Green-fleshed Kiwifruit Research Articles

Comparative of Antioxidant property of Actinidia Deliciosa extracts by DPPH Assay

Introduction: The kiwi fruit is the edible berry of a cultivar group of the woody vine of several Actinidia species. The most common commercially available, green-fleshed kiwi fruit is the cultivar 'Hayward', which belongs to the Actinidia deliciosa species. Various chemical tests such Quantitative and Qualitative analysis have been carried out on kiwi extract. Methods: The antioxidant activity was evaluated by DPPH, an antioxidative screening of kiwi fruit components (pulp) crude extracts were carried out using specific assay media characterized for the presence of highly reactive species such as 2,2'-diphenyl-1-picrylhydrazyl radical (DPPH). In-vitro the antioxidant enzymes study of DPPH. Result: In our study we have evaluated the antioxidant capacity of flesh of kiwi fruit and also evaluated the antioxidant activity of kiwi fruit constituents along with the array detector for curcumin and piperine. Conclusion: The Kiwi fruit which is highly antioxidant in nature was found to have activity against asthma. It also acts as an anti-oxidant, antidiabetic, anti-ulcer, anti-tumour, hypoglycaemic, hypolipidemic effects, anti-inflammatory and many more. Recent studies show that phytoconstituent such as curcumin and piperine have used to treat asthma.

Increased ascorbic acid synthesis by overexpression of AcGGP3 ameliorates copper toxicity in kiwifruit

The widespread application of copper (Cu) -based fertilizers and pesticides could increase the accumulation of Cu in kiwifruit. According to a global survey, red- and yellow-fleshed kiwifruit contained more elevated amounts of Cu than green-fleshed kiwifruit due to weaker disease resistance and higher use of Cu pesticides. Intriguingly, our research revealed that external and endogenous ascorbic acid (AsA) reduced the phenotypic and physiological injury of Cu toxicity in kiwifruit. Cu stress assays and transcriptional analysis have shown that Cu treatment for 12 h significantly increased the AsA content in kiwifruit leaves and up-regulated key genes involved in AsA biosynthesis, such as GDP-L-galactose phosphorylase3 (GGP3) and GDP-mannose-3′,5′-epimerase (GME). Overexpressing GGP3 in transgenic kiwifruit significantly increased the endogenous AsA content of kiwifruit, which was beneficial in mitigating Cu toxicity by decreasing levels of reactive oxygen species, malondialdehyde, and electrolyte leakage, as well as reducing damage to the chloroplast structure and photosystem II. This study presented a novel strategy to ameliorate plant Cu stress by increasing the endogenous antioxidant (AsA) content through transgenesis.

The sugar composition of the fibre in selected plant foods modulates weaning infants\u2019 gut microbiome composition and fermentation metabolites in vitro

Eight plant-based foods: oat flour and pureed apple, blackcurrant, carrot, gold- and green-fleshed kiwifruit, pumpkin, sweetcorn, were pre-digested and fermented with pooled inocula of weaning infants’ faecal bacteria in an in vitro hindgut model. Inulin and water were included as controls. The pre-digested foods were analysed for digestion-resistant fibre-derived sugar composition and standardised to the same total fibre concentration prior to fermentation. The food-microbiome interactions were then characterised by measuring microbial acid and gas metabolites, microbial glycosidase activity and determining microbiome structure. At the physiologically relevant time of 10 h of fermentation, the xyloglucan-rich apple and blackcurrant favoured a propiogenic metabolic and microbiome profile with no measurable gas production. Glucose-rich, xyloglucan-poor pumpkin caused the greatest increases in lactate and acetate (indicative of high fermentability) commensurate with increased bifidobacteria. Glucose-rich, xyloglucan-poor oats and sweetcorn, and arabinogalactan-rich carrot also increased lactate and acetate, and were more stimulatory of clostridial families, which are indicative of increased microbial diversity and gut and immune health. Inulin favoured a probiotic-driven consortium, while water supported a proteolytic microbiome. This study shows that the fibre-derived sugar composition of complementary foods may shape infant gut microbiome structure and metabolic activity, at least in vitro.

