Oral Presentation International Plant Molecular Biology Conference 2024

Plant tolerance to RNA viruses: molecular and genetic determinants (#280)

Laura Elvira Gonzalez 1 , Todd Blevins 1 , Valerie Schurdi-levraud 2 , Manfred Heinlein 1
  1. IBMP-CNRS, Strabourg, FRANCE, France
  2. Université de Bordeaux, INRAE, Bordeaux, France

Virus-infected plants in the wild often show tolerance (symptom-free infection). Tolerance is a defence response, like resistance. However, whereas resistance describes the host’s ability to limit viral multiplication and/or movement, tolerance describes the host’s ability to reduce the negative effects of infection. Certain natural accessions of A. thaliana (Col-0) are tolerant to TMV whereas other ecotypes (Sha) show disease. By contrast, Col-0 plants infected with the related tobamovirus ORMV develop strong symptoms. Nevertheless, ORMV-infected Col-0 plants have the capacity to recover from symptoms at later stages. Importantly, symptoms recovery in these plants occurs in the presence of normal virus replication and accumulation, thus indicating the achievement of “induced tolerance”. Induced tolerance in ORMV-infected Col-0 plants depends on nuclear and cytoplasmic pathways of small RNA production and correlates with the loss of the activity of the viral RNA silencing suppressor (VSR). Given that tobamoviral VSR proteins act by siRNA sequestration and inhibition of RISC assembly, recovery in the younger leaves may occur upon VSR saturation with mobile virus- and host-derived siRNAs produced in the highly infected mature leaves. Recent RNAseq analysis are aimed to identify the specific siRNA species contributing to induced tolerance and to determine their genomic origin. Moreover, additional ecotypes able to undergo induced tolerance were identified and the potential relationship between induced tolerance and tolerance is under investigation.

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