Bacterial Canker Of Kiwifruit Research Articles

Integrated Methodologies (SWOT, TOWS, LCA) for Improving Production Chains and Environmental Sustainability of Kiwifruit and Baby Kiwi in Italy

Italy’s kiwifruit growers are considered to be world-leading players of the past 20 years. However, with this success come its challenges. In the last five years, a bacterial canker of kiwifruit known as Pseudomonas syringae pv. actinidiae (Psa) has caused a dramatic reduction in the size of the areas cultivated, leading to several experienced Piedmontese Actinidia deliciosa growers beginning to cultivate the A. arguta. To better understand the potential for replacing the common kiwifruit in Italy’s Piedmont region with plantations of A. arguta and to attain a systematic approach and support for decision situations; we assessed the environmental impact of the two production chains (field and storage) from a technical-operational perspective. The assessment was conducted through interviews with producers, field and warehouse technicians and sales managers in order to reveal the strengths and weaknesses of the two systems. The work presented below considers the application of the Life Cycle Assessment (LCA) method for the field system (two different phases of the plantation) and the SWOT (Strengths, Weaknesses, Opportunities, Threats) analysis for the entire supply chain (field and warehouse management). Finally, a TOWS analysis (Threats, Opportunities, Weakness, Strengths) integrated the results of both LCA and SWOT analyses and permitted to highlight the development strategies for A. arguta in Piedmont. The total orchard cycle for A. arguta presents an impact of 0.14 kg CO2 eq (GWP) and for A. deliciosa an impact of 0.11 kg CO2 eq (GWP). Based on the synthesis of results from our TOWS analysis, we identified the following development strategies to help to shape the future A. arguta supply chain in Piedmont: Large-scale oriented; Berry fruits oriented; Export and organic oriented and Niche oriented.

Occurrence and Epidemics of Bacterial Canker of Kiwifruit in Korea.

Bacterial canker is the largest limiting factor in the cultivation and production of kiwifruit worldwide. Typical symptoms comprise necrotic spots on leaves, canker and dieback on canes and trunks, twig wilting, and blossom necrosis. Pseudomonas syringae pv. actinidiae (Psa), which is the causal agent of kiwifruit bacterial canker, is divided into four biovars based on multilocus sequence analysis of different genes, additional PCR testing of pathogenic genes (argKtox cluster, cfl, and various effector genes), and biochemical and physiological characterization. Bacterial canker caused by Psa biovar 2 designated Psa2 was detected for the first time on the green-fleshed kiwifruit cultivar Hayward in 1988 and the yellow-fleshed kiwifruit cultivar Hort16A in 2006 in Korea. Psa biovar 3 designated Psa3, responsible for the current global pandemics of kiwifruit bacterial canker, began to appear in Korea in 2011 and caused tremendous economic losses by destroying many vines or orchards of yellow-fleshed kiwifruit cultivars in one or several growing seasons. Bacterial canker epidemics caused by both Psa2 and Psa3 are prevalent in Korea in recent years. In this review, we summarize the symptomatology, etiology, disease cycle, diagnosis, and epidemiology of kiwifruit bacterial canker in Korea.

Elicitor induction of defence genes and reduction of bacterial canker in kiwifruit

Pseudomonas syringae pv. actinidiae (Psa), which causes bacterial canker, is the most serious global pathogen of kiwifruit. Like most bacterial pathogens, control options are limited, but elicitors can reduce disease significantly, particularly those that induce the salicylic acid (SA) pathway. Acibenzolar-S-methyl (ASM), a SA analogue, is one of the most effective elicitors for Psa control. In this study, real-time PCR (qPCR) was used to measure the expression of 18 putative defence genes in Actinidia chinensis var. chinensis ‘Hort16A’ in response to Psa and ASM. Application of ASM led to up-regulation of RPM1 interacting protein 4 (RIN4), phenylalanine ammonia lyase (PAL), a hypersensitivity-induced response protein (HIRP), and β-1,3-glucosidase. Expression of PAL and HIRP was further enhanced when elicitor application and Psa-inoculation were combined. Elevated gene expression was correlated with decreased disease expression, and supports the hypothesis that elicitor-treated plants are primed to react more rapidly and/or strongly to pathogens.

