1. Mention and explain the types of Mycorrhiza!

Answer:

There are two main types of Mycorrhiza according to Ianson (2014):

ectomycorrhizae (ECM) and arbuscular mycorrhizae (AM).

a. Ectomycorrhizae (ECM) :

The ECM association is specific to roots of trees such as

birches, willows, pines, oaks and spruces. The fungi physically connect

with the roots of the host plant, improving the plant’s ability to take up

water and nutrients. They also form a sheath, or mantle, around the

root, which physically protects the root from some types of disease-

causing fungi. According to Muchovej (2001), Ectomycorrhizal

inoculum is easily produced for application in forest nurseries.

b. Arbuscular Mycorrhizae (AM):

The AM relationship affects both perennials and annuals. This

mycorrhizae is belonging to the Phylum Glomeromycota are symbionts

with terrestrial plant roots. It is now generally recognized that they

improve not only the phosphorus nutrition of the host plant but also its

growth, which may result in an increase in resistance to drought stress

and some diseases.

The main difference between the AM and ECM relationship is

that the AM relationship does not create a protective mantle around the

root the way the ECM relationship does. Instead, its hyphae enter the

plant cells, producing structures that facilitate water and nutrient uptake

by the plant. One way to spread AM fungi is to collect root tissue and

the soil immediately surrounding the root from a host plant that is

known to have the AM fungi and incorporate it into the soil of the new

plant. Management of arbuscular mycorrhizae focuses on maintaining

soil conditions favoring the fungi rather than constantly adding more

fungi-colonized tissue to the host plant. Establishing a successful

mycorrhizal relationship can be difficult because some of the species of

fungi may be site specific. But the necessity of AM inoculum

production via a host plant is still an obstacle to ample utilization of

AM fungi in agricultural crops as said by Muchovej (2001).

c. Orchid mycorrhizae

Orchid mycorrhizas are mutualistic interactions between fungi

and members of the Orchidaceae, the world’s largest plant family. The

majority of the world’s orchids are photosynthetic, a small number of

species are myco-heterotrophic throughout their lifetime, and recent

research indicates a third mode (mixotrophy) whereby green orchids

supplement their photosynthetically fixed carbon with carbon derived

from their mycorrhizal fungus. Molecular identification studies of

orchid-associated fungi indicate a wide range of fungi might be orchid

mycobionts, show common fungal taxa across the globe, and support

the view that some orchids have specific fungal interactions.

Confirmation of mycorrhizal status requires isolation of the fungi and

restoration of functional mycorrhizas. New methods may now be used

to store orchid-associated fungi, and store and germinate seed, leading

to more efficient culture of orchid species. However, many orchid

mycorrhizas must be synthesised before conservation of these

associations can be attempted in the field.

According to Dearnaley et al (2012) Orchid mycorrhizas are

predominantly represented by associations between photosynthetic

plants and ‘rhizoctonia’ fungi. These associations, which likely

represent the plesiomorphic condition for orchids, gave rise through

repeated evolutionary shifts to interactions with other diverse fungal

lineages and diversification of orchid metabolism. How orchids recruit

and allow new fungi (even some ‘naı¨ve’ fungi from non-mycorrhizal

clades) to enter the dual morphogenesis of mycorrhizas remains

unclear. However, orchid mycorrhizas are excellent models to reveal

the general properties of mycorrhizal systems as well as providing

insights into the fungal world via specificity aspects, ecological

networks and evolution of the mycorrhizal state.

d. Arbutoid mycorrhizae: Found in California’s chaparral plants.

e. Ericoid mycorrhizae:

According to Straker (1996), the ericoid mycorrhiza has been

regarded as the most specific of mycorrhizas because of its limitation to

hosts belonging to a restricted number of families of the Ericales and

the participation of a small group of ascomycetous fungi as mycobionts

in the association. Primarily associated with acid-loving plants,

including Vaccinium, the blueberry genus and possibly one of the most

prevalent forms of mycorrhizae in Alaska given the diversity of berries

across the state.

2. Explain the organelles of Endomycorrhiza and Ectomycorrhiza!

Answer:

a. Endomychorriza (AM)

AM fungi show the peculiar characteristics in morphology and

physiology. Spores of AM fungi are generally formed in soil and their

sizes (50-500 μm in diameter) are much larger than those of other fungi.

There is no septum in their hyphae. No sexual growth-phase has been

observed. Spores germinate when they are under favorable conditions,

extend their hyphae and colonized plant roots. The fungi penetrate the

hyphae into cortex layer of roots and form the hyphal organs, “vesicles”

and “arbuscules” which are characteristics to AM fungi (Fig. 1). AM fungi

belonging to Gigasporaceae are known not to form vesicles. Colonization

on plant roots is essential for proliferation of AM fungi. AM fungi are thus

recognized as obligate symbiotic fungi. The interaction between AM fungi

and plants is generally mutualism based upon nutrient exchange.

Fig. 1: Schematic picture

of arbusucular mycorrhizal

fungi colonizing roots and

their hyphal extension into

soil.

b. Ectomychorriza

The hartig net is formed by an ingrowth of hyphae (often

originating from the inner part of the surrounding mantle) into the root

of the plant host. The hyphae making up the Hartig net penetrate and

grow in a transverse direction to the axis of the root, and thus form a

network between the outer cells of the root axis. This region of

juxtaposition is where nutrient and carbon exchange occurs.