Comparative analysis of volatile metabolites, quality and sensory attributes of Actinidia chinensis fruit

Volatile organic compounds, quality and sensory parameters of four yellow- (‘Dorì’, ‘G3’, ‘Jintao’ and ‘Soreli’) and two green-fleshed (‘Hayward’ and ‘Summer’) kiwifruit cultivars were assessed. Statistical analysis was performed on volatiles, quality and sensory data for the identification of biomarkers of different kiwifruit cultivars. Principal component analysis showed that for all six samples a very good discrimination based on the cultivar was achieved. In particular, 2-pentylfuran can be used to distinguish between the green- and yellow-fleshed kiwifruit cultivars, while seven volatiles, can be identified as biomarkers of ‘Dorì’. These findings are in agreement with the sensory analysis, which revealed that ‘Dorì’, the richest cultivar in esters, showed very high values of both ripe fruit smell and sweet sensory traits. Altogether, these results could offer recommendations for future breeding efforts for the production of kiwifruit cultivars with improved nutritional and aroma quality.

FT-NIR spectroscopy and multivariate classification strategies for the postharvest quality of green-fleshed kiwifruit varieties

In the present study, combining near-infrared spectroscopy (NIRs) and chemometric analysis was tested for the characterization and commercial classification of green-fleshed kiwifruit (A. deliciosa, Hayward and Bo-Erica® cvs). Two approaches were studied: 1) development of PLS models using both spectral and reference data to assess the fruit quality and nutraceutical levels and 2) supervised classification methods (LDA and SIMCA) using only spectral data in order to sort fruit on the basis of their ripening time and consumer’s acceptability. Several traditional quality indexes (i.e. soluble solids, firmness, titratable acidity, dry matter), as well as nutritional ones such as total phenols, carotenoids and antioxidant potential were evaluated. Very good prediction of the internal quality attributes, using partial least squares regressions (PLS), was observed, especially for both soluble solid content and dry matter (R2: 0.993, RMSEP: 0.40 and R2: 0.983, RMSEP: 0.33, respectively). An accurate predictive performance of PLS model was also obtained for the total titratable acidity (R2: 0.933, RMSEP: 6.65). Good model performances were obtained for the prediction of the main nutraceutical traits of the samples, developed herein for the first time on kiwifruit. However, fairly good prediction performances were obtained for both total flavans and vitamin C (R2: 0.813, RMSEP: 0.07 and R2: 0.870, RMSEP: 6.04, respectively). Linear Discriminant Analysis (LDA) and Soft Indipendent Modelling by Class Analogy (SIMCA) models provided good results with rates of 92% and 99% of correctly classified samples. This study highlights that FT-NIRs can be used successfully to improve the quality control of kiwifruit at harvest and during storage as well as to identify and segregate samples prior to distribution in order to reduce fruit loss.

Understanding flower-bud rot development caused by <i>Pseudomonas syringae </i>pv. <i>actinidiae </i>in green-fleshed kiwifruit

A greater understanding of the epidemiology of flower bud rot caused by Pseudomonas syringae pv. actinidiae (Psa) in New Zealand green-fleshed kiwifruit cultivars is required to develop successful disease-management strategies. This study sought evidence as to whether the source of Psa bacteria that causes flower bud infection is internal or external to the flower buds as they emerge in spring. Psa was detected using qPCR in asymptomatic flower buds of two green-fleshed cultivars during spring 2016 and 2017, between bud emergence and immediately before flower opening. Bacterial isolations were made from surface sterilised and non-sterilised buds. Asymptomatic and symptomatic buds were dissected and isolations made from each of the dissected flower parts over time. Significantly more Psa was detected from non-sterilised flower buds during the early stages of bud development compared with later stages. Bud dissections showed that Psa colonisation began in the outer flower parts and moved inwards and this coincided with the development of bud rot symptoms. This study supports a hypothesis that bud rot arises when buds are externally contaminated by Psa early in their development and subsequent infection moves into the inner parts of developing flowers, destroying tissue and causing bud death. Effective control must aim to prevent initial Psa contamination.

Establishment of in vitro culture systems for breeding new types of kiwifruit and forActinidiagenomics studies

During the past 20 years kiwifruit has expanded dramatically in planting area and location, in total production, and also in diversity with different types of fruit. For example, variations in flesh colour have resulted in the commercialisation of green-fleshed, yellow-fleshed and red-fleshed kiwifruit. This diversity is from two large-fruited Actinidia species, A. chinensis and A. deliciosa, now widely grown throughout many parts of the world. Other fruit types may become available through use of other Actinidia species. The New Zealand Institute for Plant & Food Research Limited (PFR) has an active kiwifruit breeding programme to produce new kiwifruit cultivars that meet market requirements. An efficient in vitro biotechnology platform had been established to preserve and create new genotypes for rapid kiwifruit breeding through in vitro culture and propagation of various Actinidia species. Petiole and nodal shoot segments are produced from cuttings collected from dormant canes of adult plants in our germplasm repositories and breeding programme. This paper reviews the establishment of in vitro culture systems to allow chromosome doubling, micro-propagation, the testing of tolerance to bacterial canker of kiwifruit, and the development of new kiwifruit cultivars.

