Pollinators interact with flowers partly through direct surface contact, yet the bacterial communities associated with their external surfaces (epibionts) remain poorly understood compared with their gut microbiomes. This study characterised the epibiont bacterial communities of four pollinator species associated with northern highbush blueberry (Vaccinium corymbosum ‘Duke’) in New Zealand: bumble bee (Bombus terrestris), honey bee (Apis mellifera), drone fly (Eristalis tenax), and a New Zealand native bee (Lasioglossum sordidum). Using 16 S rRNA gene sequencing, we detected distinct epibiont communities among pollinator species, with significant differences in alpha and beta diversity. Bumble bees consistently exhibited specialised and low‑diversity communities, whereas drone flies showed the highest bacterial diversity. Several pollinator gut‑associated core bacterial genera, including Gilliamella, Lactobacillus, and Snodgrassella, were detected across most species, representing the first reports of Snodgrassella on E. tenax and of Lactobacillus and Gilliamella on L. sordidum. Environmentally acquired taxa dominated the epibiont communities, consistent with pollinator exposure to floral and habitat‑specific bacterial sources. Differential abundance analysis identified species‑specific bacterial signatures and highlighted how pollinator identity, behavioural ecology, and life history traits shape epibiont composition.

Arbuscular mycorrhizal fungi (AMF) play vital roles in sustainable agriculture, yet evidence linking AMF community composition to plant benefits remains limited. To address this gap, we inoculated two commercial rootstocks (Schwarzmann and 5 C) with AMF communities recovered from different rootstocks from one site to determine effects on plant growth parameters and physiological responses. A glasshouse experiment using a ‘home’ and ‘away’ approach was designed to examine the interaction between rootstock variety and different AMF communities, including those from their own (‘home’) and other rootstocks’ rhizosphere soils (‘away’). Our results showed that rootstocks grown in their ‘home’ AMF communities exhibited greater above and below ground biomass compared to ‘away’ AMF communities, highlighting rootstock specificity in selecting AMF communities. AMF communities increased chlorophyll content and nutrient uptake (copper, boron) in grapevine leaves, where AMF communities dominated by Funneliformis sp., Ambispora sp. followed by Glomus spp. were associated with enhanced grapevine growth. This study enhances our understanding of community-level AMF-grapevine interactions and highlight the ecosystem services these fungi provide. Future research is needed using grafted plants to evaluate their response with different scions following AMF inoculation and to assess the effects of these AMF communities on berry biochemical composition.

Sclerotia play an important role in the disease cycle of Sclerotinia sclerotiorum. Traditional control measures do not effectively suppress germination and viability of sclerotia. This study performed a series of in-vivo bioassays to investigate the effect of biofumigants produced by Brassica juncea Caliente 199, biological control by Paraphaeosphaeria minitans (Coniothyrium minitans), and calcium cyanamide (as Perlka®) on carpogenic germination and sclerotial viability. Paraphaeosphaeria minitans resulted in complete inhibition of carpogenic germination and high sclerotial mortality. Calcium cyanamide applied at the equivalent field rates of 400 and 300 kg ha−1 Perlka resulted in 100

Arbuscular mycorrhizal fungi (AMF) are obligate biotrophs that form a symbiotic and mutualistic relationship with most terrestrial plants, playing an important role in plant growth, nutrient acquisition, and ecosystem stability. This review synthesizes current knowledge on AMF colonization in plants within New Zealand ecosystems, including the challenges and opportunities of molecular identification techniques used in characterizing AMF communities in natural and managed systems. The ecosystem services provided by AMF, such as improved growth parameters, enhanced nutrition, and disease control, are discussed in detail, highlighting their significance in sustainable agriculture and natural ecosystems. Additionally, the role of AMF in invasion ecology was examined, revealing their dual potential to either facilitate or hinder invasive plant species. Despite significant advances in understanding AMF biology, future research is needed to explore the underlying mechanisms of AMF-plant interactions and to address the challenges caused by changing environmental conditions. This review focused on the importance of AMF in promoting ecosystem resilience and suggests avenues for future research to harness their full potential in agricultural and ecological contexts.

