Fungicidal activity of essential oils of Cinnamomum zeylanicum (L.) and Syzygium aromaticum (L.) Merr et L.M. Perry against crown rot and anthracnose pathogens isolated from banana

AIMS: To develop a post-harvest treatment system against post-harvest fungal pathogens of banana using natural products. METHODS AND RESULTS: Colletotrichum musae was isolated and identified as the causative agent responsible for anthracnose peel blemishes while three fungi, namely Lasiodiplodia theobromae, C. musae and Fusarium proliferatum, were identified as causative agents responsible for crown rot. During the liquid bioassay, cinnamon [Cinnamomum zeylanicum (L.)] leaf, bark and clove [Syzygium aromaticum (L.)] oils were tested against the anthracnose and crown rot pathogens. The test oils were fungistatic and fungicidal against the test pathogens within a range of 0.03-0.11% (v/v). CONCLUSIONS: Cinnamon and clove essential oils could be used as antifungal agents to manage post harvest fungal diseases of banana. SIGNIFICANCE AND IMPACT OF THE STUDY: Cinnamon and clove essential oil could be used as alternative post-harvest treatments on banana. Banana treated with essential oil is chemically safe and acceptable to consumers. Benomyl (Benlate), which is currently used to manage fungal pathogens, can cause adverse health effects and could be replaced with volatile essential oils.     

Hand position on the bunch and source–sink ratio influence the banana fruit susceptibility to crown rot disease

The postharvest development of crown rot of bananas depends notably on the fruit susceptibility to this disease at harvest. It has been shown that fruit susceptibility to crown rot is variable and it was suggested that this depends on environmental preharvest factors. However, little is known about the preharvest factors influencing this susceptibility. The aim of this work was to evaluate the extent to which fruit filling characteristics during growth and the fruit development stage influence the banana susceptibility to crown rot. This involved evaluating the influence of (a) the fruit position at different levels of the banana bunch (hands) and (b) changing the source–sink ratio (So–Si ratio), on the fruit susceptibility to crown rot. The fruit susceptibility was determined by measuring the internal necrotic surface (INS) after artificial inoculation of Colletotrichum musae. A linear correlation (r = −0.95) was found between the hand position on the bunch and the INS. The So–Si ratio was found to influence the pomological characteristics of the fruits and their susceptibility to crown rot. Fruits of bunches from which six hands were removed (two hands remaining on the bunch) proved to be significantly less susceptible to crown rot (INS = 138.3 mm ²) than those from bunches with eight hands (INS = 237.9 mm ²). The banana susceptibility to crown rot is thus likely to be influenced by the fruit development stage and filling characteristics. The present results highlight the importance of standardising hand sampling on a bunch when testing fruit susceptibility to crown rot. They also show that hand removal in the field has advantages in the context of integrated pest management, making it possible to reduce fruit susceptibility to crown rot while increasing fruit size.     

Evaluation of an organic treatment for post-harvest control of crown rot of banana

An organic treatment for control of crown rot disease of banana was developed and evaluated at EARTH University in Costa Rica. Studies were conducted to evaluate the efficacy of Biocto 6 (seed extract from citrus) in combination with the wax-based adjuvant Verdiol for control of post-harvest crown rot of banana. The standard commercial fungicide treatment (thiabendazol, imazalil and ammonium sulfate) and an untreated control were included for comparison. Bananas with the various treatments were processed using standard commercial procedures and stored in a refrigerated chamber that was modified to simulate commercial transport, distribution and controlled ripening for exported bananas. Fruit clusters were evaluated for percent weight loss, ripening in storage and crown rot disease severity. At the end of the 28-day storage period, there were no significant differences in percent weight loss between any of the treatments. There was no significant difference in ripening (maturity level) between the organic treatment and the commercial fungicide standard in 2 years of testing. In 2003, the untreated control had a significantly higher maturity rating than the organic or standard fungicide treatment. However, there were no significant differences in any of the treatments in maturity level in 2005. There was no significant difference between the organic and standard fungicide treatment for crown rot control and both treatments had significantly less crown rot than the untreated control. Results indicate that Biocto 6 in combination with Verdiol wax provides a new organic alternative for control of post-harvest crown rot of banana.     

