伞形花内酯处理对美味猕猴桃果实品质和青霉病抗性的影响

通过体外试验,研究伞形花内酯对扩展青霉（Penicillium expansum）生长的影响;同时以美味猕猴桃‘布鲁诺’（Actinidia deliciosa‘Bruno’）为材料,研究0.5 mg · mL-1伞形花内酯处理对猕猴桃果实品质和腐烂率,以及果实损伤接种P. expansum后病斑直径和抗病相关酶活性及其基因表达的影响。结果表明,伞形花内酯能够有效抑制P. expansum孢子萌发和菌落生长（体外）;延缓猕猴桃果实可滴定酸和维生素C下降,以及可溶性固形物含量上升,降低果实的腐烂率;降低贮藏后期果实损伤接种P. expansum后病斑直径,延缓棒曲霉素的积累,提高果肉几丁质酶（CHT）、β–1,3–葡聚糖酶（GLU）和苯丙氨酸解氨酶（PAL）的活性,以及编码这些酶的基因相对表达量。结果表明伞形花内酯处理有助于保持猕猴桃采后果实品质,并诱导提高果实对青霉病的抗性。     

PEG/磷酸盐双水相体系萃取青霉TS67胞外活性蛋白的研究

[目的]研究用PEG／磷酸盐双水相体系萃取青霉TS67胞外活性蛋白,为活性蛋白的进一步提纯及工业化生产提供依据。[方法]以分配系数、下相分配率及抑菌圈直径为指标,分别研究了PEG的浓度、磷酸盐的浓度、氯化钠的浓度对青霉TS67胞外活性蛋白在PEG2000／磷酸盐和PEG6000／磷酸盐双水相系统中分配特性的影响。[结果]在24％PEG2000／12％磷酸盐的双水相体系中下相抑菌圈直径最大,达到2．50cm,此时下相分配率为87．77％;在28％PEG6000／12％磷酸盐双水相体系中,下相分配率最大,达到94．85％,此时下相抑菌圈直径为2．45cm。[结论]PEG的浓度、磷酸盐的浓度对蛋白的分配特性有显著影响,氯化钠的浓度对其影响并不明显。从成本及结果来说。PEG2000优于PEG6000。     

Metabolism of the phosphonate herbicide glyphosate by a non-nitrate-utilizing strain of Penicillium chrysogenum

A Penicillium chrysogenum strain was isolated for its ability to grow in minimal medium containing the herbicide glyphosate as the only nitrogen source. The presence of concentrations up to 25 mM progressively stimulated the fungal growth rate, which was negligible in media lacking reduced nitrogen. However, glyphosate utilization never exceeded 1 mmol g-1 mycelial dry mass, and below a threshold concentration both herbicide uptake and fungal growth were subject to a lag phase, suggesting that the herbicide may enter the cell by either simple passive diffusion or inducible carriers. Amino acids, possible products of glyphosate breakdown, as well as ammonia, were found to replace the herbicide in restoring mycelial growth. Cells were devoid of detectable nitrate reductase activity, thus the isolate seems to be impaired in its ability to convert nitrate to ammonium. In vitro activity of 5-enol-pyruvyl-shikimate-3-phosphate synthase, the target site of glyphosate action, was highly sensitive to the herbicide. Fungal growth rate was considerably lower when the herbicide was also the only phosphorus source, whereas glyphosate utilization was substantially unaffected, suggesting an unusual route for its degradation. Herbicide metabolism was strongly reduced when other sources of organic nitrogen were made available.     

Control of post‐harvest decay of apples by pre‐harvest and post‐harvest application of ammonium molybdate

Ammonium molybdate was tested as a potential fungicide for use in apples (cv Golden Delicious) against blue and grey mould, important post‐harvest diseases of pome fruits. In tests in vivo at 20 °C, ammonium molybdate (15 mM ) reduced lesion diameters of Penicillium expansum, Botrytis cinerea and Rhizopus stolonifer by 84%, 88% and 100% respectively. When apples treated with ammonium molybdate were stored at 1 °C for three months, a significant reduction in severity and incidence of P expansum and B cinerea was observed in both years of study (1998 and 1999). In the second year of the experiment the reduction in disease severity was greater than 88% for both pathogens, and the level of control was similar to, or greater than, that observed with the fungicide imazalil. When ammonium molybdate was applied as a pre‐harvest treatment, a significant reduction in blue mould decay was observed after three months in cold storage. In vitro, ammonium molybdate greatly inhibited spore germination of P expansum and B cinerea, although better inhibition was obtained against grey mould. Ammonium dimolybdate, sodium molybdate and potassium molybdate were also tested in vitro in comparison with ammonium molybdate as inhibitors of spore germination, but only ammonium molybdate inhibited spore germination by more than 50%. © 2001 Society of Chemical Industry     

Natural occurrence of citrinin in rice grains and its biocontrol byTrichoderma hamatum

Paddy rice was sampled from El-Sharkia, El-Gharbia, El-Dakahlia and Kafr El-Shekh governorates, Egypt. Of the 30 samples taken, ten were contaminated with the mycotoxin citrinin. An average of 6.79 × 10⁴ fungal spores per gram rice was found. The isolated fungi represented 47 species and 28 genera. The predominant genera wereAspergillus, Cladosporium andPenicillium. Aspergilli were represented by 22 species;Aspergillus niger andA. flavus had the highest occurrence.Penicillium viridicatum produced the highest amount of citrinin on glucose ammonium nitrate salts broth and rice grains, and hence this isolate was selected as a good producer of citrinin in this study. The presence ofTrichoderma hamatum reduced the amount of citrinin produced byP. viridicatum compared with its respective control. The excessive growth ofT. hamatum onP. viridicatum was increased with time. Viability ofP. viridicatum conidia decreased byT. hamatum with an increase in the incubation period. Chitinases and 1,3-β-glucanase enzyme activity ofT. hamatum increased with extending the incubation period onP. viridicatum mycelia up to maximum values at 72 and 84 h, respectively.T. hamatum led to a decrease in the production of citrinin byP. viridicatum on rice grains compared with the respective control values. http://www.phytoparasitica.org posting Dec. 19, 2004.     

