Submitted to: American Society of Plant Physiologists Meeting
Publication Type: Abstract Only
Publication Acceptance Date: 8/5/1999
Publication Date: N/A
Technical Abstract: Fusarium solani f. sp. glycines is the soilborne pathogen that causes sudden death syndrome (SDS) in soybean. The goal of our study was to evaluate the phenolic compounds, including the phytoalexin glyceollin, that are induced by fungal pathogen. The alteration in phenolic metabolism was studied after inoculating a susceptible soybean cultivar (Spencer) and a partially resistant plant introduction (PI567.374) with Fusarium solani f. sp. glycines. Plants were inoculated by sowing seeds directly above (2-3 cm) infested sorghum seeds in flats in the greenhouse. The dynamics of soluble and wall bound phenolics was analyzed by HPLC during 3 weeks after inoculation. The level of isoflavones conjugates was considerably higher in roots of inoculated plants both of the resistant and susceptible entries compared to untreated plants, with greater isoflavones occurring in the inoculated roots of the resistant entry 7 days after treatment. The phytoalexin glyceollin accumulated to considerably higher level in roots of infected plants from PI567.374. Lignin content was higher in non inoculated plants from PI567.374 than Spencer. In infected plants of both entries, the level of lignin in root cell walls was considerably lower than in healthy plants, although root cell walls from plants of PI567.374 contained more lignin 3 weeks after inoculation than from plants of Spencer. The data on alteration of phenylpropanoid metabolism and plant growth characteristics caused by SDS progression and the possible strategies to alter phenylpropanoid metabolism in soybean transgenic plants will be discussed.