Molecular analysis of plant root-microbe interaction

Objective

Plant roots offer mechanical support and absorb water and nutrients from soil; however, roots also help plants interact with the soil environment. The survival and productivity of plants depends largely on the ability of the root system to sense and respond to biotic and abiotic factors in the soil. Bacteria, one of the biotic factors in the rhizosphere influence the physiology of the plant root and subsequently the overall health of the plant. This opens the potential to improve plant health and productivity by selectively increasing the population of beneficial bacteria while reducing or minimizing those bacteria exhibiting pathogenic activity in the rhizosphere. To achieve this objective a clear understanding of the plant and bacterial factors that mediate root-bacteria interaction is essential. My research focuses on understanding the plant factors that influence this root-microbe interaction and exploring how this information can be used to improve agricultural productivity. One of the questions we are asking is: Are there plant genes that allow selective colonization of plant roots by beneficial bacteria? To address this question we are using the model plant Arabidospsis thaliana and bacteria Pseudomonas syringe pv tomato DC3000 [Pst DC3000] (pathogen) and Pseudomonas putida (beneficial). With the support from the previous Discovery Grant funding we have identified Arabidopsis single gene mutants that exhibited two contrasting colonization patterns: i) mutants that support growth of the pathogen Pst DC3000 and reduced colonization of the beneficial bacteria P. putida, and ii) mutants that promote colonization by P. putida linked to reduced growth of Pst DC3000. The proposed research program will use these mutants to understand the molecular basis of root-microbe interaction with emphasis on the proteins coded by the target genes. The objectives of this research program are:

1. To study the spatiotemporal expression of target genes in the presence of pathogenic and beneficial bacteria

2. To characterize the protein coded by these genes and to identify interacting proteins.

This proposed research program will add new knowledge on the genetic basis of root-microbe interactions. The genes identified in this research program will aid in the development of crop varieties that can selectively promote beneficial microbes in the rhizosphere. Development of such crop varieties will reduce the use of agricultural inputs like fertilizer, pesticides and water ultimately contributing to sustainable agricultural practices.