Rust resistance in faba bean (Vicia faba L.): status and strategies for improvement

Faba bean (Vicia faba L.) is an important grain legume used as food and feed. Its production is threatened by abiotic stresses and diseases, of which rust (Uromyces viciae-fabae) is one of the major diseases in East and North Africa, China and the northern grain growing region of Australia. Understanding the genetic and physiological mechanisms of rust resistance in faba bean is in an early phase. The presence of seedling and adult plant resistance genes has been observed. The resistance most frequently utilised in applied plant breeding is race-specific, where the interaction between resistance genes in the host and avirulence genes in the pathogen confers resistance. The main drawback of using race-specific resistance is lack of durability, when deployed singly. Slow rusting or partial resistance, controlled by multiple genes of small effect, is generally non-race specific, so it can be more durable. We present the current knowledge of host resistance and pathogen diversity and propose rational breeding approaches aided with molecular markers to breed durable rust resistance in faba bean.