Enveloping the root, and often containing more biomass than the

Hartig net interface, is a hyphal sheath known as the mantle. There

exists considerable variation in the structure of the mantle, ranging from

a loose network of hyphae to a structured and stratified arrangement of

tissue. Often, these layers resemble plant parenchyma tissue and are

referred to as pseudoparenchymatous

Extraradical hyphae extend outward from the mantle into

the soil, fulfilling the role of the suppressed root hairs by increasing the

surface area of the colonized root. These hyphae can spread out singly,

or in an aggregate arrangement known collectively as a rhizomorph.

Much as the Hartig net and mantle, composite hyphal organs can

display a wide range of structural difference. Some rhizomorphs are

simply parallel, linear collections of hyphae. Others yield more

complex organization such as aggregates where the central hyphae

possess enlarged diameters, or exhibiting apically extending hyphae

that superficially resemble meristematic activity.

A fourth section, which can be thought of as an extension of

the extraradical hyphae, is the reproductive fruiting body of the EcM

fungus. These structures vary widely in their morphology, although

certain aspects are relatively conserved among species. The fungal cell

wallsare typically composed of complex carbohydrates, and a great deal

of nitrogen is often bound in these cell walls and spores.

source of picture : wikipedia

3. What are the function of Mycorrhiza?

Answer:

Mycorrhiza increase root surface area for water and nutrients

uptake. The use of mycorrhizal biofertilizer helps to improve higher

branching of plant roots, and the mycorrhizal hyphae grow from the root

to soil enabling the plant roots to contact with wider area of soil surface,

hence, increasing the absorbing area for water and nutrients absorption of

the plant root system. Therefore, plants with mycorrhizal association will

have higher efficiency for nutrients absorption, such as nitrogen,

phosphorus, potassium, calcium, magnesium, zinc, and copper; and also

increase plant resistance to drought.

The functions of Mycorrhizae:

1. Allow plants to take up nutrients in unavailable forms or nutrients that

are fixed to the soil. Some plant nutrients, especially phosphorus, are

elements that dissolve were in water in neutral soil. In the extreme

acidic or basic soil, phosphorus is usually bound to iron, aluminum,

calcium, or magnesium, leading to water insolubility, which is not

useful for plants. Mycorrhiza plays an important role in phosphorus

absorption for plant via cell wall of mycorrhiza to the cell wall of plant

root. In addition, mycorrhiza help to absorb other organic substances

that are not fully soluble for plants to use, and also help to absorb and

dissolve other nutrients for plants by storage in the root it is associated

with.

2. Enhance plant growth, improve crop yield, and increase income for the

farmers. Arising from improved water and essential nutrients absorption

for plant growth by mycorrhiza, it leads to improvement in plant

photosynthesis, nutrients translocation, and plant metabolism processes.

Therefore, the plant has better growth and yield, reduce the use of

chemical fertilizer, sometimes up to half of the suggested amount,

which in turn increases income for the farmers. As in the trial involving

mycorrhizal biofertilizer on asparagus it was observed that, when the

farmers used suggested amount of chemical fertilizer together with

mycorrhizal biofertilizer, it was found that the crop yield improved by

more than 50%, and the farmers’ income increased 61% higher than

when chemical fertilizer alone was used.

3. Improve plant resistance to root rot and collar rot diseases. Mycorrhizal

association in plant roots will help plant to resist root rot and collar rot

diseases caused by other fungi.

4. It can be used together with other agricultural chemicals. Mycorrhiza

are endurable to several chemical substances; for example; pesticide

such as endrin, chlordane, methyl parathion, methomyl carbofuran;

herbicide such as glyphosate, fuazifopbutyl; chemical agents for plant

disease elimination such as captan, benomyl, maneb triforine,

mancozed and zineb.

REFERENCES

M.A. Turk, T.A. Assaf, K.M. Hameed and A.M. Al-Tawaha 2006. Significance of

Mycorrhizae World Journal of Agricultural Sciences 2 (1): 16-20, 2006

R. M. Muchovej 2001. Importance of Mycorrhizae for Agricultural Crops.

Institute of Food and Agricultural Sciences, University of Florida,

Gainesville

Ianson David 2014. Mycorrhizae in the Alaska Landscape. Published by the

University of Alaska Fairbanks Cooperative Extension Service in

cooperation with the United States Department of Agriculture

C. J. Straker 1996. Ericoid mycorrhiza: ecological and host specificity.

Department of Botany, University of the Witwatersrand, Private Bag 3,

Wits 2050, Johannesburg, South Africa

Dearnaley, John (2007). Further advances in orchid mycorrhizal research.

Mycorrhiza, 17 (6), 475-486. ISSN 0940-6360

Dearnaley, J.D.W., F. Martos, M.A. Selosse 2012. Orchid Mycorrhizas:

Molecular Ecology, Physiology, Evolution and Conservation Aspects.

Fungal Associations, 2nd Edition The Mycota IX B. Hock (Ed.) ©

Springer-Verlag Berlin Heidelberg 2012

Paper of Soil Biology and HealthMycorrhiza

Arranged by :

By:

E. A Lintang Wardyani ( H0713059)

THE MAJOR OF AGROTECHNOLOGY

FACULTY OF AGRICULTURE

SEBELAS MARET UNIVERSITY

SURAKARTA

2015