Reference Report for IND21994834
| Title: | Genetic analysis of phytophthora rot resistance in the soybean PI 567.504. |
| Authors: | Weber, D.J., Leitz, R.A., Nickell, C.D. |
| Source: | Soybean Genet. Newsl. 1999, 26(2):1-2 |
| Abstract: | PI 567.504 is resistant to hypocotyl inoculation of races 1, 4, 7, 13, and 25 and susceptible to races 3, 5, 12, and 20. It has been suggested, on the basis of RFLP analysis, that PI 567.504 carries the Rps3a gene for resistance to P. sojae. The objective of this study was to determine the genetic control of resistance to P. sojae race 25 in PI 567.504. During 1996, crosses were made between PI 567.504 and the following Williams isolines: Williams (rps) (designated LNX96163), L83-570 (Rps3a) (designated LNX96173), L85-2352 (Rps4) (designated LNX96178), and L85-3059 (Rps5) (designated LNX96183). F2 seedlings were evaluated for their reaction to race 25 of P. sojae using hypocotyl inoculation. Williams was susceptible to race 25 while PI 567.504, L83-570, L85-2352, and L85-3059 were all resistant. Population LNX96163 was probably the result of self-fertilization since segregation was not found in the F2 and all plants in the population were susceptible. All other populations used in this study segregated in a ratio of approximately fifteen resistant to one susceptible. The calculated χ² probability for the LNX96173 cross with a 15:1 ratio was between 0.05 and 0.01 indicating a loose fit. The calculated χ² probability for LNX96178 and LNX96183 crosses with the same 15:1 ratio was between 0.20 and 0.05 indicating a fairly good fit to the expected ratio. The data from the F2 populations suggest that there are two genes controlling resistance to race 25 in each cross with known genes. Therefore, PI 567.504 has one gene for resistance to race 25 that is not allelic to Rps3a, Rps4, or Rps5. However, this does not eliminate the possibility of a new gene |
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