Incidence, Speciation, and Morpho-Genetic Diversity of Penicillium spp. Causing Blue Mold of Stored Pome Fruits in Serbia

Blue mold, caused by Penicillium spp., is one of the most economically important postharvest diseases of pome fruits, globally. Pome fruits, in particular apple, is the most widely grown pome fruit in Serbia, and the distribution of Penicillium spp. responsible for postharvest decay is unknown. A two-year survey was conducted in 2014 and 2015, where four pome fruits (apple, pear, quince, and medlar) with blue mold symptoms were collected from 20 storage locations throughout Serbia. Detailed morphological characterization, analysis of virulence in three apple cultivars, and multilocus phylogeny revealed three main Penicillium spp. in order of abundance: P. expansum, P. crustosum, and P. solitum. Interestingly, P. expansum split into two distinct clades with strong statistical support that coincided with several morphological observations. Findings from this study are significant and showed previously undocumented diversity in blue mold fungi responsible for postharvest decay including the first finding of P. crustosum, and P. solitum as postharvest pathogens of quince and P. crustosum of medlar fruit in the world, and P. expansum of quince in Serbia. Data from this study provide timely information regarding phenotypic, morphological and genotypic plasticity in P. expansum that will impact the design of species-specific detection tools and guide the development of blue mold management strategies.

Towards a catalog of pome tree architecture genes: the draft 'd'Anjou' genome (Pyrus communis L.)

The rapid development of sequencing technologies has led to a deeper understanding of horticultural plant genomes. However, experimental evidence connecting genes to important agronomic traits is still lacking in most non-model organisms. For instance, the genetic mechanisms underlying plant architecture are poorly understood in pome fruit trees, creating a major hurdle in developing new cultivars with desirable architecture, such as dwarfing rootstocks in European pear (Pyrus communis). Further, the quality and content of genomes vary widely. Therefore, it can be challenging to curate a list of genes with high-confidence gene models across reference genomes. This is often an important first step towards identifying key genetic factors for important traits. Here we present a draft genome of P. communis 'd'Anjou' and an improved assembly of the latest P. communis 'Bartlett' genome. To study gene families involved in tree architecture in European pear and other rosaceous species, we developed a workflow using a collection of bioinformatic tools towards curation of gene families of interest across genomes. This lays the groundwork for future functional studies in pear tree architecture. Importantly, our workflow can be easily adopted for other plant genomes and gene families of interest.

Analysing temperature protocol deviations in pome fruit export cold chains: A Western Cape case

Background: A major concern plaguing South African pome fruit exporters is the volume of fruit going to waste during the export process. The senescence of fruits and the deterioration in its quality are accelerated by an increase in temperature. Thus, the first step in ultimately extending the shelf life of exported pome fruit and decreasing the risk of rejections is to ensure constant temperature control.Objectives: The study investigated the severity of temperature protocol deviations within the apple and pear export cold chains from the Western Cape, South Africa to the Netherlands. The study was undertaken in 2018 for Company X, an international fruit exporting firm, to improve the efficiency of its cold chains.Method: The research conducted temperature trials starting as close to the farm as possible and concluding as close to the end consumer as possible. Pulp and ambient temperature probes were inserted into and around the fruit to monitor export temperature profiles.Results: Firstly, the trial results show that non-compliance with temperature protocols occurred more often along the pome fruit export cold chain than initially anticipated. Secondly, the position within the pallet where the temperature breaks occurred highlighted an issue of heat retention resulting from unintentional oversights early in the cold chain. The study also identified areas of possible improvements where management could mitigate senescence factors.Conclusion: The study concluded that the efficient and effective functioning of a cold chain depends on cumulative efforts by all the supply chain partners rather than on the efforts of a single partner.

Refinement of Non-Antibiotic Spray Programs for Fire Blight Control in Organic Pome Fruit

