Responses of alfalfa pollen and callus to filtrates from two isolates of Fusarium oxysporum

Summary For 25 Medicago sativa plants, measurements were made of in vitro pollen germination and growth and callus growth on mediums containing culture filtrate from two isolates of Fusarium oxysporum f. sp. medicaginis. In vivo resistance was determined by field inoculation with one isolate. There was no correlation between any in vitro measurement and in vivo resistance, and none of the in vitro measurements on control mediums were correlated. The only significant correlation for the same measurement between the two isolates was for pollen-tube length (r = 0.65). Percent of pollen germination was negatively correlated with callus growth for both isolates. Earlier work showed that callus growth in the presence of culture filtrate was linked to plant resistance, thus it appeared that percent pollen germination on culture filtrate had decreased for the more resistant plants. The haploid pollen may be used as a progeny test for identifying heterotic loci conferring resistance to Fusarium, but if the pollen of this plant species is used in direct selection by exposure to culture filtrate, the level of resistance to Fusarium may decrease.     

Transesterification catalyzed by polystyrene-supported chymotrypsin in toluene: the effect of neutralization of basic or acidic groups attaching to polystyrene resins

Crosslinked polystyrene resins containing a low level of either basic or acidic groups were used for supports of alpha-chymotrypsin (CT), which catalyzed the transesterification of N-acetyl-L-phenylalanine ethyl ester (AcPheOEt) with propanol in toluene. With a minimal amount of water, CT was sorbed to the resins, basic or acidic groups of which were partly or fully neutralized by several soluble acids or bases. With an increasing degree of neutralization of basic resins by free acids, the rate of disappearance of AcPheOEt was decreased, whereas the by-product formation of AcPheOH, due to hydrolysis, was considerably suppressed, compared with the ester-exchange product, AcPheOPr. The pK(a) value of the neutralizing acid was also important for both CT activity and reaction selectivity. AcPheOPr was selectively produced at a certain range of pK(a) values. On the other hand, the neutralization of acidic resins with free amines enhanced the CT activity but a strong base promoted the formation of hydrolysis product. (c) 1995 John Wiley & Sons, Inc.     

Nematicidal activity of Lysobacter capsici YS1215 and the role of gelatinolytic proteins against root-knot nematodes

Lysobacter capsici YS1215 is a soil-borne strain that could inhibit the growth of phytopathogenic fungi, including Phytophthora capsici, Rhizoctonia solani and Fusarium oxysporum, as well as root-knot nematodes. The effect of different concentrations of bacterial culture filtrate (BCF) of L. capsici YS1215 on the mortality of second-stage juveniles (J2) of Meloidogyne incognita was studied using 24-well plates. The J2 mortality increased with increasing concentrations of BCF. YS1215 also produces gelatinases in the culture filtrate. To study its role in nematicidal activities, the partial purification and the characterisation of gelatinolytic proteins were done from the culture medium of the YS1215. The partially purified proteins showed three clear bands with molecular weights estimated using zymography to be 255.7, 232.1 and 146.4 kDa. The optimal pH and temperature for the proteins were 8.0 and 40°C, respectively. The activity of the proteins was inhibited by ethylenediaminetetraacetic acid, FeCl₃ and 1,10-phenanthroline, whereas it was activated by MnCl₂. The proteins may belong to the group of metalloproteases. Moreover, the proteins could hydrolyse skimmed milk, collagen, gelatin and bovine serum albumin (BSA) as substrates, but not casein. The proteins could induce 75% J2 mortality in five days and degrade the J2 bodies. The present study demonstrates the role of the gelatinolytic proteins in the nematicidal potential of L. capsici YS1215.     

