“mata analysis of mycorrhizal networks as facilitators in ecology”

8/9/2019 Mata Analysis of Mycorrhizal networks as Facilitators in Ecology

1/6


2/6

University Of Wah

Submitted by: Adiba Nigar Warda (Reg #: 013)

Department: Biological Sciences

Discipline: 8th

Semester

Course title: Mycology and Plant Pathology

Review Article:

Mata Analysis of Mycorrhizal networks as

Facilitators in Ecology

Submitted to: Dr. Aftab AfzalDate of Submission: 09/08/2010


3/6

Mata analysis of Mycorrhizal networks as

Facilitators in Ecology

Adiba Nigar Warda .Department of Biological Sciences; University of Wah (Wah Cantt,

Pakistan)E-mail: [email protected]

Abstract

The goal of this study was to substantiate the Mycorrhizal networks as

Facilitators in Ecology. My clear focus is on plant and fungi symbiotic

relationships which prove an exceptional socialism in soil. In this I shall include

the response of ectomycorrhizal (EM) and arbuscular mycorrhizal (AM)

communities.

Almost all plants show fungal associations. It may differ from specie to

specie. Mycorrhizal fungi effect the plant growth, nutrition uptake, biodiversity

and ecosystem relations, etc.

Key words:

Arbuscular Mycorrhizal, ectomycorrhizas, meta-analysis,

symbiosis.


4/6

Introduction:

Meta-analysis is the process whereby statistical techniques are used to analyze

quantitatively the results from multiple studies. A common synthetic tool in the medical andsocial sciences since the 1980s (reviewed by Schulze 2004), meta-analysis is now increasingly

being used by ecologists, and meta-analytic approaches are being developed to deal with thespecific characteristics of ecological data (Gurevitch and Hedges 1999, 2001, Gurevitch et al.

2001, Gates 2002, Lajeunesse and Forbes 2003). A survey of the top 20 journals in ecology(ranked by ISI Impact Factor) using the Web of Science database reveals a striking increase in

the number of published meta-analyses over time, from an average of fewer than 5 per year inthe mid-1990s to more than 30 per year in 2006.

1

Most plant species belong to families that typically form root symbioses with mycorrhizalfungi, often with dramatic consequences for plant growth and reproduction (Koide2000), plant

community structure (Grime et al. 1987;Hartnett & Wilson 2002) and ecosystem functions

(Rillig 2004). Although these symbioses are cited in textbooks as clear examples of mutualismand plants often benefit from the association, the interaction might better be viewed as exhibitinga continuum of outcomes as the fungi can sometimes be of little net benefit to host plants or even

function as a net parasitism. Different variables control whether a symbiosis between amycorrhizal plant and fungus will develop as a mutualism or parasitism, including host plant

characteristics, fungal characteristics, soil biotic and abiotic conditions, and experimental procedures (Modjo et al. 1987; Johnson et al. 1997; Klironomos 2003; Jones & Smith 2004);

however, predictions regarding the importance of these different variables have typically beentested in isolation, with individual studies conducted using restricted subsets of plants and fungi.

Meta-analysis provides a quantitative method for integrating results from many differentexperiments to answer broad questions, taking into account variation among studies in levels of

replication and data dispersion, and providing quantitative estimates for experimental effects andrelationships among variables (Hedges & Olkin 1985; Gurevitch & Hedges 1999). Meta-analysis

has been used to test the importance of single factors for variability in outcomes of theectomycorrhizal (EM) symbiosis (Karst et al. 2008), to examine responses of arbuscular

mycorrhizal (AM) and EM symbioses to N, P and CO2 fertilization (Treseder 2004), to testwhether AM fungi affect plantpathogen interactions (Borowicz 2001), to compare the impacts

of different agricultural management practices on AM colonization and resulting growthresponses of crop plants (Lekberg & Koide 2005), and to compare the relative importance for

plants of Mycorrhizal symbioses vs. other types of interactions (Morris et al. 2007).2

Literature search:

Many mycorrhizal fungi are not host specific and one fungal individual can colonize andinterconnect a considerable number of plants. The existence of these so-called mycorrhizal

networks implies that fungi have the potential to facilitate growth of other plants and distributeresources among plants irrespective of their size, status or identity. It was found that 60 cases

where seedling species were grown together with larger plants with or without mycorrhizal


5/6

fungal networks. Mycorrhizal networks promoted seedling growth in 48% of the cases (for 21seedling species), while negative effects (25%) and no effects (27%) were also common.

Seedlings associating with ectomycorrhizal fungi benefitted in the majority of the cases whileeffects on seedlings associating with arbuscular mycorrhizal fungi were more variable. Thus, the

facilitative effects of mycorrhizal fungal networks depend on seedling species identity,

mycorrhizal identity, plant species combinations and study system.

3

A survey of arbuscular mycorrhizal fungi (AMF), arbuscular mycorrhizae (AM), and

hyphal networks of AMF was carried out in sand dune sites of different successional stages inthe Province Lands Area of Cape Cod National Seashore, Massachusetts. The study focused on

large-scale plantings (each of 12-20 ha) of American beachgrass (Ammophila breviligulata) aged0-7 yr and five adjacent natural dune areas. Sample sites ranged in vegetative cover from barren

to forested. Spores of 17 species of AMF were recovered from the dunes. Over the successionalsequence, there were increases in the richness and spore populations of the AMF community, the

extent of colonization of A. breviligulata roots, and the mycorrhizal inoculum potential of thesoil. Unvegetated sites lacked propagules of AMF, but roots of planted culms of A. breviligulata

(which carried propagules of AMF) became mycorrhizal in


6/6

“mata analysis of mycorrhizal networks as facilitators in ecology”

Documents