Effect of a protectant copper application on Psa infection of kiwifruit trap plants

Pseudomonas syringae pv. actinidiae (Psa) causes bacterial canker of kiwifruit, which is an ongoing threat to New Zealand kiwifruit production. Disease control depends on orchard practices such as removal of visibly diseased material, pruning during low-risk periods, and the application of foliar bactericides. Although the use of copper compounds on Actinidia species (kiwifruit) can cause phytotoxicity, copper-based formulations remain a key component of Psa control in New Zealand. The effect of single copper applications on Psa infection of ‘Hort16A’ trap plants was studied over the Spring of 2014 (Sept—Nov). Psa leaf spots were observed at the beginning of October, appearing first on the untreated plants. Although the copper sprays did not achieve complete protection, particularly as the inoculum built up during November, the copper-sprayed plants always had less disease than the untreated plants.

Risk factors for kiwifruit bacterial canker disease development in ‘Hayward’ kiwifruit blocks

In November 2010 Pseudomonas syringae pv. actinidiae biovar 3, the cause of a severe disease, kiwifruit bacterial canker, was first recorded in New Zealand. This study examined risk factors relating to disease management, vine management and orchard layout that were associated with disease symptoms observed by orchardists in Actinidia chinensis var. deliciosa ‘Hayward’ orchards. A cross-sectional study using data collected via a questionnaire investigated orchard blocks that were symptom-free in March 2012. The outcome we modelled was detection of disease in the block during the study period from March 2012 to February 2013, and multivariable logistic regression was used to identify potential risk factors. Data from 194 growers were included and comprised 53 orchard blocks which remained disease free and 141 which became diseased. This cross-sectional study identified four factors that were associated with Psa symptom development. The associated factors identified in this study are not necessarily causal, but our results can be used by the kiwifruit industry to help prioritise research needs to identify processes involved in the development of kiwifruit bacterial canker in kiwifruit orchards. Priority for further research is the relationship between the timing of copper sprays, callus tissue formation and Psa mobilisation. A second priority is to determine the biological mechanism for the association between girdling and a reduction in disease risk. Use of a cross-sectional study provided a new way to investigate plant disease risk factors and this type of study could be more extensively used, especially during incursions of unwanted organisms.

Whole transcriptome sequencing of Pseudomonas syringae pv. actinidiae-infected kiwifruit plants reveals species-specific interaction between long non-coding RNA and coding genes

An outbreak of kiwifruit bacterial canker disease caused by Pseudomonas syringae pv. actinidiae (Psa) beginning in 2008 caused disaster to the kiwifruit industry. However the mechanisms of interaction between kiwifruit and Psa are unknown. Long noncoding RNAs (lncRNAs) are known to regulate many biological processes, but comprehensive repertoires of kiwifruit lncRNAs and their effects on the interaction between kiwifruit and Psa are unknown. Here, based on in-depth transcriptomic analysis of four kiwifruit materials at three stages of infection with Psa, we identified 14,845 transcripts from 12,280 loci as putative lncRNAs. Hierarchical clustering analysis of differentially-expressed transcripts reveals that both protein-coding and lncRNA transcripts are expressed species-specifically. Comparing differentially-expressed transcripts from different species, variations in pattern-triggered immunity (PTI) were the main causes of species-specific responses to infection by Psa. Using weighted gene co-expression network analysis, we identified species-specific expressed key lncRNAs which were closely related to plant immune response and signal transduction. Our results illustrate that different kiwifruit species employ multiple different plant immunity layers to fight against Psa infection, which causes distinct responses. We also discovered that lncRNAs might affect kiwifruit responses to Psa infection, indicating that both protein-coding regions and noncoding regions can affect kiwifruit response to Psa infection.

