Increasing interest in commercial cultivation of medicinal and

economically important plants on large scale has necessitated development of

various tissue culture techniques for their early growth and improvement in yield.

But sometimes micropropagated plants do not acclimatize due to lack of eco­

friendly microorganisms in the rhizosphere zones. The relevance of mycorrhiza

for the acclimatization, success of micropropagated plantlets has gained importance

in the recent past, because most of the forest trees are obligatory dependent upon

the mycorrhizal symbiosis. The influence of early mycorrhizal symbiosis undercontrolled conditions and their resistance to environmental stresses had been

reported earlier. Since Arbuscular mycorrhizal fungi do not grow like any other

fungi apart from their living hosts, an axenically cultivable mycorrhiza-like-fungus

named, Pirlformospora indica was discovered. The utilization of this fungus in

acclimatization of selected economically and medicinally important plants has beendiscussed in this paper for further explor-ation..

Keywords: Symbiotic fungi, Arbuscular mycorrhizal fungi, Piriformosporaindica, Plant growth, Green environment.

Owing to its various agro-climatic,

geo-physical conditions and vast existingknowledge base, India is at an

advantageous position to be the globalleader in the herbal market. It has become

necessary to cultivate plants of economic

importance on a large scale under organic

farming. The main reason beingincreasing biotic pressure on forests and

Rina kumarP, Pham Duong Giang2, Minu Sachdev3, Amar P. Garg1 and Ajit Vanna3*

1 Department of Advanced Microbiology, C.C.S.University,Meerut-250005, Uttar Pradesh

2 International Center for Genetic Engineering and Biotechnology,Jawaharlal Nehru University,New Delhi, India

3Schoolof Ufe-Sciences, Jawaharlal Nehru University,New Delhi &

AmityInstitute of Herbal and Microbial studies, Noida, India

Correspondent author, E-mail: ajitvanna73@hotmail.com.ajitvanna@aihmr.amity.edu

unscientific exploitation of these plants.

Thus, there is urgent need for propagation

of these plants with value additions.

Conservation of threatened species and

promotion of high yielding varieties can

be achieved by various techniques of

biotechnology, such as micropropagation,

cryopreservation and protoplast culture.

The technique is fast emerging as a tool

for more efficient manipulation andpotential rapid improvement in product

yield. Besides, it offers great potential for

agricultural, industrial and commercial

exploitation for secondary metabolites.

Application of symbioticfungal organismsas well as beneficial bacteria to medicinal

and economically important plants has

been poorly investigated and represent

undoubtedly a novel route to overcome

transplant shock, improve growth yieldand improve quality of plants in terms of

concentration of active principles.

The tissue culture-raised plantsfrequently get 'transplant failure and

transplant shock' due to weak root system.

The reason being, their complete lack ofexposure and interaction with

microorganisms e.g., bacteria, fungi and

actinomycetes, normally found in the

rhizosphere zones. However, an earlyinteraction of these plants with selected

Abstract

IPC code; Int. cl.7-AOlH 17/00

Introduction

The Indian sub-continent is

endowed with natural abundance of

diverse flor~ including an enormouslylarge number of medicinal and

economically important plants. It is now

globally accepted that biotechnology willreign over markets in the near future.

Natural Product Radiance Vol 3(6) November-December 2004

buffers the action of stress duringacclimatization.

Nlicropropagationisatechnique

of increasing importance for the

production of many crops. This includes

most of the cultivated horticultural plants

(Lovato et al, 1999; Varma & Schuepp,

1995). The influence of early

mycorrhization under controlledconditions and their resistance to the"induced environmental stresses" was

reported in horticulturally important

Hortensia plants (Varma & Schuepp,

1994) (Fig. 1). Among the important

ornamental plants, the terrestrial orchid

seeds are very tiny, normally fail to

germinate, survive and attain maturity

unless they receive appropriate

mycorrhizal colonization at the earlystage

(Singh & Varma, 2000). Over 90% tinyseeds germination and sustainability was

recorded after an early intervention by

suitable mycorrhizae (Fig. 2).

