Changes in Lipid Composition of Brassica Siliquae Upon Infection by Cuscuta

Abstract

Summary Infection of Indian rape (Brassica campestris) cv. Sarson- T42 by the shoot parasite, Cuscuta, initiated at 24 days after sowing (DAS), was more effective than that initiated at a later stage of the development of the host plant. Studies carried out on siliqua chloroplasts of rape plant showed an 83% increase in neutral lipids (pigments and free fatty acids) with a decrease in glycolipid and phospholipid contents by 19 and 34%, respectively. The content of monogalactosyl diglyceride (MGDG) and digalactosyl diglyceride (DGDG) was reduced significantly without a change in the MGDG/DGDG ratio. At 62 DAS, the chlorophyll content of siliqua chloroplasts had decreased by about 21, 18 and 15% when infection by Cuscuta was initiated, respectively at 24, 31 and 38 DAS. The carotenoid content, on the other hand, increased significantly upon infection. A significant increase was observed in all the saturated fatty acids, while unsaturated fatty acids, especially linoleic and linolenic acids, decreased significantly upon infection initiated at 24 DAS. The decrease in unsaturation was 22% upon infection initiated at 24 DAS and became negligible when initiated at 52 DAS. Thus, the severity of damage induced by Cuscuta to rape siliquae was dependent on the developmental stage of host plant at the time of infection.