Pseudomonas syringae pv. actinidiae isolated from Actinidia chinensis Var. deliciosa in Northern Italy: genetic diversity and virulence

Bacterial canker of kiwifruit, caused by Pseudomonas syringae pv. actinidiae, is responsible for significant economic losses, both in yield and quality. A collection of P.s. pv. actinidiae isolated in Northern and Central Italy, during the first severe outbreak (2008–2010) and a few years afterwards (2014), when the pathogen became endemic and established, was gathered. The genetic diversity was evaluated with rep-PCR, RAPD-PCR, and MLSA of six housekeeping and effector genes. On the same strains, the virulence was evaluated in vitro and in vivo, showing a higher disease index for the strains isolated in 2014, compared with the strains of 2010. The molecular fingerprinting, obtained by rep and RAPD analysis, revealed a high level of variability in the population of strains of P.s. pv. actinidiae from northern Italy. All the parameters considered – Na, Ne, H, I, polymorphic loci, and AMOVA – showed a higher genetic diversity within the population of northern Italy isolated in 2014, compared to the older population. The study of the genetic diversity and virulence permitted to show an increase of virulence and genetic diversity of the strains. The fast and dramatic epidemics caused by P. s. pv. actinidiae could be an interesting model to study the changes in the genetic diversity and virulence of a bacterial pathogen.

A bacterial acetyltransferase triggers immunity in Arabidopsis thaliana independent of hypersensitive response

Type-III secreted effectors (T3Es) play critical roles during bacterial pathogenesis in plants. Plant recognition of certain T3Es can trigger defence, often accompanied by macroscopic cell death, termed the hypersensitive response (HR). Economically important species of kiwifruit are susceptible to Pseudomonas syringae pv. actinidiae (Psa), the causal agent of kiwifruit bacterial canker. Although Psa is non-pathogenic in Arabidopsis thaliana, we observed that a T3E, HopZ5 that is unique to a global outbreak clade of Psa, triggers HR and defence in Arabidopsis accession Ct-1. Ws-2 and Col-0 accessions are unable to produce an HR in response to Pseudomonas-delivered HopZ5. While Ws-2 is susceptible to virulent bacterial strain Pseudomonas syringae pv. tomato DC3000 carrying HopZ5, Col-0 is resistant despite the lack of an HR. We show that HopZ5, like other members of the YopJ superfamily of acetyltransferases that it belongs to, autoacetylates lysine residues. Through comparisons to other family members, we identified an acetyltransferase catalytic activity and demonstrate its requirement for triggering defence in Arabidopsis and Nicotiana species. Collectively, data herein indicate that HopZ5 is a plasma membrane-localized acetyltransferase with autoacetylation activity required for avirulence.

Potential spread of kiwifruit bacterial canker (Pseudomonas syringae pv. actinidiae) in Europe

Pest risk analyses (PRAs) are conducted to determine whether an organism is a pest and whether and how it should be regulated. Estimation of the potential area of establishment and pest spread are key factors of this analysis. Tools for modelling and mapping of these key factors have to be quick and easily applicable for a wide variety of organisms with limited data for parameterization. For this purpose, a dispersal kernel model based on a 2Dt‐distribution had been developed in a European Union project (PRATIQUE). The aim of the present study was the evaluation of this spread model hitherto tested on insects, plants, fungi and nematodes in order to determine its applicability to bacterial pests. Therefore, the potential distribution and spread of kiwifruit bacterial canker Pseudomonas syringae pv. actinidiae in Europe was investigated based on climatic suitability and host plant availability. The results of the modelling were compared with the spread history of the pest in Europe. It is shown that this generic spread model can also be applied to a bacterial pest.

Occurrence of copper-resistant Pseudomonas syringae pv. syringae strains isolated from rain and kiwifruit orchards also infected by P. s. pv. actinidiae

