Detection of Apple Proliferation Disease Using Hyperspectral Imaging and Machine Learning Techniques.

Apple proliferation is among the most important diseases in European fruit production. Early and reliable detection enables farmers to respond appropriately and to prevent further spreading of the disease. Traditional phenotyping approaches by human observers consider multiple symptoms, but these are difficult to measure automatically in the field.

Risk Assessment for the Spread of Flavescence Dorée-Related Phytoplasmas from Alder to Grapevine by Alternative Insect Vectors in Germany.

"Flavescence dorée" (FD)-related phytoplasmas are widespread in alder in Germany and their transmission to grapevine represents a high risk for FD outbreaks when the primary vector, , becomes present in the future. Therefore, the potential role of the Deltocephalinae leafhopper species in transmitting FD-related phytoplasmas from alder to grapevine was studied in extensive transmission trials conducted between 2017 and 2020. The transmission capacity of autochthonous spp.

Delivery of Hairpin RNAs and Small RNAs Into Woody and Herbaceous Plants by Trunk Injection and Petiole Absorption.

Since its discovery, RNA interference has been widely used in crop protection. Recently, transgene-free procedures that were based on exogenous application of RNA molecules having the capacity to trigger RNAi have been reported. Yet, efficient delivery of such RNA molecules to plants and particularly to trees poses major technical challenges.

Molecular evolution of the genomic RNA of Apple stem grooving capillovirus.

The complete genome of the German isolate AC of Apple stem grooving virus (ASGV) was sequenced. It encodes two overlapping open reading frames (ORFs), similarly to previously described ASGV isolates. Two regions of high variability were detected between the ASGV isolates, variable region 1 (V1, from amino acids (aa) 532 to 570), and variable region 2 (V2, from aa 1,583 to 1,868).

An immunodominant membrane protein (Imp) of 'Candidatus Phytoplasma mali' binds to plant actin.

The phytopathogenic, cell-wall-less phytoplasmas exhibit a dual life cycle: they multiply in the phloem of their host plant and in the body of their insect vector. Their membrane proteins are in direct contact with both hosts and are supposed to play a crucial role in the phytoplasma spread within the plant as well as by the insect vector. Three types of nonhomologous but highly abundant and immunodominant membrane proteins (IDP) have been identified within the phytoplasmas: Amp, IdpA, and Imp.

Characteristics of the spread of apple proliferation by its vector Cacopsylla picta.

The distribution and natural phytoplasma infection of Cacopsylla picta were investigated during a long-term field survey between 2002 and 2009 in commercial and abandoned apple proliferation-infected orchards throughout Germany, northern Switzerland, and eastern France. Comparable population dynamics were described for the different sites whereas considerable variations in the absolute population densities were observed among the years. Individual polymerase chain reaction (PCR) testing revealed, for each year, a rather stable natural infection rate with ?Candidatus Phytoplasma mali? of ?10% for overwintered adults of C.

Multilocus sequence analysis reveals the genetic diversity of European fruit tree phytoplasmas and supports the existence of inter-species recombination.

The genetic diversity of three temperate fruit tree phytoplasmas 'Candidatus Phytoplasma prunorum', 'Ca. P. mali' and 'Ca.

Cacopsylla melanoneura has no relevance as vector of apple proliferation in Germany.

Long-term field surveys on the distribution and natural infection rates of Cacopsylla melanoneura were carried out in commercial and abandoned apple-proliferation-infected orchards throughout Germany, northern Switzerland, and eastern France. Although the infection rates of some orchards reached up to 80%, only 0.09% of all C.

Apple proliferation resistance in apomictic rootstocks and its relationship to phytoplasma concentration and simple sequence repeat genotypes.

In an effort to select and characterize apple rootstock resistant to apple proliferation (AP), progenies from seven apomictic rootstock selections and their parental apomictic species, Malus sieboldii and M. sargentii, were compared to standard stocks M 9 and M 11. Seedlings derived from open pollinated mother plants were grafted with cv.

First Report of Cacopsylla picta as a Vector of Apple Proliferation Phytoplasma in Germany.

Since 2000, a serious epidemic of apple proliferation (AP) reappeared in southwestern Germany. Molecular analyses revealed that the AP phytoplasma is associated with this disease. Since no curative treatments or resistant cultivars exist, the only means to reduce spread of the disease is the control of the insect vector.

PCR-RFLP and sequence analysis of a non-ribosomal fragment for genetic characterization of European stone fruit yellows phytoplasmas infecting various Prunus species.

A 927 bp non-ribosomal fragment was used to assess the genetic variability of the European stone fruit yellows (ESFY) phytoplasma infecting 14 different Prunus species. For this, 175 isolates originating from four different Mediterranean countries were tested by PCR-RFLP analysis with seven restriction enzymes. No polymorphism among the ESFY phytoplasma could be observed but 12 out of 18 restriction sites differed between the homologous fragments of ESFY and apple proliferation (AP) phytoplasmas.

Genetic variability of apple proliferation phytoplasmas as determined by PCR-RFLP and sequencing of a non-ribosomal fragment.

Apple proliferation phytoplasmas are considered as quarantine organisms in Europe and north America, but reliable polymerase chain reaction (PCR) primers for their identification in routine diagnosis were missing, because they show genetic variability. Therefore, 100 apple proliferation phytoplasma isolates, derived from most of the European countries where apple proliferation disease has been detected, were analysed for their genetic variability. A detailed restriction fragment length polymorphism (RFLP) analysis of a 1.

Differentiation of mycoplasmalike organisms (MLOs) in European fruit trees by PCR using specific primers derived from the sequence of a chromosomal fragment of the apple proliferation MLO.

A 1.8-kb chromosomal DNA fragment of the mycoplasmalike organism (MLO) associated with apple proliferation was sequenced. Three putative open reading frames were observed on this fragment.

cDNAs of beet necrotic yellow vein virus RNAs 3 and 4 are rendered biologically active in a plasmid containing the cauliflower mosaic virus 35S promoter.

cDNAs of beet necrotic yellow vein virus RNAs 3 and 4 could be rendered biologically active when they were placed under the control of the cauliflower mosaic virus 35S promoter and polyadenylation signal. Although the 35S in vivo transcripts should have contained up to forty 5' and several hundred 3' nonviral nucleotides, the progeny viral RNAs had the same sizes as in naturally infected sugarbeets. The progeny RNAs did not hybridize with the nonviral sequences indicating that they were apparently not replicated.

Effect of recombinant beet necrotic yellow vein virus with different RNA compositions on mechanically inoculated sugarbeets.

Beet necrotic yellow vein virus (BNYVV) inocula with different RNA compositions were prepared from infectious transcripts of RNAs 3 and 4 and the Rg 1 isolate, which has a genome consisting only of RNAs 1 and 2. The recombinant viruses were inoculated on 6- to 8-day-old sugarbeet seedlings by 'vortexing'. Inocula containing RNAs 1 and 2 or 1, 2 and 4 produced some growth reduction, but the most dramatic effects, with yield reductions of about 95% in a highly susceptible variety, were seen when RNA 3 was also present in the inoculum.

Tetanus toxin: primary structure, expression in E. coli, and homology with botulinum toxins.

A pool of synthetic oligonucleotides was used to identify the gene encoding tetanus toxin on a 75-kbp plasmid from a toxigenic non-sporulating strain of Clostridium tetani. The nucleotide sequence contained a single open reading frame coding for 1315 amino acids corresponding to a polypeptide with a mol. wt of 150,700.