In a previous study of fungal endophytes associated with grapevine trunk disease (GTD) in New Zealand vineyards, Botrytis cinerea was recovered from the inner trunk tissues of vines that were symptomatic or asymptomatic for GTD. The effect of B. cinerea, considered an endophytic latent pathogen, on colonisation and symptom development by the grapevine trunk pathogens Neofusicoccum parvum and Diplodia seriata was investigated. B. cinerea isolates recovered from both GTD symptomatic and asymptomatic grapevine trunks, and isolates from infected berries, were pathogenic on green shoots and berries. In planta interactions between B. cinerea and N. parvum or D. seriata were evaluated on detached green Sauvignon Blanc shoots and woody stems of 2-year-old potted Sauvignon Blanc vines. Lesion length and colonisation of the shoots by the pathogens was determined by reisolation, 2 and 12 weeks post-inoculation for detached and attached shoots, respectively. D. seriata did not produce lesions but was shown to endophytically colonise, being recovered from inoculated shoots. Reisolation of D. seriata was unaffected by co-inoculation with B. cinerea in both detached and attached shoots. For N. parvum, co-inoculation with B. cinerea did not affect lesion lengths in detached shoots. In contrast, in attached shoots co-inoculation by B. cinerea inhibited N. parvum lesion development. This was hypothesised to be due to contrasting infection mechanisms by the two Botryosphaeriaceae species and alteration in the host response between detached and attached tissues. The findings indicate that B. cinerea is involved in the GTD complex and affects symptom expression.

AIMS:Endophytic colonisation of apple shoots by bacterial endophytes with in vitro antagonism against Neonectria ditissima was evaluated. Their biocontrol activity against N. ditissima was assessed. METHODS AND RESULTS:Spontaneous mutants resistant to 125 ppm rifampicin produced from three Pseudomonas sp. and three Bacillus sp. strains were used to assess endophytic colonisation of detached 'Royal Gala' apple shoots. Re-isolation on rifampicin amended agar followed by enterobacterial repetitive intergenic consensus (ERIC)-PCR verified endophytic colonisation by three Pseudomonas sp. rifampicin mutants up to 4-5 cm above and below the inoculation point. Colonisation ability was not found for the three Bacillus rifampicin mutants. Recovery frequency and total length of detached shoots colonised by N. ditissima was not reduced. In attached shoots, length of shoot tissue colonised by Pseudomonas mutant strains did not differ between treatments at either assessment time. Pseudomonas sp. 1RIF inoculated 14 days before N. ditissima reduced length of shoot colonised by N. ditissima. The other treatments did not reduce length of shoot colonised by N. ditissima indicating no in planta biocontrol activity. CONCLUSION:Combination of spontaneous rifampicin resistant bacterial mutants and ERIC-PCR reliably tracked bacteria in planta. Lack of in planta biocontrol activity was not due to absence of endophytic colonisation.

Dieback of blackcurrants (Ribes nigrum) is an increasing problem worldwide with several pathogens including the Botryosphaeriaceae species, Neofusicoccum ribis, reported as being associated with dieback. To identify the species of Botryosphaeriaceae associated with blackcurrant dieback in New Zealand, isolations were carried out from plant samples with dieback symptoms collected from blackcurrant orchards in the main growing areas in the South Island of New Zealand. For one site, symptomatic grapevines in an adjacent vineyard were also sampled as they are known hosts of these species. The pathogenicity of representative isolates from each of the species recovered was determined on detached blackcurrant shoots. Of the 242 symptomatic plant materials collected, 29% were infected by Botryosphaeriaceae. Species of Botryosphaeriaceae were recovered from plant samples from all four orchards sampled. Of the 70 Botryosphaeriaceae isolates recovered from blackcurrant, Diplodia seriata (43 isolates) and D. mutila (17 isolates) were the most prevalent species, with Neofusicoccum australe (6 isolates), N. cryptoaustrale (3 isolates) and one isolate of D. sapinea also recovered. D. seriata, D. mutila, N. australe and N. cryptoaustrale were also recovered from symptomatic grapevine tissues sampled from the adjacent vineyard and all but N. cryptoaustrale were found in the blackcurrant crop adjacent to this vineyard. All species were pathogenic on detached green shoots, with N. australe and N. cryptoaustrale the most pathogenic, producing the longest lesions compared with D. seriata and D. mutila. This is the first study on the incidence and pathogenicity of species of the Botryosphaeriaceae infecting blackcurrant plants in New Zealand.