During spring 2014–2015, leaves showing extensive leaf spotting were collected from Actinidia deliciosa and A. chinensis orchards located in northern, central and southern Italy where a copper-based strategy used to control bacterial canker, caused by Pseudomonas syringae pv. actinidiae (Psa), was ineffective. In addition, bacterial isolates were recovered from wind-driven raindrops. Psa was isolated solely from raindrops, whereas P. s. pv. syringae was consistently isolated from both symptomatic leaves and rain. The P. s. pv. syringae isolates were molecularly typed using repetitive-sequence PCR and assessed in vitro for their resistance to copper sulphate and for the presence of the cop ABCDRS gene cluster. An ad hoc quantitative real-time PCR was performed to confirm the P. s. pv. syringae capability for Actinidia spp. leaf infection using a low dose of inoculum and co-inoculation with Psa. A copper-resistant P. s. pv. syringae strain isolated from rain effectively colonized Actinidia spp. leaves from a low dose of inoculum. When such a strain was co-inoculated with a reference Psa strain, they reached a higher density than in inoculations performed singly. Copper-resistant P. s. pv. syringae strains infecting the leaves of Actinidia spp. appear to be widespread in Italy and, in some circumstances, they could have replaced Psa in leaf colonization and disease development. Populations of this phytopathogen showing resistance to copper would appear to be dispersed in the environment by the rain. This raises questions concerning the reliability of long-term strategies to control kiwifruit bacterial canker caused by Psa solely with copper compounds.

키위 궤양병 효율적 관리를 위한 매뉴얼

키위 궤양병 효율적 관리를 위한 매뉴얼

Identification of Circular RNAs in Kiwifruit and Their Species-Specific Response to Bacterial Canker Pathogen Invasion.

Research studies have recently focused on circle RNAs (circRNAs) in relation to their regulatory functions in animals. However, the systematic identification of circRNAs in plants, especially non-model plants, is limited. In addition, raw report on the prediction of the potential role of circRNAs in plant response to pathogen invasion is currently available. We conducted the systematic identification of circRNAs from four materials originating from three species belonging to genus Actinidia under different situations using ribosomal RNA (rRNA) depleted RNA-Seq data. A total of 3,582 circRNAs were identified in Actinidia, of which 64.01, 21.44, and 14.55% were intergenic circRNAs, exonic circRNAs, and intronic circRNAs, respectively. Tissue-specific expression of circRNAs was observed in kiwifruit, and a species-specific response was detected when infected with Pseudomonas syringae pv. actinidiae (Psa), which is the causative agent of kiwifruit bacterial canker disease. Furthermore, we found that both exonic and intronic circRNAs were significantly positively correlated to parent protein-coding genes, and intronic circRNAs are a class of highly remarkable regulators the parent genes comparing to that of exonic circRNAs. Expression and weighted gene co-expression network analysis (WGCNA) identified a set of circRNAs that were closely associated with plant defense response. The findings of the presents study suggest that circRNAs exhibit tissue- and species-specific expression, as well as play an important role in plant immune response.

Biological control of Pseudomonas syringae pv. actinidiae (Psa), the causal agent of bacterial canker of kiwifruit, using endophytic bacteria recovered from a medicinal plant

Pseudomonas syringae pv. actinidiae (Psa) is the causal agent of bacterial canker in kiwifruit (Actinidia deliciosa). Mānuka (Leptospermum scoparium) is a New Zealand medicinal shrub that produces essential oils with antimicrobial properties. The aim of this study was to determine whether endophytes from L. scoparium could be transferred to A. deliciosa and maintain their biocontrol activity. Five endophytic bacteria showed antagonism against Psa in vitro. The endophytic bacteria possessed multiple antibiotic producing genes, such as phenazine, 2,4-DAPG, and hydrogen cyanide, compounds that are known to inhibit growth of bacterial plant pathogens. Spontaneous chloramphenicol mutants and BOX-PCR fingerprinting were used to monitor endophytic colonization of antagonistic bacteria in planta. Three endophytic bacteria were transmissible to A. deliciosa by wound inoculation where they inhibited colonization by Psa and reduced disease severity in two different commercial cultivars.

2016년 경남지역 Pseudomonas syringae pv. actinidiae Biovar 3의 2차감염에 의한 키위 궤양병의 확산

2016년 경남지역 Pseudomonas syringae pv. actinidiae Biovar 3의 2차감염에 의한 키위 궤양병의 확산

2014년과 2015년 전남 보성에서의 키위 궤양병의 계절별 발생소장

2014년과 2015년 전남 보성에서의 키위 궤양병의 계절별 발생소장

Outbreak and Spread of Bacterial Canker of Kiwifruit Caused by Pseudomonas syringae pv. actinidiae Biovar 3 in Korea.

