The production of strawberry plants from callus cultures

Shoots were regenerated from callus of the commercially important strawberry varieties Bogota, Brighton, Cambridge Favourite, Hapil, Ostara, Rapella, Red Gauntlet and JILA33 which is a promising selection from a current breeding programme.The callus was initiated from explants of petiole or lamina of leaves of micropropagated shoots in vitro or of lamina or peduncle from greenhouse plants. There was more shoot regeneration with callus from lamina than from petiole although with the variety Hapil, regeneration occurred only with callus from peduncle.With seven of the varieties, shoot regeneration occurred on culture media with BAP and 2,4-D whilst with the remaining variety, Cambridge Favourite, it occurred only with medium which contained 1AA- alanine conjugate in place of 2,4-D.Regenerated shoots rooted readily and the plants produced are being studied for somaclonal variation.     

The fungal flora of soft fruits in relation to storage and spoilage

The fungal population of freshly harvested strawberries, raspberries and blackberries was studied throughout the fruiting seasons and the relative importance of fungi responsible for spoilage of stored fruit from different harvest dates was assessed. Botrytis cinerea, Cladosporium spp., Penicillium spp., Aureobasidium pullulans and Mucor spp. were consistently present on all three fruits while Colletotrichum gloeosporioides and Didymella applanata were prevalent on raspberries only and Epicoccum purpurascens and Alternaria spp. on blackberries only. Botrytis cinerea and Mucor mucedo were the predominant spoilage organisms of all three fruits, although the relative importance of the two fungi changed as the season progressed, especially for strawberries. Rhizopus stolonifer, Cladosporium spp., Penicillium spp. and Colletotrichum gloeosporioides were only of minor importance as spoilage organisms.     

Dynamics in the microbiology of maize silage during whole‐season storage

Aims: To monitor seasonal variations in the microbiology of maize silage and to determine whether the risk of fungal spoilage varies during whole‐year storage. Methods and Results: A continuous survey of 20 maize silage stacks was conducted over a period from three to 11 months after ensiling. Filamentous fungi, yeasts and lactic acid bacteria (LAB) were enumerated at five time‐points, and cultivable species of filamentous fungi were identified. Significant differences in the numbers of filamentous fungi, yeast and LAB were detected. The highest numbers of fungi were five to seven and the lowest 11 months after ensiling, while the LAB decreased in numbers during the study. Filamentous fungi were isolated from all stacks at all time‐points. The most abundant toxigenic mould species were Penicillium roqueforti, Penicillium paneum and Aspergillus fumigatus. Conclusions: There are significant variations in the microbiology of maize silage over a whole storage season. The risk of fungal spoilage was highest 5–7 months after ensiling and lowest after 11 months. Significance and Impact of the Study: This information is valuable in the assessment of health risks connected with spoiled maize silage and may be useful in the management of maize silage stacks, when whole‐season storage is applied.     

Analysis of Cross-Reactive Antigens of Phytophthora fragariae and Strawberry and their Relation to Resistance and Susceptibility

The presence of cross-reactive antigens between five isolates of P, fragariae (Pf 1, Pf 2, Pf 3, Pf 10 and Pf 11) belonging to five physiological races of the fungus and five strawberry cultivars (Cambridge Favourite, Hapil, Red Gauntlet, Siletz and 52AC18) exhibiting different disease responses to the five isolates was demonstrated by Western blotting. Antiserum anti-H, raised against extracts of healthy Cambridge Favourite roots, detected two antigens which were common to all isolates. Concentration of one of these antigens might be related to the pathogenicity of P. fragariae isolates. Antiserum anti-PfM, raised against mycelial suspensions from the five isolates, detected a doublet of 64 and 61 kDa in the soluble extracts of healthy roots from the five cultivars tested. The corresponding root suspensions revealed numerous other antigens which reacted with anti-PfM. In susceptible interactions, the doublet described above and two additional polypeptides of 38 and 31 kda were detected in large concentrations in both the soluble extracts and root suspensions. These four polypeptides were shown to be present in the healthy roots as well as in the mycelial extracts. In resistant interactions, a 116 kDa polypeptide, present in the root suspensions of the healthy host, was detected in the soluble extracts of the infected roots. It is suggested that these antigens might have a role in resistance and susceptibility.     