Incidence Rates of Major Diseases on Green-Fleshed Kiwifruit cv. Hayward and Yellow-Fleshed Kiwifruit cv. Haegeum

Incidence rates of bacterial canker, bacterial leaf spot and postharvest fruit rot on the Korean yellow-fleshed kiwifruit cv. Haegeum were compared with those on the most popular green-fleshed kiwifruit cv. Hayward grown in several naturally infected kiwifruit orchards in 2013 and 2014. The percentages of diseased leaves caused by bacterial canker were 18.5% and 17.3% on Hayward in 2013 and 2014, but those on Haegeum were 1.2% and 0%, respectively. The percentages of diseased leaves caused by bacterial leaf spot on Hayward were 63.5% and 16.2% in 2013 and 2014, respectively, but no bacterial leaf spots were observed on Haegeum in both years. The average percentages of diseased fruits caused by postharvest fruit rot were 24.2% and 20.5% on Hayward in 2013 and 2014, while 6.3% and 4.4% and Haegeum, respectively. Botryosphaeria dothidea was turned out to be the major pathogen of postharvest fruit rot on both cultivars.

Effect of the application timing of 1-MCP on postharvest traits and sensory quality of a yellow-fleshed kiwifruit

Chile is the third largest exporter of kiwifruit in the world. Its varietal production has traditionally been focused on green-fleshed kiwifruit varieties, with ‘Hayward’ being the most exported variety. ‘Soreli’ is a new Italian kiwifruit variety, which is characterized by its early ripening, big size, sweet taste, as well as its yellow flesh. This gives ‘Soreli’ a good opportunity to promote the consumption of yellow-fleshed varieties, and a wider assortment of kiwifruit in the market. The aim of this work is to evaluate postharvest traits and consumer acceptance in kiwifruit var. ‘Soreli’, with a combination of storage temperatures of 0 °C and 20 °C and 1-methylcyclopropene (1-MCP) applications.Cold storage and 1-MCP treatments caused a positive response in kiwifruit var. 'Soreli'. In the case of fruits stored at 20 °C, 1-MCP treatment extended the postharvest life of the fruits at least 3 weeks while the fruits stored in cold at 0 °C treated with 1-MCP reached 8 weeks. In general, the respiration rate was higher in the control treatments with respect to the 1-MCP treatments, as well as the ethylene emission occurred earlier in the control. In addition, the kiwifruit sensory quality attributes were adequate in all cases, reaching a medium or high acceptability in the evaluation panel.

Analysis of Antioxidant Enzyme Activity Involved in Ascorbate-glutathione Cycle in Green-flesh Kiwifruits

To compare the activities of enzymes related to ascorbate-glutathione cycle (AsA-GSH cycle) in different varieties, the fruits of five green-fleshed kiwifruit varieties were used as materials and activities of ascorbate peroxidase (APX), monodehydroascorbic acid (MDHA), dehydroascorbate reductase (DHAR) were measured by ultraviolet spectrophotometry. Results showed that ‘Cuiyu’ had higher MDHAR activities. The higher enzyme activity is responsible for the higher accumulation of AsA in kiwifruit. All of these results indicated that there were significant differences in the activities of enzymes in 5 kiwifruit genotypes.

Survival of Escherichia coli O157:H7, Salmonella spp., and Listeria monocytogenes on Fresh and Sliced Green and Golden Kiwifruits.

Kiwifruit (Actinidia deliciosa) is a high-acidity fruit, with two varieties available on the market. One is the green-fleshed, fuzzy, sweet but tangy-tasting kiwifruit, and the other is the yellow-fleshed variety called "golden" kiwifruit. While the whole kiwifruit is sold at room temperature at grocery stores, sliced kiwifruit is usually sold as a part of fruit salad in the refrigerated section. The survival of a five-strain Escherichia coli O157:H7 cocktail, a five-strain Salmonella cocktail, and a five-strain Listeria monocytogenes cocktail was evaluated on whole and sliced green and golden kiwifruit. Two inoculation levels were tested (∼7 and ∼4 Log colony-forming unit (CFU)/kiwi). A significantly higher amount of wet inoculum was attached to the green kiwifruit than to the golden kiwifruit (p < 0.05). The scanning electron microscope examination showed that pathogens can attach on both the surface and the hair structure of green kiwi skin. At room temperature, all three pathogens survived for 30 days on whole kiwifruit. Although the pH of sliced kiwifruit was low (∼3.5), all three pathogens survived on sliced kiwifruit for 7 days when stored at 4°C. These results highlight the importance of preventing contamination of fresh fruit during the preharvest and processing stages.