Fungal Pathogens Associated with Banana Fruit in Sri Lanka,and their Treatment with Essential Oils

The crown rot pathogens isolated from banana samples collected from 12 localities in Sri Lanka were Lasiodiplodia theobromae, Fusarium proliferatum and Colletotrichum musae. Fungal pathogens isolated were able to cause crown rot disease alone or in combination. Disease severity was higher when combinations of virulent pathogens were used. Cymbopogon nardus and Ocimum basilicum oils displayed fungicidal activity against C. musae and F. proliferatum between 0.2-0.6% (v/v) in a Poisoned food bioassay. Slightly lower concentrations of the test oils were needed for similar activity during liquid bioassays. The combination of Cymbopogon nardus and O. basilicum oils demonstrated synergistic action during both in-vivo bioassays.     

Phases of infection and gene expression of Fusarium graminearum during crown rot disease of wheat

Fusarium graminearum causes head blight (FHB) and crown rot (CR) diseases in wheat. Compared with FHB, CR symptom development occurs slowly, usually taking 4 to 8 weeks to become visible. To characterize CR development, we used histological and real-time quantitative polymerase chain reaction analyses to assess fungal colonization during a timecourse of infection. Three distinct phases of infection were identified: i) initial spore germination with formation of a superficial hyphal mat at the inoculation point, ii) colonization of the adaxial epidermis of the outer leaf sheath and mycelial growth from the inoculation point to the crown, concomitant with a drop in fungal biomass, and iii) extensive colonization of the internal crown tissue. Fungal gene expression was examined during each phase using Affymetrix GeneChips. In total, 1,839 F. graminearum genes were significantly upregulated, including some known FHB virulence genes (e.g., TRI5 and TRI14), and 2,649 genes were significantly downregulated in planta compared with axenically cultured mycelia. Global comparisons of fungal gene expression with published data for FHB showed significant similarities between early stages of FHB and CR. These results indicate that CR disease development involves distinct phases of colonization, each of which is associated with a different fungal gene expression program.     

Hypoxic culture and in vivo inflammatory environments affect the assumption of pericyte characteristics by human adipose and bone marrow progenitor cells

Previous studies have shown that exposure to a hypoxic in vitro environment increases the secretion of pro-angiogenic growth factors by human adipose-derived stromal cells (hASCs) [Cao Y, et al., Biochem Biophys Res Commun 332: 370-379, 2005; Kokai LE, et al., Plast Reconstr Surg 116: 1453-1460, 2005; Park BS, et al., Biomed Res (Tokyo) 31: 27-34, 2010; Rasmussen JG, et al., Cytotherapy 13: 318-328, 2010; Rehman J, et al., Circulation 109: 1292-1298, 2004]. Previously, it has been demonstrated that hASCs can differentiate into pericytes and promote microvascular stability and maintenance during angiogenesis in vivo (Amos PJ, et al., Stem Cells 26: 2682-2690, 2008; Traktuev DO, et al., Circ Res 102: 77-85, 2008). In this study, we tested the hypotheses that angiogenic induction can be increased and pericyte differentiation decreased by pretreatment of hASCs with hypoxic culture and that hASCs are similar to human bone marrow-derived stromal cells (hBMSCs) in these regards. Our data confirms previous studies showing that hASCs: 1) secrete pro-angiogenic proteins, which are upregulated following culture in hypoxia, and 2) migrate up gradients of PDGF-BB in vitro, while showing for the first time that a rat mesenteric model of angiogenesis induced by 48/80 increases the propensity of both hASCs and hBMSCs to assume perivascular phenotypes following injection. Moreover, culture of both cell types in hypoxia before injection results in a biphasic vascular length density response in this model of inflammation-induced angiogenesis. The effects of hypoxia and inflammation on the phenotype of adult progenitor cells impacts both the therapeutic and the basic science applications of the cell types, as hypoxia and inflammation are common features of natural and pathological vascular compartments in vivo.     

