[ Objective ] This study aimed to confirm the roles of cell wall degrading enzymes （CWDEs） produced by Botryodiplodia theobromae Pat. in the infec- tion of mango fruits. [ Method] Change of activities of five types ...[ Objective ] This study aimed to confirm the roles of cell wall degrading enzymes （CWDEs） produced by Botryodiplodia theobromae Pat. in the infec- tion of mango fruits. [ Method] Change of activities of five types of CWDEs produced by B. theobromae Pat. were studied under both in vitro culture and inocula- tion conditions, along with the pathogenicity and the ability of producing CWDEs of four post-harvest fangal pathogens（B, theobromae Pat. , Colletotrichum gloeos- porioides Penz. , Phomopsis mangiferae Ahmad and Dothiorella dominicana Pet. et Cif. ） which cause stem-end rot of mangoes. [ Result] B. theobromae Pat. was a- ble to produce polygalacturonase（PG）, pectinmethylgalacturonase（PMG）, polygalacturonic acid trans-eliminase （PGTE）, pectin methyltrans-eliminase （PMTE） and cellulase （ Cx. ） under both in vitro culture and inoculation conditions, of which activities of PG, Cx and PMG were significantly higher in than that in either PGTE or PMTE. Among three primary CWDEs, the peak of activities of PG and Cx appeared earlier and that of PMG occured later. The pathogenicity of B. theo- bromae Pat. was significantly higher than that of any other three pathogens; it is the same with the abilities of producing pectinase. [ Conclusion] This paper pro- vides theoretical bases for further exploring the mechanism of host-pathogen interaction and decreasing the post-harvest loss of mango fruits.展开更多
Species of the fungus Trichoderma, a genus of Hyphomycetes, are ubiquitous in the environment, but especially in soil. They have been used in a wide range of commercial applications including the production of hydrola...Species of the fungus Trichoderma, a genus of Hyphomycetes, are ubiquitous in the environment, but especially in soil. They have been used in a wide range of commercial applications including the production of hydrolases and in the biological control of plant diseases. A fundamental part of the Trichoderma antifungal system consists of a series of genes coding for a surprising variety of extracellular cell wall degrading enzymes (CWDE). Characterisation and identification of strains at the species level is the first step in utilizing the full potential of fungi in specific applications. One aim when isolating Trichoderma strains is to identify those which can be used in new agricultural and industrial applications. In the past it was not uncommon that biocontrol strains were defined as T. harzianum Rifai, due to the limited classification system of the genus Trichoderma. In recent years, several PCR-based molecular techniques have been used to detect and discriminate among microorganisms. Sequence analysis of the ITS regions of the ribosomal DNA and gene fragments as those corresponding to tef1 gene have been helpful in the neotypification, description and characterization of species in the genus Trichoderma. Another useful method for the identification of Trichoderma strains is the randomly amplified polymorphic DNA (RAPD) technique. Isozyme polymorphisms evaluation of five putative extracellular lytic enzymes loci (β-1,3-glucanase, β-1,6-glucanase, cellulase, chitinase and protease antivities) were carried out using representative strains of defined molecular groups. CWDE groupings obtained from biocontrol strains are discussed in relation to their phylogenetic location and antifungal activities. Compiling morphological, biochemical and sequence information data into a common database would provide a useful resource that could be used to accurately name new haplotypes identified in the future and correctly place them within the genus Trichoderma.展开更多
