Breeding soybeans with resistance to soybean rust (Phakopsora pachyrhizi)

Soybean rust, caused by the fungal pathogen Phakopsora pachyrhizi, continues to be a global threat to soybean production, decreasing productivity and increasing the pesticide burden of cropping systems. However, breeders now have access to resistance genes that map to at least seven independent loci which can help protect crops against soybean rust infection. Efficient greenhouse screening protocols have been developed, and low-cost SNP genotyping technology is available for marker-assisted selection and backcrossing of resistance to Phakopsora pachyrhizi (Rpp) loci. Soybean breeders can now employ these technologies for the development of high-yielding soybean cultivars with two, three, or even four pyramided Rpp genes. Such cultivars should provide resistance against the most virulent P.pachyrhizi populations and would be of great help to both large-scale growers in the Americas and subsistence farmers in developing countries. We hope that a better understanding of the history and unique characteristics of P.pachyrhizi, the discovery of Rpp resistance alleles and the latest molecular breeding techniques will empower breeders across the globe to develop cultivars with durable resistance.