Reference Report for IND21994829
| Title: | Genetic analysis of phytophthora rot resistance in the soybean PI 567.496. |
| Authors: | Jenks, A.D., Leitz, R.A., Nickell, C.D. |
| Source: | Soybean Genet. Newsl. 1999, 26(1):1-2 |
| Abstract: | After re-evaluating PI 567.496, it was found to be resistant to races 1, 3, 4, 5, 13, and 25 and susceptible to races 7, 12, 17, and 20 of Phytophthora sojae, and was predicted to carry a single gene, either the Rps3a gene or possibly a new gene, based on previous genetic analysis. This resistance pattern is the same as that of Rps3a. The objective of this study was to determine the genetic control of resistance to race 25 of Phytophthora sojae in PI 567.496. In 1996, crosses were made between four different isolines of cv. Harosoy and PI 567.496. During 1998, 50 F2 plants from each cross were evaluated for their reaction to race 25 of P. sojae 4 days after inoculation where numbers of surviving plants were recorded. After inoculation with race 25 of P. sojae, Harosoy 62xx, Harosoy 32xx and PI 567.496 were resistant, while Harosoy 15xx and Harosoy were susceptible. The cross of Harosoy with PI 567.496 appeared to segregate approximately 3 resistant:1 susceptible suggesting segregation of one gene for resistance. In crosses with known alleles for resistance to P. sojae, Harosoy 15xx (Rps1k) √ó PI 567.496 segregated 3 R:1 S (P = 0.274), again suggesting that the PI has a single gene for resistance to race 25. All progeny from the cross of Harosoy 32xx (Rps3a) with PI 567.496 were resistant suggesting the gene in PI 567.496 is allelic to the Rps3a gene. The segregation of progeny from the cross of Harosoy 62xx (Rps6) with PI 567.496 should segregate 15 R:1 S when inoculated with race 25 of P. sojae. However, this population appeared to segregate 3 R:1 S. This ratio could be explained if the wrong pollen source, perhaps Harosoy or Harosoy 15XX, were used in this cross instead of Harosoy 62XX. The results of this study suggest that PI 567.496 carries the Rps3a gene for resistance to P. sojae. |
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