Systemic fungicides in the control of strawberry wilt (Verticillium dahliae)

In a series of experiments between 1970 and 1973 the application of benomyl or thiophanate methyl to field-grown strawberries, planted on Verticillium-mtested land, gave control of wilt for up to 5 months, the duration of control being related to the amount of fungicide applied in the spring. Treatment of inoculated plants grown on in chloropicrin-fumigated soil was effective for at least two seasons. An autumn-planted multi-factorial experiment in heavily-infested soil showed that, to achieve maximum wilt control, it was advantageous to grow cv. Gorella rather than cv. Cambridge Vigour; to drench the runners at planting rather than to dip them in the fungicide suspension; and to use a high concentration (0–075 % a-i-) and large volume (600 ml per plant) for a supplementary treatment in May rather than a lower concentration (0.025 %) ^or smaller volume (400 ml). There were small but significant advantages in applying benomyl rather than thiophanate methyl, and in using 0–2% a.i. suspension at planting rather than 0–05%. No advantage was gained by dividing the spring application into two equal doses applied 2 wk apart. Extrapolation from the logarithmic relation between wilt index and total dose of fungicide applied in the spring suggested that I.I g/plant would have given almost complete control until October; such control had been achieved in an earlier experiment in which 1–2 g/plant was applied. Crop yield in the second year was determined by the treatment applied in the first year, but although these treatments had given significantly better control of wilt in Gorella than in Cambridge Vigour, the greater growth and yield potentials of the latter cultivar had an over-riding effect on crop production; Cambridge Vigour yielded more than Gorella under all chemical treatments, but in the absence of treatment Gorella gave a larger crop than Cambridge Vigour. A proposed regime, entailing spring and autumn applications, is aimed at minimizing the colonization of the plant throughout the year, thus reducing the production of new inoculum and, by limiting the quantity of the pathogen in contact with the systemic chemicals, minimizing the probability of selecting fungicide-resistant variants of V. dahliae.     

Effects of Pratylenchus penetrans on development of strawberry wilt caused by Verticillium dahliae

The nematode Pratylenchus penetrans or the closely related P. fallax occurred in three out of four strawberry plantations infested with Verticillium dahliae surveyed in Kent. When plants of cv. Cambridge Vigour were inoculated with P. penetrans and V. dahliae together in field ‘micro-plots’ the nematode increased the rate of wilt development except when the concentration of V. dahliae microsclerotia in the soil was very low. In a pot experiment, under conditions not conducive to symptom expression, the incidence of infection was increased by nematodes in Cambridge Favourite, Cambridge Vigour and Redgauntlet; the incidence was least in Red-gauntlet, the most resistant cultivar. The nematode appeared to cause local changes in the root cortex which aided hyphal penetration of the adjacent tissues. Growth of strawberry plants in the absence of V. dahliae was not significantly affected even by large populations of the nematode, but growth was reduced by V. dahliae at all rates of inoculation in the field. Infection by Verticillium did not affect the total numbers of nematode per plant at the end of the experiments, although the number per g fresh weight was greater on the small amount of white root on severely diseased plants than on the larger amount on healthy or mildly diseased plants.     

Variation in the virulence of Verticillium dahliae from strawberry

Isolates of V. dahliae from strawberry, tested in 1968 against cv. Cambridge Vigour, showed differences in virulence; in cvs Talisman and Cambridge Favourite there were no significant differences between plants that were inoculated and those that were not. Evidence from this experiment, and from an earlier non-replicated experiment with Cambridge Favourite, in which differences of virulence had been apparent, showed that environmental factors can cause variations in disease development that are of similar magnitude to those attributable to genetic variations in host and parasite.     

