The Community Structure and Biomass of Arbuscular Mycorrhizal Fungi

in Field Soil was Changed by Soil Depth

K.Isobe1, M.Higo1, M.Yamaguchi1, R.A.Drijber2 and R.Ishii1

1College of Bioresource Sciences, Nihon University, Fujisawa Kanagawa, Japan2Department of Agronomy and Horticulture, University of Nebraska-Lincoln NE, USA

Arbuscular mycorrhizal fungi (AMF) improve the uptake of phosphate from soil through symbiotic associations with plant roots. The colonization in plant roots is necessary for the proliferating and new s

pore formation of AMF. In generally, the amount of plant roots is different on the soil depth. Therefore, it is thought that the biomass and community structure of AMF is also different on the soil depth. T

hus, the purpose of this research is to determine the accurate sampling method to assess AMF biomass and community structure in crop field.

Material and Method A field experiment was conducted at Nihon University in Fujisawa-city, Kanagawa Pref., Japa

n. Replicated plots of winter sown wheat (Triticum aestivum L.) and fallow (no weeds during win

ter) were established in October 2008. In June 3, 2009, three soil samples were collected from dif

ferent soil depth (0-10, 10-20, 20-35, 35-50, 50-70, and 70-100cm) in both plots (Fig.1). AM funga

l biomass in soil was measured by spore density and analysis of the fatty acid biomarker C16:1ci

s11. AM fungal community structure was characterized on the basis of the large subunit riboso

mal DNA (LSU r DNA).

0～10cm

10～20cm

20～ 35cm

35～50cm

50～70cm

70～ 100cm

1.5 cm

0.05.010.015.020.025.0

70 - 100cm

50 - 70cm

35 - 50cm

20 - 35cm

10 - 20cm

0 - 10cm

0.0 2.0 4.0 6.0

Wheat

Fallow

Spore density

(spore/dry soil g)

C16： 1cis11 content

(nmol/dry soil g)

Soil depht

Plot

Interaction

***

ns

ns

Soil depth

Plot

Interaction

***

***

ns

Fig.2 AMF spore density and C16:1cis11 in dry soil of both plots.

0.0

4.0

8.0

12.0

16.0

20.0

0.0 1.0 2.0 3.0 4.0 5.0

R=0.854*

R=0.917*Wheat

Fallow

C16 ： 1cis11 content (nmol/dry soil g)

AM

F s

po

re d

ensi

ty (

/dry

so

il g

)

　　　　　　0-10cm 10-20cm 20-35cm 35-50cm 50-70cm 70-100cm 0-10cm 10-20cm 20-35cm 35-50cm 50-70cm 70-100cm

Glo1 ◆ ◆ ◆ ◆ ◆ ◆ ◆ ◆ ◆ ◆ ◆

Glo3 ◆ ◆

Glo4 ◆ ◆ ◆ ◆ ◆ ◆ ◆ ◆ ◆ ◆ ◆ ◆

Glo5 ◆ ◆ ◆ ◆ ◆ ◆ ◆

Glo6 ◆ ◆

Glo7 ◆ ◆ ◆ ◆ ◆ ◆ ◆ ◆ ◆

Glo8 ◆ ◆ ◆ ◆ ◆ ◆ ◆

Glo9 ◆ ◆ ◆ ◆ ◆ ◆ ◆ ◆ ◆ ◆ ◆ ◆

Glo11 ◆ ◆ ◆ ◆

Scu1 ◆

Scu2 ◆ ◆ ◆ ◆ ◆ ◆ ◆ ◆ ◆ ◆ ◆ ◆

Giga1 ◆ ◆ ◆ ◆ ◆ ◆ ◆ ◆ ◆

Giga2 ◆ ◆ ◆ ◆ ◆ ◆ ◆

Div1 ◆ ◆ ◆

Para1 ◆

Unk1 ◆

OTUWheat Plot Fallow Plot

　　　　 Glo=Glomus ， Scu=Scutellospora ， Giga=Gigaspora ， Aca=Acaulospora ，　　 　　　 Div=Diversispora ， Para=Paraglomus ， Unk=Unknown species.

Table 1 OUT of arbuscular mycorrhizal fungi in each soil depthof both plots.

1.6

0.0

0.2

0.4

0.6

0.8

1.0

1.2

1.4

Soil depth 　＊Plot　　　　　 ns

Interaction ns

Shannon-Wiener diversity index (H’)

0-10 10-20 20-35 35-50 50-70 70-100 (cm)

Soil depth

Fig.4 Shannon-Wiener diversity index (H’) of both plots.

-1.5 -1.0 -0.5 0.0 0.5 1.0 1.5

-1.5

-1.0

-0.5

0.0

0.5

1.0

1.5

Axis1(36.8%)

- - -

--

- - -

--

70-100cm70-100cm

10-20cm

20-35cm

35-50cm

0-10cm

50-70cm

10-20cm

20-35cm

35-50cm

0-10cm

50-70cm

20-20-35cm

10-20cm

35cm

10-20cm

35-50cm

0-10cm70-100cm

50-70cm

35-50cm

0-10cm70-100cm

50-70cm

Axi

s2(2

9.0%

)

Wheat

Fallow

Fig.5 DCA (Detrended Correspondence Analysis) of both plots.

Result and Discussion The AMF biomass (Concentration of C16:1cis11 and spore density in dry soil) decrease

d with increasing the soil depth in both plots (Fig.2). In addition, a positive correlation

(r=0854, P<0.05 in wheat plot, r=0.917, P<0.05 in fallow plot) was observed between the

concentration of C16:1cis11 and the spore density in dry soil (Fig.3). AM fungal commu

nities in the soil of sown wheat field were different in wheat and fallow plot (Table 1). Sh

annon-Wiener diversity index (H’) of fallow plot decreased with increasing the soil dept

h and that of wheat plot did not change (Fig.4). Glo4 and Scu2 of OUTs were found in al

l soil samples of both plots. We consider that these OUTs (Glo4 and Scu2) were general

AMF in experiment field. AM fungal communities in the soil of sown wheat field were m

ore diverse than that of fallow. However, there was not the distinct difference of AMF c

ommunities by soil depth in both plots. Moreover, by DCA (Detrended Correspondence

Analysis), AMF communities were different in wheat and fallow plot (Fig.5). In conclusi

on, more detail soil sampling must be conducted to assess the AMF communities and bio

mass in agricultural field.

Fig.1 General view of soil sampling in June 2009.

Fig.3 Relationship between C16:1cis11 and AMF spore density in dry soil of both plots.