Plant-parasitic nematodes threaten horticultural crops, causing damage by feeding on plant roots, reducing yields, and affecting global food security. We present preliminary results on nematode genera found in soil around two varieties of grapevine (Sauvignon blanc and Pinot noir) with different rootstocks (101-14, SO4, 5C, Riparia Gloire, 3309, Schwarzmann) in ten vineyards located in Blenheim, part of the largest grape-growing area in New Zealand. Soil samples were collected, and nematodes were extracted using a modified centrifugal-flotation technique. Nematode counting and morphological identification to genus level was conducted based on characteristics such as stylet size and overall body shape. Soil texture analysis was performed, and the influences of grape variety and rootstock as well as soil type on nematode diversity were assessed. Four genera of plant-parasitic nematodes, including Pratylenchus, Paratylenchus, Helicotylenchus, and Criconomella, were recovered from the vineyard soils and a snapshot of relative abundance was determined. Differences in the nematode genera and their relative abundance among varieties and rootstocks were found, which suggests potential interactions between nematode genera and grapevine rootstocks/scions. This preliminary survey provides updated information on nematodes since the last survey conducted 20 years ago in New Zealand. This work indicates the presence of various genera of plant-parasitic nematodes in soils around grapevines grown around Blenheim, New Zealand. These findings highlight the need for further research to understand the interactions between nematodes, grape varieties, and rootstocks. The importance of addressing this knowledge gap for biosecurity measures and potential implications on grapevine growth and vineyard productivity is discussed.

ABSTRACTPreviously genetically characterised strains of Pseudomonas syringae. pv. syringae (Pss), [P. amygdali pv. morsprunorum] (Pam, syn. P. s. pv. morsprunorum race 1) and Pseudomonas spp. from New Zealand were characterised for their pathogenicity and aggressiveness in plant tissue and associated virulence factors. Lesions on detached, Pss‐inoculated immature fruit increased rapidly in size and, at 10 days post inoculation (dpi), had larger areas under the disease progress curve (AUDPC) than Pam‐inoculated fruit (48.9 and 22.0, respectively). Detached leaves infiltrated with Pss‐developed symptoms within 1 dpi and from 2 dpi for Pam. Necrosis from most Pss strains extended into the leaf veins by 7 dpi, while Pam strains' necrosis was confined to the inoculation site. On detached 1‐year‐old cherry shoots, Pseudomonas spp. strains exhibited the smallest mean lesion size (2.1–2.4 mm), whereas larger mean lesion sizes were observed with Pss strains (5.7–13.7 mm) and Pam strains (3.9–14.0 mm). A functional T3SS was inferred for Pss and Pam strains based on the hypersensitivity reactions observed on tobacco leaves and symptoms elicited on cherry tissue. Syringomycin production was prevalent (88%) among Pss strains. In contrast, only 1.4% of Pam strains produced coronatine. Most Pss strains (97.0%) were able to catalyse ice formation. The coexistence of strains with varying degrees of virulence and non‐pathogenic strains suggests a complex ecological balance, where multiple factors, including genetic variation, virulence traits and environmental conditions, shape the population dynamics and disease outcomes.

Insect pollinators acquire microorganisms when they visit flowers for nutrients. The interactions that occur at the floral interface are complex with three participants - pollinators, plants and microorganisms. The majority of the insect pollinator's microbiome is shaped by their behaviour, diet and environment. At present the bee (Apidae family) microbiome is the best documented and contributes to our understanding of the bi-directional exchange of microbes between pollinators and flowers. The transferred microorganisms may be mutualistic, commensal or pathogenic. We identify a lack of information due to limited studies concerning the diversity of pollinators and a focus on pathogenic microorganisms and their gut microbiome influence on their health. Each candidate, the insect, plant and microbe, makes their own contribution which aids the interaction, but some participants may benefit more than others. The benefits for pollinators include enhanced acquisition of nutritional resources; for microorganisms dispersal and a 'new' habitat to colonise and for plants pollination is the outcome. Finally, we explore a novel concept of whether the fruit acts as a potential vector for insect microorganisms to hibernate and extend their lifecycle in the absence of a pollinator host.