The plant growth-promoting fungus Penicillium simplicissimum GP17-2 induces resistance in Arabidopsis thaliana by activation of multiple defense signals

Arabidopsis thaliana grown in soil amended with barley grain inocula of Penicillium simplicissimum GP17-2 or receiving root treatment with its culture filtrate (CF) exhibited clear resistance to Pseudomonas syringae pv. tomato DC3000 (Pst). To assess the contribution of different defense pathways, Arabidopsis genotypes implicated in salicylic acid (SA) signaling expressing the NahG transgene or carrying disruption in NPR1 (npr1), jasmonic acid (JA) signaling (jar1) and ethylene (ET) signaling (ein2) were tested. All genotypes screened were protected by GP17-2 or its CF. However, the level of protection was significantly lower in NahG and npr1 plants than it was in similarly treated wild-type plants, indicating that the SA signaling pathway makes a minor contribution to the GP17-2-mediated resistance and is insufficient for a full response. Examination of local and systemic gene expression revealed that GP17-2 and its CF modulate the expression of genes involved in both the SA and JA/ET signaling pathways. Subsequent challenge of GP17-2-colonized plants with Pst was accompanied by direct activation of SA-inducible PR-2 and PR-5 genes as well as potentiated expression of the JA-inducible Vsp gene. In contrast, CF-treated plants infected with Pst exhibited elevated expression of most defense-related genes (PR-1, PR-2, PR-5, PDF1.2 and Hel) studied. Moreover, an initial elevation of SA responses was followed by late induction of JA responses during Pst infection of induced systemic resistance (ISR)-expressing plants. In conclusion, we hypothesize the involvement of multiple defense mechanisms leading to an ISR of Arabidopsis by GP17-2.     

食药用菌酸乳制作中深层发酵滤液添加量的比较

利用深层发酵培养基对两种食药用菌（香菇、猴头菌）进行深层发酵培养,然后分别将香菇（猴头菌）发酵滤液、奶粉、无菌水按不同比例配制成相应的复原奶,并接种乳酸菌制成酸乳。同时检测不同比例发酵滤液添加量所制得的酸乳的营养和理化特性,选择出了最佳比例的滤液添加量,即香菇滤液添加量以3份较好,而猴头菌则以4份滤液添加量最佳。     

Identification of proteins of potential diagnostic value for bovine paratuberculosis

Previously we showed that Mycobacterium paratuberculosis culture filtrates (CFs) contain more antigens that react with sera from infected cattle than do cellular extracts of the organism. The goal of the present study was to identify proteins of potential diagnostic value among these CF proteins. Proteins of potential interest were first separated by 2-DE. Roughly 240 CF protein spots were detected on CBB-stained gels using Phoretix 2D software. Of these, 83% reacted with serum from M. paratuberculosis-infected cattle in immunoblots. When bovine serum was absorbed with M. phlei antigens, however, only 37 of these antigenic protein spots were reactive. Twenty-four of these spots were selected for identification based on their immunoblot staining intensity and differences in pI and mass. A total of 14 proteins were ultimately identified by MS and BLAST searches as ModD, PepA, ArgJ, CobT, Antigen 85C, and nine hypothetical proteins. N-terminal peptide analysis of PepA, Antigen 85C, ModD, MAP1693c, MAP2168c, and MAP1022c showed that each protein has 27-39 amino acids that may function as a signal sequence suggesting they are secreted through a Sec-dependent pathway. These 14 proteins from M. paratuberculosis CF are strong candidates for use as antigens for improved serodiagnostic tests for bovine paratuberculosis.     

<Emphasis Type="Italic">In vitro</Emphasis> selection and regeneration of chrysanthemum (<Emphasis Type="Italic">Dendranthema grandiflorum</Emphasis> Tzelev) plants resistant to culture filtrate of <Emphasis Type="Italic">Septoria obesa</Emphasis> Syd

Callus cultures derived from leaf segments of chrysanthemum cultivar ‘Snow Ball’ which was susceptible to Septoria obesa were successfully used for in vitro selection for resistance to this pathogenic fungus. Resistant cell lines were selected by culturing callus on growth medium containing various concentrations of S. obesa filtrate. Resistant calluses obtained after two cycles (30 d each cycle) of selection were used for plant regeneration. About 30% of the plants regenerated from the resistant calluses and 70–80% of the plants raised from cuttings had acquired considerable resistance against the pathogen in the field. No phenotypic variation was observed in the selected regenerates.     

In vitro selection at cellular level for red rot resistance in sugarcane (<Emphasis Type="Italic">Saccharum</Emphasis> sp.)

