Search

A cockspur coral tree (Erythrina crista-galli, Fabaceae) from the collection of woody ornamentals of the Botanical Garden (Faculty of Science) in Zagreb showed conspicuous virus-like symptoms. The leaf tissue was analyzed by high throughput sequencing (HTS), revealing the presence of two viruses: prune dwarf virus (PDV, genus Ilarvirus) and an unknown virus belonging to the genus Capillovirus (family Betaflexiviridae). The complete sequence of PDV RNA3 of 2,129 nucleotides (nts) coding for the coat and movement proteins was obtained. The complete coding region spanning 6,483 nts was obtained for the capillovirus. It contained all expected open reading frames, and its maximum nucleotide identity was 42% with apple stem grooving capillovirus sequence (GenBank accession number LC143387). As this is far below the threshold for species delineation within the genus Capillovirus, we propose the name Erythrina capillovirus (ErCV) for this putatively new virus and a new virus species Capillovirus ErCV in the family Betaflexiviridae. RT-PCR confirms the presence of ErCV and PDV in symptomatic E. crista-galli, an unusual and exotic fabaceous host with no viruses recorded yet. Asymptomatic Erythrina plants were tested negative for the two viruses in RT-PCR, which, together with their presence in the symptomatic plant, suggests the capillovirus and/or PDV might play a role in eliciting observed symptoms and deserve further investigations. [ABSTRACT FROM AUTHOR]

The cypress bark beetle, Phloeosinus aubei (Coleoptera, Curculionidae, Scolytinae) prefers to build breeding galleries in decaying host trees. However, volatile cues specific to decaying or actively infested trees have not yet been reported. Any such information would be useful for the management of this invasive, wood-boring species that has become established across Europe in the temperate zone and is now a key pest of ornamental Cupressaceae in nurseries and urban landscapes. Our objective was to reveal key components in host volatiles specific to stressed trees, which could be potential signals for the pest of its suitability for colonisation. Volatile profiles of arborvitae, Thuja occidentalis 'Smaragd' suffering from either dehydration or fresh infestation of P. aubei was collected and compared to that samples from healthy control trees. Analyses of volatiles by gas chromatography coupled to an electroantennographic detector revealed substantial differences between healthy, dehydrated and infested trees. Structural elucidation of the major antennally active components revealed that both α-pinene and α-thujene were prevalent in the volatiles of infested trees, whilst α-thujone was the major component in volatiles of healthy trees. In volatiles collected from trunks housing fresh P. aubei female nuptial chambers, sharp increases of β-pinene, myrcene, limonene, and p-cymene were noticed, alongside trace amounts of camphene and fenchene. Volatiles collected from fresh frass showed a similar profile, but with a somewhat smaller amount of limonene. Fenchone was present in each type of volatiles, however, only in low amounts. Further studies should be directed to reveal the behavioural role of these components, which could be helpful in developing kairomone-based techniques for monitoring the flight of the pest in stands of scale-leafed trees. [ABSTRACT FROM AUTHOR]

Sweet acacia (Vachellia farnesiana (L.) Wight and Arn) is an attractive small- to medium-sized evergreen tree native to southern North America spanning from southern California, east to southern Florida. Despite its ornamental appeal, sweet acacia has limited commercial availability. A series of experiments were conducted to determine the effect of hydrothermal scarification on in vitro seed germination, and an efficient level of BA (6-benzylaminopurine) for in vitro multiplication, auxin rooting treatments, and acclimatization of sweet acacia. Results revealed that hydrothermal scarification and visual selection of imbibed seeds are the most effective for rapid in vitro seed germination. The source of seed utilized for the in vitro germination exhibited an unusual characteristic of producing seedlings with 2, 3, or 4 cotyledons. Regardless of the cotyledon number observed, sweet acacia can be efficiently micropropagated using multiplication media supplemented with either 1.0 or 2.0 mg L-1 BA followed by rooting media supplemented 0.5 mg L-1 IBA (indole-3-butyric acid) and 0.5 mg L-1 NAA (1-naphthaleneacetic acid). In vitro derived plantlets were subsequently acclimatized with high survival ranging from 72.7 to 100%. [ABSTRACT FROM AUTHOR]

Key message: Cytokinin supplementation was essential for the induction of shoot proliferation and in vitro organogenesis from shoot apices and cotyledons of D. regia, respectively. Micropropagation techniques have been established for woody species to facilitate their mass clonal propagation and to better understand their processes of regeneration. The goal of this work was to evaluate the potential of shoot apex and cotyledonary explants of Delonix regia, commonly known as royal poinciana, to be induced to undergo shoot proliferation and in vitro organogenesis, respectively. Shoot apices and cotyledons obtained from in vitro-germinated seedlings were inoculated onto Murashige and Skoog (MS) medium supplemented with different concentrations (0.125, 0.250, 0.5, 1.0 and 2.0 mg L−1) of 6-benzyladenine (BA) and a control without BA. After 30 days of cultivation, multiple shoot formation and adventitious shoots were observed in shoot apices and cotyledonary segments of D. regia, respectively. Both explant sources exhibited a dose-dependent behavior with increased fresh mass and shoot number with increasing BA concentrations. The greatest number of shoots was observed in explants cultured on BA-supplemented (2.0 mg L−1) medium; however, the leaflets of shoots grown in MS medium with higher BA concentrations were smaller. Histological analysis revealed that the formation of adventitious shoots occurred through the reprogramming of mesophyll cells in the edge regions of the cotyledonary explants. The results obtained here provide new information for optimizing and establishing efficient regeneration systems and micropropagation of royal poinciana, an important ornamental tree species. [ABSTRACT FROM AUTHOR]

The begomovirus infection in plants has been widely reported throughout the world. The chief carrier of this virus is the whitefly. All of the reports, however, concern plants that grow at a stumpy height from the ground; moreover, the whitefly transmits the begomovirus infection to plants at this low height only by residing under their leaves. To date, there has been no record of the begomovirus infection in trees as the prevalence of the whitefly at tree level is unlikely. For this reason, this study focuses on and presents the first report of airborne begomovirus infection in an ornamental tree-the Melia azedarach (or Pride of India) found on the Indian subcontinent. [ABSTRACT FROM AUTHOR]

Japanese flowering cherry ( Prunus subgenus Cerasus) cultivars, which are characterized by beautiful flowers, have been developed through hybridization among wild Prunus taxa. The long history of cultivation has caused significant confusion over the origins of these cultivars. We conducted molecular analysis using nuclear simple sequence repeat (SSR) polymorphisms to trace cultivar origins. Bayesian clustering based on the STRUCTURE analysis using SSR genotypes revealed that many cultivars originated from hybridization between two or more wild species. This suggests that morphological variations among flowering cherry cultivars probably arose through a complex sequence of hybridizations. Our findings generally supported estimates of the origins of cultivars based on morphological study, although there were some exceptions. [ABSTRACT FROM AUTHOR]