Fungal and plat metabolites for the biocontrol of some parasitic plant species

Abstract

Broomrapes (Orobanche and Phelipanche spp.) and dodders (Cuscuta spp.), belonging to Orobanchaceae and Convolvulaceae families, respectively, are parasitic weeds infesting a large number of important crops and causing severe yield losses. The main obstacle for long-term management of broomrape infested fields is the durable seed bank with evolved mechanisms of host recognition upon perception of host-derived germination factors. The continuous spread of broomrapes and dodders strongly affect on the farmers work as heavy infestations lead not only to a complete crop failure, but also have a great negative impact over many years, because seeds can survive in soil for a long period of time. Although a large number of certain agronomic practices have been proposed, effective management of parasitic weeds is very difficult to be reached because of their physiological traits and life cycle. Current control relies on the use of resistant crop varieties and herbicides, albeit success has been marginal. Considering that seed germination is a key phase for parasitic plant development and infestation, a further approach proposed for the management of these weeds has been to use microbial or plant metabolites to stimulate, in absence of the host, and/or inhibit the broomrape seed germination. Some metabolites induced a rapid cessation of radicle growth with the promotion of a layer of papillae at the radicle tip hampering the contact of the parasite to the host. The development of herbicides based on natural metabolites from microbial and plant origin, targeting early stages on parasitic plant development, might contribute to the reduction of broomrape seed bank in agricultural soils. Plant and fungal metabolites were also evaluated for their inhibitory effects on germination and growth of dodder species. This communication will illustrates the results obtained in the isolation and chemical characterization of some plants, plant root exudates and fungal metabolites and their effect on the seed germination of different broomrape and dodder species, to develop alternative and ecofriendly strategies for the management of these dangerous parasitic plants.