Molecular Plant-Microbe Interactions (2015) 28, 30-41

Marika Rossi, Marta Vallino, Simona Abbà, Marina Ciuffo, Raffaella Balestrini, Andrea Genre and Massimo Turina (2015)
The importance of the KR-rich region of the coat protein of Ourmia melon virus for host specificity, tissue tropism, and interference with antiviral defense
Molecular Plant-Microbe Interactions 28 (1), 30-41
Abstract: The N-terminal region of the Ourmia melon virus (OuMV) coat protein (CP) contains a short lysine/arginine-rich (KR) region. By alanine scanning mutagenesis, we showed that the KR region influences pathogenicity and virulence of OuMV without altering viral particle assembly. A mutant, called OuMV₆₇₁₀, with three basic residue substitutions in the KR region, was impaired in the ability to maintain the initial systemic infection in Nicotiana benthamiana and to infect both cucumber and melon plants systemically. The integrity of this protein region was also crucial for encapsidation of viral genomic RNA; in fact, certain mutations within the KR region partially compromised the RNA encapsidation efficiency of the CP. In Arabidopsis thaliana Col-0, OuMV₆₇₁₀ was impaired in particle accumulation; however, this phenotype was abolished in dcl2/dcl4 and dcl2/dcl3/dcl4 Arabidopsis mutants defective for antiviral silencing. Moreover, in contrast to CP_wt, in situ immunolocalization experiments indicated that CP₆₇₁₀ accumulates efficiently in the spongy mesophyll tissue of infected N. benthamiana and A. thaliana leaves but only occasionally infects palisade tissues. These results provided strong evidence of a crucial role for OuMV CP during viral infection and highlighted the relevance of the KR region in determining tissue tropism, host range, pathogenicity, and RNA affinity, which may be all correlated with a possible CP silencing-suppression activity.
(The abstract is excluded from the Creative Commons licence and has been copied with permission by the publisher.)
Link to article at publishers website
Database assignments for author(s): Massimo Turina

Research topic(s) for pests/diseases/weeds:
molecular biology - genes

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Pest and/or beneficial records:

Beneficial	Pest/Disease/Weed	Crop/Product	Country	Quarant.
	Ourmia melon virus