The cadmium-tolerant pea (Pisum sativum L.) mutant SGECdt is more sensitive to mercury: assessing plant water relations

Abstract

Heavy metals have multiple effects on plant growth and physiology, including perturbation of plant water status. These effects were assessed by exposing the unique Cd-tolerant and Cd-accumulating pea (Pisum sativum L.) mutant SGECd(t) and its wild-type (WT) line SGE to either cadmium (1, 4 μM CdCl2) or mercury (0.5, 1, 2 μM HgCl2) in hydroponic culture for 12 days. When exposed to Cd, SGECd(t) accumulated more Cd in roots, xylem sap, and shoot, and had considerably more biomass than WT plants. WT plants lost circa 0.2 MPa turgor when grown in 4 μM CdCl2, despite massive decreases in whole-plant transpiration rate and stomatal conductance. In contrast, root Hg accumulation was similar in both genotypes, but WT plants accumulated more Hg in leaves and had a higher stomatal conductance, and root and shoot biomass compared with SGECd(t). Shoot excision resulted in greater root-pressure induced xylem exudation of SGECd(t) in the absence of Cd or Hg and following Cd exposure, whereas the opposite response or no genotypic differences occurred following Hg exposure. Exposing plants that had not been treated with metal to 50 μM CdCl2 for 1h increased root xylem exudation of WT, whereas 50 μM HgCl2 inhibited and eliminated genotypic differences in root xylem exudation, suggesting differences between WT and SGECd(t) plants in aquaporin function. Thus, root water transport might be involved in mechanisms of increased tolerance and accumulation of Cd in the SGECd(t) mutant. However, the lack of cross-tolerance to Cd and Hg stress in the mutant indicates metal-specific mechanisms related to plant adaptation.

Role of Plant Genotype and Soil Conditions in Symbiotic Plant-Microbe Interactions for Adaptation of Plants to Cadmium-Polluted Soils

“…Accordingly to this observation, treatment with 4 μM CdCl 2 decreased root biomass of pea SGE line and SGECd t mutant by a factor of 5 and by 20 %, respectively (Belimov et al 2015). These Cd concentrations were much less compared to TGI concentrations found for 61 strains of nodule bacteria (Fig.…”

Nighttime evaporative demand induces plasticity in leaf and root hydraulic traits

“…Another easier‐to‐measure whole‐root system trait that has been recently linked to water use is the root xylem exudation (XEX) rate (or ‘bleeding’). Root exudation rates of de‐topped rice and pea plants were recently associated with differences in root aquaporin expression (Henry et al , Belimov et al , respectively), changes in root hydraulic conductance (Henry et al ) and even with enhanced yield in field‐grown maize plants expressing higher bleeding rates that were associated with enhanced delivery of key nutrients to the shoot (Guan et al ). These findings support the hypothesis that root endodermis and XEX rate might be responsive to variation in VPD N imposed over developmental scales.…”

Mercury Distribution in Tobacco (<i>Nicotiana tabacum</i>) Cell

“…More and more scientists have been interested in phytoremediation and much work has been done [4] [14] [15]. However, mercury is an inhibitor for aquaporin in plant [16] [17]. The mercury in plant will be a block for plants' absorbing water [16] [17].…”

“…However, mercury is an inhibitor for aquaporin in plant [16] [17]. The mercury in plant will be a block for plants' absorbing water [16] [17]. And so, identifying where the mercury was stored in plant cell is very important for understanding the mechanism that mercury inhibited water in plant cell.…”