Search Results
Chickpea (Cicer arietinum) seeds treated with powdered preparation of Gliocladium virens (Gv) alone @ 3 g/kg seed or in combination with vitavax (0.1%) showed colonization of G. virens on seed coat, collar region, plumule and radicle. Microscopic examination revealed that colonization of seed with mycelia and spores of antagonist started 24 h after incubation. Major portion of the seedling was covered with in 48 hrs. Population dynamics of G. virens monitored at different time intervals in spermosphere, rhizosphere and non-rhizosphere region in pathogen infested and non-infested soil using Trichoderma Selective Medium showed that population of G. virens increased initially up to 30 days and then gradually declined. The highest population was observed in spermosphere (7 x 105/g) followed by rhizosphere (6.3 x 104/g), when seeds treated with Gv + vitavax were sown in pathogen infested soil.
Effects of three antagonistic fungi ( Paecilomyces lilacinus, Pochonia chlamydosporia , and Trichoderma harzianum ) alone and together with wastes materials (saw dust and neem leaf litter) and urea were studied on the growth of tomato and on the reproduction of Meloidogyne incognita in glass house experiments. Individually neem leaf litter was better in improving growth of plants without nematodes compared with any other single treatment. However, use of P. lilacinus against plants with M. incognita caused higher increase in plant growth than caused by P. chlamydosporia / T. harzianum or urea but similar to that caused by neem leaf litter or saw dust. Maximum increase in the growth of nematode inoculated plants was observed when P. lilacinus was used with neem leaf litter. P. lilacinus caused higher reduction in galling and nematode multiplication followed by P. chlamydosporia , neem leaf litter, urea, T. harzianum and saw dust. Maximum reduction in galling and nematode multiplication was observed when P. lilacinus was used with neem leaf litter.
Surveys were carried out in the 11 major wine regions of Hungary from 2003 to 2005 to identify pathogenic grapevine wood fungi. Occurrence of the disease in vineyards younger than 12 years, was studied separately. Sixty-six percent of the vineyards were free, thus symptoms of early decline were present in 34% of the plantations with 0,3–2,6% incidences. All vineyards over 12 years were affected by esca and early decline pathogens. Several fungi were consistently associated with these symptoms: The most frequently isolated species from older stocks were Fomitiporia sp., Phaeomoniella chlamydospora, Phomopsis viticola, Botryosphaeria sp. and Eutypa lata . On younger, 2–4-year-old plants, mostly Phaeomoniella chlamydospora, Phaeoacremonium sp., Cylindrocarpon sp. and Fomitiporia sp.occurred. Several associated species were identified on the declining stocks: Fusarium spp., Penicillium spp., Alternaria alternata, Aspergillus spp., Trichoderma spp., Verticillium spp., Pestalozzia pezizoides and Monochaetia viticola .
Harman G.E.: 2000. Myths and dogmas of Biocontrol. Changes in Perceptions Derived from Research on Trichoderma harzianum T-22. — Plant Disease vol.84 no.4 377–393 pp. Harman G
In this study, we analyzed the expression of the structural genes encoding the five enzymes comprising the Leloir pathway of D-galactose catabolism in the industrial cell factory Penicillium chrysogenum on various carbon sources. The genome of P. chrysogenum contains a putative galactokinase gene at the annotated locus Pc13g10140, the product of which shows strong structural similarity to yeast galactokinase that was expressed on lactose and D-galactose only. The expression profile of the galactose-1-phosphate uridylyl transferase gene at annotated locus Pc15g00140 was essentially similar to that of galactokinase. This is in contrast to the results from other fungi such as Aspergillus nidulans, Trichoderma reesei and A. niger, where the ortholog galactokinase and galactose-1-phosphate uridylyl transferase genes were constitutively expressed. As for the UDP-galactose-4-epimerase encoding gene, five candidates were identified. We could not detect Pc16g12790, Pc21g12170 and Pc20g06140 expression on any of the carbon sources tested, while for the other two loci (Pc21g10370 and Pc18g01080) transcripts were clearly observed under all tested conditions. Like the 4-epimerase specified at locus Pc21g10370, the other two structural Leloir pathway genes – UDP-glucose pyrophosphorylase (Pc21g12790) and phosphoglucomutase (Pc18g01390) – were expressed constitutively at high levels as can be expected from their indispensable function in fungal cell wall formation.
In the process of making ethanol from lignocellulosics, enzyme production is still the most crucial and costly step. Trichoderma reesei Rut C-30 is the best known cellulase producer. This fungus is very good in endo- and exoglucanase production, however, the amount of β-glucosidase excreted is not sufficient for hydrolysis. In addition, T. reesei Rut C-30 is sensitive to inhibitors generated during steam-pretreatment of wood. In the present study, two good cellulase producers were selected from 16 fungal strains and investigated regarding filter paper activity (FPU) and β-glucosidase activity using inexpensive lignocellulosic carbon sources for cultivation. T. reesei Rut C-30 proved to be a good cellulase producer, resulting in a maximum FPU of 1.39 FPU ml &1 on washed, steam-pretreated willow, but the β-glucosidase activity was insufficient. High β-glucosidase activities were reached with T. viride OKI B1 on all substrates, with a maximum activity of 1.62 IU ml &1 on steam-pretreated spruce.