In the present study, in vitro selection technique using pathogen culture filtrate of Colletotrichum falcatum Went was employed with the aim to identify associations (if any), between selection at the cellular and plant level for red rot resistance in sugarcane (Saccharum sp.). Five to eight months old sugarcane calli of genotypes CoJ 88 and CoJ 64 were screened in vitro against pathogen culture filtrate for two selection cycles. Effect of pathogen culture filtrate on callus survival and/or proliferation was observed to be directly related to its concentration in the selection media. Calli survived and exhibited further proliferation at 5, 10 and 15% v/v pathogen culture filtrate concentrations whereas, at higher concentrations (20 and 25% v/v) proliferation was completely inhibited. Shoot regeneration percent was higher in calli selected on 5% pathogen culture filtrate concentration than those selected on 10 and 15% concentrations. In vivo screening of field transferred somaclones against two pathtypes (Cf 03 and Cf 08) showed considerable variation for red rot resistance. Somaclones regenerated from resistant and/or tolerant calli exhibited better resistance than the parental genotypes. The results indicated that in vitro selection for red rot resistance was effective and expressed when somaclones were screened in the field. This indicated a positive association between in vitro and in vivo methods of selection for disease resistance in sugarcane.     

Evaluation of Pochonia chlamydosporia var. chlamydosporia as a control agent of Meloidogyne javanica on pistachio

The potential of isolates of Pochonia chlamydosporia var. chlamydosporia as biocontrol agents for root-knot nematodes was investigated in vitro and on pistachio plants. On potato dextrose agar, growth of all isolates started at temperatures above 10°C, reached maximum between 25 and 28°C and slowed down at 33°C. On water agar, all isolates parasitized more than 85% of the eggs of Meloidogyne javanica at 18°C after 3 weeks. Filtrates of isolates grown on malt extract broth did not cause more than 5% mortality on second-stage juveniles of M. javanica after 48 h of incubation. A single application of 10×10³ chlamydospores (produced on sand–barley medium) g^–1 soil, was applied to unsterilised soil planted with pistachio cv. Kalehghochi, and plants were inoculated with 3000 nematode eggs. After 120 days in the glasshouse, nematode multiplication and damage were measured. Ability of fungus isolates to survive in the soil and to grow on roots were estimated by counting colony forming units (cfu) on semi-selective medium. Fungal abundance in soil increased nearly 3-fold and 10×10³ and 20×10³ cfu g^–1 root of pistachio were estimated in pots treated with isolates 40 and 50, respectively. Strain 50 was more abundant in soil and on the roots, infected more eggs (40%) on the roots and controlled 56% of total population of M. javanica on pistachio roots, whereas isolate 40 parasitized 15% of the eggs on the roots and controlled ca. 36% of the final nematode population.     

乳酸杆菌发酵滤液对人宫颈癌细胞株Hela细胞的抑制作用

目的观察乳酸杆菌DM9811发酵滤液及其主要成分对宫颈癌细胞株Hela细胞的体外增殖的影响,探索乳酸杆菌发酵滤液对宫颈癌细胞是否有抑制作用及解析作用的有效成分。方法用MTr法研究不同浓度乳酸杆菌DM9811发酵滤液在不同时间对Hela细胞的抑制作用,在此基础上研究脂肪酸、菌体核酸在不同时间对Hela细胞的抑制作用。结果不同浓度乳酸杆菌DM9811发酵滤液及相关物质在不同时间对Hela细胞的抑制作用显示：（1）乳酸杆菌DM9811发酵滤液各浓度组对Hela细胞的生长均有抑制作用,且这种抑制作用呈剂量-时间依赖方式。24、48、72h达到半数抑制率的发酵滤液浓度分别为8．9％、5．3％、3．8％。（2）乳酸杆菌DM9811发酵滤液脂肪酸对Hela细胞的生长有一定抑制作用,抑制率在7．0％～34．0％。（3）乳酸杆菌DM9811菌体核酸对Hela细胞的生长有抑制作用,抑制率为9．7％-53．4％,呈剂量一时间依赖方式。72h达到半数抑制率核酸的浓度为5．5μg/ml。结论乳酸杆菌DM9811发酵滤液对Hela细胞的生长具有显著的抑制作用,其中脂肪酸组分是有效成分之一。