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The aim of this study was to determine the changes in chemical composition of fresh red raspberry 'Willamette' fruits caused by the presence of raspberry leaf blotch emaravirus (RLBV). In three experimental orchards of 'Willamette' raspberry, fruits were harvested from RLBV-free and RLBV-infected plants in 2019 and 2020. Fruits were collected at appropriate maturity stages and further analyzed in terms of total phenolics, total anthocyanins, and selected individual phenolics. In all three experimental orchards, the phenolic profiles of the infected and uninfected fruit samples were considerably different during both studied years. Nonetheless, the intensity of the modifications varied greatly depending on the location and harvest year. Statistical analysis revealed that the influence of RLBV infection on the studied features was undeniable, although the influences of weather conditions and soil composition outweighed the influence of RLBV. Taking into consideration all the experimental and statistical data, it can be concluded that RLBV had an impact on the phenolic profile of raspberry 'Willamette' fruits, while sensitivity to environmental conditions and soil composition is emphasized. [ABSTRACT FROM AUTHOR]

The aim of this study was to determine the changes in chemical composition of fresh red raspberry ‘Willamette’ fruits caused by the presence of raspberry leaf blotch emaravirus (RLBV). In three experimental orchards of ‘Willamette’ raspberry, fruits were harvested from RLBV-free and RLBV-infected plants in 2019 and 2020. Fruits were collected at appropriate maturity stages and further analyzed in terms of total phenolics, total anthocyanins, and selected individual phenolics. In all three experimental orchards, the phenolic profiles of the infected and uninfected fruit samples were considerably different during both studied years. Nonetheless, the intensity of the modifications varied greatly depending on the location and harvest year. Statistical analysis revealed that the influence of RLBV infection on the studied features was undeniable, although the influences of weather conditions and soil composition outweighed the influence of RLBV. Taking into consideration all the experimental and statistical data, it can be concluded that RLBV had an impact on the phenolic profile of raspberry ‘Willamette’ fruits, while sensitivity to environmental conditions and soil composition is emphasized.

Raspberry leaf blotch emaravirus (RLBV) is a recently characterised virus infecting raspberries reported in several European countries. RLBV causes yellow blotching, the distortion of leaf margins, and the twisting of raspberry leaves. For a long time, similar symptoms were attributed to the feeding damage caused by raspberry leaf and bud mite (Phyllocoptes gracilis). From 2014−2017, a large-scale survey was conducted in Serbia to investigate the degree of association of the observed symptoms with the RLBV infection. A total of 98 symptomatic and asymptomatic samples were collected from 30 locations. All collected samples were tested on the RLBV presence by reverse transcription and polymerase chain reaction (RT-PCR) using three sets of RNA-specific primers targeting RNA-1, RNA-3, and RNA-5 of the RLBV genome. RT-PCR analysis revealed high incidence of RLBV in tested samples (68.7%). RLBV was confirmed in raspberries ‘Fertödi Zamatos’, ‘Glen Ample’, ‘Meeker’, ‘Polana’, ‘Tulameen’ and ‘Willamette’. Twenty-one isolates were selected for sequencing the portion of the nucleocapsid (NC) gene. The nucleotide sequences of the isolates showed 93.2−100% identity. Phylogenetic analysis confirmed significant genetic variability of the Serbian RLBV isolates based on the nucleocapsid-encoding sequences and revealed the existence of two main clusters. Phylogenetic analysis of the 45 RLBV sequences from Finland, Slovakia, Scotland, and this study also confirmed the existence of two main clusters of isolates.

Raspberry leaf blotch virus (RLBV) is a recently described (-)ssRNA virus (genus Emaravirus) associated with the long-known, severe raspberry leaf blotch disorder (RLBD). The virus is presumably transmitted by the raspberry leaf and bud mite (Phyllocoptes gracilis; Eriophyidae). Cultivated and wild raspberries (Rubus idaeus) displaying RLBD or yellowing symptoms were sampled in 14 districts in Finland and tested for RNA3 and RNA5 of RLBV by reverse transcription PCR (RT-PCR) and dot blot hybridization. A total of 59 samples were tested for RLBV, including 36 plants of cultivated raspberry, 20 wild raspberry plants, one ornamental purple flowering raspberry plant (Rubus odoratus), and two samples of P. gracilis (20 mites pooled per sample) collected from RLBD-affected Glen Ample. Fifty-three (93%) of the 57 plants tested were RLBV-positive, including seven raspberry cultivars (Balder, Glen Ample, Jenkka, Malling Minerva, Maurin Makea, Muskoka, Ottawa) and purple flowering raspberry, which is a new host for RLBV. RLBV was also detected by RT-PCR in mites (P. gracilis) collected from buds of RLBV-positive raspberry plants. The partial nucleotide (nt) sequence of the RLBV NP gene (nt 835-1284 of RNA3) was determined for 21 isolates obtained from 10 districts in Finland. Identical isolates were detected in distant districts, and distinctly different isolates were found in the same raspberry cultivation. Furthermore, eight different NP sequence variants were detected in the nine plants of a single raspberry cultivar (Glen Ample) tested from two districts. The nt and deduced amino acid sequences of the 21 isolates were 92.0-100% and 89.3-100% identical, respectively. Phylogenetic analysis revealed two main clusters. One cluster included three isolates, of which two isolates were from one farm in Finland and one isolate was previously characterised in Scotland. The other cluster contained the remaining 19 isolates characterised in this study. The results indicate that RLBV is widely distributed in cultivated and wild raspberries in Finland and shows considerable genetic variability. [ABSTRACT FROM AUTHOR]