Microbiology- and Biodiversity-Based Modeling of Suppression of Cottony Leak of Scarlet Runner Bean in Soils with Diverse and Uniform Ecology

Abstract

Soil-borne plant disease suppression is a primary solution to the pressing global need for stable food supply. However, no indicators of Soil-borne plant disease suppression have been established as yet. Hence, disease prevention through proper soil control has not been possible. In this paper, we propose a new biological indicator for Soil-borne plant disease suppression: the ability of microorganisms to consume carbon resources in the soil, which can be automatically observed with an OmniLog PM system over a period of one or two day duration. This indicator could be used to distinguish disease suppression potential soils for cottony leak of scarlet runner bean from other soils. We modelled the characteristic time developments of carbon resource consumption using a simple ecological model in which microorganisms compete with each other for carbon resources. The measured ecological structures of soil microorganism match well with the theoretical prediction. In order to determine the characteristic features for each type of soil, the observed time developments are embedded into a two-dimensional space by a non-metric multidimensional scaling method. This results in an almost one-dimensional arrangement of embedded points. An analysis of the spatial distributions of each carbon resource in the embedded space shows that healthy soils have a mostly uniform distribution along this one-dimensional arrangement. Since sick soil and non-soil samples have rather localized distributions, the ecological systems in a more disease- suppressive soil are both more diverse and more uniform. Since this indicator can easily and quickly be obtained automatically, it is expected to be useful for validating the various soil improvement methods that are used before a type of soil is employed for cultivation.