Host plant resistance in wheat to barley yellow dwarf viruses and their aphid vectors: a review.

Cereal aphids are vectors of at least 11 species of Barley Yellow Dwarf Viruses (BYDV) in wheat that alone and/or in combination can cause between 5%-80% grain yield losses. They establish complex virus-vector interactions, with variations in specificity and transmission efficiency that need to be considered for control purposes. In general, these viruses and vectors have a global distribution, however, BYDV-PAV is the most prevalent and abundant virus species worldwide, likely due to its vectoring efficiency and the wide distribution of its primary vector Rhopalosiphum padi. Host plant resistance (HPR) is an environmentally friendly, efficient and cost-effective tool to reduce crop losses to biotic stressors such as aphids and viruses. Finding resistance sources is paramount to breed for HPR. Currently, most of the resistance identified for aphids and BYDV derives from wheat related and wild relative species. However, breeding for HPR to BYDV and its vectors has additional challenges besides the source identification, for example, the lack of selection tools for certain aphid species, which likely prevents the development of elite wheat germplasm carrying resistance to these constraints. Nonetheless, modern technologies such as high-throughput phenotyping, genomic and advanced statistical tools can contribute to make HPR to aphids and BYDV more efficient. In the present review we describe the main sources of resistance, discuss the challenges and opportunities for incorporating the resistance in wheat breeding programs and present a workflow to breed for BYDV and its vectors in wheat.