This document summarizes the effects of heavy metals in the environment on plant physiology. It discusses how industrialization and mining have increased heavy metal levels and how plants uptake metals through their roots and foliage. It then examines the physiological effects on plants, including cellular interactions where metals are stored, transport mechanisms using proteins, impacts on metabolism like oxidative stress, and effects on photosynthesis, reproduction, and hyperaccumulation. The document concludes that understanding plant uptake and resistance strategies could help with phytoremediation and addressing metal deficiencies in foods.

1. Heavy metal in the environment and effect on plant physiology Muhammad Arifin Sandhi Masters Student, Ecology Stockholm University SE- 10691, Sweden

3. Some Real Scenario…….

4. Why? Burning Fossil fuels Rapid Industrilization Mining and Smelting Sewage Sludge Chemical fertilzers Pesticide, herbicide residues ( Memon et al., 2001)

9. Availabilty & Uptake Persistence Bonding of negetive (Soil) and positive (metal) charge. Metal binds with hydroxyl (-OH), Carboxyl group (COOH) and phenolic group of soil and 98% metal binds with inorganic compounds. In terrestrial system metal ions enter in the plant through root hair > cortex and in aquatic system ,through foliage either crack on the cuticle or stomata >plasmolema.

11. H+ -ATPaseworks for pumping the proton in both plasma membrane and tonoplast.

12. Transporter proteins (in membrane) works as carrier and channels for metal transport.

13. These protein classfied as Phytochelatins (PC), Metallothioneinin (MT) originated from plant and animal respectively.

14. Proteins bind with metals and also works as a chelator.

15. Some organic acid helps to transport metals from root to shoot.(Streit & Stumm, 1993)

17. Responce and tolerance of metal stress of plants depends on the concentration level and on essentiality of the metal.

19. Germination rate (81-89%) and pollen tube length (89-96%) decrease in tobacco with Hg, Ni and Cd exposure.

20. Pectin-Calcium based pollen tube cell complexed with metal and reduce cell elasticity.

22. Electron transport in PS2, Phosporylation and NADPH.

23. Reduced chlorophyll pigment and alter leaf architecture.

24. PS1 and carotenoid pigment less disturbed. (Striborova et al., 1987)

26. R. R. Brooks (1977)

27. Metal uptake higher due to detoxification mechanism well developed or need metal for protection from pest and pathogen.

28. Deposit metal in shoot, whereas accumulator deposit in root.

29. 400 plant species, major comes from Brassicasae, Alyssum and Thlaspi genus.

30. Disadvantage: low biomass production.(Wittig, 1993)

32. Metal uptake exclusion

33. Enzymatic change

34. Binding with cell wall and other cell components.

35. Tolerance

36. Binding with MT , PC

37. Vacuole compartmentalizationSome other ways metal release from plant like volatilazation, leaf fall,decaying of bark, leaching from leaf, fluid secretion from xylem or hydrathods.

39. Be a solution for solving required metal deficiency of infants (Ex. Zinc).

40. Needs further research to understand the amount of metal in the food grain. (Striborova et al., 1987)

42. Tack såmycket !