Various cadmium （Cd） concentrations （0, 50, 100, 200 and 300 μmol L-1） affected Elymus dahuricus seed germination, seed- ling growth, antioxidative enzymes activities （AEA）, and amounts of malondialdehyde （MDA...Various cadmium （Cd） concentrations （0, 50, 100, 200 and 300 μmol L-1） affected Elymus dahuricus seed germination, seed- ling growth, antioxidative enzymes activities （AEA）, and amounts of malondialdehyde （MDA） and proline present. These in- fluences were determined for separate E. dahuricus cohorts known to be either infected （E＋） or non-infected （E-） by a Neo- typhodium endophyte. Under high Cd concentrations （100, 200 and 300 lamol L-l）, E＋ specimens showed a significantly （P〈0.05） higher germination rate and index, as well as higher values for shoot length, root length and dry biomass. However, the germination rate and index, root length and dry weight did not show a significant （P〈0.05） difference under the low Cd concentrations （0 and 50 μmol L^-1）. AEA and proline content increased, as did MDA content, in the E＋ （vs. E-） specimens under high Cd concentrations. There was no significant （P〉0.05） difference under low Cd concentrations. Endophyte infection was concluded to be of benefit to E. dahuricus exposed to high Cd concentrations.展开更多
An evaluation was performed on the influence of mowing height (2.5,5.0 or 7.5 cm) and mowing frequency (weekly or fortnightly) on levels of ergot alkaloids (ergine and ergonovine) formed in drunken horse grass,Achnath...An evaluation was performed on the influence of mowing height (2.5,5.0 or 7.5 cm) and mowing frequency (weekly or fortnightly) on levels of ergot alkaloids (ergine and ergonovine) formed in drunken horse grass,Achnatherum inebrians,grown under greenhouse conditions.Samples were taken monthly and alkaloids were extracted and analyzed by reverse-phase HPLC.Alkaloid levels increased more or less linearly with plant age over the first four months following establishment.Levels were higher in samples cut fortnightly compared to those cut weekly,and were higher when plants were cut at a mowing height of 7.5 cm vs.2.5 cm.In most cases,the highest alkaloid levels observed were almost three times those of the lowest.If plant protection applications are developed for the endophytic fungus,Neotyphodium gansuense,it will be necessary to be aware of the potential role of plant husbandry practices (e.g.,defoliation frequency and intensity) for reducing or enhancing levels of plant alkaloids.Similar husbandry factors may affect alkaloid levels in other Neotyphodium-grass associations,which would be interesting for further study.展开更多
Epichloae endophytes of family Clavicipitaceae(comprising genera Epichloëand Neotyphodium)are fungal symbionts of Pooideae grasses.The associations formed,range from mutually beneficial to antagonistic and the na...Epichloae endophytes of family Clavicipitaceae(comprising genera Epichloëand Neotyphodium)are fungal symbionts of Pooideae grasses.The associations formed,range from mutually beneficial to antagonistic and the nature of this relationship is dependent upon the importance of vertical(via host seeds)versus horizontal(ascospore mediated)transmission of the fungus.These endophytes can enhance their hosts’survival through protection from abiotic and biotic stresses and can thus be utilized in an agricultural context.Animal-safe grass-endophyte associations that confer bio-protective properties for increased pasture persistence and productivity have been developed and commercialized.One of the crucial drivers underpinning the selection of epichloae strains for commercial development is endophyte derived bioactivity.The potential of next generation endophytes is determined by testing a number of attributes such as agronomic fitness,animal and food safety as well as compatibility with host plants of interest.Strategic research supports these activities by focusing on elucidating mechanisms of compatibility between host and fungal symbiont,as well as investigating other molecular drivers of symbiosis such as siderophore mediated iron-uptake,fungal signalling,fungal growth in host plants and fungal secondary metabolism.This review weaves together the different strands of multidisciplinary research aimed at ultimately exploiting epichloae endophytes for increased pasture performance.展开更多
Reactive oxygen species are in all types of organisms from microbes to higher plants and animals.They are by-products of normal metabolism,such as photosynthesis and respiration,and are responsive to abiotic and bioti...Reactive oxygen species are in all types of organisms from microbes to higher plants and animals.They are by-products of normal metabolism,such as photosynthesis and respiration,and are responsive to abiotic and biotic stress.Accumulating evidence suggests reactive oxygen species play a vital role in programmed cell death,stress responses,plant defense against pathogens and systemic stress signaling in conjunction with antioxidant production.Here,we propose that reactive oxygen species and antioxidants,as both universal and evolutionarily conserved,are likely to play important role(s)in symbiotic interactions.To support this hypothesis we review the root and foliar fungal endophyte literature specific to fungal-plant symbiotum production of reactive oxygen species and antioxidants in response to stress.These asymptomatic fungi can produce antioxidants in response to both biotic and abiotic stress when grown in culture as well as in planta.In addition,there is a growing but nascent literature reporting a significant impact of endophyte colonization on the antioxidant activity of colonized(E+)hosts when compared to uncolonized(E-)hosts,especially when exposed to stress.Here we summarize general patterns emerging from the growing literature specific to antioxidant activity of endophytes in colonized hosts and bring up possible future research questions and approaches.The consequences of changes in reactive oxygen species production and increased antioxidant activity in the symbiotum appear to be beneficial in many instances;but costs are also indicated.Unexplored questions are:1)to what extent do antioxidants originating from the fungal endophyte mediate host metabolism,and thereby control host responses to endophyte colonization;(2)what role do fungal,plant,or symbiotum produced reactive oxygen species and antioxidants have in determining symbiotic outcome between extremes of pathogenicity and mutualism;and(3)what role if any,do the production of reactive oxygen species and their antioxidant counterparts play in th展开更多
