The possibility of factors other than phytoalexin accumulation preventing fungal growth in the incompatible interactions of soybean with Phytophthora megasperma f. sp. glycinea |
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Authors: | K Abe E Fujikawa Y Takeuchi Y Takada N Yamaoka† |
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Institution: | Cell Function and Structure, Division of Biological Sciences, Graduate School of Science, Hokkaido University, Sapporo 060–0810, Japan |
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Abstract: | Soybean ( Glycine max ) cv. Harosoy 63 is resistant to race 1 and susceptible to race 9 of Phytophthora megasperma f. sp. glycinea (Pmg). In detached primary leaves inoculated with zoospores, growth of race 1 was completely suppressed 16 h after inoculation, while race 9 was unaffected. The amount of the phytoalexin glyceollin that accumulated, however, was not significantly different in either the incompatible or compatible interaction 16 h after inoculation. At the circumference of the inoculated area, a slight accumulation of phytoalexin was observed only in the incompatible interaction 20 h or more after inoculation. Tolerance of race 9 to the phytoalexin was significantly higher than that of race 1 when the phytoalexin was added to agar. Moreover, race 9 degraded glyceollin faster than race 1. On leaves inoculated at separate points with either race, the lesion associated with race 9 never colonized areas inoculated with race 1. These results suggest that factor(s) other than the accumulation of phytoalexin in soybean tissue might cause cessation of growth of Pmg. |
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Keywords: | host–parasite interaction phytoalexin P megasperma f sp glycinea soybean |
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