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					                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, Japan
                                          2Department 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
spore 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.
Thus, the purpose of this research is to determine the accurate sampling method to assess AMF biomass and community structure in crop field.                                                                                                                                                  Spore density                                C16:1cis11 content
                                                                                                                                                                                                                               1.5 cm


Material and Method
                                                                                                                                                                                                                                                                                                                           0 - 10cm


                                                                                                                                                                                                         0~10cm
                                                                                                                                                                                                                                                                                                                           10 - 20cm


 A field experiment was conducted at Nihon University in Fujisawa-city, Kanagawa Pref., Japan.                                                                                                         10~20cm
                                                                                                                                                                                                                                                                                                                           20 - 35cm


Replicated plots of winter sown wheat (Triticum aestivum L.) and fallow (no weeds during                                                                                                               20~35cm
                                                                                                                                                                                                                                                                                                                           35 - 50cm

winter) were established in October 2008. In June 3, 2009, three soil samples were collected from
                                                                                                                                                                                                       35~50cm                                                                                                             50 - 70cm

different soil depth (0-10, 10-20, 20-35, 35-50, 50-70, and 70-100cm) in both plots (Fig.1). AM                                                                                                                                                        Soil depht ***
                                                                                                                                                                                                                                                                                                                                                                                    Soil depth ***
                                                                                                                                                                                                                                                                                                                                                                                    Plot        ***
                                                                                                                                                                                                                                                       Plot       ns                           Wheat
                                                                                                                                                                                                                                                                                                                         70 - 100cm
                                                                                                                                                                                                                                                                                                                                                                                    Interaction ns
fungal biomass in soil was measured by spore density and analysis of the fatty acid biomarker                                                                                                          50~70cm                                         Interaction ns                          Fallow


                                                                                                                                                                                                                                                                                  25.0 20.0 15.0 10.0 5.0            0.0                   0.0          2.0         4.0       6.0
                                                                                                                                                                                                                                                                                              (spore/dry soil g)                                 (nmol/dry soil g)
C16:1cis11. AM fungal community structure was characterized on the basis of the large subunit                                                                                                      70~100cm
                                                                                                                                                                                                                                                        Fig.2 AMF spore density and C16:1cis11 in dry soil of both plots.
ribosomal DNA (LSU r DNA).
                                                                                                            Fig.1 General view of soil sampling in June 2009.                                                                                           Table 1 OUT of arbuscular mycorrhizal fungi in each soil depth

Result and Discussion                                                                                                                           20.0
                                                                                                                                                                                                                                                        of both plots.
                                                                                                                                                                                                                                                         OTU
                                                                                                                                                                                                                                                                0-10cm            10-20cm       20-35cm
                                                                                                                                                                                                                                                                                                       Wheat Plot
                                                                                                                                                                                                                                                                                                           35-50cm   50-70cm 70-100cm             0-10cm      10-20cm
                                                                                                                                                                                                                                                                                                                                                                                Fallow Plot
                                                                                                                                                                                                                                                                                                                                                                          20-35cm   35-50cm   50-70cm 70-100cm
                                                                                                                                                                                                                                   Wheat

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




                                                                                                              AMF spore density (/dry soil g)
                                                                                                                                                16.0         R=0.917*                                                              Fallow               Glo1      ◆                       ◆        ◆         ◆          ◆            ◆              ◆           ◆           ◆         ◆         ◆
                                                                                                                                                                                                                                                        Glo3                                                            ◆            ◆
                                                                                                                                                                                                                                                        Glo4      ◆                       ◆        ◆         ◆          ◆            ◆              ◆           ◆           ◆         ◆         ◆        ◆
                                                                                                                                                                                                                                                        Glo5      ◆                       ◆                  ◆                       ◆              ◆           ◆           ◆

decreased with increasing the soil depth in both plots (Fig.2). In addition, a positive                                                         12.0                                                                                                    Glo6
                                                                                                                                                                                                                                                        Glo7      ◆
                                                                                                                                                                                                                                                                                          ◆
                                                                                                                                                                                                                                                                                          ◆        ◆         ◆
                                                                                                                                                                                                                                                                                                                        ◆
                                                                                                                                                                                                                                                                                                                        ◆            ◆              ◆                                 ◆         ◆
                                                                                                                                                                                                                                                        Glo8      ◆                       ◆        ◆         ◆          ◆            ◆                                                ◆
                                                                                                                                                                                                                                                        Glo9      ◆                       ◆        ◆         ◆          ◆            ◆              ◆           ◆           ◆         ◆         ◆        ◆

correlation (r=0854, P<0.05 in wheat plot, r=0.917, P<0.05 in fallow plot) was observed                                                         8.0
                                                                                                                                                                                     R=0.854*
                                                                                                                                                                                                                                                        Glo11                             ◆        ◆                                                            ◆                     ◆

