Striga: A Persistent Problem on Millets

Abstract

Striga are obligate root-parasitic plants of the major agricultural cereal crops, including millets, in tropical and semi-arid regions of Africa, Middle East, Asia, and Australia. Consequently, they cause severe to even complete losses in crop grain yield. Though limited in their efficiency, the control strategies available today represent major progress toward combating Striga when compared with the absence of any means some years ago. Hence, efforts have led to the development of powerful approaches for understanding and exploiting the complex intricate host-parasitic plant interactions. It is widely agreed that genetic resistance is the most practical and economically feasible method for sustainable control of Striga. Hence, research efforts have been deployed over the past decades to identify resistance sources in certain millet crops, principally sorghum and pearl millet, to characterize the mechanisms underlying the resistance and to understand the genetic basis of the identified resistance phenotype. Furthermore, application of the modern breeding tools, such as molecular markers, has revolutionized the field of search for Striga resistance. Information thus generated have been extensively used to identify several sources of resistance to Striga and individual genes/QTLs conferring host-plant resistance have been deployed for improving Striga resistance in sorghum varieties. More interestingly, we are facing an accelerated progress in the genomic and biotechnological research that should soon provide important understanding of some crucial developmental mechanisms in both the parasite and their host plants, thereby enhancing the efficiency of breeding for Striga resistance in millets. In this paper we provide a detailed state-of-the-art account on the recent progress and perspectives for Striga research and management in millets.