Gene expression dynamics in alfalfa under lead-induced stress
DOI:
https://doi.org/10.59463/n6e7jp78Keywords:
Medicago sativa, biotic stress, heavy metals, RT-qPCRAbstract
Gene expression in response to heavy metal stress plays a crucial role in plant adaptation and survival. High concentrations of metals like cadmium (Cd) and lead (Pb) can be toxic to cells, disrupting metabolic and physiological functions. To mitigate this stress, plants activate complex genetic regulatory networks, including genes involved in heavy metal homeostasis, detoxification, chelation, oxidative stress response, and transcriptional regulation. Phytochelatins, chelating proteins that bind toxic metals and reduce their harmful effects, are not directly produced by the expression of a heavy metal tolerance gene. Instead, they result from a metabolic pathway that utilizes glutathione as a substrate, involving the enzymes γ-glutamylcysteine synthetase, glutathione synthetase, serine acetyltransferase, and cysteine synthetase. This study aimed to evaluate the expression of genes encoding these enzymes in alfalfa plants exposed to varying lead concentration. Gene expression varied based on cultivar type (tolerant/sensitive), treatment duration, and Pb concentration in the substrate. Individual variability was also observed within the same cultivar. The most significant effect of Pb treatment occurred after one day, with increased expression of γ-glutamylcysteine synthetase and glutathione synthetase genes, particularly in the sensitive cultivar, which consistently exhibited higher gene expression levels.
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