5. Requirements for phytoremediation
High growth rate
More biomass production
Easily cultivated
Hyperaccumulators and metallophytes
Can form symbiotic relationships
5
11. Why legumes form symbiosis?
▰Their growth
depends on plant
microbe
interaction
▰Symbiotrophic
organisms
possess
mechanism for
tolerance
11
12. EFFECTS OF SYMBIOTROPHIC
MICROORGANISMS ON LEGUMES IN
THE PRESENCE OF HMS
▰Mono-
Inoculations with
Different Types of
Microorganisms
▰Combined
Inoculations with
Different Types of
Microorganisms
12
13. Mono-Inoculations with Different
Types of Microorganisms
1. AMF
▰ ecologically safe
and efficient
biological
instrument
▰ better growth and
uptake of
phosphorus
▰ stimulation of
nodule formation
▰ high
photosynthetic
activity
Legume species used:
▰ Cicer arietinum
▰ Lens culinaris
▰ Pisum sativum
13
18. Combined Inoculations with Different Types
of Microorganisms
▰exert multiple effects on plants
▰increase their activity and persistence
▰additive and synergistic effects on plant
growth and nutrition
18
19. Combined Inoculations with Different Types
of Microorganisms
▰Cultivation of Trifolium repens
▰Co-inoculation with AMF Glomus mosseae
and PGPR Brevibacillus brevis
▰accumulation of nutrient elements and toxic
Cd.
▰Stimulated nodulation on roots
19
20. Combined Inoculations with Different Types
of Microorganisms
▰Increased tolerance of plants to stress
▰Stimulated nodulation on roots
20
21. CHEMICALLY ASSISTED HM ACCUMULATION
BY LEGUME-MICROBE SYMBIOSES
▰Legume plants are capable of actively
accumulate HMs from polluted soils and
hydroponics
21
22. CHEMICALLY ASSISTED HM ACCUMULATION BY
LEGUME-MICROBE SYMBIOSES
▰Cassia fistula accumulated Cr, Cu, Zn
and Mn
▰Medicago sativa actively accumulated
Cd, Cu, Ni and Zn and Cd, Cr and Ni
22
23. CHEMICALLY ASSISTED HM ACCUMULATION
BY LEGUME-MICROBE SYMBIOSES
▰Actively accumulate HMs from polluted
But...
accelerated HM uptake may cause:
▰toxic effects
▰inhibit plant growth
23
24. INTRASPECIFIC VARIABILITY OF PLANTS IN
THEIR INTERACTIONS WITH MICROORGANISMS
▰Plants significantly differ in their
tolerance to and accumulation of HMs
and intraspecific genetic variation of
these traits exists
24
25. INTRASPECIFIC VARIABILITY OF PLANTS IN
THEIR INTERACTIONS WITH MICROORGANISMS
▰Cultivars of Glycine max differed in Zn
and Cd tolerance
▰Cultivars of Phaseolus vulgaris differed
in Zn and Cu tolerance
25
26. ▰Experiments showed significant genotypic
variability in Cd tolerance and accumulation of
different HMs (Cd, Cr, Cu, Ni, Pb, Sr and Zn)
among 99 Pisum sativum varieties
26
INTRASPECIFIC VARIABILITY OF PLANTS IN
THEIR INTERACTIONS WITH MICROORGANISMS
27. ▰Genetic traits may show negative co
relation between growth parameters
▰Increased energy expenditure for
operation of the mechanisms of metal
tolerance
▰Slower growth and lower biomass
production
27
INTRASPECIFIC VARIABILITY OF PLANTS IN
THEIR INTERACTIONS WITH MICROORGANISMS
28. RELATIONSHIPS BETWEEN HM TOLERANCE
OF SYMBIOTIC PARTNERS
▰Nodulation and symbiotic nitrogen
fixation is sensitive to HMs
▰Growth inhibited
▰Resulting in nitrogen deficiency and plant
growth limitation
28
29. ▰For example
Symbiotic interaction between Vigna
unguiculata and rhizobia
&
more sensitive to Cu toxicity than both
partners separately
29
RELATIONSHIPS BETWEEN HM TOLERANCE
OF SYMBIOTIC PARTNERS
30. So,,, plant genotype is of prime
consideration, because…
▰plants, being on a higher evolution level,
are less tolerant to metal toxicity as
compared to microorganisms
30
RELATIONSHIPS BETWEEN HM TOLERANCE
OF SYMBIOTIC PARTNERS
31. PHYTOREMEDIATION WITH GENETICALLY
MODIFIED LEGUMES AND SYMBIOTROPHIC
MICROORGANISMS
▰No natural metalliferous and hyper-
accumulating species
▰Genetically modified plants species are
introduced
via transgenic techniques
&
mutagenesis
31
32. ▰Introduction of Arabidopsis
metallothionein genes AtMT1 and
AtMT2
▰To guard cells of Vicia faba
▰Resulted in reduction of the level of
reactive oxygen species and thereby
increased tolerance to supplemented Cd
32
PHYTOREMEDIATION WITH GENETICALLY
MODIFIED LEGUMES AND SYMBIOTROPHIC
MICROORGANISMS
33. Advantages of using legumes
▰High potential to form symbioses
▰Short life cycle so faster yield with faster
results of microbe interaction
▰Phytostabilizing ability
33
34. Potential problems
▰Required a deep understanding of the
complex interactions in the rhizosphere
involving a number of biological,
biochemical and physico-chemical
processes
34
35. ▰Still mostly research is based on pot
experiments
▰Only specific HM stress is observed
▰Not applied to field for practical use
35
Potential problems