Fungal endophytes have significant effects on host performance including but not limited to changes in reproductive output,as well as,biotic and abiotic stress tolerance.The ultimate mechanisms for resistance to herbi...Fungal endophytes have significant effects on host performance including but not limited to changes in reproductive output,as well as,biotic and abiotic stress tolerance.The ultimate mechanisms for resistance to herbivory have been documented in a number of fungal-plant symbiota and involve the production of alkaloids by the fungus.Alkaloids have thus been defined as a currency responsible for increased host resistance to herbivory.We provide support for the hypothesis that another currency may be responsible for increased host tolerance to abiotic stress resulting from endophyte colonization;namely antioxidants.We report comparatively higher activity of antioxidants in endophyte colonized hosts resulting from abiotic stress and propose antioxidants are another currency via which mutualistic interactions between fungal endophytes and their hosts can occur.We recognize fungal endophyte interactions are diverse and complex and include antagonisms,commensalisms,and mutualisms.展开更多
Dear Editor,Achnatherum inebrians （Hance） Keng （drunken horse grass, DHG） is a toxic perennial bunchgrass, which is so-named because it is associated with the narcosis of livestock which graze on native grasslands...Dear Editor,Achnatherum inebrians （Hance） Keng （drunken horse grass, DHG） is a toxic perennial bunchgrass, which is so-named because it is associated with the narcosis of livestock which graze on native grasslands in the northwest of China [1]. DHG is distributed mainly throughout the harsh conditions of alpine or sub-alpine grasslands, and this species is usual- ly infected by the fungal endophyte Neotyphodium gan- suense [2], which apparently enhances its resistance to the abiotic and biotic stress [3].展开更多
基金supported by the National Basic Research Program of China(Grant No.2007CB108902)the National Natural Science Foundation of China(Grant No.30771531)+2 种基金the Program for a New Century of Excellent Talents in the University(Grant No.NCET-08-0256)Fundamental Research Funds for the Central Universities(Grant No.lzujky-2012-k01)the Scholarship Award for Excellent Doctoral Student granted by Ministry of Education(Grant No.224000-860008)
文摘Various cadmium （Cd） concentrations （0, 50, 100, 200 and 300 μmol L-1） affected Elymus dahuricus seed germination, seed- ling growth, antioxidative enzymes activities （AEA）, and amounts of malondialdehyde （MDA） and proline present. These in- fluences were determined for separate E. dahuricus cohorts known to be either infected （E＋） or non-infected （E-） by a Neo- typhodium endophyte. Under high Cd concentrations （100, 200 and 300 lamol L-l）, E＋ specimens showed a significantly （P〈0.05） higher germination rate and index, as well as higher values for shoot length, root length and dry biomass. However, the germination rate and index, root length and dry weight did not show a significant （P〈0.05） difference under the low Cd concentrations （0 and 50 μmol L^-1）. AEA and proline content increased, as did MDA content, in the E＋ （vs. E-） specimens under high Cd concentrations. There was no significant （P〉0.05） difference under low Cd concentrations. Endophyte infection was concluded to be of benefit to E. dahuricus exposed to high Cd concentrations.
基金supported by the National Basic Research Program of China (Grant No. 2007CB108902)the National Natural Science Foundation of China (Grant No. 30771531)+1 种基金Program for New Century Excellent Talents in University (Grant No. NCET-08-0256)the Fundamental Research Funds for the Central Universities (Grant No. LZUJBKY-2009-156)
文摘An evaluation was performed on the influence of mowing height (2.5,5.0 or 7.5 cm) and mowing frequency (weekly or fortnightly) on levels of ergot alkaloids (ergine and ergonovine) formed in drunken horse grass,Achnatherum inebrians,grown under greenhouse conditions.Samples were taken monthly and alkaloids were extracted and analyzed by reverse-phase HPLC.Alkaloid levels increased more or less linearly with plant age over the first four months following establishment.Levels were higher in samples cut fortnightly compared to those cut weekly,and were higher when plants were cut at a mowing height of 7.5 cm vs.2.5 cm.In most cases,the highest alkaloid levels observed were almost three times those of the lowest.If plant protection applications are developed for the endophytic fungus,Neotyphodium gansuense,it will be necessary to be aware of the potential role of plant husbandry practices (e.g.,defoliation frequency and intensity) for reducing or enhancing levels of plant alkaloids.Similar husbandry factors may affect alkaloid levels in other Neotyphodium-grass associations,which would be interesting for further study.
