Disease suppressive soil has both diverse and uniform ecology : Modeling and characterizationY-h. Taguchi, Chuo University,

Kazunari Yokoyama, NARO

sector　１disease rate19.2％

sector　３disease rate100％

sector　２disease rate69.2％

0. Introduction (so far, long hostory over more than 20 years ...)

replant failure

No cultivations without disinfect

Soil Sample

dilute suspension agar plate

culture

random sampled colony to biolog plate

Step A

step C

Step B

Cluster Analysis

digitized carbon resource consumption abilityplate reader

Experimental procedure of biodiversity index method for soil bacteria

GN MicroPlateBasically, carbon resources

Appearance of biolog plate coloring

This bacteria consumethis carbon resources

Bacteria 1 Bacteria 2

Bacteria 3 Bacteria 4

bacteria A

B

C

D

Adistance - B

distance AB -C

distance ABC -D

Colony method

biodiversity independent of taxon =

Squared total cluster distance / number of bacteria

Estimation of biodiversity by biolog plate

(Yokoyama 1992)

Soil bacteria is isolated by diluted plate method and 95 carbon resources consumption ability is used for the estimation of biodiversity

bacteria

bacteria

bacteria

Many kinds of species are in suppressive soil

多様性指数

replant failure（％）

An example of spinach repeat failure (Hida, Gifu)

bio

dive

rsity inde

x

soil sample

dilute suspension dilute suspension to

biolog plate

ステップC有機物分解能を数

値化プレートリーダー

Experimental Procedure of soil bacteria biodiversity/activity measurement

Skip

low biologically activity soil High biologically activity soil

Carbon resource consumption rates in soil are measured over 48 hours

OmniLog Robot eye automatically measure carbon resources consumption rate and put into data base

Cottony Leak of Scarlet Runner Bean (Phaseolus coccineus:ベニバナインゲン)

and soil bacteria biodiversity/activity

　 Sector　１ Sector　２ Sector　３

disease rate（％） 19.2 69.2 100

soil bacteria biodiversity/activity（＊）

1,114,100 412,000 306,097

sector　１disease rate19.2％

sector　３disease rate100％

sector　２disease rate69.2％

Katakura Chikkarin CO. LTD, Tsukuba Research Institute Co.,Ltd. 、 Agricultural Research I nstitute, I baraki Agricultural Center, DGC Technology Inc.

Cottony Leak, which causes repeat failure, can be suppressive by the soil with high biodiversity/activity

10

（＊）　Integration of time development

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１.Model

Assumptions

Carbonresource A

Carbonresource B

TimeSoil

bacteriaconsume

Rapidly consumedcarbon resources

are consumed by more kinds of soil bacteria ⇔

Slowly consumedcarbon resources

are consumed by less kinds of soil bacteria ⇔

Co

nsum

ptio

n

Creator:LibreOffice 3.3 LanguageLevel:2

Carbon resources vs Soil Bacteria : Interaction Matrix

Carbon Resources

Interactive region

The ｉ1 th species soil

bacteria consumes carbon resource ｊ

1

The ｉ ２th species soil

bacteria does not consume carbon resource ｊ

２

# of carbon resources consumed by at least a bacteria

Soil Ba

cteria

Model ：Lotka-Volterra type

d x i

d t =(Σ j=1

M0

Niy j )x i

d y j

d t=−(Σ

i= NM0

j

N x i)y j , j⩽M0

0, j> M0

xi : Population of the i th species bacteria

yj: The amount of unconsumed ｊ th carbon resources

Initial condition:xi=0,yj=1 -ε 、（ε：random number、0 < ε < 0.1)M（# of kinds of carbon resources）９０N（# of species of soil bacrteria）９０M

0=20

M0=４0

M0=８0

Title:(fig1a.eps) Creator:(ImageMagick) CreationDate:(2011-11-25T15:50:48+09:00) LanguageLevel:1

Title:(fig1b.eps) Creator:(ImageMagick) CreationDate:(2011-11-25T15:50:53+09:00) LanguageLevel:1

Title:(fig1c.eps) Creator:(ImageMagick) CreationDate:(2011-11-13T14:00:59+09:00) LanguageLevel:1

M0=20 M

0=４0 M

0=８0

diseaserate：１００％

disease rate：69.2％

diseaserate：１9.2％

Sick Healthy

Actual measurement （？） of disease supressive soil　（carbon resources consumption rate of each soil bacteria: colonized and isolated well ）

Carbon Resource ID

Soil b

acte

ria ID

Conclusion・We have developed a model reproducing carbon resource consumption rate time development of soil bacteria. ・Disease suppression is suggested to be enabled bu diverse carbon resources consumption rates. ・It does not disagree with the actual measurements of interaction matrix.

Furthermore.. （omitted, see the next slide） ・ nMDS embedding exhibits that homogeneity

and uniformity of time development are important for disease suppressive soil.

△disease rate：１００％＋disease rate：６９．２％◯disease rate ：１９．２％☓compost

specialists（specialized to a few carbon resources）

generalist (not specialized)

specialist ＞ generalist

specialist ＝ generalist

specialist ＜generalist

points＝carbon resources

Collaborator wanted!