In order to understand the pathogenic mechanisms of Sclerotium rolfsii on peanut and to analyze the variation of virulence in S.rolfsii strains,the highly virulent strain(ZY2)and weakly virulent strain(GP3-1)were inve...In order to understand the pathogenic mechanisms of Sclerotium rolfsii on peanut and to analyze the variation of virulence in S.rolfsii strains,the highly virulent strain(ZY2)and weakly virulent strain(GP3-1)were investigated under both in vivo and in vitro conditions.The results indicated that S.rolfsii directly infected peanut by producing infection cushions.ZY2 formed infection cushions earlier than GP3-1,and ZY2 produced a greater number of infection cushions compare to GP3-1.Both strains could utilize cellulose,xylose,or polygalacturonic acid in the Czapek medium.The activities of cellulase(CL)and polygalacturonase(PG)in the inoculated peanut stems increased significantly at 9 h after inoculation.The activities of CL and PG produced by ZY2 in the inoculated stems were significantly higher than that produced by GP3-1.Both strains could produce oxalic acid(OA),and the content of OA produced by ZY2 in the inoculated stems was higher than that produced by GP3-1.In summary,it suggested that S.rolfsii destroyed peanut cells through physical and biochemical factors by secreting a large amount of OA,CL and PG during the formation of infection cushions.The difference in OA content,activity of CL and PG produced by highly and weakly virulent strains played important roles in variation of virulence.展开更多
Green macroalgae,e.g.,Ulva lactuca,are valuable bioactive sources of nutrients;but algae recalcitrant cell walls,composed of a complex cross-linked matrix of polysaccharides,can compromise their utilization as feedstu...Green macroalgae,e.g.,Ulva lactuca,are valuable bioactive sources of nutrients;but algae recalcitrant cell walls,composed of a complex cross-linked matrix of polysaccharides,can compromise their utilization as feedstuffs for monogastric animals.This study aimed to evaluate the ability of pre-selected Carbohydrate-Active enZymes(CAZymes)and sulfatases to degrade U.lactuca cell walls and release nutritive compounds.A databank of 199 recombinant CAZymes and sulfatases was tested in vitro for their action towards U.lactuca cell wall polysaccharides.The enzymes were incubated with the macroalga,either alone or in combination,to release reducing sugars and decrease fluorescence intensity of Calcofluor White stained cell walls.The individual action of a polysaccharide lyase family 25(PL25),an ulvan lyase,was shown to be the most efficient in cell wall disruption.The ulvan lyase treatment,in triplicate measures,promoted the release of 4.54 g/L(P<0.001)reducing sugars,a mono-and oligosaccharides release of 11.4 and 11.2 mmol/100 g of dried alga(P<0.01),respectively,and a decrease of 41.7%(P<0.001)in cell wall fluorescence,in comparison to control.The ability of ulvan lyase treatment to promote the release of nutritional compounds from alga biomass was also evaluated.A release of some monounsaturated fatty acids was observed,particularly the health beneficial 18:1c9(P<0.001).However,no significant release of total fatty acids(P>0.05),proteins(P?0.861)or pigments(P>0.05)was found.These results highlight the capacity of a single recombinant ulvan lyase(PL25 family)to incompletely disrupt U.lactuca cell walls.This enzyme could enhance the bioaccessibility of U.lactuca bioactive products with promising utilization in the feed industry.展开更多
基金Supported by the Special Fund for Agro-scientific Research(3-44-2)the Special Fund for Basic Research of Central Universities in the Public Interest,China(N0.2009hzs1J011,NO.2011hzs1J027,NO.2011hzs1J004)
文摘[ Objective ] This study aimed to confirm the roles of cell wall degrading enzymes （CWDEs） produced by Botryodiplodia theobromae Pat. in the infec- tion of mango fruits. [ Method] Change of activities of five types of CWDEs produced by B. theobromae Pat. were studied under both in vitro culture and inocula- tion conditions, along with the pathogenicity and the ability of producing CWDEs of four post-harvest fangal pathogens（B, theobromae Pat. , Colletotrichum gloeos- porioides Penz. , Phomopsis mangiferae Ahmad and Dothiorella dominicana Pet. et Cif. ） which cause stem-end rot of mangoes. [ Result] B. theobromae Pat. was a- ble to produce polygalacturonase（PG）, pectinmethylgalacturonase（PMG）, polygalacturonic acid trans-eliminase （PGTE）, pectin methyltrans-eliminase （PMTE） and cellulase （ Cx. ） under both in vitro culture and inoculation conditions, of which activities of PG, Cx and PMG were significantly higher in than that in either PGTE or PMTE. Among three primary CWDEs, the peak of activities of PG and Cx appeared earlier and that of PMG occured later. The pathogenicity of B. theo- bromae Pat. was significantly higher than that of any other three pathogens; it is the same with the abilities of producing pectinase. [ Conclusion] This paper pro- vides theoretical bases for further exploring the mechanism of host-pathogen interaction and decreasing the post-harvest loss of mango fruits.