A proteometabolomic study of Actinidia deliciosa fruit development

Green-fleshed kiwifruit is worldwide appreciated for its flavor and macronutrients that are related to its physiological development. Fruit ripe stage for harvesting does not correspond to an optimal edible condition due to firmness/acidity pome characteristics; this is overcome with postharvest fruit processing. To describe the metabolic pathways/molecular effectors underlying Actinidia deliciosa cv. Hayward pome physiological development, kiwifruits were harvested at four growth stages (from fruit set to physiological maturity), and corresponding outer endocarp samples were analysed for metabolite and protein content. Combined NMR/LC-UV/ESI-IT-MSn procedures quantified 46 metabolites at these developmental stages; similarly, integrated 2D-DIGE/nLC-ESI-LIT-MS/MS analyses described corresponding proteomic changes. Quantitative protein dynamics showed that components related to disease/defense, protein destination/storage, metabolism, energy and cell structure functions were highly affected at specific moments of fruit development, suggesting a rationale to pomological and metabolite content characteristics at those times. Bioinformatic interaction prediction revealed a main network of differentially represented proteins, which may control metabolic changes in developing kiwifruit. Main pome allergens were also quantified, demonstrating their highest levels at the mature stage. By aligning kiwifruit development to a proteometabolomic representation, this investigation integrates previous metabolic observations and provides a reference framework for further physiological/nutritional studies, also allowing cross comparison among crop species. Biological significanceCompared with some other fruits, green-fleshed kiwifruit is unique for its nutrient density, health benefits, and consumer appeal; in fact, it is exceptionally rich in vitamins, carotenoids, potassium, fibre and phytochemicals acting in synergy to achieve multiple health advantages. However, kiwifruit is allergenic, and although symptoms in most susceptible individuals are mild, severe reactions have also been described. In the course of their 6-month development, kiwifruit undergoes radical changes in its morphology and chemical composition; these modifications may highly affect fruit nutraceutical and allergenic properties. To gain a better understanding of the molecular processes regulating metabolite concentration during fruit development but also affecting general pomological characteristics, a time-course metabolomic and proteomic analysis of kiwifruit flesh tissues was undertaken. Combined information on modified levels of 46 metabolites and 241 proteins showed that molecular processes underlying central and secondary metabolism, energy, cell structure, protein destination/storage, disease/defense kiwifruit functions were highly affected during fruit development, providing a rationale to the corresponding changes in organic acids, sugars, amino acids, polyphenols, fatty acids, phospholipids and allergens content, but also to the corresponding modifications in pome firmness, pulp colour, protein and total solid content. By providing original information on fruit development, this multiomic study integrates previous metabolomic/transcriptomic observations in describing molecular mechanisms associated with nutritional and agronomic traits of great interest for kiwifruit molecular breeding.

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.

RECORDS OF PSEUDOMONAS SYRINGAE pv. ACTINIDIAE ON ACTINIDIA spp. IN TRENTINO (NORTH-EAST ITALY)

During 2012-2015, extensive field surveys were performed in new and old kiwifruit orchards located in the province of Trento (North-East of Italy). Symptoms resembling those incited by Pseudomonas syringae pv. actinidiae (Psa) (i.e, leaf spotting, twig wilting) were observed mainly on Actinidia deliciosa cv. Hayward and in a new orchard planted with A. chinensis cv. Soreli. The incidence of the disease ranged from 1% to 80%, and some old Hayward orchards (i.e., 35 years old) resulted severely damaged. From all infected orchards, samples were collected and, subsequently, processed in the laboratory for isolation by following routinely procedures (Ferrante and Scortichini, 2009). Bacterial isolates were obtained from all infected kiwifruit orchards; they were identified according to the techniques described by Ferrante and Scortichini (2010). Upon repetitive-sequence PCR using BOX, ERIC and REP primer sets, their fingerprint pattern perfectly matched that shown by the pandemic Psa 3 strain CRA-FRU 8.43. In addition, with isolates representative of all the sites from where the samplings were obtained, pathogenicity tests were carried out by artificially inoculating one-year-old, pot-cultivated A. deliciosa cv. Hayward plants according to the techniques described by Ferrante and Scortichini (2009, 2010). All the isolates induced, upon 10-15 days from the inoculation, the leaf spot and wilting symptoms. On the basis of these results, we conclude that P. s. pv. actinidiae was the causal agent of the field symptoms observed in green-fleshed and yellow-fleshed kiwifruit orchards located in Trentino. This is the first record of the disease in this region.

