Endophytes are hypothesized to be transferred across the soil-plant continuum, suggesting both the transfers of endophytes from environment to plant and from plant to soil. To verify this hypothesis and to assess the ...Endophytes are hypothesized to be transferred across the soil-plant continuum, suggesting both the transfers of endophytes from environment to plant and from plant to soil. To verify this hypothesis and to assess the role of locality, we evaluated the similarity of microbial communities commonly found both in soils and endophytic communities in three arid regions, i.e. the Jornada LTER （Long Term Ecological Research） site in New Mexico, USA, and the research station of Jordan University of Science and Technology （JUST） and Khanasd research station in Badia region of Jordan. Rhizosphere and non-rhizosphere soils, leaves and seeds of Atriplex spp. were sampled. Diversity and distribution of bacteria and fungi across the soil-plant continuums were assessed by tag-encoded FLX amplicon pyrosequencing and sequence alignment. Of the total bacterial OTUs （operational taxonomic units）, 0.17% in Khanasri research station, 0.16% in research station of JUST, and 0.42% in Jornada LTER site were commonly found across all the plant and soil compartments. The same was true for fungi in two regions, i.e. 1.56% in research station of JUST and 0.86% in Jornada LTER site. However, in Khanasri research station, 12.08% of total fungi OTUs were found in at least one soil compartment and one plant compartment. Putative Arthrobacter, Sporosarcina, Cladosporium and members of Proteobacteria and Actinobacteria were found across all the soil-plant continuums. Ascomycota, mainly including Didymellaceae, Pleosporaceae and Davidiellaceae were present across all the soil-plant continuums. Microbial communities in two regions of Jordan were similar to each other, but both of them were different from the Jornada LTER site of USA. SIMPER （similarity percentage） analysis of bacterial and fungal taxa for both soil and endophyte communities revealed that dissimilarities of two bacterial genera （Arthrobacter and Sporosarcina） and two fungal genera （Cladosporium and Alternaria） are very high, so they play key roles in the soil-plant continuums. A weighed Pearson correlation analysis for the specific bacterial OTUs in the soil-plant continuums only showed high similarity between the two regions of Jordan. However, fungal groups showed higher similarities among all regions. This research supports the hypothesis of continuity of certain bacterial and fungal communities across the soil-plant continuums, and also explores the influences of plant species and geographic specificity on diversity and distribution of bacteria and fungi.展开更多
Phytophthora species are particularly aggressive plant pathogens and are often associated with the decline of many tree species, including oak and beech. Several fungi and bacteria species are known as potential antag...Phytophthora species are particularly aggressive plant pathogens and are often associated with the decline of many tree species, including oak and beech. Several fungi and bacteria species are known as potential antagonists usable as biological control agents. Phosphonate （H3PO3）, commonly branded as phosphite, has also been used in the past years to protect trees against invasive Phytophthora spp.. This study aimed at comparing the effects of selected antagonist microorganisms and phosphonate, when applied by microinjection or leaf treatment. Antagonistic species were first selected for their high inhibitory activity against problematic Phytophthora species, such as Phytophthora cactorum, P. quercina and P. plurivora attacking Quercus robur and Fagus sylvatica in Polish forests. Three endophytic species Trichoderma atroviride （two strains）, T. harzianum and Bacillus amyloliquefaciens showed a high control activity, and their efficacy was then assessed in comparison with a phosphonate treatment. Two application methods were experimented in this study： injection of a solution of spores or phosphonate into the sap vessels of beech or a foliar treatment on oak. Phosphonate and two strains of Trichoderma significantly reduced the necrotic area on oak leaves inoculated with P. plurivora and one strain of T. atroviride significantly reduced necrotic areas on beech branches. These results are therefore promising of a novel way to control Phytophthora spp. in forest stands and nurseries.展开更多
文摘Endophytes are hypothesized to be transferred across the soil-plant continuum, suggesting both the transfers of endophytes from environment to plant and from plant to soil. To verify this hypothesis and to assess the role of locality, we evaluated the similarity of microbial communities commonly found both in soils and endophytic communities in three arid regions, i.e. the Jornada LTER （Long Term Ecological Research） site in New Mexico, USA, and the research station of Jordan University of Science and Technology （JUST） and Khanasd research station in Badia region of Jordan. Rhizosphere and non-rhizosphere soils, leaves and seeds of Atriplex spp. were sampled. Diversity and distribution of bacteria and fungi across the soil-plant continuums were assessed by tag-encoded FLX amplicon pyrosequencing and sequence alignment. Of the total bacterial OTUs （operational taxonomic units）, 0.17% in Khanasri research station, 0.16% in research station of JUST, and 0.42% in Jornada LTER site were commonly found across all the plant and soil compartments. The same was true for fungi in two regions, i.e. 1.56% in research station of JUST and 0.86% in Jornada LTER site. However, in Khanasri research station, 12.08% of total fungi OTUs were found in at least one soil compartment and one plant compartment. Putative Arthrobacter, Sporosarcina, Cladosporium and members of Proteobacteria and Actinobacteria were found across all the soil-plant continuums. Ascomycota, mainly including Didymellaceae, Pleosporaceae and Davidiellaceae were present across all the soil-plant continuums. Microbial communities in two regions of Jordan were similar to each other, but both of them were different from the Jornada LTER site of USA. SIMPER （similarity percentage） analysis of bacterial and fungal taxa for both soil and endophyte communities revealed that dissimilarities of two bacterial genera （Arthrobacter and Sporosarcina） and two fungal genera （Cladosporium and Alternaria） are very high, so they play key roles in the soil-plant continuums. A weighed Pearson correlation analysis for the specific bacterial OTUs in the soil-plant continuums only showed high similarity between the two regions of Jordan. However, fungal groups showed higher similarities among all regions. This research supports the hypothesis of continuity of certain bacterial and fungal communities across the soil-plant continuums, and also explores the influences of plant species and geographic specificity on diversity and distribution of bacteria and fungi.
文摘Phytophthora species are particularly aggressive plant pathogens and are often associated with the decline of many tree species, including oak and beech. Several fungi and bacteria species are known as potential antagonists usable as biological control agents. Phosphonate （H3PO3）, commonly branded as phosphite, has also been used in the past years to protect trees against invasive Phytophthora spp.. This study aimed at comparing the effects of selected antagonist microorganisms and phosphonate, when applied by microinjection or leaf treatment. Antagonistic species were first selected for their high inhibitory activity against problematic Phytophthora species, such as Phytophthora cactorum, P. quercina and P. plurivora attacking Quercus robur and Fagus sylvatica in Polish forests. Three endophytic species Trichoderma atroviride （two strains）, T. harzianum and Bacillus amyloliquefaciens showed a high control activity, and their efficacy was then assessed in comparison with a phosphonate treatment. Two application methods were experimented in this study： injection of a solution of spores or phosphonate into the sap vessels of beech or a foliar treatment on oak. Phosphonate and two strains of Trichoderma significantly reduced the necrotic area on oak leaves inoculated with P. plurivora and one strain of T. atroviride significantly reduced necrotic areas on beech branches. These results are therefore promising of a novel way to control Phytophthora spp. in forest stands and nurseries.
