Mycorrhizae-biocontrol agent

Mycorrhizae as biocontrol agent

GUIDED BY:- (Prof. H K kehri)

MADE BY:-Deepak Yadav(M.sc. Iv –sem.)

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What is Mycorrhizae?

ares

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Evolution

• Life first emerged on land = pre-cambrian period

• Zygomycete hyphae = Cambrian• Endomycorrhizas = Devonian period,

discovered by Kidstone & Lang• Fossil mycorrhizas were first discovered

by Weiss(1904) in lower carboniferous.

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Discovery

• Symbiosis was studied by Franciszek Kamieński in 1879–1882. 

•  Albert Bernhard Frank, who introduced the term mycorrhiza in 1885.

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Kinds of Mycorrhizae

• Marks (1991) classified on the basis of types of relationships with the hosts .

• Ectomycorrhiza =Harting nets……ascomycetes and Basidiomycetes

• Endomycorrhizae =The fungus grows within the cortical cells.

• Ectendomycorrhiza• Vesicular Arbuscular Mycorrhiza • Arbutoid Mycorrhiza• Monotropoid Mycorrhiza• Ericoid Mycorrhiza• Orchid Mycorrhiza

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Distribution of Mycorrhizal Fungi

HOST• 83% Dicots• 79% Monocots• 100% Gymnosperms• Cherry, Coconut , Hibiscus,

Banana ,Garlic = ENDO• Eucalyptus , Pine, Cypress,

Poplar = ECTO• Cedar ,willow=ENDO

& ECTO

NON HOST• Amaranthaceae,

Brasicaceae, Caryophyllaceae, Chenopodiaceae, Commelinaceae, Lecythidaceae, Portolaceae, Proteaceae, Restionaceae, Sapotaceae, Zygophyllaceae

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VAM as biocontrol agentThe prodigious research made during last four decades clearly established its widespread occurrence in various plants species and under different agroclimatic conditions covering broad ecological range including deserts,forests and mangroves.

It established that this symbiotic association benefits the plants through enhanced nutrient uptake, biological control of root pathogen and synergistic interaction with nitrogen fixing microorganisms,hormones production and drought resistance.

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This biotool has now attracted the attention of microbiologist, agronomists, horticulturists and foresters at the global level.

Extensive studies have explored the possibility of using mycorrhizal model system in inducing suppressions of potential soil-borne pathogens.

Its relevence becomes all the more important since most of the soil-borne diseases, by and large, are not easily controlled by conventional method.

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Interaction of vam fungi and fungal pathogen results in decrease in severity of disease,thus the vam fungi determine the severity of the disease they may be used as biocontrol agents.

Morphological, anatomical, biochemical or physiological changes in the host due to mycorrhization may suppress the pathogen and its activity and imparts resistance against it.

It curtails the damage caused by the pathogen resulting in a curtailment of disease expression.

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Mycorrhizal roots are functionally longer than non- Mycorrhizal ones,and are less susceptible to certain types of pathogen attack.

The major relevance is in the control of soil borne diseases,

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Success of VAM fungi as biocontrol agent has been established beyond doubt as they proved their potential to check a number of soil-borne diseases including root rot of tomato due to Fusarium oxysporium f. sp. radices lucopersici (Caron et al. 1986) and root rot of green gram, black gram and chick pea due to Macrophomina phaseolina, (Kehri and Chandra,1990,Chandra et. al.,1995)

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Physiological alterationsQualitative and quantitave differences in chemical constituents in roots of mycorrhizal and non mycorrhizal plants,

Higer level of amino acids specially arginine have been reported in the mycorrhizal plant species,

High level of chitinolytic activity has been reported in mycorrhizal roots and it is suggested that the chitinolytic enzymes are produced by the host for the digestion of arbuscules

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Mycorrhizal roots have been reported to exhibit a low level of starch but higher level of soluble carbohydrate and reducing sugar.

mycorrhizal roots have been shown to contain more phenols than non mycorrhizal roots.

accumulation of phenols in root tissue of mycorrhizal plants has been reported to be the cause of inhibition of growth of pathogen like Sclerotium and Fusarium in tomato.

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COMPETITION FOR PHOTOSYNTHATE

In plants, a pathogen shares the photosynthate produced by the host

In mycorrhizal plants loss in carbon is compensated by increase in photosynthesis, which may inturn nullify the growth depression

Carbon drain is eliminated due to additional photosynthate produced by the host as a result of mycorrhizal association.

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Competition for photosynthate

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ROOT EXUDATESThe root exudates affect the pathogenesis of root pathogen.

