Characterization of cadmium-resistant endophytic fungi from Salix variegata Franch. in Three Gorges Reservoir Region, China

Abstract

The community and Cd-resistance of endophytic fungi from roots of Salix variegata Franch. collected from the water-level-fluctuation zone of Three Gorges Reservoir Region, China, were investigated. A total of 53 strains were isolated and identified to 13 morphotaxa, in which Chromosporium, Fusarium and Gonatobotrys were dominant genera. Among them, 27 isolates were selected to measure their resistance to 0.02 mg ml(-1) Cd(2+) and 11 were growth stimulated (Tolerance index>100%). Of these active isolates, four dark septate endophyte (DSE) isolates (Paraphaeosphaeria sp. SR46, Pyrenochaeta sp. SR35, Rhizopycnis vagum SR37 and R. vagum SR44) were further tested for minimum inhibitory concentrations (MICs) against Cd and SR46 was found to be the most tolerant isolate with MIC of 0.39 mg ml(-1). Additionally, the maximum uptake values of these DSEs ranged from 3.01 to 7.89 mg g(-1), but there was no significant correlation between metal uptake with fungal biomass and metal tolerance. Subsequently, a pot experiment was conducted for investigating the impact of SR46 on corn seedlings in Cd-enriched soil. The results obtained suggested that SR46 reduced the Cd bioaccumulation of plant under low (100 mg kg(-1)) Cd stress and enhanced the Cd translocation from root zone to aerial parts under high (200 mg kg(-1)) Cd stress. Besides, it promoted plant growth without Cd stress. These findings indicated S. variegata harbors an endophytic fungal flora showing a high genetic diversity as well as a high level of metal resistance to Cd that has potential values in cadmium cycling and restoration of plant, soil and water system.

Endophytic fungal communities of Polygonum acuminatum and Aeschynomene fluminensis are influenced by soil mercury contamination

“…The community of endophytic fungi in areas contaminated by heavy metals has been evaluated to obtain tolerant strains for use in bioremediation programs [15,16,20,63,64]. However, the effects of toxic metals on the structure and function of the endophytic fungal communities have been poorly investigated.…”

“…Although many endophytic Fusarium isolates are representative of host communities of areas contaminated with heavy metals [17,20,57,64], the species F . oxysporum colonizes only plants from places that are free from contamination with heavy metals [29,45,73,80,81].…”

“…While the P92 strain is resistant to Pb +2 and sensitive to other metals (Zn +2 and Cd +2 ), A49 showed sensitivity only for Pb +2 and did not grow in the presence of Zn +2 and Pb +2 (S3 Table). Results obtained by Li [57] Shen [15], An [64] and Li [94] show that heavy metal tolerance often varies between strains of the same species. This plasticity seems to equate with multigenic control of metal resistance [95].…”

“…The occurrence endophytic fungal strains tolerant to heavy metals may be an important attribute for plant survival in areas impacted by heavy metals [99]. Therefore, endophytic fungi are reported to increase plant biomass in systems contaminated with toxic metals [15,54,57,63,64,69]. …”

Potencial biorremediador do fungo endofítico Mucor sp. isolado da macrófita aquática Eichornia crassipes (Mart)

“…Resultados similares foram apresentados por An et al (2015) cultivar Calabash Rouge, na raíz e parte aérea foi confirmada pelo re-isolamento do endófito das plantas inoculadas após o período em hidroponia, atrelando os resultados obtidos a presença do fungo endofítico Mucor sp.…”