A bacterial pathogen, Pseudomonas syringae pv. actinidiae (Psa), is a causal agent of kiwifruit bacterial canker worldwide. Psa biovar 3 (Psa3) was first detected in 2011 at an orchard in Dodeok-myeon, Goheunggun, Jeonnam Province in Korea. In this study, we present the results of an epidemiological study regarding Psa3 occurrence on kiwifruit orchards in Korea for the period of 2013 to 2015. Since the first detection of Psa3 in 2011, there was no further case reported by 2013. However, Psa3 was rapidly spreading to 33 orchards in 2014; except for three orchards in Sacheonsi, Gyeongnam Province, most cases were reported in Jeju Island. Entering 2015, bacterial canker by Psa3 became a pandemic in Korea, spreading to 72 orchards in Jeju Island, Jeonnam, and Gyeongnam Provinces. Our epidemiological study indicated that the first Psa3 incidence in 2011 might result from an introduction of Psa3 through imported seedlings from China in 2006. Apart from this, it was estimated that most Psa3 outbreaks from 2014 to 2015 were caused by pollens imported from New Zealand and China for artificial pollination. Most kiwifruit cultivars growing in Korea were infected with Psa3; yellow-fleshed cultivars (Yellow-king, Hort16A, Enza-gold, Zecy-gold, and Haegeum), red-fleshed cultivars (Hongyang and Enza-Red), green-fleshed cultivars (Hayward and Daeheung), and even a kiwiberry (Skinny-green). However, susceptibility to canker differed among cultivars; yellow- and red-fleshed cultivars showed much more severe symptoms compared to the green-fleshed cultivars of kiwifruit and a kiwiberry.

Bacterial disease management: challenges, experience, innovation and future prospects: Challenges in Bacterial Molecular Plant Pathology.

Plant diseases caused by bacterial pathogens place major constraints on crop production and cause significant annual losses on a global scale. The attainment of consistent effective management of these diseases can be extremely difficult, and management potential is often affected by grower reliance on highly disease-susceptible cultivars because of consumer preferences, and by environmental conditions favouring pathogen development. New and emerging bacterial disease problems (e.g. zebra chip of potato) and established problems in new geographical regions (e.g. bacterial canker of kiwifruit in New Zealand) grab the headlines, but the list of bacterial disease problems with few effective management options is long. The ever-increasing global human population requires the continued stable production of a safe food supply with greater yields because of the shrinking areas of arable land. One major facet in the maintenance of the sustainability of crop production systems with predictable yields involves the identification and deployment of sustainable disease management solutions for bacterial diseases. In addition, the identification of novel management tactics has also come to the fore because of the increasing evolution of resistance to existing bactericides. A number of central research foci, involving basic research to identify critical pathogen targets for control, novel methodologies and methods of delivery, are emerging that will provide a strong basis for bacterial disease management into the future. Near-term solutions are desperately needed. Are there replacement materials for existing bactericides that can provide effective disease management under field conditions? Experience should inform the future. With prior knowledge of bactericide resistance issues evolving in pathogens, how will this affect the deployment of newer compounds and biological controls? Knowledge is critical. A comprehensive understanding of bacterial pathosystems is required to not only identify optimal targets in the pathogens, but also optimal seasonal timings for deployment. Host resistance to effectors must be exploited, carefully and correctly. Are there other candidate genes that could be targeted in transgenic approaches? How can new technologies (CRISPR, TALEN, etc.) be most effectively used to add sustainable disease resistance to existing commercially desirable plant cultivars? We need an insider's perspective on the management of systemic pathogens. In addition to host resistance or reduced sensitivity, are there other methods that can be used to target these pathogen groups? Biological systems are variable. Can biological control strategies be improved for bacterial disease management and be made more predictable in function? The answers to the research foci outlined above are not all available, as will become apparent in this article, but we are heading in the right direction. In this article, we summarize the contributions from past experiences in bacterial disease management, and also describe how advances in bacterial genetics, genomics and host-pathogen interactions are informing novel strategies in virulence inhibition and in host resistance. We also outline potential innovations that could be exploited as the pressures to maximize a safe and productive food supply continue to become more numerous and more complex.