Understanding host-microbe interactions in planta is an expanding area of research. Amplicon sequencing of the 16S rRNA gene is a powerful and common method to study bacterial communities associated with plants. However, the co-amplification of mitochondrial and plastid 16S rRNA genes by universal primers impairs the sensitivity and performance of 16S rRNA sequencing. In 2020, a new method, Cas-16S-seq, was reported in the literature to remove host contamination for profiling the microbiota in rice, a well-studied domestic plant, by engineering RNA-programmable Cas9 nuclease in 16S rRNA sequencing. For the first time, we tested the efficiency and applicability of the Cas-16S-seq method on foliage, flowers, and seed of a non-domesticated wild plant for which there is limited genomic information, Leptospermum scoparium (mānuka). Our study demonstrated the efficiency of the Cas-16S-seq method for L. scoparium in removing host contamination in V4-16S amplicons. An increase of 46

A collection of isolates of the fungi Leptosphaeria maculans and L. biglobosa, which cause blackleg disease on Brassica napus (canola/oilseed rape) and other Brassicaceae species, was assembled to represent the global diversity of these pathogens and a resource for international research. The collection consists of 226 isolates (205 L. maculans and 21 L. biglobosa) from 11 countries. The genomes of all 205 L. maculans isolates were sequenced, and the distribution and identity of avirulence gene alleles were determined based on genotypic information and phenotypic reactions on B. napus lines that hosted specific resistance genes. Whilst the frequencies of some avirulence alleles were consistent across each of the regions, others differed dramatically, potentially reflecting the canola/oilseed rape cultivars grown in those countries. Analyses of the single-nucleotide polymorphism (SNP) diversity within these L. maculans isolates revealed geographical separation of the populations. This "open access" resource provides a standardized set of isolates that can be used to define the basis for how these fungal pathogens cause disease, and as a tool for discovery of new resistance traits in Brassica species.

AIMS:Arbuscular mycorrhizal fungi (AMF) can perform significant functions within sustainable agricultural ecosystems, including vineyards. Increased AMF diversity can be beneficial in promoting plant growth and increasing resilience to environmental changes. To effectively utilize AMF communities and their benefits in vineyard ecosystems, a better understanding of how management systems influence AMF community composition is needed. Moreover, it is unknown whether AMF communities in organically managed vineyards are distinct from those in conventionally managed vineyards. METHODS AND RESULTS:In this study, vineyards were surveyed across the Marlborough region, New Zealand to identify the AMF communities colonizing the roots of different rootstocks grafted with Sauvignon Blanc and Pinot Noir in both conventional and organic systems. The AMF communities were identified based on spores isolated from trap cultures established with the collected grapevine roots, and by next-generation sequencing technologies (Illumina MiSeq). The identified AMF species/genera belonged to Glomeraceae, Entrophosporaceae, and Diversisporaceae. The results revealed a significant difference in AMF community composition between rootstocks and in their interaction with management systems. CONCLUSIONS:These outcomes indicated that vineyard management systems influence AMF recruitment by rootstocks and some rootstocks may therefore be more suited to organic systems due to the AMF communities they support. This could provide an increased benefit to organic systems by supporting higher biodiversity.

Fungal endophytes inhabit a similar ecological niche to that occupied by many phytopathogens, with several pathogens isolated from healthy tissues in their latent phase. This study aimed to evaluate the pathogenicity, the colonisation ability, and the enzyme activity of 37 endophytic fungal isolates recovered from apparently healthy apple shoot and leaf tissues. The pathogenicity of the isolates was assessed on ‘Royal Gala’ and ‘Braeburn’ fruit and detached ‘Royal Gala’ shoots. For the non-pathogenic isolates, their ability to endophytically colonise detached ‘Royal Gala’ shoots was evaluated. Enzyme activity assays were undertaken to determine whether the pathogenicity of the endophytes was related to the production of the extracellular enzymes, amylase, cellulase, pectinase, protease, and xylanase. Of the 37 isolates studied, eight isolates, representing the genera Colletotrichum, Diaporthe, Fusarium, and Penicillium, were shown to be pathogenic on both apple shoots and fruit. Two isolates identified as Trichoderma atroviride, were pathogenic only on shoots, and three isolates, representing the genus Diaporthe, were pathogenic only on fruit. Of the remaining 24 isolates, 22 (Biscogniauxia (n=8), Chaetomium (n=4), Trichoderma (n=3), Epicoccum (n=2), Neosetophoma (n=2), Xylaria (n=1), Daldinia (n=1), and Paraphaeosphaeria (n=1)) were recovered from the inoculated apple shoots but two failed to colonise the shoot tissues. Of the isolates tested, 20 produced amylase, 15 cellulase, 25 pectinase, 26 protease, and 13 xylanase. There was no correlation between the range and type of enzymes produced by the isolates and their pathogenicity or ability to endophytically colonise the shoot tissue. The study showed that approximately one-third (13/37) of the isolates recovered from the apparently healthy apple shoot tissues were observed as latent pathogens. The isolates that did not cause disease symptoms may have the ability to reduce colonisation of apple tissues by pathogens including Neonectria ditissima associated with European canker of apple.