基金the support and funding of PGG Wrightson Seeds for research pertaining to the development and selection of endophyte strains for commercialization.
文摘Epichloae endophytes of family Clavicipitaceae(comprising genera Epichloëand Neotyphodium)are fungal symbionts of Pooideae grasses.The associations formed,range from mutually beneficial to antagonistic and the nature of this relationship is dependent upon the importance of vertical(via host seeds)versus horizontal(ascospore mediated)transmission of the fungus.These endophytes can enhance their hosts’survival through protection from abiotic and biotic stresses and can thus be utilized in an agricultural context.Animal-safe grass-endophyte associations that confer bio-protective properties for increased pasture persistence and productivity have been developed and commercialized.One of the crucial drivers underpinning the selection of epichloae strains for commercial development is endophyte derived bioactivity.The potential of next generation endophytes is determined by testing a number of attributes such as agronomic fitness,animal and food safety as well as compatibility with host plants of interest.Strategic research supports these activities by focusing on elucidating mechanisms of compatibility between host and fungal symbiont,as well as investigating other molecular drivers of symbiosis such as siderophore mediated iron-uptake,fungal signalling,fungal growth in host plants and fungal secondary metabolism.This review weaves together the different strands of multidisciplinary research aimed at ultimately exploiting epichloae endophytes for increased pasture performance.
文摘Reactive oxygen species are in all types of organisms from microbes to higher plants and animals.They are by-products of normal metabolism,such as photosynthesis and respiration,and are responsive to abiotic and biotic stress.Accumulating evidence suggests reactive oxygen species play a vital role in programmed cell death,stress responses,plant defense against pathogens and systemic stress signaling in conjunction with antioxidant production.Here,we propose that reactive oxygen species and antioxidants,as both universal and evolutionarily conserved,are likely to play important role(s)in symbiotic interactions.To support this hypothesis we review the root and foliar fungal endophyte literature specific to fungal-plant symbiotum production of reactive oxygen species and antioxidants in response to stress.These asymptomatic fungi can produce antioxidants in response to both biotic and abiotic stress when grown in culture as well as in planta.In addition,there is a growing but nascent literature reporting a significant impact of endophyte colonization on the antioxidant activity of colonized(E+)hosts when compared to uncolonized(E-)hosts,especially when exposed to stress.Here we summarize general patterns emerging from the growing literature specific to antioxidant activity of endophytes in colonized hosts and bring up possible future research questions and approaches.The consequences of changes in reactive oxygen species production and increased antioxidant activity in the symbiotum appear to be beneficial in many instances;but costs are also indicated.Unexplored questions are:1)to what extent do antioxidants originating from the fungal endophyte mediate host metabolism,and thereby control host responses to endophyte colonization;(2)what role do fungal,plant,or symbiotum produced reactive oxygen species and antioxidants have in determining symbiotic outcome between extremes of pathogenicity and mutualism;and(3)what role if any,do the production of reactive oxygen species and their antioxidant counterparts play in th
文摘Fungal endophytes have significant effects on host performance including but not limited to changes in reproductive output,as well as,biotic and abiotic stress tolerance.The ultimate mechanisms for resistance to herbivory have been documented in a number of fungal-plant symbiota and involve the production of alkaloids by the fungus.Alkaloids have thus been defined as a currency responsible for increased host resistance to herbivory.We provide support for the hypothesis that another currency may be responsible for increased host tolerance to abiotic stress resulting from endophyte colonization;namely antioxidants.We report comparatively higher activity of antioxidants in endophyte colonized hosts resulting from abiotic stress and propose antioxidants are another currency via which mutualistic interactions between fungal endophytes and their hosts can occur.We recognize fungal endophyte interactions are diverse and complex and include antagonisms,commensalisms,and mutualisms.
基金supported by the National Basic Research Program of China(2014CB138702)the Fundamental Research Funds for the Central Universities(Lzujbky-2014-75)the Program for Changjiang Scholars and Innovative Research Team in University(IRT13019)
文摘Dear Editor,Achnatherum inebrians （Hance） Keng （drunken horse grass, DHG） is a toxic perennial bunchgrass, which is so-named because it is associated with the narcosis of livestock which graze on native grasslands in the northwest of China [1]. DHG is distributed mainly throughout the harsh conditions of alpine or sub-alpine grasslands, and this species is usual- ly infected by the fungal endophyte Neotyphodium gan- suense [2], which apparently enhances its resistance to the abiotic and biotic stress [3].