Studies on the Infection, Colonization, and Movement of Pseudomonas syringae pv. actinidiae in Kiwifruit Tissues Using a GFPuv-Labeled Strain.

Kiwifruit bacterial canker, an economically important disease caused by Pseudomonas syringae pv. actinidiae (Psa), has caused severe losses in all major areas of kiwifruit cultivation. Using a GFPuv-labeled strain of Psa, we monitored the invasion, colonization, and movement of the pathogen in kiwifruit twigs, leaves and veins. The pathogen can invade twigs through both wounds and natural openings; the highest number of Psa is obtained in cut tissues. We determined that, following spray inoculation, Psa-GFPuv could infect leaves and cause lesions in the presence and absence of wounds. Light and transmission electron microscopic observations showed that bacterial cells colonize both phloem and xylem vessels. Bacterial infection resulted in marked alterations of host tissues including the disintegration of organelles and degeneration of protoplasts and cell walls. Furthermore, low temperature was conducive to colonization and movement of Psa-GFPuv in kiwifruit tissues. Indeed, the pathogen migrated faster at 4°C than at 16°C or 25°C in twigs. However, the optimum temperature for colonization and movement of Psa in leaf veins was 16°C. Our results, revealing a better understanding of the Psa infection process, might contribute to develop more efficacious disease management strategies.

Genome analysis of the kiwifruit canker pathogen Pseudomonas syringae pv. actinidiae biovar 5.

Pseudomonas syringae pv. actinidiae (Psa) is a destructive pathogen of kiwifruit bacterial canker disease, causing severe economic losses to kiwifruit industry worldwide. Biovar 5 is the most recently reported biovar of Psa, and is found in only a local area of Japan at present. There is not much information of genetic characteristics of biovar 5. Thus, the genome of biovar 5 was sequenced and analyzed to clarify its detailed genetic characteristics. Here, the genomes of strain MAFF 212056 and MAFF 212061 of biovar 5 were estimated to be about 6.3 Mbp and 6.5 Mbp, respectively, and their phylogenetic positions were proved to be near that of biovar 2 in the phylogenetic tree. However, it was confirmed that biovar 5 had neither the coronatine biosynthetic genes conserved in biovar 2, its phylogenetic neighbor, nor the phaseolotoxin biosynthetic genes conserved in biovar 1, Japanese native pathogen. In addition, 45 genes of type III secreted effectors were identified in biovar 5 genomes, showing that their composition is different from that in the other biovars. Moreover, some biovar 5-specific regions were identified. Then, biovar 5-specific PCR primers for targeting these regions were designed, and proved to be applicable for detecting biovar 5 specifically.

Pseudomonas syringae pv. Actinidiae isolated from non-kiwifruit plant species in China

Kiwifruit bacterial canker (KBC), incited by Pseudomonas syringae pv. actinidiae (Psa), may cause severe economic losses to kiwifruit (Actinidia deliciosa and A. chinensis). Many studies have been conducted to clarify relationships between this pathogen and Actinidia species. Conversely, little is known about the chance to colonize alternate hosts and the implications of this possibility on disease spread. In this study, 11 bacterial isolates have been isolated from three wild plant species, Setaria viridis (L.) Beauv., Alternanthera philoxeroides (Mart.) Griseb. and Paulownia tomentosa (Thunb.) Steud., found under or nearby kiwifruit plants affected by bacterial canker. All were identified as Psa based on biochemical tests, specific end-point PCR assays, sequence analysis of single effector genes and MLST. The strains tested positive for pathogenicity, both on wild hosts and on kiwifruit plants. To our knowledge, this is the first report on Psa isolated from non-kiwifruit plants. The proof that Psa can migrate to non-kiwifruit plants raises new issues about the means by which the disease can spread at local and international scales, and the measures to be taken to prevent and control effectively KBC disease.