Genetic resistance to sunflower broomrape (Orobanche cumana Wallr.)

Abstract

Orobanche cumana Wallr causes important economic damage in sunflower production in a number of countries around the world. Historically, breeders have been successful in developing cultivars resistant to this parasite, but the introduction of new resistance sources has been followed by the appearance of new pathogenic races overcoming resistance. Sunflower selection for broomrape resistance makes use of different methods for testing breeding materials, looks for resistance sources, and has so far produced significant results. Dominant genes for resistance to races A, B, C, D, E, and F have been found and incorporated into cultivated sunflower genotypes. However, in the last fifteen years, new broomrape populations are being discovered for which very limited or none of the existing commercial hybrids have proven to be resistant. In this review, we will focus on recent contributions on breeding for broomrape resistance, including the identification and characterization of new sources and mechanisms of resistance, their the genetic and molecular characterization, and also recent research about important aspects on the parasite side. Additionally, we will discuss the need of long term strategies involving (i) the complete host-parasite system and the integration of classical and molecular approaches, (ii) international cooperation to establish a common designation of the new races of the parasite and genes for resistance in different countries, and (iii) a greater level of collaboration between breeders from public institutions and private companies, which will all contribute to the development of more durable sources of resistance.