Egyptian Broomrape Sucrose Metabolism In Response To Different Host Plants

Broomrapes are important parasitic weeds in many vegetable crops in dry and warm regions of the world. The study of weed parasite physiology will increase knowledge of broomrape-host interactions that may be applied to the development of improved parasitic plant control programmes. In this study, developmental patterns of activities of essential enzymes (sucrose synthase [SUS], mannose 6-phosphate reductase [M6PR], cell wall invertase [CWI] and soluble acid invertase [SAI]) involved in Egyptian broomrape osmoregulation were investigated using three hosts (celery, tomato and cucumber). The earliest broomrape emergence occurred on cucumber; however, the total biomass of the parasite did not differ between cucumber and tomato. The reducing sugars content, gene expression and enzyme activity in the parasite significantly varied with the parasite organs and the hosts. Maximum SAI activity was observed in the apical part (AP) of the flowering shoot of parasite growing on cucumber. However, the peak of genes expression occurred in the same organ across the three hosts, for example SAI1 was expressed maximally in tubercle bearing the flowering shoot (Tub-FS). The largest amount of reducing sugars was observed in the AP of the parasite grown on tomato. High M6PR activity in the parasite and its matching with M6PR transcriptional levels in three hosts are deemed promising for broomrape management through the deployment of the proteinaceous inhibitors or gene silencing constructs in host plants. Overall, the results indicated that differences in sugar metabolism of Egyptian broomrape grown on different hosts can potentially be exploited for effective management of this difficult-to-control parasite.