Differences in susceptibility to attack by Brevicoryne brassicae (L.) on brussels sprouts

The attack by alate and other forms of Brevicoryne brassicae (L.) and the amount of leaf malformation they caused on each of eighteen varieties or plant breeders' lines of brussels sprout were assessed in both 1967 and 1968 over the first 6 weeks following planting out. The results of the two years agreed closely despite differences in the dates of planting relative to aphid immigration. As a group, the Dutch varieties Roodnerf, Gravendeel, Tribune, Hercules and Castricum Glory were preferred by the incoming alates but suffered less damage than the least preferred inbred line, 3BL, of Cambridge No. 3. Some evidence of antibiosis was obtained, especially from a later experiment with three Cambridge inbred lines. However, in 1969 when there was a high rate of aphid multiplication on six varieties representing sprout types from Holland, Cambridge, Bedford and Ireland, any expression of host non-preference or antibiosis was soon obscured by the development of large aphid infestations and much damage. Under these circumstances, considerable varietal differences in tolerance to attack were found. Irish Elegance sustained most damage yet its most heavily attacked plants supported little more than half of the aphid numbers of equivalent plants of the most tolerant variety Darkmar 21. The Dutch varieties Vremo Inter and Seven Hills were almost as tolerant as Darkmar 21 and recovered quickly from damage. Darkmar 21 also showed high tolerance to attack in 1970, as did the Dutch varieties Rollo, Roodnerf and Stiekema, when large aphid infestations developed on the eight varieties then grown. Lack of plant tolerance to damage appeared to be associated with incurling foliage, a characteristic of Irish Elegance, Cambridge No. 1 and No. 3.     

Antifungal lactic acid bacteria with potential to prolong shelf-life of fresh vegetables

AIM: The aim of this study was to isolate and identify antifungal lactic acid bacteria from fresh vegetables, and evaluate their potential in preventing fungal spoilage of vegetables. METHODS AND RESULTS: Lactic acid bacteria from fresh vegetables were enriched in MRS (de Man Rogosa Sharpe) broth and isolated by plating on MRS agar. All the isolates (359) were screened for activity against Aspergillus flavus of which 10% showed antifungal activity. Potent antifungal isolates were identified by phenotypic characters and confirmed by partial 16S rRNA gene sequencing. These were screened against additional spoilage fungi viz. Fusarium graminearum, Rhizopus stolonifer, Sclerotium oryzae, Rhizoctonia solani, Botrytis cinerea and Sclerotinia minor by overlay method. Most of the isolates inhibited wide range of spoilage fungi. When fresh vegetables were inoculated with either cell suspension (10(4) cells ml(-1)) or cell-free supernatant of Lact. plantarum, followed by application of vegetable spoilage fungi (A. flavus and F. graminearum, R. stolonifer, B. cinerea each with 10(4) conidia ml(-1)) the vegetable spoilage was significantly delayed than control. CONCLUSIONS: Fresh vegetables constitute a good source of lactic acid bacteria with ability to inhibit wide range of spoilage fungi. Such bacteria can be applied to enhance shelf-life of vegetables. In the present study, we report for the first time the antifungal activity of Weissella paramessenteroides and Lact. paracollinoides isolated from fresh vegetables, against wide range of food spoilage fungi. SIGNIFICANCE AND IMPACT OF THE STUDY: Fresh vegetables can be used as a source of antifungal lactic acid bacteria. Their exploitation as biopreservative will help in prolonging shelf-life of fresh vegetables.     

Vertical and Temporal Distribution of Aphis gossypii Glover and Coccinellid Populations on Different Chilli (Capsicum annuum) Varieties

The vertical and temporal distribution of an aphid, Aphis gossypii Glover, and the coccinellid populations on six chilli varieties were studied. The total number of apterous aphid per plant stratum was significantly different among plant strata of a particular variety (treatment) as well as among the treatments. Generally, the total number of aphids was significantly greater in the lower stratum than in the middle and upper strata. However, the varieties with erect and open plant architecture (Kulai and MC 11) had significantly less number of apterous aphids at all strata as compared to varieties with compact or prostrate plant architectures. There was a significant difference in the total number of coccinellids per plant strata among the treatments but not within a treatment. The distribution of apterous aphid populations varied significantly among sampling periods and treatments. The temporal distribution of coccinellids showed a similar trend as that of apterous aphids. The total number of alate aphids caught per week was significantly different among the sampling periods. However, its population was significantly greater during the early season and gradually declined as the season progressed except during June 18 to 24. The importance of recording the most observed coccinellids species, which limit the aphid populations at each particular plant stratum per variety, and the conditions that favor natural enemies are also discussed.     

