Interaction Between Soybean and Phytophthora Sojae

Phytophthora sojae is a major pathogen of soybean, causing an estimated yield loss of 560,300 metric tons in 1994 in the United States. Thirteen resistance alleles at seven loci have been identified in soybean that control race-specific resistance. There are currently 53 races of P. sojae. The resistant reaction appears to be effective in the early colonization stages of pathogenesis, with growth of hyphae of the pathogen being reduced. The objectives of this research were: (1) to isolate and identify races of P. sojae in Illinois soybean fields; (2) to determine the inheritance of resistance to P. sojae in the soybean PI 567574A; and (3) to observe the response of race 1 of P. sojae to 'Williams' isolines with different race-specific resistance alleles. Thirty-three isolates of P. sojae were obtained from soil samples, and two from plant samples. Most of the P. sojae isolates from soil were races 1, 3, and 4, or variants with the addition of Rps1d virulence. These race patterns are similar to other surveys conducted in other states in the Midwestern United States. Two isolates were obtained from plants with race-specific alleles and those isolates were virulent on those alleles. Two new isolates were also collected from soil samples. Combining currently used alleles with alleles at other loci could effectively control P. sojae in Illinois. PI 567574A has two alleles for resistance to P. sojae, which were found to be Rps1c and Rps3a. Results from the cytological experiments indicate that resistance is effective within 12 hours after inoculation as observed by a reduction in hyphal growth, and the resistance reaction is similar among all currently known P. sojae resistance alleles.

Name thesis:degree_name

Ph.D.

Level thesis:degree_level

Dissertation

Discipline thesis:degree_discipline

Crop Sciences

Grantor

University of Illinois at Urbana-Champaign

Year dc:date

2015

Author dc:creator

• Leitz, Richard Alfred

Contributors dc:contributor

• Nickell, Cecil D.
• Hartman, Glen L.

• Agriculture, Agronomy

Language dc:language

eng

Identifier

(MiAaPQ)AAI9953076

OAI identifier oai:identifier

oai:www.ideals.illinois.edu:2142/85061