The effect of inoculating flowers and developing fruits with Botrytis cinerea on post-harvest grey mould of red raspberry

Raspberry flowers were inoculated in the glasshouse and field with dry conidia of Botrytis cinerea and the fruits derived from them subjected to post-harvest rot tests at c. 20°C and high humidity. Apparently healthy fully-ripe picked fruits derived from inoculated flowers developed grey mould faster than those from non-inoculated flowers in all tests. In the glasshouse experiments, fruits from inoculated tightly closed flower buds rotted more slowly than those from inoculated open flowers or those at later developmental stages. Fruits from inoculated whole flowers rotted more rapidly than those from emasculated flowers; the addition of pollen to emasculated flowers had little effect on post-harvest grey mould. In the dry summer of 1984 no fruits in the field from inoculated whole flowers rotted before ripening, but in the wet season of 1985 pre-harvest grey mould was common and the surviving healthy fruits rotted in c. 1 day after picking. Only minor differences were detected in host susceptibility to post-harvest grey mould in both glasshouse and field tests, the ranking of genotypes varied depending on whether or not flowers had been inoculated. The susceptibility of pistils of 40 Rubus genotypes to infection was examined 7 and 28 days after inoculation of stigmas with dry conidia. Conidia germinated on the stigmas and produced hyphae which grew through transmitting tissues of the styles to infect carpels symptomlessly in 17 red raspberries, one blackberry, two Rubus spp. and one hybrid. No germination occurred on stigmas of cv. Carnival and New York Selection 817.     

The effect of intruded events on peak time: the role of reinforcement history during the intruded event

Pigeons were studied in an extension of a study by Aum et al. [Aum, S., Brown, B.L., Hemmes, N.S. 2004. The effects of concurrent task and gap events on peak time in the peak procedure. Behav. Process. 65, 43-56] on timing behavior under a discrete-trial fixed-interval (FI) procedure during which 6-s intruded events were superimposed on peak-interval (PI) test trials. In Aum et al., one event consisted in termination of the timing cue (gap trial); the other was a stimulus in the presence of which subjects had been trained to respond under an independent random-interval (RI) schedule of reinforcement (concurrent task trial). Aum et al. found a disruption of timing on concurrent task trials that was greater than that on gap trials. The present study investigated history of reinforcement associated with intruded events as a possible explanation of this earlier finding. After training to peck a side key on a 30-s PI procedure, discrimination training was conducted on the center key in separate sessions; red or green 6-s stimuli were associated with RI 24s or EXT (extinction) schedules. During testing under the PI procedure, three types of intruded events were presented during probe trials--the stimulus associated with the RI (S+) or EXT (S-) schedule during discrimination training, or a gap (termination of the side-keylight). Intruded events occurred 3, 9, or 15s after PI trial onset. Effects of reinforcement history were revealed as substantial disruption of timing during the S+ event and relatively little disruption during the S- event. Intermediate effects were found for the gap event. Results indicate that postcue effects are at least partially responsible for the disruptive effects of the S+ event.     

Evaluation of methods of screening strawberry cultivars for resistance to crown rot caused by Phytophthora cactorum