Application of electronic nose technology for the detection of fungal contamination in library paper

Studies were carried out in vitro on a cellulose based agar at two water activities (a_w,0.975,0.995) and on three types of paper at two relative humidities (75, 100% RH) for the potential for differentiation of contamination and colonisation by Aspergillus terreus, A. holandicus and Eurotium chevalieri. In vitro studies showed that conducting polymer sensor array gave different responses to each of these species when grown on cellulose agar at both a_w levels. Discriminant function analyses of the data showed differentiation of the controls from the spoilage fungi. Cluster analysis gave a significant (P=0.05) separation of the control and each spoilage fungus. In situ studies on three types of paper showed that using natural substrates the volatile patterns produced by each of these fungi was different from each other and from the control. The results obtained were better at the higher humidity. The three paper types could be successfully differentiated into clusters. For a single paper type, differentiation of controls from spoilage fungal treatments was better at the higher humidity. This study has shown that this technology has potential for the early detection of fungal contamination in library materials and archives for the improved protection of cultural heritage.     

Monitoring Seasonal Changes in Winery-Resident Microbiota

During the transformation of grapes to wine, wine fermentations are exposed to a large area of specialized equipment surfaces within wineries, which may serve as important reservoirs for two-way transfer of microbes between fermentations. However, the role of winery environments in shaping the microbiota of wine fermentations and vectoring wine spoilage organisms is poorly understood at the systems level. Microbial communities inhabiting all major equipment and surfaces in a pilot-scale winery were surveyed over the course of a single harvest to track the appearance of equipment microbiota before, during, and after grape harvest. Results demonstrate that under normal cleaning conditions winery surfaces harbor seasonally fluctuating populations of bacteria and fungi. Surface microbial communities were dependent on the production context at each site, shaped by technological practices, processing stage, and season. During harvest, grape- and fermentation-associated organisms populated most winery surfaces, acting as potential reservoirs for microbial transfer between fermentations. These surfaces harbored large populations of Saccharomyces cerevisiae and other yeasts prior to harvest, potentially serving as an important vector of these yeasts in wine fermentations. However, the majority of the surface communities before and after harvest comprised organisms with no known link to wine fermentations and a near-absence of spoilage-related organisms, suggesting that winery surfaces do not overtly vector wine spoilage microbes under normal operating conditions.     

Fungi associated with sorghum seeds

Summary A study of the external and internal fungi associated with different varieties ofSorghum seeds has been made. The varieties tested included eighteen local varieties and twelve newSorghum varieties obtained from the Rockefeller Foundation. The external fungi were studied by preparing suspensions of superficial fungi and growing on potato dextrose agar. The internal fungi were studied by planting surface sterilized seeds on P.D.A. and pure cultures of all these fungi were prepared.The external fungi found to be associated with the different varieties included different species ofPhycomyces, Circinella, Syncephalastrum, Chaetomium, Curvularia, Cladosporium, Helminthosporium, Montospora, Pullularia, Aspergillus, Penicillium, Cephalosporium, Trichoderma, Phoma, Fusarium.The internal fungi recovered from these varieties included species ofChaetomium, Cladosporium, Curvularia, Helminthosporium, Heterosporium, Hormodendron, Pullularia, Alternaria, Aspergillus, Blastomyces, Monilia, Penicillium, Fusarium, Phoma, Phomopsis. Varieties 4403B, 1060 and 503 were found to carry a large number of fungi. Variety Black spanish was found to be entirely free from any internal or external fungus. Varieties which were free from endophytic fungi but possess external fungi only were Kaoling 301, African variety 901 and Shallus 475. Three fungi viz.,Pullularia, Heterosporium, Monilia have been recovered from theSorghum seeds for the first time.     

A QTL on chromosome 6A in bread wheat (<Emphasis Type="Italic">Triticum aestivum</Emphasis>) is associated with longer coleoptiles,greater seedling vigour and final plant height

Wheat crops with greater early vigour shade the soil surface more rapidly and reduce water loss. Evaporative losses affect water-use efficiency particularly in drier regions where most of the rainfall occurs early in the growing season before canopy closure. Greater seedling leaf area and longer coleoptiles are major determinants of increased vigour and better crop establishment. A previously developed high vigour breeding line ‘Vigour 18’ was used to establish a large recombinant inbred family and framework map to identify a QTL on chromosome 6A that accounted for up to 8% of the variation for coleoptile length, 14% of seedling leaf width and was associated with increased plant height. The SSR marker NW3106, nearest to the 6A QTL, was also associated with greater leaf width in a breeding population that was also derived from a cross involving the high vigour donor line ‘Vigour18’. The association between the NW3106 marker and coleoptile length was validated in a second breeding population which was developed using an unrelated long coleoptile donor line. The ‘Vigour18’ allele of the QTL on chromosome 6A promoted coleoptile length and leaf width during early plant growth but was also associated with increased plant height at maturity. Markers linked to the QTL are being used to increase the frequency of increased vigour and long coleoptile alleles in early generations of breeding populations.     