---- -- - .----- -------- - -------

mycorrhiza and plant growth promoting

rhizobacteria (PGPRs) promises to

improve plant survival and performance

and minimizes the use of chemical inputs.

The relevance of mycorrhiza for the

acclimatization, success of micro­

propagated plantlets has gainedimportance in the recent past, because

most of the forest trees are obligatory

dependent upon the mycorrhizalsymbiosis. Mycorrhiza seems to act in

two ways: firstly they help the plant to

attain its best performance and secondly

Fig. 1 (a-d): The biological hardeningof micropropagated Hortensia plants

and cultivation in the field

lea

Fungus colonization

Fig. 2: Orchid Laelia purpuvataa. flowers b. anatomy of seed

The term mycorrhiza comes from

the Greek word (Myco-Fungus; rhiza­

root) and is a symbiotic association of a

fungus and root of a plant. Mycorrhizal

associations involve 3-way interactions

between host plants, mutualistic fungi andsoil factors (Read, 1999). Vesicular­

arbuscular mycorrhizas (= arbuscular

mycorrhizas, VAM or AM) are

associations, which belong to a veryancient category of the fungus, the

Zygomycetesand had been regrouped in

a single order, the Glomeromycota(SchUEler et al, 2001) which includes

all the species capable of living

symbiotically with plants. They producearbuscules and vesicles within roots

(Smith, 1995; Walker, 1995). Spores are

formed in soil or on the root system.

Arbuscules are very specific organs found

onlyin AMfungi. Theyare responsible for

bi-directional flux, whereby

photosynthates from root tissues areexported to fungal hyphae into the soil andvice-versa nutrients and water

transported through the fungal hyphae into

the plant system. Hyphae generally are

substantially smaller in diameter than theroot hairs. Thenarrow diameter facilitates

the fungal symbionts to explore a largevolume of soil and provides the plant the

vital nutrients (mycorrhizosphere),

hitherto, not mediated by the root bairsalone. Almost 90% terrestrial plants are

colonized by these fungi. The effect of

mycorrhizas on phosphorus uptake and.their transportation by hyphae in

particular caused the ability of the roots

b I access and exploit soil P located beyondP depletion zone around roots (Joner &Johansen,'-2000; Joner et al, 2000).Among the various functions attributed

to AMfungi (Singh et al, 2002, 2003),

Natural Product Radiance Vol 3(6) November-December 2004

however, there has been a great emphasis

on its role against drought and water stress

resistance and their obviation (Fig. 3).

Cultivation of Arbuscular

Mycorrhizal Fungi

Arbuscular mycorrhizal (AM)

fungi are obligate symbionts and can not

be multiplied on artificial media.

Inoculum production of arbuscular

mycorrhizal fungipresents a verydifferent

problem and challenge to scientists all

over the world. These fungi will not grow

like any other fungi apart from their living

hosts (obligate symbionts). These fungi

are usually propagated by growing themon a livinghost plant in soil pot cultures

(obligate photosymbiont). Because of the

absence of an authentic pure culture,

commercial production is the greatestbottleneck in the use and application of

mycorrhizal biotechnology. However,

there is silver lining. An axenically

cultivable mycorrhiza-like-fungus hasbeen discovered by Varma and hiscollaborators from the School of Life

Mycorrhiza are considered to play vita~role in overcoming the drought stress. :

Fig. 3: Mycorrhizal fungi havemulti-ferrous functions (Diagram

postulates the role ofthe fungi to obviate the stress)

Sciences,Jawaharlal Nehru University,New

Delhi and was named -Piriformosporaindica (Fig. 4) (Verma et al, 1998). The

properties of the fungus,

Piriformospora indica, have been

patented (Varma A and Franken p, 1997,

European Patent Office, Muenchen,

Germany. Patent No. 97121440.8-2105,Nov. 1998). The culture has been

deposited at Braunsweich, Germany (DMS

No.11827). 18S-rDNA fragment was

deposited with GenBank, Bethesta, AF014929.