The nutritional composition of Zespri® SunGold Kiwifruit and Zespri® Sweet Green Kiwifruit

The composition of kiwifruit is important for understanding the nutritional value of kiwifruit for consumption. Our aim was to develop a reference nutritional composition profile for a gold-fleshed kiwifruit Zespri® SunGold Kiwifruit and a green-fleshed kiwifruit Zespri® Sweet Green Kiwifruit. Ten representative single-replicate (10 growers) samples, each containing 40 fruit, were prepared for both kiwifruit varieties. Samples were analysed for macronutrients, minerals, and vitamins. The analytical results reveal that the nutrient composition of SunGold and Sweet Green are largely similar to other commercially available kiwifruits. However, a key difference is the elevated levels of vitamin C in SunGold (161mg/100g edible flesh) and Sweet Green, (150mg/100g), compared to 85mg/100g commonly found for the green ‘Hayward’ variety. Levels of dietary fibre, potassium, vitamin E, and folate are similar to other commercial kiwifruit Zespri® Gold Kiwifruit (‘Hort16A’) and Green Kiwifruit (‘Hayward’), confirming kiwifruit as a good source of these nutrients.

Omics, epidemiology and integrated approach for the coexistence with bacterial canker of kiwifruit, caused by Pseudomonas syringae pv. actinidiae

Bacterial canker of kiwifruit, caused by Pseudomonas syringae pv. actinidiae, is a destructive disease found in all major areas of production of green-fleshed (Actinidia deliciosa) and yellow-fleshed (A. chinensis) kiwifruit of the world (i.e, Europe, China, New Zealand and Chile). A series of studies and field trials concerning epidemiology, agronomical techniques, new bactericides effectiveness as well as molecular typing analysis, genomic and proteomic, allowed us to elucidate the cycle of disease of the pathogen, to dissect its main genomic features, to point out the plant proteins involved in resistance/tolerance to the bacterium, to modify some basic agronomical techniques and to propose new compounds that currently, at least in the province of Latina and Rome, Italy, allow the farmers to coexist with the pathogen by reaching the full yield and quality of the crop as before the appearance of the disease.

Crystal structure of kiwellin, a major cell-wall protein from kiwifruit.

Kiwellin is a cysteine-rich, cell wall-associated protein with no known structural homologues. It is one of the most abundant proteins in kiwifruit (Actinidia spp.), and has been shown to be recognised by IgE of some patients allergic to kiwifruit. Cleavage of kiwellin into an N-terminal 4 kDa peptide called kissper and a core domain called KiTH is mediated by actinidin in vitro, and isolation of the kissper peptide from green-fleshed kiwifruit extracts suggested it may result from in vivo processing of kiwellin. In solution, kissper is highly flexible and displays pore-forming activity in synthetic lipid-bilayers. We present here the 2.05 Å resolution crystal structure of full-length kiwellin, purified from its native source, Actinidia chinensis (gold-fleshed kiwifruit). The structure confirms the modularity of the protein and the intrinsic flexibility of kissper and reveals that KiTH harbours a double-psi β-barrel fold hooked to an N-terminal β hairpin. Comparisons with structurally-related proteins suggest that a deep gorge located at the protein surface forms a binding site for endogenous ligands.

New insights on the bacterial canker of kiwifruit (Pseudomonas syringae pv. actinidiae)

Since 2008, Pseudomonas syringae pv. actinidiae , the causal agent of bacterial canker of kiwifruit has become the main pathogen of yellow and green fleshed kiwifruit. All major kiwifruit producing countries in the world have been affected by this ba

First Report of Pseudomonas syringae pv. actinidiae the Causal Agent of Bacterial Canker of Kiwifruit on Actinidia arguta Vines in New Zealand.

