•Early Classification of AM Fungi •New Classification of AM Fungi •Basis of Classification of AM Fungi •Classification of Acaulospora •Characteristic of Glomeromycota •Characteristic of Glomrromycetes •Characteristic of Diversisporales •Characteristic of Acaulosporaceae •Characteristic of Acaulosopra •How Acaulosopra differentiate from other common AM Fungi genus

1. Acaulospora –
Classification &
Characteristics
Presented by
Nurulhasan Khatri
SEM 1 M.Sc.(Botany) 2020
BOT 2101 UNIT IV :
Mycorrhizal Biotechnology

2. Zygomycota
Glomerales
• Acaulosporaceae
• Gigasporaceae
• Glomeraceae
Phylum :
Order :
Family :
Genus : 1. Acaulospora 4.Glomus
2. Entrophospora 5.Sclertocystis
3.Gigaspora 6.Scutellospora
Earlier classification of AM fungi (Morton & Benny 1990):

3. Recent classification of AM fungi (Oehl et al.2008):
Glomeromycota
Archaeosporomycetes
Archaeosporales
Glomeromycetes
Diversisporales Gigasporales Glomerales
Paraglomeromycetes
Paraglomerales
3 families 4 families 4 families 2 families 1 family
4 genus 8 genus 8 genus 8 genus 1 genus
Approximately 230 Species

4. Basis of the identification of Mycorrhizal Fungi :
1. Colonization patterns in roots(quite difficult way)
2. Hyphal branching patterns
3. The diameter & structure of hyphae(especially near entry
points)
4. Staining intensity of hyphae
5. Spore size, shape & abundance
6. Spore (morphology) Wall thickness and layers
7. Spore formation and position
8. The way the spore is formed on the hypha (mode of spore
formation) has been important to circumscribe genera and
families, and the layer structure of the spore wall to distinguish
species
9. Molecular Phylogenetic Tools

5. Classification of Genus Acaulospora (Oehl et
al.2008):
PHYLUM Glomeromycota
CLASS Glomeromycetes
ORDER Diversisporales
FAMILY Acaulosporacea
Genus Acaulospora
• Obligate symbiosis
• Formation of arbuscules
• Non-septate hyphae
• Spore single or in cluster or in sporocarp
• Produce large spores (20-1000μm)
• Spores multilayered and multinucleate(very infrequent recombination)
• Lack of sexual reproduction
• New symbioses formed from
1. fragments in the soil
2. spore germination near root
3.spread from neighbouring hosts
Phylum : Glomeromycota

6. • Mycorrhizal structures stain blue to dark blue in “typhan blue”.
• Form intraradical vesicles
• Spore formation laterally or within the neck of terminal or intercalary
sporiferous saccules
• Triple-walled and the characteristic granular, “beaded” inner wall surface of
spore
Classification of Genus Acaulospora (Oehl et
al.2008):
Class : Glomeromycetes
Order: Diversisporales
Family: Acaulosporaceae

7. Genus : Acaulospora
 We know 37 Acaulosopra species .
 In Greek, acaulospora means “spore without a stem” or sessile spores.
 In this genus, spores are borne laterally from the neck of a pre-
differentiated “sporiferous saccule” or “vesicle” or “mother spore”.
 The genus includes spores which are formed singly and ectocarpically in
the soil.
 Spore formation begins with the formation of large, thin-walled vesicles at
the end of wide hyphae. The contents of this vesicle then migrate back in to the
hyphae and enter the sessile resting spores which form on the side of the
parent hypha.

8. mother
hypha
(a) diagrammatic (b) microscopic
Spore formation in Acaulospore :

9. Genus : Acaulospora
 These resting spores are having two or more wall layers and in some cases
complex ornamentation occurs on the outer surface (pits, projections, spines or
reticulations).
 The spore germinastion is through peripheral wall compartments generally.
 Spores are globose to ellipsoid ranging from 40-400μm in diameter.
Acaulospora spinosa resting
spore with the remains of the
outer wall layer(o) covering the
spines and ridges which
ornament the second wall layer
Acaulospora
bireticulata resting
spore showing the
network of the outer
reticulum and the
small pores within
the inner reticulum
Acaulospora spore
with deep pits in the
outer wall(arrows)
and inner wall layers
stained by Melzer’s
reagent

10. Genus : Acaulospora
 Entry point hyphae have characteristic branching patterns.
 Hyphae in outer cortex generally are more irregularly branched, looped or coiled
than for glomus.
 Colonies in roots are often relatively small.
 Thin-walled, non-persistent Intracellular “oil-filled vesicles”, that are initially
rectangular, but often become irregularly lobed due to expansion into adjacent cells, are
characteristic feature.
Oil-filled vesiclesirregularly
branched
hypha

11. A. A.foveata B. Outer wall layer with saucer-shaped pits
C. A.laevis D. With homogenous smooth wall layer
E. A.lacunosa F. Different wall layers with concentric rings
G. A.scrobiculata H. Wall layers and pits with pores
I. A.bireticulata J. With polygonal reticulation
K. A.gerdemannii L. alveolate wall layer
M. A.rehmii N. With different wall layers

12. How Acaulospora Differentiate from other
common genera of AM fungi :
 Contrary to Glomus and Sclerocystis, spores of
Acaulospora do not formed on simple hypha
 In Sclerocystis sporocarp present while in
Acaulospora its absence
 In Gigaspora spore produced on swollen tips, in
Acaulospora laterally
Gigasopre Glomoid sporeScutellospore Entrophospore Sporocarp

13. References :
1. A monograph of Acaulospora spp. (VAM fungi) in sunflower rhizosphere in
Haryana, India (Article in Helia January∙2009)
2. Advances in Glomeromycota taxonomy and classification (Article in IMA
Fungus December ∙2011)
3. https://mycorrhizas.info/vam.html
4. VA Mycorrhiza- Conway Ll. Powell, Ph.D.
5. Handbook of Arbuscular Mycorrhizal Fungi- Tancredo Souza
6. https://sciencedirect.com/topics/agricultural-and-bilogical-
sciences/acaulospora

14. Thank You