Grapevine trunk diseases (GTDs) are a substantial challenge to viticulture, especially with a lack of available control measures. The lack of approved fungicides necessitates the exploration of alternative controls. One promising approach is the investigation of disease escape plants, which remain healthy under high disease pressure, likely due to their microbiome function. This study explored the microbiome of grapevines with the disease escape phenotype. DNA metabarcoding of the ribosomal internal transcribed spacer 1 (ITS1) and 16S ribosomal RNA gene was applied to trunk tissues of GTD escape and adjacent diseased vines. Our findings showed that the GTD escape vines had a significantly different microbiome compared with diseased vines. The GTD escape vines consistently harbored a higher relative abundance of the bacterial taxa Pseudomonas and Hymenobacter. Among fungi, Aureobasidium and Rhodotorula were differentially associated with GTD escape vines, while the GTD pathogen, Eutypa, was associated with the diseased vines. This is the first report of the link between the GTD escape phenotype and the grapevine microbiome.

AIMS:Sclerotinia sclerotiorum is an important pathogen of a wide range of crops, with current control mostly relying on the use of fungicides. This study assessed the effect of biofumigation on in vitro inhibition of mycelial growth and reduction of sclerotial viability of S. sclerotiorum as an attempt to seek an alternative management strategy.METHODS AND RESULTS:The effect of different biofumigant crop types to inhibit mycelial growth of ten S. sclerotiorum isolates was investigated, with Brassica juncea 'Caliente 199' being the most effective biofumigant crop. The efficacy of 'Caliente 199' to inhibit mycelial growth and reduce sclerotial viability was influenced by different crop factors. Plant tissue of 'Caliente 199' harvested at 50% or 100% flowering and adjusted to 80% (w/w) moisture resulted in greater mycelial inhibition and a reduction in the sclerotial viability compared with the vegetative tissue with the same plant moisture. Mycelial inhibition and reduction of sclerotial viability were affected by tissue quantity. Whole plant tissue and shoots only resulted in a similar inhibition of mycelial growth, but whole plant tissue resulted in a greater reduction of sclerotial viability. The S. sclerotiorum isolates differed in sensitivity to the volatile bioactive compounds released by the biofumigant plant tissue.CONCLUSIONS:The volatile bioactive compounds released by 'Caliente 199' resulted in effective mycelial inhibition but did not kill sclerotia completely.

Sooty mould describes the complex of superficial, Ascomycota fungi that grow upon the honeydew exudates from different Hemiptera species. Kiwifruit affected by sooty mould were harvested from a commercial orchard in June 2021 and cool-stored for six months at 1 degrees C. Fungal communities were isolated from the lenticels, skin and flesh of 'Zesy002' and 'Hayward' kiwifruit at three time periods: 0-, 3- and 6-months postharvest. Fruit tissue samples were grown on potato dextrose agar (PDA), morphotyped and identified to genus level using DNA sequencing. A total of 1862 fungal isolates were obtained from 450 'Zesy002' and 450 'Hayward' tissue samples. Forty-two different fungal morphotypes, belonging to 17 different genera were identified, with Cladosporium spp. being the most commonly isolated taxa from both 'Zesy002'and 'Hayward' fruit (23.3 and 40.9% of isolates, respectively). Differences occurred between cultivars, for example, Alternaria spp. was relatively common on 'Zesy002' but not on 'Hayward'. Additionally, the community composition of sooty mould changed as time increased in cool storage. This research will inform the development sustainable control strategies to reduce insect honeydew excretions.