海洋青霉T03对4种热带植物病原真菌的拮抗作用

T03是从多个海洋青霉菌株中筛选出的对植物病原真菌有拮抗作用的一个菌株。采用对峙培养和无菌发酵液抑制菌丝生长方法比较了T03对4种热带植物病原菌香蕉炭疽菌、橡胶炭疽菌、粉蕉镰刀菌、凤梨镰刀菌的拮抗作用。结果显示青霉T03对香蕉炭疽菌、橡胶炭疽菌、粉蕉镰刀菌、凤梨镰刀菌均有一定的拮抗作用,其中对香蕉炭疽菌菌丝生长的抑制作用最好,EC50为17.1%;其次是橡胶炭疽菌,EC50为49.6%。对粉蕉镰刀菌、凤梨镰刀菌菌丝生长的抑制效果不理想。     

Enhancement of Postharvest Disease Resistance in Ya Li Pear (Pyrus bretschneideri) Fruit by Salicylic Acid Sprays on the Trees during Fruit Growth

The Ya Li pear (Pyrus bretschneideri) trees were sprayed three times with 2.5 mM salicylic acid (SA) around 30, 60 and 90 days after full flowering. The fruit were harvested at commercial maturity (about 120 days after full flowering), inoculated with Penicillium expansum, and incubated at 20 °C, 95–100% RH. The results showed that resistance to the pathogen of the mature pear fruit was remarkably enhanced by the SA sprays. Disease incidence in the SA-treated fruit was 58.0% or 26.5%, and lesion diameter on SA-treated fruit was 58.4% or 29.0% lower than that in/on fruit without SA treatment (control) on day 12 or 17 after incubation, respectively. The SA spray applied to the trees around 30 days after full flowering notably enhanced accumulation of hydrogen peroxide in the young fruit. Meanwhile, activities of defense enzymes, including peroxidase, phenylalanine ammonia-lyase (PAL), chitinase or β-1,3-glucanase in the young fruit from SA-treated trees was 29.5%, 60.0%, 24.4% or 35.7% higher than that in the control fruit 4 days after the SA spraying. Furthermore, after harvest, activities of PAL, chitinase and β-1,3-glucanase were still significantly higher in the mature pear fruit from the trees sprayed three times with SA than those of the control fruit. Activities of the antioxidant enzymes including catalase and ascorbate peroxidase in the young fruit were significantly reduced by SA spraying. However, the activity of another antioxidant enzyme, glutathione reductase in the young fruit was significantly enhanced by SA spraying. These results suggest that enzymes exerting their functions in different ways may be coordinately regulated by SA in the pear fruit. Our study indicates that treatment of SA sprays on the trees may provide further protection against postharvest disease of Ya Li pear fruit in practice and could be used as an alternative and economical approach to reduce application of chemical fungicides.     

Cytotoxic Indole-Diterpenoids from the Marine-Derived Fungus Penicillium sp. KFD28

Four new indole-diterpenoids, named penerpenes K-N (1–4), along with twelve known ones (5–16), were isolated from the fermentation broth produced by adding L-tryptophan to the culture medium of the marine-derived fungus Penicillium sp. KFD28. The structures of the new compounds were elucidated extensively by 1D and 2D NMR, HRESIMS data spectroscopic analyses and ECD calculations. Compound 4 represents the second example of paxilline-type indole diterpene bearing a 1,3-dioxepane ring. Three compounds (4, 9, and 15) were cytotoxic to cancer cell lines, of which compound 9 was the most active and showed cytotoxic activity against the human liver cancer cell line BeL-7402 with an IC₅₀ value of 5.3 μM. Moreover, six compounds (5, 7, 10, 12, 14, and 15) showed antibacterial activities against Staphylococcus aureus ATCC 6538 and Bacillus subtilis ATCC 6633.     

Structure Revision and Protein Tyrosine Phosphatase Inhibitory Activity of Drazepinone

From the marine-derived fungus Penicillium sumatrense (Trichocomaceae), a pair of enantiomers [(+)-1 and (−)-1] were isolated with identical 1D NMR data to drazepinone, which was originally reported to have a trisubstituted naphthofuroazepinone skeleton. In this study, we confirmed the structures of the two enantiomers as drazepinone and revised their structures by detailed analysis of extensive 2D NMR data and a comparison of the calculated ¹³C chemical shifts, ECD, VCD, and ORD spectra with those of the experiment ones. (+)-1 and (−)-1 were evaluated for their PTP inhibitory activity in vitro. (−)-1 showed selective PTP inhibitory activity against PTP1B and TCPTP with IC₅₀ values of 1.56 and 12.5 μg/mL, respectively.