Neutral-to-positive cadmium effects on germination and seedling vigor, with and without seed priming

This review gathered and analyzed data about (i) the Cd-induced impacts on seed germination and seedling vigor, and (ii) the use of different priming agents to mitigate Cd-induced impacts on the early plant development. Critical evaluation of the obtained data revealed intriguing results. First, seeds of diverse species can endure exposures to Cd. Such endurance is exhibited as maintenance of or even improvement in the seed germination and vigor (up to 15% and 70%, respectively). Second, the main factors influencing seed tolerance to Cd toxicity are related to temporal variations in anatomical, physiological, and/or biochemical features. Third, Cd can trigger diverse transgenerational effects on plants by shaping seed endophytes, by modulating seed provisioning with resources and regulatory elements, and/or by altering seed (epi)genomics. Fourth, different chemical, biological and physical priming agents can mitigate Cd-induced impacts on seeds, sometimes enhancing their performance over the control (reference) values. Overall, this review shows that the impacts of Cd on seed germination and vigor encompass not only negative outcomes but also neutral and positive ones, depending upon the Cd dose, media properties, plant species and genotypes, plant developmental stage and organ, and management approaches. Increasing our understanding of plant tolerance mechanisms against the growing background Cd pollution is relevant to support breeding programs, agricultural practices, and health -environmental policies.

Automated summary

This review analyzes the impacts of Cd on seed germination and seedling vigor and the use of priming agents to mitigate these impacts. Results show that seed endurance to Cd exposure varies among species, with some seeds maintaining or improving their germination and vigor. Factors influencing seed tolerance include temporal variations in anatomical, physiological, and biochemical features. Cd can also have transgenerational effects on plants by affecting seed endophytes, provisioning of resources and regulatory elements, and seed (epi)genomics. Different priming agents can mitigate Cd-induced impacts on seeds, sometimes even enhancing their performance. Overall, understanding plant tolerance mechanisms against Cd pollution is important for breeding programs, agriculture, and environmental policies.