This fungus can be cultivated on

a variety of synthetic media (Pham et al,2004a) (Fig. 5). like AMfungi this fungus

can transport phosphate and act as plant

growth promoting biological tool. The

fungus also helps in better establishment

and development of tissue culture-raised

plants including members of terrestrialorchids (Pham et al, 2004b). P. indica

tremendously improves the growth and

overall biomass production of diverse

Fig. 4: A typical growth ofPiriformospora indica on solid

Aspergillus medium

hosts, including legumes, medicinal and

economically important plants.

In following paragraphs we

have described our experience in

acclimatization of selected economically

and medicinally important plants where

we have successfullyapplied the biological

tool for the hardening of the plants. The

success story for transfer technology from

laboratory to field is also illustrated.

Effect of P. indica on Abrus

precatorius Linn. growth

Indian Liquorice, Abrusprecatorius is also known as Gunchi,Rati (Hindi), Kaincha, Runja (Oriya)

and Kawa (Santhal). It is a perennialclimber that twines around trees, shrubs,

and hedges. The seeds contain an amino

acid known as abrine (N-methyl-L­

tryptophan), glycyrrhizin and a lipolytic

enzyme. The roots, stems and leaves also

contain glycyrrhizin.The seeds were alsoused to treat diabetes and chronic

nephritis. The plant is also used to treat

scratches and sores, and wounds caused

cPear shaped spores

Fig. 5 (a-c): Morphology and growthof symbiotic fungus P. indica

Natural Product Radiance Vol 3(6) November-December 2004

Feature

Conclusion

Fig. 8: Functions and applications ofsymbiotic fungus

Piriformospora indica

A number of plants important in

agriculture and flori-horticulture and

social forestry showed tremendous

positive response as a result of interaction

byPiriformospora indica. This fungus

not only promotes the plant growth and

maintains soil health but also act as plant

protectants againstfungal diseases, insectsand nematodes (Pham et ai, 2004c).

In conclusion, an early

intervention by eco-friendly symbiotic

fungi, viz. AMFand P. indica promisesfor healthyplant cultivationon normal and

stressed soils resulting there-by green

environm~nt (Fig. 8).

Acknowledgements

Authors are thankful to

Departments of Science and Technology,

Biotechnology and Council of Scientific

and Industrial Research, UniversityGrantsCommission, Biotech. International Ltd.

and Government of India for partialfinancial assistance.

Fig. 7: Piriformospora indica

interacting with Populus sp.

Plants grown in pots for 2 months

of the inoculated plants was higher than

that of the corresponding controls(Fig. 6).

Effect of P. indica on Populustremula Linn. growth

Populus wood is light coloured,

straight grained, finely textured and soft.

It is primarily used for pulp, but is also

used to make particle board especiallywafer board and oriented strand board

and structural panels. Populus fibers are

well suited for making fine paper. Minoruses include log homes, pallets, boxes,

match splints, chopsticks, hockey stickcomponents, crates, ladders, furniture and

lumber. Both sapwood and heartwood

have low decay resistance and are difficult

for presetvatives to penetrate. Populus

wood warps withconventionalprocessing,but saw-dry-rip processing controls

warping. This success story was also true

for tissue culture raised Populus plants(Varma et ai, 1999) (Fig. 7).

Fig. 6: Growth Promotion of Abrus

precatorius by Piriformospora indica

a. Control; b. Treated

by dogs, cats and mice. It is also used with

other ingredients to treat leucoderma. The

leaves are used for their anti-suppurative

properties. The plant is also traditionallyused to treat tetanus and to prevent rabies.

The plant extracts are used for abdominal

discomfort, abortion, contraceptive,

cough, greying of hair, spermatorrhoea

and worm infection. Because of their high

medicinal value, there is an increasingdemand for this plant in national ,andinternational markets. Thus, enhancement

of the growth and bioactive agents of these

plants is desirable. This may be achievedby inoculation of the roots with

microorganisms like AMfungi or other

growth-promoting root endophytes like

P. indica. A pronounced growthresponse following inoculation with

P. indica was obsetved in these plants.The plants treated with P. indica showed

early germination and superior in

development to control plants. A

significant increase in shoot length wasobsetved in inoculated plants. The basal

stem and leaf areas of treated plants werealso enhanced. The overall root biomass

Natural Product Radiance Vol 3(6) November-December 2004, 399

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