Fire blight-susceptible, certified organic pome fruit is produced currently on 9,000 ha in the Pacific Northwest region of the United States with acreage continuing to expand in spite of a 2014 prohibition on antibiotics as allowable materials for infection suppression. Non-antibiotic practices for fire blight suppression mirror conventional management, but the full bloom to petal fall period when antibiotics are typically sprayed for fire blight control continues to receive research scrutiny owing to drawbacks and weaknesses of alternative materials. As solitary treatments, effective non-antibiotic materials (e.g., a yeast biocontrol, soluble coppers, and alum) raise the risk of a crop-value reducing, phytotoxic response termed fruit russeting. Conversely, materials with less russeting risk (e.g., Bacillus-based biorationals) are less effective for fire blight control. Spray programs using a combination of materials applied from mid-bloom to petal fall have the potential to provide high levels of protection with reduced russeting risk. In orchard trials, the effects of non-antibiotic spray programs on epiphytic population size of Erwinia. amylovora in flowers, yeast biocontrol population size, floral pH, infection suppression, and fruit russeting revealed strategies for sequencing sprays of non-antibiotic materials. The yeast biocontrol, Blossom Protect (Aureobasidium pullulans), sprayed at 70% bloom was an important contributor to fire blight suppression as was the soluble copper material, Previsto, when applied at full bloom. Choice of material for the petal fall spray timing was important to fruit russeting risk but apparently less important to overall infection incidence. Consequently, treatment programs of Blossom Protect at 70% bloom, a soluble copper at full bloom, and a Bacillus-based biorational at petal fall best balances the quality of infection suppression with risk of fruit russeting.

Robotic Cultivation of Pome Fruit: A Benchmark Study of Manipulation Tools—From Research to Industrial Standards—

In pome fruit cultivation, apples and pears need to be handled in various processes such as harvesting and sorting. Currently, most processes require a vast amount of manual labor. Combined with a structural shortage of seasonal workers, innovation in this field is crucial. Automated processes could provide a solution wherein the search for an appropriate manipulation tool is essential. Aside from several grippers, customized for harvesting by various researchers, the industry also provides a wide variety of standardized manipulation tools. This paper benchmarks a wide set of the most relevant gripping principles, primarily based on their ability to successfully handle fruit, without causing damage. In addition, energy consumption and general feasibility are evaluated as well. The performed study showed that the customized foam gripper scores the overall best for all test scenarios at the cost of being the least energy efficient. Furthermore, most other gripping tools excelled at certain specific tasks rather than being generally deployable. Impactive grippers are better suited for harvesting at low energy consumption, while astrictive grippers are more suited for sorting tasks constricted by the available space. The results also showed that commercially available soft grippers are not always capable of handling sensitive fruits such as pears without causing damage.

Molecular Advances in Larval Fruit Moth Identification to Facilitate Fruit Export From Western United States Under Systems Approaches

Molecular advances facilitate fruit export by improving rapid pest diagnosis by polymerase chain reaction (PCR) and advanced sequencing technology. Improved pest detection provides timely certification of the quarantine pest-free status in the commodity being exported, avoiding unnecessary commodity treatment. The U.S.–Japan Systems Approach to export fresh cherries from the Western United States that targets the codling moth, Cydia pomonella (Linnaeus) (Lepidoptera: Tortricidae), is used as an example. Suspect codling moth larvae interdicted at cherry packing houses are distinguished by PCR from other internal fruit moth larvae such as the oriental fruit moth, Grapholita molesta (Busck) (Lepidoptera: Tortricidae); lesser appleworm, G. prunivora (Walsh) (Lepidoptera: Tortricidae); cherry fruitworm, G. packardi (Zeller) (Lepidoptera: Tortricidae); and filbertworm, Cydia latiferreana (Walsingham) (Lepidoptera: Tortricidae). Identification is confirmed by sequencing the amplicon of a 301 bp region of the COI gene produced by PCR of the DNA from a suspect moth and comparing this sequence of COI gene sequences of other internal fruit feeders of pome fruit. This sequence comparison results in unambiguous pest identification. These findings are discussed in the context of systems approach research to meet evolving needs of phytosanitary requirements for global export of fruits.

Tracking the dissemination of Erwinia amylovora in the Eurasian continent using a PCR targeted on the duplication of a single CRISPR spacer

Fire blight is the most devastating disease affecting pome fruit production globally. The pathogen is native to North America and was imported to western Europe in the 1950s, progressively spreading over the continent in the ensuing decades. Previous phylogenetic studies have revealed the extreme genetic homogeneity of the pathogen outside its center of origin, which makes epidemiological studies difficult. These are generally only possible using hypervariable regions of the genome such as those represented by CRISPRs (Clustered Regularly Interspaced Short Palindromic Repeats), which are, however, not practical to sequence due to their size and variability. Here, we present a simple PCR assay targeting the duplication of a single CRISPR spacer in Erwinia amylovora that was found to be an important marker to discriminate between two main European populations of the pathogen. We implemented the assay on a total of 582 isolates to follow the spread of fire blight across the continent over several decades and, wherever possible, within single countries. The results obtained point to the occurrence of two major separate introduction events for E. amylovora in Europe that occurred approximately 20 years apart, and confirmed the existence of two principal distribution areas located in Northeastern Europe and the Eastern Mediterranean Basin from which the pathogen moved on to colonize the Eurasian continent.