Current Scenario of Pb Toxicity in Plants: Unraveling Plethora of Physiological Responses

Metal and Metalloid Toxicity in Plants: An Overview on Molecular Aspects

“…This represents a serious problem for different plant species, since it is not part of any metabolic pathway, and low concentrations are considered toxic [ 119 ]. In general, most of it is translocated to the shoots after its absorption into the roots using passive mechanisms that rely on H+/ATPase systems; thus, most of these metal ions are first translocated via apoplast through the endodermis (which acts as a natural barrier in deeper tissues, such as the stele) and then transported via symplast to vascular tissues [ 79 , 120 ].…”

Nitric oxide‐mediated regulation of oxidative stress in plants under metal stress: a review on molecular and biochemical aspects

“…Up to date, numerous studies have highlighted the phytotoxic effects of metals on plant growth and development, studying their interaction with different biological events, like photosynthesis and cellular respiration (Sidhu et al , Kohli et al , Yadav et al , Kaur et al ). Although the responses of plants to metals can be metal‐ and species‐specific, the induction of oxidative stress under metal(loid) exposure seems to be a common feature (Soares et al , Kohli et al ). Indeed, high levels of metals increase the production and accumulation of ROS, such as O 2 ·− , H 2 O 2 , ·OH and 1 O 2 .…”

“…After root uptake, Pb may remain accumulated in this organ or be translocated towards the aerial portion of the plants, although, in most plants, only a small fraction of Pb is translocated to shoots (Pourrut et al ). The exposure to this metal is associated with detrimental effects for the plants, impairing germination and growth, as well as damaging membrane permeability, which in turn causes a disruption in the water status and mineral nutrition homeostasis (Kohli et al ). Furthermore, Pb toxicity also portrays antimitotic and photosynthesis‐inhibiting effects, as well as causing the occurrence of oxidative stress that can ultimately lead to irreversible damages and cell death (Nagajyoti et al , Pourrut et al ).…”

The Fungicide Tetramethylthiuram Disulfide Negatively Affects Plant Cell Walls, Infection Thread Walls, and Symbiosomes in Pea (Pisum sativum L.) Symbiotic Nodules

“…Light and electron microscopy analyses revealed inclusions, presumably consisting of phenolic compounds, in vacuoles of meristematic cells in the nodules of the TMTD-sensitive pea cultivar 'Finale' ( Figure 4F or Figure 5F or Figure 6F or Figure 11A). Phenolic compounds are important biomarkers of xenobiotic detoxification [75,76]. A previous study showed that the use of benzo-(1,2,3)-thiadiazole-7 resulted in the deposition of phenol-rich occlusal material and the formation of structural barriers that prevented the pathogen Pythium ultimum Trow from entering the vascular stele of cucumber plants [77].…”

“…As a result of exposure to TMTD, the cytoplasm of infected cells became less electron dense and showed clear signs of plasmolysis, including nuclear pyknosis ( Figure 6I), but the morphology of the remaining organelles was unaffected. The cytotoxic effect of most xenobiotics, especially heavy metal ions, is manifested as damage to mitochondria as a result of oxidative stress, damage to the plasma membrane, vacuolization of the endoplasmic reticulum and dictiosomes, and damage to nuclei [68,76,[92][93][94]. The use of TMTD led to earlier and more abundant formation of starch granules ( Figure 4G-I or Figure 5G-I or Figure 6G-I), which is one of the signs of an ineffective symbiosis [89,95].…”