Project Number: 6619-13000-002-03
Project Type: Reimbursable

Start Date: Apr 01, 2004
End Date: Sep 30, 2008

Objective:
1) Collect and isolate of rhizobia strains able to nodulate the native legumes species of interest for the project; 2) Authentification and preliminary selection of rhizobia strains for the ability to fix nitrogen under controlled conditions; 3) Characterization of selected strains using biochemical and molecular technologies; 4) Production of experimental inoculants and preliminary evaluation in the field; and 5) Interchange and conservation of rhizobia strains from the project.

Approach:
Rhizobium collection missions will be undertaken in Uruguay by Uruguayan cooperators to collect a wide array of rhizobium strains (n=200-300) associated with the targeted legume genera from the four major edapho-climatic regions of the country. Additionally in the USA, a rhizobium collection mission will be made by a team of US and Uruguayan cooperators in California and Oregon to secure a diverse array of rhizobium strains (n=200-300) associated with targeted native North American Trifolium spp. identified as having potential in Uruguay. Strain assays will be conducted in Uruguay under controlled conditions (light room) using a randomized block design with four replicates using two controls (without inoculating, in presence and absence of nitrogen). In some cases, interactions between strains and legume species will be studied. Selected rhizobia isolates will be also characterized by biochemical (profile of isoenzimes, and others) and molecular (PCR) technologies. Inoculants will be prepared at the Dep. of Soil Microbiology in Montevideo in liquid or peat base according to the requirements of the cultivar development programs, and strain selection tests will be done for every legume species. Rhizobia isolations will be added to the MGAP, Dep.of Soil Microbiology collection (http://www.chasque.net/microlab), and a database will be generated using edafo-climatic geographical information. Duplicate materials will be deposited at the USDA, ARS, National Rhizobium Gentetic Resource Center.