Plant pathogens transmitted by pollen

Pollen is a valuable source of germplasm for breeding and has few associated pests compared with other sources of genetic material. This review seeks to assist the development of appropriate phytosanitary measures by considering the pests that are transmitted by pollen. There are no invertebrates, bacteria, phytoplasmas or spiroplasmas that are pollen-transmitted. Only a limited number of fungal pathogens are associated with the pollen of a restricted number of hosts. In contrast, 39 viruses are pollen-transmitted and a further six are tentatively considered to be pollen-transmitted. The majority of these viruses belong to the Alphacryptovirus, Ilarvirus, Nepovirus or Potyvirus genera. Five viroids have also been identified as being pollen-transmitted.