CMV1 is a gate for cucumber mosaic virus transport from bundle sheath cells to phloem in melon

GUIU-ARAGONÉS, CÈLIA; SÁNCHEZ-PINA, MARÍA AMELIA; DÍAZ-PENDÓN, JUAN ANTONIO; PEÑA, EDUARDO JOSÉ; HEINLEIN, MANFRED; MARTÍN-HERNÁNDEZ, ANA MONTSERRAT

MOLECULAR PLANT PATHOLOGY

WILEY-BLACKWELL PUBLISHING, INC

Lugar: Londres; Año: 2015 vol. 17 p. 973 - 984

1464-6722

Cucumber mosaic virus (CMV) has the broadest host range among plant viruses, causing enormous losses in agriculture. In melon, strains of subgroup II are unable to establish a systemic infection in the near isogenic line SC12-1-99, which carries the recessive resistance gene cmv1 from the accession PI 161375, cultivar ?Songwhan Charmi?. Strains of subgroup I overcome cmv1 resistance in a manner dependent on the movement protein. We have characterized the resistance conferred by cmv1 and established that CMV-LS (subgroup II) can move cell-to-cell up to the veins in the inoculated leaf, but cannot enter the phloem. Immunogold labeling at transmission electron microscopy level showed that CMV-LS remains restricted to the bundle sheath (BS) cells in the resistant line, and does neither invade vascular parenchyma nor intermediary cells, whereas in the susceptible line ?Piel de Sapo? (PS) the virus invades all vein cell types. These observations indicate that the resistant allele of cmv1 restricts systemic infection in a virus strain- and cell type-specific manner by acting as an important gatekeeper for virus progression from BS cells to phloem cells. Graft inoculation experiments show that CMV-LS cannot move from the infected PS stock into the resistant cmv1 scion, thus suggesting an additional role for cmv1 related to CMV transport within or exit from the phloem. The characterization of this new form of recessive resistance, based on a restriction of virus systemic movement, will open the possibility of designing alternative approaches for breeding strategies in melon. This article is protected by copyright. All rights reserved.