Leaf nutrient homeostasis and maintenance of photosynthesis integrity contribute to adaptation of the pea mutant SGECd t to cadmium

Belimov AA, Dodd IC, Safronova VI, Dietz K-J. Leaf nutrient homeostasis and maintenance of photosynthesis integrity contribute to adaptation of the pea mutant SGECd t to cadmium. BIOLOGIA PLANTARUM. 2020;64:447-453.Cadmium (Cd) is a highly toxic and widespread soil pollutant, which negatively affects various aspects of plant growth and physiology. Here, the role of photosynthesis in response to Cd was investigated in the Cd-tolerant pea (Pisum sativum L.) mutant SGECd t . The wild type SGE and the mutant SGECd t were grown in a hydroponic solution supplemented with 1, 3, or 4 ?M CdCl 2 for 12 d. Root and shoot biomasses of the Cd-treated SGECd t were significantly higher than of SGE. Cadmium had little effect on the quantum yield of photosystem II (4)PSII) and chlorophyll content of intact leaves of both pea genotypes. However, when leaf slices were taken from Cd-exposed plants and incubated with high Cd concentrations, the SGECd t mutant showed 1.5 - 2 times higher 4)PSII values than SGE, with genotypic differences maximal at 0.1 and 1 mM CdCl 2 . In contrast, when leaf slices were taken from plants previously unexposed to Cd, both pea genotypes exhibited similar 4)PSII values. Cadmium content in leaves and mesophyll protoplasts of Cd-treated SGECd t were about 2 - 3 times higher than in SGE ones. The mutant leaves and mesophyll protoplasts had also higher Ca, Mg, Mn, and Zn content. Thus, SGECd t acclimated to Cd during growth in the Cd-supplemented nutrient solution by developing a molecular mechanism related to photosynthetic integrity. A higher foliar nutrient content likely allows enhanced photosynthesis by counteracting the damage of leaves caused by Cd