Actinidia arguta is commercially grown in New Zealand and few other countries; the fruit are sometimes sold as kiwiberry or hardy kiwi. In New Zealand, two biovars of Pseudomonas syringae pv. actinidiae have recently been found to cause bacterial canker on both A. chinensis and A. deliciosa, which produce the yellow and green fleshed kiwifruit, respectively (4). In November 2011, in a commercial orchard in the Bay of Plenty, New Zealand, A. arguta 'Tahi' and 'Rua' showed small angular necrotic leaf spots. About 50% of the vines randomly located throughout the orchard showed symptoms. Canker or shoot dieback were not detected on any of the infected plants. Four strains, labeled 13093 to 13096, were isolated onto King's B medium (KB) from leaves selected from four different plants showing symptoms. These four strains were gram-negative, induced a hypersensitive reaction when infiltrated in tobacco plants, lacked cytochrome c oxidase, arginine dehydrolase, and urease activity, and were unable to hydrolyze esculin, starch, and gelatine, and to induce ice nucleation. When plated on KB, these strains showed the same weak fluorescence associated with some strains of P. syringae pv. actinidiae (4). All these characteristics support identification of the strains as P. syringae pv. actinidiae. Using P. syringae pv. actinidiae-specific primers PsaF1/R2 (2), the expected 280-bp fragment was amplified by PCR from genomic DNA extracted from the four strains. The four amplicons were sequenced (GenBank Accession Nos. KF206138 to 41) and found to be 100% identical to each other and to the corresponding DNA fragment of the pathotype strain, ICMP 9617 (AY342165). A similar conclusion was reached using the duplex PCR targeting the ompP1 and the avrD genes (1); two amplicons of 492 and 226 bp were obtained with each of the four strains as expected for P. syringae pv. actinidiae. The DNA sequence of the 492-bp amplicon (KF206134 to 37) was 100% identical to that of strains of P. syringae pv. actinidiae, such as Psa 10627 (JQ934475.1). Strain 13094 isolated from A. arguta and pathotype strain ICMP 9617 were sprayed at a concentration of 3 × 109 cfu/ml on to the undersides of leaves of three 6- to 8-week-old seedlings of A. chinensis'Hort16A' and three similar seedlings of A. deliciosa 'Bruno.' Those are the conditions under which the pathogenicity of strains of P. syringae pv. actinidiae is usually evaluated (4). After 2 weeks of incubation, small necrotic angular spots were observed on all plants inoculated with 13094 or ICMP 9617 but not on the water-treated control plants. The bacteria isolated from those necrotic spots had the same morphological characteristics on KB as P. syringae pv. actinidiae and gave a 280-bp amplicon after PCR with the PsaF1/R2 primers. Leaves of two rooted cuttings of A. arguta'Tahi' were spray inoculated with strain 13094 at a concentration of 2.7 × 109 cfu/ml or with water. Necrotic spots developed on leaves 1 week after inoculation. No spots developed on the water-treated plants. The bacteria isolated from those necrotic spots had the same morphological characteristics on KB as P. syringae pv. actinidiae and gave a 280-bp amplicon after PCR with the PsaF1/R2 primers. Isolation of P. syringae pv. actinidiae from A. arguta has been reported only once before (3). This is this is the first report of P. syringae pv. actinidiae being isolated from A. arguta vines in New Zealand. This limited outbreak did not lead to any loss of production and since then only very few symptoms have been observed in this particular orchard.

Elucidating the sugar import pathway into developing kiwifruit berries (Actinidia deliciosa)

The aim of this work was to investigate the roles of the apoplasmic and symplasmic pathways in the delivery of solutes to the outer pericarp of developing green-fleshed kiwifruit berries (Actinidia deliciosa [A. Chev.] C. F. Liang et A. R. Ferguson var. deliciosa ‘Hayward’). Experiments with the symplasmic tracer 5(6)-carboxyfluorescein (CF) showed symplasmic movement of dye during the initial rapid growth stage of the fruit, but as fruit growth slowed and starch content increased, a reduction in symplasmic spread of CF was observed (+126 DAA [days after anthesis]). Measurements of sugar uptake rates from the apoplasm were sufficient to account for the dry matter accumulation in growing fruit at each stage of fruit growth, and could potentially operate alongside a symplasmic pathway for post-phloem unloading of sugars during the rapid growth period. Energy requirements driving uptake from the apoplasm appear to depend on the sugar concentration gradients across the cell membrane throughout fruit development. Together, these data suggest: 1) the post-phloem symplasmic pathway is important during the fruit rapid growth stage, 2) the uptake of sugars from the apoplasm has a role in the transport of carbohydrates in the fruit, especially later in fruit development when the symplasmic pathway is reduced, and 3) apoplasmic sugar has an important role in the flow of water into the apoplasm of the fruit, providing a mechanism to maintain hydrostatic pressure gradients along the phloem supplying the fruit.