Molecular identification of isolated fungi from stored apples in Riyadh,Saudi Arabia

Fungi causes most plant disease. When fruits are stored at suboptimal conditions, fungi grows, and some produce mycotoxin which can be dangerous for human consumption. Studies have shown that the Penicillium and Monilinia species commonly cause spoilage of fruits, especially apples. Several other genera and species were reported to grow to spoil fruits. This study was conducted to isolate and identify fruit spoilage by fungi on apples collected in Riyadh, Saudi Arabia and conduct a molecular identification of the fungal isolates. Thus, we collected 30 samples of red delicious and Granny Smith apples with obvious spoilage from different supermarkets between February and March of 2012 in Riyadh, Saudi Arabia. Each apple was placed in a sterile plastic bag in room temperature (25–30 °C) for six days or until fungal growth was evident all over the sample. Growth of fungal colonies on PDA was counted and sent for molecular confirmation by PCR. Six fruit spoilage fungi were isolated, including Penicillium chrysogenum, Penicillium adametzii, Penicillium chrysogenum, Penicillium steckii, Penicillium chrysogenum, and Aspergillus oryzae. P. chrysogenum was the most frequent isolate which was seen in 14 of a total of 34 isolates (41.2%), followed by P. adametzii and A. oryzae with seven isolates each (20.6%) and the least was P. steckii with six isolates (17.6%). Penicillium species comprised 27 of the total 34 (79.4%) isolates. Sequence analysis of the ITS regions of the nuclear encoded rDNA showed significant alignments for P. chrysogenum, P. adametzii and A. oryzae. Most of these fungal isolates are useful and are rarely pathogenic; however they can still produce severe illness in immune-compromised individuals, and sometimes otherwise healthy people may also become infected. It is therefore necessary to evaluate the possible production of mycotoxins by these fungi to determine a potential danger and to establish its epidemiology in order to develop adequate methods of control.     

BARK-SPLIT–A VIRUS DISEASE OF PLUMS

The bark-split disease of plums commences with necrotic lesions in the outer bark, causing depressions on the surface; these lesions extend in area and depth, resulting in split and roughened bark, and crippling or killing trees of sensitive varieties like Cambridge Gage.
The causal virus was transmitted by grafting in the dormant season, but, probably because it is localized in older tissues, it was rarely transmitted or scion-perpetuated by summer budding.
About 90% of Common Plum clonal rootstocks from East Malling Research Station's layer-beds were found to be infected. Apparently virus-free Common Plum was propagated by cuttings from the roots of Common Plum under normal Cambridge Gage trees.
A different type of bark-split disease developed on Shiro Plum inoculated with virus from a tree of Quetsche Précoce de Zimmer. Leaf symptoms accompanying infection with this and with the virus from Common Plum were similar.
Bark-split disease is compared and contrasted with diamond canker of French Prune in California, and features that distinguish bark-split from bacterial canker are described.     

Detection of rope spoilage in bread caused by Bacillus species

Rope spoilage of bread by eight Bacillus isolates obtained from a bakery environment was examined via direct inoculation of slices of bread with bacterial culture. The three types of loaf examined were two soft grain varieties, one containing vinegar and the other containing calcium propionate as the preservative agent, and a white variety containing calcium propionate. Differences in rope production caused by batch variation were studied by comparing seven loaves of each type of bread. Not all isolates were capable of causing extensive rope, but isolates of Bacillus subtilis , B. licheniformis , B. megaterium and B. pumilus were able to produce such spoilage. Limited rope was also caused by pre-existing Bacillus species within the loaves. The amount of rope production by an isolate was not constant on all loaf types or even between different batches of the same variety, indicating that approaches that rely on direct inoculation of loaves with culture are not applicable for assessing the rope-inducing potential of Bacillus isolates. However, it was clear from this study that vinegar in soft grain loaves was more effective than calcium propionate at inhibiting rope.     

