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An evaluation of protocols for stabilizing pathotypes of Phytophthora Sojae isolates and characterizing race-specific resistant genes in soybean plant introductions

Jia, Hongtao
http://rave.ohiolink.edu/etdc/view?acc_num=osu1413365001

Abstract Details

2003, Master of Science, Ohio State University, Plant Pathology.
Phytophthora sojae isolates that have stable pathotypes (virulence formulae) and high levels of aggressiveness are needed to identify resistance genes (Rps). Pathotypes of P. sojae isolates are designated based on a set of standard soybean differentials carrying different Rps genes. In this study, protocols were evaluated for isolates collected from the field to reduce or eliminate variability in pathotype reaction from successive single-¬zoospores and single-oospores. Isolates of P. sojae representing races 1, 3, 4, 7, and 25 from IN and OH were also compared on three separate sets of soybean differentials using three separate seed sources. Substantial variation in the pathotypes was found in single-¬zoospores both within a generation and successive generations. P. sojae races 1, 3, 4, 7, and 25 from IN and OH had the expected reaction on all three sets of differentials for Rps1b, Rps1c, Rps1k, Rps2, Rps3a, Rps4, Rps5, Rps7, and on the differential Harlon, L59-731 and Union for Rps1a. Differentials L88-8470 for Rps1a and L93-3312 for Rps1d did not have the expected response. Additional races are needed to differentiate reactions on Rps3b, Rps3c, and Rps6. Utilizing different sources of resistance for Rps alleles may also account for some of the differences in reactions among P. sojae isolates. Incorporating race-specific resistant genes (Rps) to Phytophthora sojae into modern soybean cultivars is the major management strategy for controlling Phytophthora damping-off, root and stem rot disease. Some plant introductions (PIs) from China were identified that were resistant to P. sojae isolates R7, R17 and R25. Two accessions PI567.642A and PI567.550 were among these PIs. They were crossed with soybean differentials to determine which Rps alleles were present in these PIs. F2:3 lines of these two PIs with Williams and Harosoy segregated in 15 resistant to 1 susceptible following inoculation with race 1 which indicates both PIs have two Rps genes. These F2:3 lines as well as other populations were then evaluated with 9 P. sojae isolates to determine which Rps gene(s) may be present. For PI567.642A X Williams population, a 3 resistant to 1 susceptible segregation ratio in F2:3 lines for both R17 and R25 was identified. Following inoculation of these lines with R2, R3, R4, R7, a 15 resistant to 1 susceptible segregation ratio was found. For PI567.550, there was a 3 resistant to 1 susceptible segregation ratio following inoculation of F2:3 lines of PI567.550 X Harosoy 63 (Rps1a) with R3 which indicates PI567.550 has Rps1a. A 3 resistant to 1 susceptible segregation ratio was also found following inoculation of F2:3 populations of PI567.550 X Harosoy (Rps7), PI567.550 X Haro4272 (Rps4), PI567.550 X Haro5272 (Rps5), PI567.550 X Haro6272 (Rps6) with R17. In addition, both PI567.550 and PI567.642A are resistant to R30-T, R31 and susceptible to R20. Based on the inoculation data, we proposed that PI567.642A has Rps1k plus Rps3b and PI567.550 has Rps1a and Rps3b.
Anne E. Dorrance (Advisor)
Michael J. Boehm (Committee Member)
Steven St. Martin (Committee Member)
Randall C. Rowe (Committee Member)
78 p.
Plant Pathology

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Citations

  • Jia, H. (2003). An evaluation of protocols for stabilizing pathotypes of Phytophthora Sojae isolates and characterizing race-specific resistant genes in soybean plant introductions [Master's thesis, Ohio State University]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=osu1413365001

    APA Style (7th edition)

  • Jia, Hongtao. An evaluation of protocols for stabilizing pathotypes of Phytophthora Sojae isolates and characterizing race-specific resistant genes in soybean plant introductions. 2003. Ohio State University, Master's thesis. OhioLINK Electronic Theses and Dissertations Center, http://rave.ohiolink.edu/etdc/view?acc_num=osu1413365001.

    MLA Style (8th edition)

  • Jia, Hongtao. "An evaluation of protocols for stabilizing pathotypes of Phytophthora Sojae isolates and characterizing race-specific resistant genes in soybean plant introductions." Master's thesis, Ohio State University, 2003. http://rave.ohiolink.edu/etdc/view?acc_num=osu1413365001

    Chicago Manual of Style (17th edition)

osu1413365001
183
© 2003, all rights reserved.
This open access ETD is published by The Ohio State University and OhioLINK.