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Summary: Plant virus infections are often difficult to characterize as they result from a complex molecular and physiological interplay between a pathogen and its host. In this study, the impact of the phloem‐limited grapevine virus B (GVB) on the Vitis vinifera L. wine‐red cultivar Albarossa was analysed under field conditions. Trials were carried out over two growing seasons by combining agronomic, molecular, biochemical and ecophysiological approaches. The data showed that GVB did not induce macroscopic symptoms on 'Albarossa', but affected the ecophysiological performances of vines in terms of assimilation rates, particularly at the end of the season, without compromising yield and vigour. In GVB‐infected plants, the accumulation of soluble carbohydrates in the leaves and transcriptional changes in sugar‐ and photosynthetic‐related genes seemed to trigger defence responses similar to those observed in plants infected by phytoplasmas, although to a lesser extent. In addition, GVB activated berry secondary metabolism. In particular, total anthocyanins and their acetylated forms accumulated at higher levels in GVB‐infected than in GVB‐free berries, consistent with the expression profiles of the related biosynthetic genes. These results contribute to improve our understanding of the multifaceted grapevine–virus interaction. [ABSTRACT FROM AUTHOR]

Micro(mi)RNAs play crucial roles in plant developmental processes and in defense responses to biotic and abiotic stresses. In the last years, many works on small RNAs in grapevine (Vitis spp.) were published, and several conserved and putative novel grapevine-specific miRNAs were identified. In order to reorganize the high quantity of available data, we produced “miRVIT,” the first database of all novel grapevine miRNA candidates characterized so far, and still not deposited in miRBase. To this aim, each miRNA accession was renamed, repositioned in the last version of the grapevine genome, and compared with all the novel and conserved miRNAs detected in grapevine. Conserved and novel miRNAs cataloged in miRVIT were then used for analyzing Vitis vinifera plants infected by Flavescence dorée (FD), one of the most severe phytoplasma diseases affecting grapevine. The analysis of small RNAs from healthy, recovered (plants showing spontaneous and stable remission of symptoms), and FD-infected “Barbera” grapevines showed that FD altered the expression profiles of several miRNAs, including those involved in cell development and photosynthesis, jasmonate signaling, and disease resistance response. The application of miRVIT in a biological context confirmed the effectiveness of the followed approach, especially for the identification of novel miRNA candidates in grapevine. miRVIT database is available at http://mirvit.ipsp.cnr.it. Highlights: The application of the newly produced database of grapevine novel miRNAs to the analysis of plants infected by Flavescence dorée reveals key roles of miRNAs in photosynthesis and jasmonate signaling. [ABSTRACT FROM AUTHOR]

The article presents answers to questions related to grapevine-virus environment interactions.

Interspecific somatic hybridization is a noteworthy breeding strategy that allows the production of novel genetic variability when crossing barriers exist between two parental species. Although the genetic consequences of somatic hybridization have been well documented, little is known on its impact at the epigenetic level. The objective of our research was to investigate the epigenetic changes, in particular DNA methylation, occurring in a population of potato somatic hybrids. The analysis of 96 Solanum × michoacanum (+) S. tuberosum somatic hybrids from five fusion combinations and their parents was carried out by methylation-sensitive amplified polymorphism (MSAP) and high-performance liquid chromatography (HPLC) methods. Six MSAP primer combinations generated 622 unique bands, of which 295 were fully methylated. HPLC analysis showed from 15.5% to 16.9% total cytosine methylation within the parental forms. Overall, the MSAP and HPLC methods indicated an increase in DNA methylation in the somatic hybrids in comparison to their parents. Among the latter, a lower degree of DNA methylation in the wild S. × michoacanum species than S. tuberosum was found. Our findings indicated that somatic hybridization changed the level of cytosine methylation in the studied potato somatic hybrids. [ABSTRACT FROM AUTHOR]