Effect of pre-harvest fungicides on the spoilage of soft fruit after harvest

In the 1972 season, Elvaron and Benlate reduced the count of Botrytis cinerea, Cladosporium spp., Penicillium spp. and Aureobasidiutn pullulans on strawberry and raspberry fruits during the first 2 wk of the season, but not subsequently. No such reduction was recorded for Hainesia lythri (strawberries only), Phoma state of Didymella applanata (raspberries only), Mucor spp., and Rhizopus spp. Similar results were obtained in 1973. In the first half of either season, both fungicides decreased the rate of fungal spoilage of stored fruit (except for Benlate in the 1973 season), although in the latter part of the season, there was little difference in the incidence of fungal spoilage between sprayed and unsprayed fruit. Both fungicides, however, reduced the development of B. cinerea (and Cladosporium spp. on raspberries) on stored fruit irrespective of season or harvest date except for Benlate in the 1973 season where Benlate-resistant strains of the fungi developed on the fruit. The failure of either fungicide to reduce fungal spoilage in the latter part of the harvesting season was due to the development of Phycomycetes, particularly Mucor mucedo and to a lesser extent Rhizopus stolonifer and R. sexualis, except where Benlate-resistant strains of B. cinerea and Cladosporium spp. were present.     

Growth and wilt (Verticillium dahliae) development in strawberry cultivars over a transition between two soil series

On a site infested with V. dahliae the incidence of wilt was low consistently in strawberry cvs Talisman and Redgauntlet, high in Merton Herald and Gorella, and very high in Merton Ruby, Cambridge Vigour, Prizewinner, Templar and Crusader. Changes in mean volume per plant for the whole population of each cultivar were closely related to disease incidence and therefore differed between high-resistance and low-resistance cultivars. Height and spread measurements of diseased and symptomless plants in certain cultivars showed differences in the severity of the effect of the pathogen on growth that were not closely related to wilt incidence. Gradients of disease incidence and plant growth in 1966 and 1967 were associated with a transition from one soil series to another. Review of two earlier experiments on the same site revealed a similar gradient of disease incidence in 1963-64, but a reversed gradient in 1960-62. Variations related to soil conditions were smaller in the earlier experiments than in 1966-67.     

Susceptibility of selected apple cultivars to the Mediterranean fruit fly

Ceratitis capitata (Wiedemann), the Mediterranean fruit fly, is one of the key pest species affecting deciduous fruit orchards along the Mediterranean coasts. Because of global warming, C. capitata is gradually spreading north and is becoming a major pest of apples. Determining the susceptibility of the main apple varieties grown in the region will serve as a cornerstone to the management of this pest. In this study, we show the results of a field and laboratory no‐choice test conducted to determine the Medfly preferences on different apple cultivars. The seven main varieties of apples (Gala, Red Delicious, Golden Delicious, Granny Smith, Kanzi, Morgen Dallago and Fuji) were tested. The results demonstrate that C. capitata lays eggs on all apple cultivars in both field and laboratory conditions. The Granny Smith, Red Delicious and Morgen Dallago varieties showed the lowest susceptibility in laboratory conditions, (0.75, 1.55, 2 oviposition punctures/fruit, respectively), with significant differences in oviposition compared to the Golden Delicious, Kanzi and Fuji (3.27, 3.31, 3.1 oviposition punctures/fruit, respectively) varieties, which were shown to be the most susceptible to Medfly attack in laboratory conditions. On the other hand, only slight and not statistically significant differences emerged from the field trials. In relation to the physico‐chemical characteristics, the apple cultivars showing the lowest susceptibility (Granny Smith, Red Delicious and Morgen Dallago) had harder peels and pulps and lower sugar contents than the most susceptible cultivars (Golden Delicious, Fuji and Kanzi). These results were also confirmed through evaluation of larval development on different varieties. In fact, Granny Smith, Red Delicious and Morgen Dallago were the three varieties that did not allow adequate larval and adult development and reduced the possibility of the emergence of a new generation.