Exert a favorable effect or unfavorable effect on germination or penetration of pethogen

Exert the same effect on the pathogen directly through the non pathogenic root microflora which have a important role in pathogen activity

Alternation in pattern of root exudation due to VAMassociation proposed to be causal of soil borne disease reduction

VAM symbiosis reported to be regulated by amount of nutrients that is amino acids and reducing sugars.

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For collection of exudates

20Root exudates

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Higher root exudation in the zone root elongation, the zone most susceptible to VAM colonization.

Mycorrhization induce qualitative and quantitative changes in the root exudatin resulting in a modification of microbial population in rhizosphere and rhizoplane modification encourages or suppresses the activity of pathogen and pathogenesis Resistance against the pathogens due to additional metabolities in root exudates change in quantity of a specific metabolite related to the activity of pathogen.

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COMPETITION FOR SPACE

VAM fungi and pathogen share the space in the tissue of roots , competiton for space between the two share holders

VAM symbiont provides additional root tissue increasing growth of roots resultant of improved nutrition, competition hypothesis for resistance has been doubted.

Pathogen fungus reduce the apex diameter and the number of mitoticaly active and viable apices inducing plasmolysis,cell and nucleus degeneration and necrosis.

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Competition for space

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The AM fungus produced an increase in apex size and reduced the percentage of necrosis both uninfected and infected roots

AM fungus protected the apices from the pathogenic infection,allowing normal root growth.

Thus produced thicker roots, might indirectly contribute to plant protection.

Increased volumes of colonizable tissues favour the spreading the symbionts.

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Competition for space

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Primary goal of mycorrhizal inoculation

• Improve the uniformity of tree growth • It produce fruiting bodies• Increase resistance • Increase the diversity of soil fungi • Inoculate any size of plant by spraying or

dusting the roots, drenching containerized plants or incorporating the mycorrhizal spores into growing media.

27Mycorrhizal spores

How does the AM fungus benefit?AM fungi are “obligate symbionts”

• They must live in symbiosis with plants to complete their life cycles

• Why?– Metabolic division of labor among the structures of

the fungus– Only the fungus within the root can absorb sugars

for energy and make lipids necessary for storage and growth

– Germinating spores can only grow as long as their stored lipids hold out

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Tips to Choose a Quality Mycorrhizal Inoculant

Some researchers lucky enough to find an excellent manufacturer.

• Spore count• The quality of the manufacturing process• The health of the spores • Cost price• Ectomycorrhizal inoculant are more plentiful.

Collection of plant sample-

• The plant samples both healthy and diseased (arhar plants) were collected from-

• phaphamau, Allahabad and;• pratapgarh

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MATERIAL AND METHODS

MYCORRHIZAE

Slide preparation of Mycorrhizal roots-

Root washing with water

Cut roots into small 1 cm pieces

Washed with 10% KOH for 24 hrs at room temp.

Washed with water

Kept solution in 3% Sodium hypochlorite

Washed with water

Kept in HCl for 3-4 mints.

Kept in tryphanblue for 24 hrs at room temp .

Kept in destain

Stained roots were kept on slide and were covered with cover slip

Observed under microscope

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MYCORRHIZAL SPORE ISOLATION

Take rhizospheric soil with roots ↓↓

Take a beaker full of sterilized water(50ml)↓↓

Dissolve the soil of rhizosphere with roots in beaker ↓↓

Dissolve the soil with magnetic stirrer or glass rod↓↓

Sieve the water in beaker by placing whatman filter paper↓↓

Wach the filter paper under microscope ↓↓

Pick the spores with needle↓↓

Place it on slides,by putting glycerine and cover slip

35Root-bits of mycorrhizal infection

Root–bits on slide

Root–bits on slide

% Root bits infected

Locality Healthy plant Diseased plant

pratapgarh

Field-1 70% 20%

Field-2 70% 10%

Field-3 80% 30%

phaphamau

Field-1 80% 40%

Field-2 80% 25%

Field-3 70% 20%

Table-1 Mycorrhizal intensity in the roots of healthy and wilted plants of arhar growing in the fields of pratapgarh and phaphamau

