Submitted to: Molecules
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/30/2014
Publication Date: 6/6/2014
Publication URL: http://handle.nal.usda.gov/10113/59013
Citation: Zernova, O., Lygin, A., Pawlowski, M., Hill, C., Hartman, G.L., Widholm, J., Lozovaya, V. 2014. Regulation of plant immunity through modulation of phytoalexin synthesis. Molecules. 19: 7480-7496; DOI:10.3390/molecules19067480. Interpretive Summary: Diseases and pests can keep soybean grain producers from achieving maximum productivity. Host plant resistance is an economical and sustainable disease and pest management option. There is a strong demand for soybean cultivars with improved pest and disease resistance. Molecular and biochemical characteristics of soybean hairy roots expressing resveratrol synthase and resveratrol oxymethyl transferase were used to deter infection caused by the soybean generalist fungus, Rhizoctonia solani. The results showed that transgenic modulation of soybean hairy roots reduced root necrosis by 20% to 50% compared to the controls. This research will be useful to soybean pathologists and molecular biologists interested in tranformation events that reduce the affect of fungal pathogens.
Technical Abstract: Soybean hairy roots transformed with the resveratrol synthase and resveratrol oxymethyl transferase genes driven by constitutive Arabidopsis actin and CsVMV promoters were characterized. Transformed hairy roots accumulated the stilbenic compounds resveratrol and pterostilbene, which are normally not synthesized by soybean plants. Expression of the non-native stilbenic phytoalexin synthesis in soybean hairy roots greatly affected their resistance to the soybean pathogen Rhizoctonia solani. The expression of the AhRS3 gene resulted in 20 to 50% decreased root necrosis compared to that of untransformed hairy roots. The expression of two genes, AhRS3 and ROMT, needed for pterostilbene synthesis, resulted in significantly decreased level of necrosis caused by R. solani in transgenic roots that accumulated stilbene phytoalexins of up to 8% of untransformed roots. Results of overexpression of the soybean prenyltransferase (dimethylallyltransferase), G4DT gene in soybean hairy roots are also reported, as well as changes in the capacity of these hairy roots to accumulate native phytoalexin glyceollin in response to fungal infection.