Submitted to: Plant Physiology Supplement
Publication Type: Abstract Only
Publication Acceptance Date: 9/14/2000
Publication Date: N/A
Technical Abstract: Phenylpropanoid metabolism plays an important role in providing leguminous plants resistance to various pathogens. Our goal is to identify the alterations in phenolic metabolism that are critical for soybean resistance to sudden death syndrome (SDS), caused by the soil-borne fungal pathogen Fusarium solani P. sp, Glycines (FSG). SDS has become a wide-spread and consistent problem worldwide. Some sources of resistance have been identified that do not show foliar symptoms but still have damaging root infection. Using soybean plant and hairy roots we study a) what changes occur in phenolics in SDS infected root tissues; b) how do these changes impart resistance to cultured roots and c) what genes are effective for SDS resistance in roots. The development of SDS infection was monitored by sampling the roots for biochemical assays of soluble and wall bounded phenolics. Simple pulse and pulse-chase radioactive labeling (from exogenous labeled phenylalanine - **14**C-PA) of phenolic compounds was applied, which helped to detect the dynamics of phenolic metabolism alteration in soybean root tissues during pathogenesis. Considerable changes were found both in compounds of isoflavone and lignin branches of phenylpropanoid pathway. Data on synthesis and metabolism of soluble (phenolic acids, daidzein conjugates, glyceollin) and wall bound phenolics in plant materials with different resistance to FSG during development of SDS infection will be presented. Genetic manipulation of phenolic metabolism that are effective in providing resistance to SDS will be discussed.