文摘Species of the fungus Trichoderma, a genus of Hyphomycetes, are ubiquitous in the environment, but especially in soil. They have been used in a wide range of commercial applications including the production of hydrolases and in the biological control of plant diseases. A fundamental part of the Trichoderma antifungal system consists of a series of genes coding for a surprising variety of extracellular cell wall degrading enzymes (CWDE). Characterisation and identification of strains at the species level is the first step in utilizing the full potential of fungi in specific applications. One aim when isolating Trichoderma strains is to identify those which can be used in new agricultural and industrial applications. In the past it was not uncommon that biocontrol strains were defined as T. harzianum Rifai, due to the limited classification system of the genus Trichoderma. In recent years, several PCR-based molecular techniques have been used to detect and discriminate among microorganisms. Sequence analysis of the ITS regions of the ribosomal DNA and gene fragments as those corresponding to tef1 gene have been helpful in the neotypification, description and characterization of species in the genus Trichoderma. Another useful method for the identification of Trichoderma strains is the randomly amplified polymorphic DNA (RAPD) technique. Isozyme polymorphisms evaluation of five putative extracellular lytic enzymes loci (β-1,3-glucanase, β-1,6-glucanase, cellulase, chitinase and protease antivities) were carried out using representative strains of defined molecular groups. CWDE groupings obtained from biocontrol strains are discussed in relation to their phylogenetic location and antifungal activities. Compiling morphological, biochemical and sequence information data into a common database would provide a useful resource that could be used to accurately name new haplotypes identified in the future and correctly place them within the genus Trichoderma.
基金supported by Central Public-interest Scientific Institution Basal Research Fund (1610172021003)Supported by the earmarked fund for CARS-13Key Area Research and Development Program of Hubei Province (2021BBA077)
文摘In order to understand the pathogenic mechanisms of Sclerotium rolfsii on peanut and to analyze the variation of virulence in S.rolfsii strains,the highly virulent strain(ZY2)and weakly virulent strain(GP3-1)were investigated under both in vivo and in vitro conditions.The results indicated that S.rolfsii directly infected peanut by producing infection cushions.ZY2 formed infection cushions earlier than GP3-1,and ZY2 produced a greater number of infection cushions compare to GP3-1.Both strains could utilize cellulose,xylose,or polygalacturonic acid in the Czapek medium.The activities of cellulase(CL)and polygalacturonase(PG)in the inoculated peanut stems increased significantly at 9 h after inoculation.The activities of CL and PG produced by ZY2 in the inoculated stems were significantly higher than that produced by GP3-1.Both strains could produce oxalic acid(OA),and the content of OA produced by ZY2 in the inoculated stems was higher than that produced by GP3-1.In summary,it suggested that S.rolfsii destroyed peanut cells through physical and biochemical factors by secreting a large amount of OA,CL and PG during the formation of infection cushions.The difference in OA content,activity of CL and PG produced by highly and weakly virulent strains played important roles in variation of virulence.
基金Fundaçao para a Ciencia e Tecnologia(FCT,Lisbon,Portugal)through grant PTDC/CAL-ZOO/30238/2017 associated post-doc contract to MMC,CIISA(Project UIDB/00276/2020)a PhD fellowship to DFC(SFRH/BD/126198/2016).
文摘Green macroalgae,e.g.,Ulva lactuca,are valuable bioactive sources of nutrients;but algae recalcitrant cell walls,composed of a complex cross-linked matrix of polysaccharides,can compromise their utilization as feedstuffs for monogastric animals.This study aimed to evaluate the ability of pre-selected Carbohydrate-Active enZymes(CAZymes)and sulfatases to degrade U.lactuca cell walls and release nutritive compounds.A databank of 199 recombinant CAZymes and sulfatases was tested in vitro for their action towards U.lactuca cell wall polysaccharides.The enzymes were incubated with the macroalga,either alone or in combination,to release reducing sugars and decrease fluorescence intensity of Calcofluor White stained cell walls.The individual action of a polysaccharide lyase family 25(PL25),an ulvan lyase,was shown to be the most efficient in cell wall disruption.The ulvan lyase treatment,in triplicate measures,promoted the release of 4.54 g/L(P<0.001)reducing sugars,a mono-and oligosaccharides release of 11.4 and 11.2 mmol/100 g of dried alga(P<0.01),respectively,and a decrease of 41.7%(P<0.001)in cell wall fluorescence,in comparison to control.The ability of ulvan lyase treatment to promote the release of nutritional compounds from alga biomass was also evaluated.A release of some monounsaturated fatty acids was observed,particularly the health beneficial 18:1c9(P<0.001).However,no significant release of total fatty acids(P>0.05),proteins(P?0.861)or pigments(P>0.05)was found.These results highlight the capacity of a single recombinant ulvan lyase(PL25 family)to incompletely disrupt U.lactuca cell walls.This enzyme could enhance the bioaccessibility of U.lactuca bioactive products with promising utilization in the feed industry.