                                                                                                                                                                                                                                                        Scu1                                                                                                    ◆
                                                                                                                                                                                                                                                        Scu2      ◆                       ◆        ◆         ◆          ◆            ◆              ◆           ◆           ◆         ◆         ◆        ◆

between the concentration of C16:1cis11 and the spore density in dry soil (Fig.3). AM                                                           4.0                                                                                                     Giga1
                                                                                                                                                                                                                                                        Giga2
                                                                                                                                                                                                                                                                  ◆
                                                                                                                                                                                                                                                                  ◆                       ◆
                                                                                                                                                                                                                                                                                                   ◆
                                                                                                                                                                                                                                                                                                   ◆
                                                                                                                                                                                                                                                                                                                        ◆                           ◆
                                                                                                                                                                                                                                                                                                                                                    ◆
                                                                                                                                                                                                                                                                                                                                                                ◆
                                                                                                                                                                                                                                                                                                                                                                ◆
                                                                                                                                                                                                                                                                                                                                                                            ◆
                                                                                                                                                                                                                                                                                                                                                                            ◆
                                                                                                                                                                                                                                                                                                                                                                                      ◆         ◆
                                                                                                                                                                                                                                                                                                                                                                                                ◆
                                                                                                                                                                                                                                                                                                                                                                                                         ◆



                                                                                                                                                                                                                                                        Div1      ◆                                                                                             ◆                     ◆

fungal communities in the soil of sown wheat field were different in wheat and fallow                                                           0.0                                                                                                     Para1
                                                                                                                                                                                                                                                        Unk1                                       ◆
                                                                                                                                                                                                                                                                                                                                                                ◆


                                                                                                                                                       0.0           1.0           2.0           3.0           4.0       5.0
                                                                                                                                                                                                                                                       Glo=Glomus,Scu=Scutellospora,Giga=Gigaspora,Aca=Acaulospora,
plot (Table 1). Shannon-Wiener diversity index (H’) of fallow plot decreased with                                                                               C16:1cis11 content (nmol/dry soil g)
                                                                                                                                                                                                                                                       Div=Diversispora,Para=Paraglomus,Unk=Unknown species.
                                                                                                         Fig.3 Relationship between C16:1cis11 and AMF spore density in dry soil

increasing the soil depth and that of wheat plot did not change (Fig.4). Glo4 and Scu2 of                of both plots.




                                                                                                                                                                                                                                                                                  1.5
                                                                                                                                                         Shannon-Wiener diversity index (H’)                                                                                                                                                                   35 - 50cm                            Wheat

OUTs were found in all soil samples of both plots. We consider that these OUTs (Glo4                                                             1.6                                                                                                                                                                                                                                                Fallow




                                                                                                                                                                                                                                                                                  1.0
                                                                                                                                                 1.4
and Scu2) were general AMF in experiment field. AM fungal communities in the soil of                                                                                                                                                                                                                          10 - 20cm




                                                                                                                                                                                                                                                                                  0.5
                                                                                                                                                 1.2                                                                                                                                                                             0- 10cm




                                                                                                                                                                                                                                                                   Axis2(29.0%)
                                                                                                                                                                                                                                                                                                                                                 0- 10cm
                                                                                                                                                                                                                                                                                                                     20 - 35cm
sown wheat field were more diverse than that of fallow. However, there was not the                                                                                                                                                                                                                                                                     70 - 100cm




                                                                                                                                                                                                                                                                                  0.0
                                                                                                                                                 1.0                                                                                                                                                        50 -70cm
                                                                                                                                                                                                                                                                                                                                                         50 - 70cm
                                                                                                                                                                                                                                                                                                                       35 - 50cm
                                                                                                                                                 0.8
distinct difference of AMF communities by soil depth in both plots. Moreover, by DCA




                                                                                                                                                                                                                                                                                  - 0.5
                                                                                                                                                                                                                                      Soil depth *                                                               70 - 100cm         20 - 35cm
                                                                                                                                                 0.6                                                                                  Plot       ns                                                                                                            10 - 20cm


(Detrended Correspondence Analysis), AMF communities were different in wheat and




                                                                                                                                                                                                                                                                                  - 1.0
                                                                                                                                                                                                                                      Interaction ns
                                                                                                                                                 0.4




                                                                                                                                                                                                                                                                                  - 1.5
fallow plot (Fig.5). In conclusion, more detail soil sampling must be conducted to assess                                                        0.2


                                                                                                                                                 0.0                                                                                                                                              -1.5       -1.0          - 0.5         0.0         0.5            1.0         1.5

the AMF communities and biomass in agricultural field.                                                                                                       0- 10         10-20         20-35
                                                                                                                                                                                          Soil depth
                                                                                                                                                                                                       35-50     50-70    70-100    (cm)
                                                                                                                                                                                                                                                                                                                              Axis1(36.8%)

                                                                                                                                                                                                                                                                  Fig.5 DCA (Detrended Correspondence Analysis) of both plots.
                                                                                                             Fig.4 Shannon-Wiener diversity index (H’) of both plots.

				
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