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Biology and Biotechnology of Environmental Stress Tolerance in Plants, Volume 3

population, are the most sensitive features for detecting environmental stress

(Yeates & Bongers, 1999). Plant parasitic nematodes, bacterial, and fungal

feeders, predators, and omnivores all have various levels of susceptibility

to soil pollutants. The eating habits and anatomy of the stoma determine

the trophic groups (Gomes, Huang, & Cares, 2003; Sochová, Hofman, &

Holoubek, 2006). Various ecological indices and characteristics are used

to quantify soil disturbance levels and decomposition routes, as well as to

monitor community changes in diversity and trophic structure (Table 1.5).

Nematode community indices can also be used to characterize heavy metal’s

long-term impacts (Nagy et al., 2004).

Pollution levels (heavy metal or organic) in the environment have been

shown to have a negative impact on soil ecology. Severe pollution causes a

notable reduction in species variety and is generally straightforward to iden­

tify, but adequate environmental protection necessitates the identification of

less severe consequences. Furthermore, any minor changes in community

structure or population caused by pollution are frequently obscured by other

external variables, making it difficult to track. Thus, to avoid this, pollution

tolerant species of nematode could be used as indicators that detect the impact

of pollutants but do not respond to changes in other environmental variables

(Millward & Grant, 2000; Beeby, 2001). Nematodes have been shown to

react distinctively to different pollutants. Some commonly found tolerance

mechanisms towards organic and inorganic pollutants are outlined in Figure

1.4. Due to its extensive host range and tolerance to a variety of climatic

situations, Xiphinema vuittenezi, a plant pathogenic nematode, has been used

as a test organism in laboratory toxicity and heavy metal absorption investi­

gations (Sávoly et al., 2016; Hrács et al., 2018). The greater resistance of X.

vuittenezi to bulk ZnO was attributed by Hrács et al. (2018) to higher internal

Zn levels in the species owing to cuticular absorption of Zn. Panagrellus

redivivus, a free-living bacterivore nematode and r-strategist nematode,

is also commonly employed as a test organism for aquatic and terrestrial

toxicity investigations (Leitgib, Kálmán, & Gruiz, 2007). Nematodes can

stop pharyngeal pumping and avoid ingesting hazardous chemicals by doing

so (Jones, Peter, & Candido, 1999). The detoxification of organic xenobi­

otics and the discharge of metal ions from the cell are both aided by GSH and

glutathione S-transferases (GST). GSH is a redox regulator and antioxidant

that aids in the elimination of reactive oxygen species (ROS), particularly

hydrogen peroxide (H2O2) (van den Hoogen et al., 2019; Tiwari et al., 2021;

Lal, Vengavasi, & Pandey, 2019). This is thought to be an essential nematode

tolerance mechanism.