Soybean sterol composition and utilization by Phytophthora sojae
Marshall. J. A Nes. W. D Dennis. A. L Kumazawa. T Haynes. A. M
Phytochemistry ; 2001 [Vol.58] Pages:423-428
Abstract
The sterol fraction of Glycine max (soybean) was found to contain a mixture of 13 major sterols which differed dramatically in composition between seeds and shoots. Typical C4-desmethyl Δ5-sterols, including sitosterol, predominate the sterol mixture of shoots, whereas C4-methyl sterol intermediates, cycloartenol and 24(28)-methylene cycloartanol, accumulate in seeds. The significance of modified sterol profile of shoot compared to seed was relevant to the physiology of Phytophthora sojae, a phytopathogen of soybean shown to be auxotrophic for sterol. Sterols native to the host plant containing a C4-methyl group, such as cycloartenol, were not utilized by the fungus. Alternatively, all Δ5-sterols added to the culture media of P. sojae supported normal growth and promoted viable oospore production. The results demonstrate the importance of sterols in plant–fungal interactions and offer the possibility of bioengineering the phytosterol pathway for resistance to phytopathogens which scavenge specific sterols of the host plant to complete the life cycle.
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