Polar lipids in healthy and Phytophthora capsici-infected leaflets of Lycopersicon esculentum
1992
Soulie, M.C. | Bompeix, G. | Laval-Martin, D.
The effects of infection by Phytophthora capsici on the repartition and fatty acid composition of polar lipids in three different foliar tissues of Lycopersicon esculentum (May seedlings) were investigated. The tissues studied were: (i) highly infected tissues, under explant, 6 mm diameter; (ii) infected tissues, margin of the lesions, 9 mm width; and (iii) adjacent peripheral tissues, about 52% total area, apparently sound, compared with uninfected control leaflets. The fatty acid composition of each lipid class was drastically altered in the highly infected area. The desaturation pathway of polyunsaturated fatty acids, specific to plants, was either partly inhibited for glycoglycerolipids, or replaced by the desaturation pathway for the formation of parasite phospholipids. Consequently, the long chain fatty acids characterizing P. capsici increased progressively from peripheral to highly infected tissues and the phosphatidylcholine (PC) of the plant was replaced by the PC of the parasite. The increase in the percentage of parasite PC could be used as an infection index. The amounts of all polar lipid classes were increased in the peripheral zone, except phosphatidic acid. A possible distance effect of infection is enhancement of membrane biosynthesis. Phosphonate treatment was found to favour the synthesis of all polar lipid classes in the control leaflet but to be inactive in preserving the integrity of the fatty acid composition of the lipid classes in infected tissues.
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