Arbuscular mycorrhizal fungi (AMF) deliver potentially significant services in sustainable agricultural ecosystems, yet we still lack evidence showing how AMF abundance and/or community composition can benefit crops. In this study, we manipulated AMF communities in grapevine rootstock and measured plant growth and physiological responses. Glasshouse experiments were set up to determine the interaction between rootstock variety and different AMF communities, using AMF communities originating under their own (i.e., "home") soil and other rootstocks' (i.e., "away") soil. The results revealed that specific AMF communities had differential effects on grapevine rootstock growth and nutrient uptake. It was demonstrated that a rootstock generally performed better in the presence of its own AMF community. This study also showed that AMF spore diversity and the relative abundance of certain species is an important factor as, when present in equal abundance, competition between species was indicated to occur, resulting in a reduction in the positive growth outcomes. Moreover, there was a significant difference between the communities with some AMF communities increasing plant growth and nutrient uptake compared with others. The outcomes also demonstrated that some AMF communities indirectly influenced the chlorophyll content in grapevine leaves through the increase of specific nutrients such as K, Mn, and Zn. The findings also indicated that some AMF species may deliver particular benefits to grapevine plants. This work has provided an improved understanding of community level AMF-grapevine interaction and delivered an increased knowledge of the ecosystem services they provide which will benefit the wine growers and the viticulture industry.

Genetic diversity and virulence variability of Diplodia mutila isolates recovered from grapevines in New Zealand were in-vestigated. The universally primed PCR (UP-PCR) and vegeta-tive compatibility group (VCG) methods were used to investi-gate the genetic diversity. Pathogenicity tests with 'Sauvignon Blanc' detached shoots and potted vines were used to de-termine the virulence diversity. UP-PCR analysis determined eight genetic groups of D. mutila with 70% of the population within one group. Phylogenetic analysis also determined that New Zealand isolates were more closely related to Australi-an isolates than Californian isolates. Vegetative compatibility grouping analysis placed the isolates into three VCG groups with 57% of isolates belonging to all three VCGs. Vegetative compatibility reactions were observed among isolates, but this was not correlated with the genetic clustering. Viru-lence assays proved that all isolates tested were pathogenic on grapevine stems. Differences in necrotic lesions lengths caused by D. mutila isolates were identified, indicating differ-ent virulence levels among isolates, however, no relationship was found between the genetic groups and the virulence. The results of the study indicated movement of D. mutila isolates between nurseries, vineyards, and other sources in New Zea-land. This information will inform control strategies to lim-it the further spread of this pathogen into vineyards in the same region or new regions.

Bacterial canker of cherry, caused by Pseudomonas syringae pathovars, is a major constraint to cherry growing in New Zealand. The prevalence of strains from cherry orchards in Central Otago, the main growing area for cherries in New Zealand, was studied, to better understand the epidemiology of the disease. Pseudomonas spp. isolates were collected from symptomatic and asymptomatic cherry tissue from 23 commercial cherry orchards in 2015. Isolates were classified into strains belonging to three different taxonomic groups by determining their phylogeny using the gltA gene sequence for all the strains and multilocus sequence analysis (MLSA) of four housekeeping genes for 35 strains. Pathogenicity of all Central Otago strains was tested on immature cherry fruit to support the phylogenetic classification. The two main taxonomic groups were P . syringae pv. syringae (Pss) and P . syringae pv. morsprunorum race 1 (Psm1), in Phylogroup 2 (PG2) and Phylogroup 3 (PG3), respectively. The third group comprised nonpathogenic strains classified as Pseudomonas spp. Strains of Psm1 formed a monophyletic group, representing an almost clonal population. There was more variation detected within strains of Pss, although they were restricted to group PG2d. Nonpathogenic Pseudomonas spp. and pathogenic Pss and Psm1 strains coexisted in the same orchard. It was concluded that Pss is the predominant pathovar in Central Otago. This is the first detailed study of the P . syringae species complex in cherry orchards in New Zealand and provides the basis for future epidemiology studies.