RESULT

Field 1 Field 2 Field 30

10

20

30

40

50

60

70

80

90

Healthy plants Diseased plants

% R

oot b

its

infe

cted

in h

ealt

hy a

nd d

isea

sed

plan

ts o

f arh

ar

Wilted plant at pratapgarh

Field 1 Field 2 Field 30

10

20

30

40

50

60

70

80

90

Healthy plants Diseased plants

% r

oot b

its

infe

cted

in h

ealt

hy a

nd d

isea

sed

plan

ts o

f ar

har

Wilted plant at phaphamau

% Root bits infected

Locality Healthy plant Diseased plant

pratapgarh

Field-1 80% 10%

Field-2 70% 20%

Field-3 70% 10%

phaphamau

Field-1 80% 40%

Field-2 80% 30%

Field-3 70% 20%

Table-2 Mycorrhizal intensity in the roots of healthy and fusarium infected plants of arhar growing in the fields of pratapgarh and phaphamau

Field 1 Field 2 Field 30

10

20

30

40

50

60

70

80

90

Healthy plants Diseased plants

% r

oot b

its

infe

cted

in h

ealt

hy a

nd d

isea

sed

plan

ts o

f arh

ar

infected plant at pratapgarh

Field 1 Field 2 Field 30

10

20

30

40

50

60

70

80

90

Healthy plants Diseased plants

% r

oot b

its

infe

cted

in h

ealt

hy a

nd d

isea

sed

plan

ts o

f arh

ar

infected plant at phaphamau

% Root bits infected

Locality Healthy plant Diseased plant

pratapgarh

Field-1 80% 10%

Field-2 70% 20%

Field-3 70% 20%

phaphamau

Field-1 70% 20%

Field-2 70% 10%

Field-3 80% 10%

Table-3 Mycorrhizal intensity in the roots of healthy and Fusarium infected plants of arhar growing in the fields of pratapgarh and phaphamau

Field 1 Field 2 Field 30

10

20

30

40

50

60

70

80

90

Healthy plants Diseased plants

% r

oot b

its

infe

cted

hea

lthy

and

dis

ease

d pl

ants

of a

rhar

Fusarium infected plant at pratapgarh

Field 1 Field 2 Field 30

10

20

30

40

50

60

70

80

90

Healthy plants Diseased plants

% ro

ot b

its in

fect

ed in

hea

lthy

and

dise

ased

pla

nts o

f arh

ar

Fusarium infected plant in phaphamau

Result Healthy and wilted plant from pratapgarh and phaphamau- the mycorrizal intensity is greater in phaphamau fields than pratapgarh .

Healthy and infected plants- The mycorrizal intensity is greater in phaphamau than pratapgarh.

Healthy and Fusarium infected plant –Mycorrizal intensity is same in pratapgarh and phaphamau fields . Their same intensity in both places healthy plants and Fusarium infected plants.

Field 1 Field 2 Field 364%

66%

68%

70%

72%

74%

76%

78%

80%

82%

phaphamaupratapgarh

Healthy Plant

% ro

ot b

its

infe

cted

in h

ealt

hy p

lant

of a

rhar

Field 1 Field 2 Field 30%

5%

10%

15%

20%

25%

30%

35%

40%

45%

phaphamaupratapgarh

Wilted Plant

% ro

ot b

its

infe

cted

in w

ilted

pla

nt o

f arh

ar

Field 1 Field 2 Field 30%

5%

10%

15%

20%

25%

30%

35%

40%

45%

phaphamaupratapgarh

infected Plant

% ro

ot b

its

infe

cted

in p

lant

of a

rhar

Field 1 Field 2 Field 30%

5%

10%

15%

20%

25%

phaphamaupratapgarh

Fusarium infected Plant

% ro

ot b

its

in fu

sari

um in

fect

ed p

lant

of a

rhar

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References• Bagyaraj, D.J. (1984). Biological interactions with VA mycorrhizal

fungi. In: VA mycorrhizae (eds.). C.L. Bailey and J.W. Mansfield. CRC Press, Boca Raton, Florida,USA, pp.131-154.

• Brundrett, M., Bougher, N., Dell, B., Grove, T and Malajczuk, N. (eds.) Working with mycorrhizas in forestry and agriculture, 02/01/1995, Publication Code: MN032

• Crush, J.R. (1974). Plant growth response to vesicular-arbuscular mycorrhizal. VII. Growth and nodulation of some herbage legumes. New Phytologists, 73: 743-749.

• http://www.sciencedirect.com/science/article/pii/S0166248108702009

• HTTP://WWW.JSTOR.ORG/DISCOVER/10.2307/2442619?UID=2&UID=4&SID=21105407197063

• HTTP://WWW.DAVIDMOORE.ORG.UK/ASSETS/MOSTLY_MYCOLOGY/DIANE_HOWARTH/ERICOID.HTML

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