| Cuscuta pentagona is a non-selective angiospermic holoparasite derived from the family Convolvulaceae. Having undergone morphological reduction, including reduction of functional leaves and roots, the parasite employs penetrating haustoria, to establish vascular connections to its host, from which it derives water and nutrients. The anatomical and morphological changes in the parasite reflect the physiological adaptation and molecular changes accompanying the adoption of the parasitic habit. Our study investigates these molecular and physiological changes relative to the non-parasitic angiospermic lineage. Using differential display, we identified a differentially expressed sequence specific to haustorial tissues, though its functional significance, if any, remains to be determined as the conceptual translation identified no significant sequence similarity among current protein database entries. In this work, we characterized and compared the carbon and nitrogen metabolic process with the non-parasitic relative,Ipomoea hederacea, measuring the enzyme activity in differential development stages and tissues. Using a biochemical approach, we detected the activity of the enzymes MDH, AAT and NR, in seedlings and mature tissues of both species but lower in level forCuscuta pentagona. However, GDH activity was at detection limit in C. pentagona for any tissues used in assay. Further, in I. hederacea we observed that the induced NR activity in presence of external nitrate was suppressed by light in embryonically derived tissues which was in contrast to light-enchanced NR activity in mature tissues. Finally, we found the light suppression of NR induction correlates with seedlings' overall developmental sensitivity to light. |
