Investigation of host factors regulating virus proliferation in plant stem cells and germline

With this proposal I will address a long-known but still not understood phenomenon in plant virology.

Despite extreme replication rates in infected somatic tissues, many plant viruses are excluded from stem cells in the shoot apical meristem and subsequently from the progeny of flowering plants, suggesting that reproductive cells possess an exceptionally efficient antiviral defense.

Yet some viruses overcome this barrier and pose a substantial agricultural risk of spreading viral diseases through seeds over great distances.

Insight into the molecular basis of virus exclusion from stem cells and germline/progeny is therefore of utmost importance.

Recent work by the host group leader indicates that RNA interference and plant defense hormones prevent viruses from entering the meristematic stem cells.

If this exclusion is sufficient to prevent virus entry to the germline, which factors restrict seed transmission of different viruses, and at what stage of development they are relevant, will be addressed in this action by two independent unbiased screens.

First, I will identify candidates regulating virus exclusion from plant germlines and vertical transmission by performing cell-specific transcriptomic analysis of gametes from healthy and infected plants aiming to identify enriched and depleted transcripts suggesting involvement of their products in antiviral defense.

Second, I will compare viral seed transmission rates in natural accessions of Arabidopsis to perform a genome-wide association study and identify underlying genomic polymorphisms.

The proposed work is expected to deliver ground-breaking insight into the mechanisms of transgenerational antiviral defense and novel mechanisms of antiviral immunity, with a high potential to contribute to disease control in plants.