium in Zoysia japonica

“…Under Cd stress, plant hormones (such as ABA and IAA) undergo significant changes, and the expression levels of antioxidant synthesis and transport protein genes are affected [35]. ABA treatment counteracts Cd-induced fluctuations in non-enzymatic proteins and antioxidant enzymes [36].…”

Physiological and Biochemical Responses to Heavy Metals Stress in Plants

“…In comparison to Wild -type plants, ddc mutants were reported to have an instantaneous overexpression of IAOX (indole-3-acetaldoxime), which is connected to auxin biosynthesis genes (CYP71A13 and NIT2). As an alternative, the AUX/IAA gene family, which controls the regulation of auxin, was suppressed in ddc plants, improving phytohormonal signal transmission and increasing HM resistance (Pacenza et al, 2021).…”

“…Abscisic acid (ABA) is another hormone that is involved in regulating plant stress responses. Various plants subjected to HMs have shown elevated endogenous ABA concentrations, including Helianthus annuus L., Lactuca sativa, Populus canescens, Tritium aestivum, Oryza sativa, Cucumis sativus, and Solanum (Pacenza et al, 2021). ABA biosynthesis gene OsNCED4 was shown to be overexpressed in a transcriptomics-based study on Cd-stressed rice, highlighting the critical function of ABA in reducing Cd toxicity (Tandon et al, 2015).…”