Four methods were evaluated in measuring resistance of strawberry cultivars to crown rot caused by Phytophthora cactorum. Meristem propagated plants grown in vitro were inoculated with mycelial discs. Four to five days after inoculation, it was possible to distinguish between cultivars with large differences in susceptibility to the disease. Ten days later, all plants were totally necrotic making it impossible to distinguish between cultivars. When detached leaves were inoculated by inoculating a plug of mycelium into the petiole, disease symptoms developed more slowly in resistant cultivars, but leaf age greatly affected the rate of symptom development. When plug plants (not cold stored) were lightly wounded in the rhizome with a scalpel and inoculated with either zoospores or mycelium, differences in disease development between cultivars were mainly as would be expected from previous information on susceptibility, but both age and size of plants influenced the rate of disease development. Unwounded, inoculated plants did not develop symptoms. When cold‐stored plug plants were either unwounded or lightly wounded with a scalpel in the rhizome and inoculated with zoospores, the relative rates of disease development consistently reflected the susceptibility to crown rot. At the time of final assessment, disease was much more severe in wounded plants, but the relative susceptibility of cultivars was not affected by the wounding.     

Identification and characterization of a novel Iraqi isolate of Fusarium pseudograminearum causing crown rot in wheat

Crown rot is one of the main important fungal diseases affecting wheat in many areas of the world, including Australia, USA, and Iran. Until now, there had been no report of this pathogen in Iraq. Plants displaying crown rot symptoms were observed in Shaat Alarab (Basra, Iraq); we investigated the causal agent of the disease. Samples were surface-sterilized in bleach (1% available chlorine) and cultured on quarter-strength potato dextrose agar plates. DNA was extracted from fungal mycelia, using a modified CTAB protocol. The ITS/5.8S regions were amplified using primer pair ITS1 and ITS4. PCR products purified using a gel extraction kit were sequenced. The sequence that was detected was used to BLAST against NCBI data. The most similar sequence was the ITS/5.8S rDNA region of Fusarium pseudograminearum (strain NRRL28062), showing 97.95% identity. This species normally causes crown rot, resulting in severe damage under dry spring conditions. A pathogenicity test employed to assess the disease-causing ability of the strain showed significant disease symptoms up to 57% infected spikelets. The results confirmed the presence of F. pseudograminearum as a causal agent of wheat crown rot in Iraq. The presence of this pathogen demands further investigations to develop resistant cultivars and/or mechanical control.     

Gibberella musae (Fusarium musae) sp. nov., a recently discovered species from banana is sister to F. verticillioides

Several strains of Fusarium isolated from banana were identified previously as F. verticillioides (Sacc.) Nirenberg but described as unable to produce fumonisin. Here we report biochemical and morphological evidence, as well as multilocus phylogenetic analyses based on elongation factor (EF-1α), calmodulin, β-tubulin, and the second largest subunit of RNA polymerase II (RPB2) sequences, indicating that these isolates represent a unique lineage in the Gibberella fujikuroi species complex related to but distinct from F. verticillioides. Together with previous results of molecular studies, as well as with results of metabolite analyses, crossing experiments, pathogenicity tests and morphological characterization, these new data indicate that these strains isolated from banana represent a new species, Gibberella musae Van Hove et al. sp. nov. (anamorph: Fusarium musae Van Hove et al. sp. nov.), which is described herein.     

峡东地区早寒武世水井沱组古盘虫类三叶虫的再研究

对峡东和邻近地区早寒武世古盘虫类三叶虫的再研究,支持将Emeidiscus Li,1980;Mianxrindiscus S．Zhang et Zhu in Zhang et al,1980;Mianxiandiscus(Liangshandiscus)S．Zhang in Zhang et al．,1980;Hupeidiscus Chang in Lu et al．,1974;Guizhoudiscus S．Zhang in Zhang et al．,1980;Shizhudiscus S．Zhang et Zhu in Zhang et al．,1980等属作为Tsunyidiscus Chang,1966的同义名的意见。并对前人所建立的有关属的种,进行了重新研究和整理,作了大量的归并和修订。就目前所知道,峡东地区早寒武世水井沱组的古盘虫类三叶虫仅有Tsunyidiscus Chang,1966和Sinodiscus Chang in Lu et al,1974两属。Hupeidiscus经修订归入Tsunyidiscus Chang,1966后,原Hebediscus orientalis Chang,1953(即原Hupeidiscus的模式种)一种的种名与Tsunyidiscus orientalis(Walcott,1905)重名,故将前者重新命名为Tsunyidiscus pertenus nom．nov．。文中还记述了湖北宜昌、秭归等地的早寒武世古盘虫类三叶虫2属3种,包括Tsunyidiscus yanjiazhaiensis S．Zhang,Zhou et Yuan in Yin and Li,1978;Tsunyidisacutus(Sun,1983);Sinodiscus changyangensis S．Zhang in Zhou et al．,1977。     

