Examining the effects of Prunus necrotic ringspot virus (PNRSV) and prune dwarf virus (PDV) on peach (Prunus persica) pollen health

Abstract

Pollen health is a key determinant of successful plant reproduction and crop yield. Prunus necrotic ringspot virus (PNRSV) and prune dwarf virus (PDV) are pollen-borne viruses of stone fruits, including peaches, primarily transmitted through vegetative propagation (i.e., grafting) and pollen. Here we investigated the effects of PNRSV and PDV infection on peach pollen morphology, viability, and germination. Our scanning electron microscopy (SEM) on pollen morphology as well as pollen viability and germination assays show that PNRSV has cultivar-specific effects on pollen health: Compared to pollen from virus-negative trees, PNRSV infection resulted in distorted shape, reduced viability, and germination of pollen grains of peach cultivar Red Top while no significant effects on viability nor germination were detected on cultivar Zee Lady pollen grains. PDV infection affected pollen width and also reduced pollen viability but did not affect pollen germination when compared between PDV-positive and PDV-negative pollen grains. We discuss our results in terms of potential evolutionary consequences and implications on virus epidemiology and disease management in orchards. Investigating the effects of viral infection on pollen health will ultimately enhance our understanding of the transmission of pollen-borne viruses.