A Bacillus thuringiensis cry1Ab endotoxint termelő transzgénikus kukorica (DK440BTY) és izogénes, toxint nem termelő kukorica (DK440) rizoszféráját jellemeztük talajbiológiai eszközökkel, illetve összehasonlító értékelést végeztünk egy vegetációs periódus három mintavételi időszakában. Telepszámlálásos módszerrel meghatároztuk néhány kitenyészthető mikrobacsoport (heterotrófok, oligotrófok, spórás mikrooganizmusok, szabadon élő N2-kötők és mikroszkopikus gombák) csíraszámát a rizoszféra talajában. Elvégeztük a mikrobiális össz-aktivitás vizsgálatát fluoreszcein-diacetát (FDA) hidrolízisének mérésével, illetve nyomon követtük a gyökérrendszer szimbiotikus struktúráinak, azaz az arbuszkuláris mikorrhiza gombák kolonizációjának a működőképességét is. A rizoszférához szorosan kapcsolódó talajrészben a szabadon élő szaprotróf Trichoderma gombák faji diverzitásának az alakulását ellenőriztük. Megállapítottuk, hogy a belső rizoszféra (endoriza) mikroszimbiontás kolonizációja az első mintavétel során (2001. június) szignifikánsan kisebb aktivitást mutatott, és csökkent a gomba működőképességét jelző arbuszkulumok mennyisége is. A további mintavételek során (2001. augusztus és október) azonban ezek a különbségek nem jelentkeztek, a szimbiózis működőképessége helyreállt. A varianciaanalízis azonban összesített hatásban szignifikáns különbséget jelzett. A gyökérfelszín kitenyészthető mikrobacsoportjainak csíraszámában nem adódott statisztikailag igazolható különbség a kétféle növény között. Az FDA módszerrel kimutatható össz-mikrobiális aktivitást ugyanakkor mindegyik mintavételnél nagyobbnak találtuk a Bt-kukorica rizoszférájában, amiből a fiziológiai tulajdonságok megváltozására következtettünk. A transzgénikus növény gyökérhatásának távolabbi részén, a külső rizoszférában a Trichodema gombák száma és faji összetétele csak szezonális változásokat mutatott, de nem különbözött szignifikánsan a génmódosított növénynél. Eredményeink jelzik a génmódosítás közvetett hatását a rizoszférában található „nem célzott” szervezetek összetételére vagy aktivitására, és felhívják a figyelmet a további, tartamjellegű vizsgálatok szükségességére is.
Proteases constitute a significant part of cell wall-degrading enzymes (CWDEs) produced by fungal biocontrol agents and particularly crucial in mycoparasitism of fungal phytopathogens. Plate-based screening methods are routinely used for screening protease-producing microorganisms including fungi. Skim milk agar (SMA) is one of the most popular media for the detection of protease producing bacteria. However, SMA is not efficient to test fast growing fungi, because it does not give an estimation of the actual amount of secreted protease produced by fungal inocula. In the current study, the efficacy of two modified plate-screening methods, including split-SMA (SSMA) and minimal medium supplemented with skim milk (MSMW) was assessed for detection of protease production by three representative fungal strains including Trichoderma longibrachiatum strain N, Beauveria bassiana strain B and Purpureocillium lilacinum strain PL. Protease production was revealed on the three tested media by the three strains. However, the halo diameter of the fungal strains (a proxy for protease production) was the smallest on SMA. Furthermore, protease production could not be detected for T. longibrachiatum strain N on SMA due to its fast growth; while it showed the highest protease activity on both modified media compared with the other strains. According to the result of this study, the SSMA medium is an easy and more accurate method compared with the two other different methods as it displays the actual amount of protease produced by fungal strains and therefore this method is recommended for quantitative and qualitative detection of protease production by slow and fast growing fungi.
Seed extracts of 50 plant species belonging to different families were evaluated for their ability to inhibit growth of Trichoderma viride in vitro. Of the various seed extracts, the seed extracts of Harpullia cupanioides (Roxb) belonging to Sapindaceae family exhibited very high antifungal activity. The seed extract of H. cupanioides strongly inhibited the growth of Rhizoctonia solani, Curvularia lunata, Colletotrichum musae and Alternaria alternata. Seed extract of H. cupanioides retained its antifungal activity even after heating at 100 °C for 10 min or autoclaving at 121 °C for 20 min. For partial purification of antifungal proteins, H. cupanioides seed extract was subjected to ammonium sulphate fractionation followed by gel filtration on Sephadex G-200 column. The fractions from sephadex G-200 were individually tested for their antifungal activity against T. viride. SDS-PAGE analysis of the fractions from Sephadex-G200 column indicated that the fractions with antifungal activity contained a 68-kDa band as well as other low molecular weight protein bands. The N-terminal amino acid sequence of the 68-kDa protein (13 residues) was determined by Edman degradation. However, comparison with sequences in the GenBank database (Swiss Prot) did not reveal any homology with known protein sequences.
Five isolates of Trichoderma viride, Pseudomonas fluorescens and four isolates of Bacillus subtilis were evaluated for their ability to control Rhizoctonia solani, the causal agent of stem and stolon rot of peppermint (Mentha piperita Lin.). Of the various isolates of T. viride, P. fluorescens and B. subtilis tested, TVUV10, PFMMP and BSG3 showed the maximum inhibition of mycelial growth of R. solani. Among these isolates, P. fluorescens, PFMMP recorded the highest inhibition zone against R. solani in vitro and was very effective in reducing disease incidence in greenhouse condition. The effective isolates were evaluated for their ability to induce defense related enzymes and chemicals in plants. Increased activity of phenylalanine ammonia lyase (PAL), peroxidase (PO), polyphenoloxidase (PPO) and total phenolics were recorded in the biocontrol agents pretreated peppermint plants challenged with R. solani. P. fluorescens isolate PFMMP recorded early and increased synthesis of all defense related enzymes and total phenol. Thus, the present study shows that application of biocontrol agents; induce defense related enzymes involved in phenyl propanoid pathway in addition to direct antagonism which collectively contribute for enhanced resistance against invasion of R. solani in M. piperita.