Social stress increases fecal shedding of Salmonella typhimurium by early weaned piglets

"Segregated early weaning" (SEW) of pigs reduces exposure to pathogenic bacteria, but upon arrival at grower facilities pigs may be co-mingled regardless of farm of origin. The present study was designed to examine the effect of mixing (social) stress on populations of Salmonella enterica Typhimurium in SEW pigs. Piglets (7 days old; n = 28 in each of 2 replicates) were separated into 2 treatments (control and mixed groups) of 2 pens per treatment (7 piglets/pen). One (n = 1) "seeder" pig/pen was inoculated with 10(9) CFU of S. Typhimurium. Each seeder was placed with non-inoculated "contact" piglets (n = 6). A"contact" piglet was swapped each day between the "mixed" pens for 5 days; pigs in control pens were not exchanged. On day 5, the incidence of fecal Salmonella shedding was higher in the mixed contact pigs (P < 0.05). Rectal Salmonella and cecal coliform populations in mixed pigs were significantly (P < 0.05) greater than in control pigs but cecal Salmonella populations were not different. Mixed pigs were more susceptible to tissue invasiveness (i.e., Salmonella-positive tonsils and lymph nodes) than control pigs. These results indicate that social stress of weaned pigs may increase susceptibility to and/or fecal shedding of Salmonella. Food-borne Salmonella infections in the United States are estimated to cost the economy dollar 2.4 billion annually (ERS/USDA, 2001). Approximately 6-9% of human salmonellosis is associated with the consumption of pork products (Frenzen et al., 1999). Salmonella is relatively common on swine farms and has been isolated from all stages of the pork production chain (Davies et al., 1999; Fedorka-Cray et al., 1997b; Rostagno et al., 2003). Salmonella is a threat to the pork industry not only from a food-safety perspective as a public health concern, but some Salmonella serotypes can cause clinical illnesses in swine, negatively impacting production efficiency and profitability (Schwartz, 1991).     

Occurrence of Bacterial Wilt and Soft Rot of Seed Cabbage Plants (Brassica oleracea var. capitata L.) in Yugoslavia

Soft rot and wilt symptoms were noticed on 2-year-old seed cabbage plants grown in field crops. Soft rot Erwinia was isolated from the diseased tissues. Pathogenicity tests showed that the bacterium effectively colonised different vegetable species and sunflower, indicating a wide host range.
Pathogenicity, morphological, biochemical and physiological characteristics showed that the investigated strains are of Erwinia carotovora subsp. carotovora (Jones) Bergey et al.     

The reaction of near-isogenic lines of flax to the rust fungus Melampsora lini. II. Biochemical studies

The nature of resistance to rust fungus Melampsora lini (Pers.) Lev. was studied in two near-isogenic lines of flax, the susceptible Redwing (rr) and the immune S-66-53 (RR). Proteins of theses lines were immunologically and electrophoretically similar. Hydrolytic enzymes which release phenolic moities, i.e., -glucosidase and esterase(s), and phenol-oxidizing enzymes, i.e., peroxidase and polyphenol oxidase(s), did not appear to be involved in resistance or susceptibility as controlled by the R locus. Catalase activity was found to be higher in younger tissues of Redwing than in S-66-53 or their immune F₁ hybrid (Rr). Older tissues in both lines, whether inoculated or not, did not show any detectable catalase activity. A hypothesis to explain the genetic control of resistance and susceptibility in these lines before and after inoculation is suggested.This work has been supported by the National Research Council of Canada.