ISHS Acta Horticulturae 510: VII Eucarpia Meeting on Cucurbit Genetics and Breeding
CUCURBIT-POTYVIRUS INTERACTIONS INFLUENCING VIRUS MOVEMENT AND ACCUMULATION |
| Authors: | R. Grumet, Z. Ullah, A. Gal-On, B. Raccah |
| Keywords: | Cucumis sativus, Cucurbita pepo, zucchini yellow mosaic virus |
| Abstract:
Cucurbit crops are subject to severe losses due to several potyviruses including the highly aggressive zucchini yellow mosaic virus (ZYMV). We sought to examine potyvirus/host interactions resulting in successful resistance or infection, and to test the role of the variable amino terminus (NT) of the coat protein (CP) in the infection process. Analysis of patterns of virus accumulation in the ZYMV-resistant cucumber (Cucumis sativus) genotype Dina-1 indicated that expression of resistance is developmentally controlled and is due to a block in virus movement. After initial replication and movement out of the cotyledon, virus remains localized to the immediate area surrounding class III veins. Switches of CP domains, with an infectious clone (ZYMV-NAA) that does not cause veinal chlorosis, indicated that the resistance response likely involves interaction with the CP-NT. Switches of the CP-NT with other potyviruses indicated, that despite extensive variability, the heterologous CP-NTs could facilitate systemic infection in ZYMV hosts, but did not extend host range to non-hosts. Following initial infection, susceptible squash (Cucurbita pepo) or cucumber plants infected with tobacco etch virus-ZYMV hybrids exhibited a distinct recovery phenotype of reduced symptoms, virus titer, and virus-specific protection against secondary infection, suggesting that recognition of the non-adapted CP-NT leads to initiation of host defense responses. | |
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